Glossary of definitions and abbreviations

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A (back to search)

Acceptable daily intake	Estimated maximum amount of an agent, expressed on a body mass basis, to which individuals in a (sub)population may be exposed daily over their lifetimes without appreciable health risk [IPCS Risk Assessment Terminology].
Acceptable risk	This is a risk management term. The acceptability of the risk depends on scientific data, social, economic, and political factors, and the perceived benefits arising from exposure to an agent [IPCS Risk Assessment Terminology].
Active substance	A substance or a micro-organism that has an action on or against harmful organisms [Biocidal Products Regulation, 528/2012].
Activity involving chemical agents	Any work in which chemical agents are used, or are intended to be used, in any process, including production, handling, storage, transport or disposal and treatment, or which result from such work [Chemical Agents Directive, 98/24/EC].
Actors in the supply chain	All manufacturers and/or importers and/or downstream users in a supply chain [REACH Regulation, 1907/2006].
Acute aquatic toxicity	The intrinsic property of a substance to be injurious to an aquatic organism in a short-term aquatic exposure to that substance [CLP Regulation, 1272/2008]. See also: short-term (acute) hazard. Cf: chronic aquatic toxicity.
Acute toxicity	Those adverse effects occurring following oral or dermal administration of a single dose of a substance or a mixture, or multiple doses given within 24 hours, or an inhalation exposure of 4 hours [CLP Regulation, 1272/2008].
Acute toxicity estimate	This is the acute toxicity value for a substance, used in calculating the toxicity of a mixture. The ATE is usually based on animal testing: (i) older testing that gives an LD50 or LC50 value, which would be the same as the ATE; (ii) more recent testing that gives a range of value (based on toxic effects, rather than mortality).
Additive	A substance that has been intentionally added to stabilise the substance (in other areas an additive can also have other functions, eg pH-regulator or colouring agent). However, in the REACH regulation an additive is a stabilising agent [REACH Substance ID].
ADR	The European Agreement Concerning the International Carriage of Dangerous Goods by Road (as amended).
Adverse effect	A change in the morphology, physiology, growth, development, reproduction, or life span of an organism, system, or (sub) population that results in an impairment of functional capacity, an impairment of the capacity to compensate for additional stress, or an increase in susceptibility to other influences [IPCS Risk Assessment Terminology].
Adverse effects on sexual function and fertility	Any effect of substances that has the potential to interfere with sexual function and fertility. This includes, but is not limited to, alterations to the female and male reproductive system, adverse effects on onset of puberty, gamete production and transport, reproductive cycle normality, sexual behaviour, fertility, parturition, pregnancy outcomes, premature reproductive senescence, or modifications in other functions that are dependent on the integrity of the reproductive systems [CLP Regulation, 1272/2008]. See: reproductive toxicity.
Aerosols, Aerosol dispensers	Aerosol dispensers, are any non-refillable receptacles made of metal, glass or plastics and containing a gas compressed, liquefied or dissolved under pressure, with or without a liquid, paste or powder, and fitted with a release device allowing the contents to be ejected as solid or liquid particles in suspension in a gas, as a foam, paste or powder or in a liquid state or in a gaseous state [CLP Regulation, 1272/2008].
The Agency (ECHA)	The European Chemicals Agency established by Regulation (EC) No 1907/2006 [CLP Regulation, 1272/2008 and REACH Regulation, 1907/2006].
Agglomerate	A collection of weakly bound particles or aggregates where the resulting external surface area is similar to the sum of the surface areas of the individual components [Nanomaterial Definition, 2011/696/EU]. See also: aggregate.
Aggregate	A particle comprising of strongly bound or fused particles [Nanomaterial Definition, 2011/696/EU]. See also: agglomerate.
Alloy	A metallic material, homogeneous on a macroscopic scale, consisting of two or more elements so combined that they cannot be readily separated by mechanical means; (alloys are considered to be mixtures for the purposes of this Regulation) [CLP Regulation, 1272/2008 and REACH Regulation, 1907/2006].
Antioxidant	Substance that retards oxidation, rancidity, deterioration, and gum formation; used to maintain the quality, integrity, and safety of finished products by inhibiting the oxidative degradation of the ingredients in the formulation. Saturated polymers have greater oxidative stability and require relatively low concentrations of stabilizers [REACH Use Descriptors (R.12)].
Antistatic agent	Any substance that prevents or reduces the tendency of a material to accumulate a static charge or alters the electrical properties of materials by reducing their tendency to acquire an electrical charge [REACH Use Descriptors (R.12)].
Article	An object which during production is given a special shape, surface or design which determines its function to a greater degree than does its chemical composition [CLP Regulation 1272/2008 and REACH Regulation 1907/2006]. See also: producer of an article.
Article category (AC)	Element of the use descriptor system characterising the type of article in which a substance is contained [ECHA Guide R.20]. [ACs are part of the use descriptor system (UDS) used in the Chemical Safety Assessment for the exposure assessment of a substance for particular uses].
Asphyxiant	Simple asphyxiant means a substance or mixture that displaces oxygen in the ambient atmosphere, and can thus cause oxygen deprivation in those who are exposed, leading to unconsciousness and death. Cf chemical asphyxiants, whcih cause suffocation by either preventing the uptake of oxygen in the blood or by preventing the normal oxygen transfer from the blood to the tissues or within the cell itself [US Hazard Classification Guidance]
Aspiration	The entry of a liquid or solid substance or mixture directly through the oral or nasal cavity, or indirectly from vomiting, into the trachea and lower respiratory system. Although the definition of aspiration […] includes the entry of solids into the respiratory system, classification […] is intended to apply to liquid substances and mixtures only [CLP Regulation 1272/2008].
Aspiration hazard	The propensity of substances and mixtures, usually hydrocarbons or other low-viscosity products, to be aspirated into the lung, either directly or following swallowing and vomiting, with the potential to cause lung damage.
Assessment factor (AF)	Numerical adjustment used to extrapolate from experimentally determined (dose–response) relationships to estimate the agent exposure below which an adverse effect is not likely to occur [IPCS Risk Assessment Terminology]. [Th AF is a ‘safety’ or ‘uncertainty’ factor typically used to account for extrapolation of parameters (eg NOAEL) from animal studies to humans].
ATE	See: acute toxicity estimate.
ATP	Adaptation to technical progress. An update to legislation, eg the CLP Regulation is updated with new harmonised classifications through ATPs.
Authorisation	The process by which a manufacturer, importer or downstream user can place a substance on the market for a use or use it himself if that substance is included in the Authorisation list [REACH Regulation, Annex XIV], unless an exemption applies. See also: Susbstance of very high concern. More information: Authorisation under REACH.
Auto-ignition temperature	The lowest temperature at which the test substance will ignite when mixed with air under the conditions defined in the test method [Test Method Regulation, 440/2008]. The test method is described for liquids and gases. Cf: self-ignition temperature for solids.
Availability of a substance	The extent to which this substance becomes a soluble or disaggregate species. For metal availability, the extent to which the metal ion portion of a metal (M°) compound can disaggregate from the rest of the compound (molecule) [CLP Regulation, 1272/2008].

B (back to search)

BCF	Bioconcentration Factor. See: bioconcentration.
Benchmark dose (BMD)	The BMD concept involves fitting a mathematical model to dose–response data. The BMD is defined as the dose causing a predetermined change in response [eg a 10% increase in tumours upon lifetime exposure, after correction for spontaneous incidence] [ECHA Guide R.20].
Bioaccumulation	The net result of uptake, transformation and elimination of a substance in an organism due to all routes of exposure (i.e. air, water, sediment/soil and food) [CLP Regulation, 1272/2008]. Cf: bioconcentration, biomagnification.
Bioavailability or biological availability	The extent to which a substance is taken up by an organism, and distributed to an area within the organism. It is dependent upon physico-chemical properties of the substance, anatomy and physiology of the organism, pharmacokinetics, and route of exposure. Availability is not a prerequisite for bioavailability [CLP Regulation, 1272/2008].
Biocidal product	(a) any substance or mixture, in the form in which it is supplied to the user, consisting of, containing or generating one or more active substances, with the intention of destroying, deterring, rendering harmless, preventing the action of, or otherwise exerting a controlling effect on, any harmful organism by any means other than mere physical or mechanical action, (b) any substance or mixture, generated from substances or mixtures which do not themselves fall under [(a)], to be used with the intention of destroying, deterring, rendering harmless, preventing the action of, or otherwise exerting a controlling effect on, any harmful organism by any means other than mere physical or mechanical action. A treated article that has a primary biocidal function shall be considered a biocidal product [Biocidal Product Regulation, 528/2012].
Bioconcentration	The net result of uptake, transformation and elimination of a substance in an organism due to waterborne exposure [CLP Regulation, 1272/2008]. Cf: bioaccumulation, biomagnification.
Bioconcentration factor (BCF)	The ratio between the concentration of the chemical in biota and the concentration in the surrounding medium, here water, at steady state. BCF can be measured experimentally directly under steady state conditions or calculated by the ration of the first-order uptake and elimination rate constants, a method that does not require equilibrium conditions [GHS Rev 8, 2019]. [For organic substances the potential for bioaccumulation is normally estimated from the octanol–water partition coefficient (log Kow), with a value of ≥ 4 indicating a substance with a potential to bioconcentrate. An experimentally determined BCF provides a better measure, with a value ≥ 500 is indicative of the potential to bioconcentrate for classification purposes].
Biodegradation	See: rapidly biodegradable.
Biological limit value (BLV)	The limit of the concentration in the appropriate biological medium of the relevant agent, its metabolite, or an indicator of effect [Chemical Agents Directive, 98/24/EC].
Biomagnification factor (BMF)	Biomagnification refers to accumulation via the food chain. It may be defined as an increase in the (fat-adjusted) internal concentration of a substance in organisms at succeeding trophic levels in a food chain. The biomagnification potential can be expressed as either: • a trophic magnification factor (TMF; concentration increase in organisms with an increase of one trophic level); or • a biomagnification factor (BMF; ratio of the concentration in the predator and the concentration in the prey) [ECHA Guidance Chapter R.7c].
Bleaching agent	A material that lightens or whitens a substrate through chemical reaction. The bleaching reactions usually involve oxidative or reductive processes that degrade colour systems. Bleaching and decolourization can occur by destroying one or more of the double bonds in the conjugated chain, by cleaving the conjugated chain, or by oxidation of one of the other moieties in the conjugated chain [REACH Use Descriptors (R.12)].
BLV	Biological limit values, as established by the Chemical Agents Directive, 98/24/EC.
BSI	British Standards Institute. BSI is appointed by the UK Government as the national standards body, and represents UK interests at the International Organization for Standardization (ISO), and the European Standards Organizations (CEN, CENELEC and ETSI).
BOELV	Binding Occupational Exposure Limits, as established by the Chemical Agents Directive, 98/24/EC.
Boiling Point	See: initial boiling point.

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Candidate List	The Candidate List of Substances of Very High Concern for Authorisation. [Identified SVHCs are included in the Candidate List. Inclusion obliges suppliers to: (i) supply a safety data sheet (ii) communicating on safe use (iii) respond to consumer requests within 45 days and (iv) notify ECHA if the article they produce contains an SVHC in quantities above one tonne per producer/ importer per year and if the substance is present in those articles above a concentration of 0.1wt%. More information: Candidate List of SVHCs.
Carcinogen	A substance or mixture which induce cancer or increase its incidence [GHS Rev 8, 2019]. See also: carcinogenicity.
Carcinogenicity	The process of forming an invasive cancer cell from a normal cell. This is a multi-step process characterised by successive genetic mutations cause by carcinogens. See also: carcinogen.
CAS numbers	Chemical Abstract Service Numbers. [CAS issue product identifiers for new substances at the request of manufacturers, and CAS numbers are the most widely used international identifier (eg aspirin, CAS 50-78-2). However, many substances have multiple CAS numbers, cf EC numbers that are unique but applicable only in the EU].
Catalyst	Substances that increase the efficiency of a chemical reaction, ie the reaction needs less energy. Catalysts take part in the reaction but are not consumed during the process [REACH Use Descriptors (R.12)].
CEN	Comité Européen de Normalisation (European Committee for Standardization) [an association that brings together the National Standardization Bodies of 34 European countries, such as the BSI in the UK].
Chemical agent	Any chemical element or compound, on its own or admixed, as it occurs in the natural state or as produced, used or released, including release as waste, by any work activity, whether or not produced intentionally and whether or not placed on the market [Chemical Agents Directive, 98/24/EC].
Chemically unstable gas	A flammable gas that is able to react explosively even in the absence of air or oxygen [CLP Regulation, 1272/2008].
Chemical Safety Assessment (CSA)	A chemical safety assessment of a substance shall include the following steps: (a) human health hazard assessment; (b) physicochemical hazard assessment; (c) environmental hazard assessment; (d) persistent, bioaccumulative and toxic (PBT) and very persistent and very bioaccumulative (vPvB) assessment. [If the substance is classified as hazardous (with a few exceptions, such as gases under pressure, or narcotic effects)], or is assessed to be a PBT or vPvB, the chemical safety assessment shall include the following additional steps: (a) exposure assessment including the generation of exposure scenario(s) (or the identification of relevant use and exposure categories if appropriate) and exposure estimation; (b) risk characterisation. [REACH Regulation, 1907/2006]. See also: risk assessment.
Chemical Safety Report (CSR)	The report from the Chemical Safety Assessment.
Chesar	CHEmical Safety Assessment and Reporting tool) is a web application developed by ECHA to support registrants – carrying out their chemical safety assessment and generating their exposure scenario for communication in the Annex of the extended Safety Data Sheet).
Chronic aquatic toxicity	The intrinsic property of a substance to cause adverse effects to aquatic organisms during aquatic exposures which are determined in relation to the life-cycle of the organism [CLP Regulation 1272/2008]. See also: long-term (chronic) hazard. Cf: acute aquatic toxicity.
Cleaning	The process by which an undesirable deposit is dislodged from a substrate or from within a substrate and brought into a state of solution or dispersion [Detergents Regulation, 648/2004].
Cleaning agent	Substance or material used to remove dirt or impurities from surfaces; acts to loosen and remove dirt and grease from surfaces [REACH Use Descriptors (R.12)]. See also: detergent.
CLP Regulation	Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures (as amended).
CMRs	Substances meeting the criteria for classification in the following hazard classes: Carc 1A or 1B, Muta 1A or 1B, Repr 1A or 1B. These substances are expected to cause cancer, transmissible genetic defects, or reproductive or developmental effects in humans. See: substances of very high concern (SVHC).
COMAH Regulations	Control of Major Accident Hazards Regulations (COMAH), 2015. The UK implementation of the EU Seveso III Directive, requiring industry to take measures to prevent major accidents involving dangerous substances, and limit the consequences to people and the environment of any major accidents which do occur.
Combustion	Energy releasing (exothermic) oxidation reaction of (or with) combustible substances/mixtures/solid materials [GHS Rev 8, 2019].
Combustible dust	Finely divided solid particles of a substance or mixture that are liable to catch fire or explode on ignition when dispersed in air or other oxidizing media [GHS Rev 8, 2019].
Competent authority	The authority or authorities or bodies established by the Member States to carry out the obligations arising from this Regulation [CLP Regulation, 1272/2008 and REACH Regulation, 1907/2006].
Component	Substance intentionally added to form a mixture [REACH Substance ID]. See also: constituent.
Concentration limit	A threshold of any classified impurity, additive or individual constituent in a substance or in a mixture that may trigger classification of the substance or the mixture, respectively [CLP Regulation 1272/2008]. These values are the minimum concentrations for a substance which trigger the classification of a mixture if exceeded by the individual concentration or the sum of concentrations of relevant substances; they are set out in parts 2 to 5 of Annex I to CLP for those hazard classes where they apply. Specific cut-off values are available for certain substances. Compare: cut-off value. See also: generic concentration limit. See also: specific concentration limit.
Conditions of use	Include the operational conditions (OC) and risk management measures (RMM) as described in an exposure scenario [ECHA Guide R.20].
Constituent	Any single species present in a substance that can be characterised by its unique chemical identity [REACH Substance ID]. See also: main constituent. See also: component.
Consumer automatic dishwasher detergent	A detergent placed on the market for use in automatic dishwashers by non- professionals.
Consumer laundry detergent	A detergent for laundry placed on the market for use by non-professionals, including in public laundrettes [Detergents Regulation, 648/2004].
COPR	The Control of Pesticides (Amendment) Regulations; Statutory Instrument 1997 No. 188; 30th January 1997 [UK biocidal products regulations].
Corrosive to metals	A substance or a mixture that is corrosive to metals means a substance or a mixture which by chemical action will materially damage, or even destroy, metals [CLP Regulation 1272/2008].
Cosmetic product	Any substance or mixture intended to be placed in contact with the external parts of the human body (epidermis, hair system, nails, lips and external genital organs) or with the teeth and the mucous membranes of the oral cavity with a view exclusively or mainly to cleaning them, perfuming them, changing their appearance, protecting them, keeping them in good condition or correcting body odours [Cosmetic Products Regulation, 1223/2009].
COSHH Regulations	UK Control of Substances Hazardous to Health (COSHH) Regulations (2002, as amended) requires employers to undertake workplace risk assessment, and provide risk management methods to reduce harm to worker’s health. It includes UK occupational exposure limits in the EH40/2005 publication.
CSA	See: Chemical Safety Assessment.
CSR	Chemical Safety Report. See: Chemical Safety Assessment.
Cut-off value	A threshold of any classified impurity, additive or individual constituent in a substance or in a mixture, above which threshold these shall be taken into account for determining if the substance or the mixture, respectively, shall be classified [CLP Regulation 1272/2008]. These values are minimum concentrations for a substance to be taken into account for classification purposes, ie it contributes to the mixture classification even if it does not trigger classification of the mixture directly. Generic cut-off values are used for most substances. Specific cut-off values are available for certain substances. Compare: concentration limit.

D (back to search)

DEFRA	Department for Environment Food and Rural Affairs
Degradation	The decomposition of organic molecules to smaller molecules and eventually to carbon dioxide, water and salts [CLP Regulation 1272/2008].
Detergent	Any substance or mixture containing soaps and/or other surfactants intended for washing and cleaning processes. Detergents may be in any form (liquid, powder, paste, bar, cake, moulded piece, shape, etc.) and marketed for or used in household, or institutional or industrial purposes. Other products to be considered as detergents are: (a) ‘Auxiliary washing mixture’, intended for soaking (pre-washing), rinsing or bleaching clothes, household linen, etc.; (b) ‘Laundry fabric-softener’, intended to modify the feel of fabrics in processes which are to complement the washing of fabrics; (c) ‘Cleaning mixture’, intended for domestic all purposes cleaners and/or other cleaning of surfaces (e.g.: materials, products, machinery, mechanical appliances, means of transport and associated equipment, instruments, apparatus, etc.); (d) ‘Other cleaning and washing mixtures’, intended for any other washing and cleaning processes. [Detergents Regulation, 648/2004].
Developmental toxicity	Developmental toxicity includes, in its widest sense, any effect which interferes with normal development of the conceptus, either before or after birth, and resulting from exposure of either parent prior to conception, or exposure of the developing offspring during prenatal development, or postnatally, to the time of sexual maturation. However, it is considered that classification under the heading of developmental toxicity is primarily intended to provide a hazard warning for pregnant women, and for men and women of reproductive capacity. Therefore, for pragmatic purposes of classification, developmental toxicity essentially means adverse effects induced during pregnancy, or as a result of parental exposure. These effects can be manifested at any point in the life span of the organism. The major manifestations of developmental toxicity include (1) death of the developing organism, (2) structural abnormality, (3) altered growth, and (4) functional deficiency [CLP Regulation, 1272/2008]. See: reproductive toxicity.
Differentiation	The distinction within hazard classes depending on the route of exposure or the nature of the effects [CLP Regulation 1272/2008]. [Usually the differentiation is the Hazard Category, eg Acute Toxicity, Category 4, but for some hazard classes called Division, or Type]
Disinfectant	A product that reduces the number of microorganisms in or on an inanimate matrix, achieved by the irreversible action of a product, to a level judged to be appropriate for a defined purpose [BPR Guidance].
Distributor	Any natural or legal person established within the Community, including a retailer, who only stores and places on the market a substance, on its own or in a mixture, for third parties [CLP Regulation 1272/2008 and REACH Regulation 1907/2006].
DMEL	Derived minimum effect level. [A key parameter from the Chemical Safety Assessment giving an acceptable risk level for human exposure, particularly where there is no minimum threshold for the effect, such as most carcinogens].
DNEL	Derived no effect level. [A key parameter from the Chemical Safety Assessment giving a ‘safe’ level for human exposure, usually derived from repeated-dose toxicity studies].
Dose–response relationship	Relationship between the amount of an agent administered to, taken up by, or absorbed by an organism, system, or (sub)population and the change developed in that organism, system, or (sub)population in reaction to the agent [IPCS Risk Assessment Terminology].
Downstream user	Any natural or legal person established within the Community, other than the manufacturer or the importer, who uses a substance, either on its own or in a mixture, in the course of his industrial or professional activities. A distributor or a consumer is not a downstream user. A re-importer exempted pursuant to Article 2(7)(c) of Regulation (EC) No 1907/2006 shall be regarded as a downstream user [CLP Regulation 1272/2008 and REACH Regulation 1907/2006].
Downstream User Import Notification (DUIN)	Transitional provision in UK REACH for GB-based downstream users and distributors under EU REACH that they wish to continue importing substances into GB from the EU. This notification must be made withing the first 300 days of the date of exit [ie 27 October 2021; UK HSE Glossary]
Dye	Substance used to impart colour to other materials or mixtures. Molecularly dispersed within a liquid, transferred to a material, and bound to that material through intermolecular forces. Typically an organic substance, although exceptions do exist. A dye requires some degree of solubility that allows it diffuse into the polymeric matrix of a textile fibre [REACH Use Descriptors (R.12)]. See also: pigment.

E (back to search)

ECx [eg EC50]	The effect concentration associated with x% response [CLP Regulation, 1272/2008].
EC Number	The official number of the substance within the European Union, compiled from previous inventories: EINECS, ELINCS, and NLP. The EC number is a seven-digit system of the type XXX-XXX-X which starts at 200-001-8 (EINECS), at 400-010-9 (ELINCS) and at 500-001-0 (NLP).
ECHA	The European Chemicals Agency established by Regulation (EC) No 1907/2006 [ie the REACH Regulation].
ED	See: endocrine disruptor.
EINECS	European Inventory of Existing Commercial Chemical Substances [an official list that contains EC numbers for certain substances].
ELINCS	European List of Notified Substances [an official list that contains EC numbers for certain substances].
Endocrine disruptor	An exogenous substance or mixture that alters functions(s) of the endocrine system and consequently causes adverse health effects in an intact organism, or its progeny, or (sub)populations.’ [World Health Organisation (WHO/IPCS)]. More information: Endocrine disruption. [A substance that causes adverse effects in organisms via interference with its hormonal system].
Endpoint	Denote physicochemical properties (such as melting point or water solubility), and also properties that are subject to hazard classification (such as flammable liquid, skin irritation, or acute aquatic toxicity) that are the subject of a test study or other investigation, for a REACH registration or other regulatory purpose.
Environmental release catego-ries (ERC)	A pre-set combination of life cycle stage, distribution of emission sources, fate of substance in the technical process, level of containment, default emission factors (uncontrolled) and presence of waste water treatment, typical for an identified use [ECHA Guide R.20]. [ERCs are part of the use descriptor system (UDS) used in the Chemical Safety Assessment for the calculation of environmental concentrations of a substance for particular uses].
ERC	See: environmental release category.
ES	See: exposure scenario.
Evaluation	The process in REACH whereby ECHA checks if registrations are in compliance, the quality of the registration dossier and any testing proposals, and whether the substance as used poses a risk to human health or the environment. Once the evaluation is done, registrants may be required to submit further information.
Explosible dust atmosphere	A dispersion of a combustible dust in air which after ignition results in a self-sustaining flame propagation [GHS Rev 8, 2019].
Ex vivo	Latin for ‘outside of the living body.’ Refers to testing that uses organs, cells, or tissue are taken from a living body. Regarded as more humane alternative to intact animal testing. See: in vitro. See: in vivo.
Explosive article	An article containing one or more explosive substances or mixtures [CLP Regulation, 1272/2008].
Explosive substance or mixture	A solid or liquid substance or mixture-of-substances which is in itself capable by chemical reaction of producing gas at such a temperature and pressure and at such a speed as to cause damage to the surroundings. Pyrotechnic substances are included even when they do not evolve gases [CLP Regulation, 1272/2008]. See also: intentional explosive. See also: unstable explosive.
Exposure estimation	Quantification of exposure related to the operational conditions and risk management measures as described in an exposure scenario. Exposure scenario building and the related exposure estimate together build the exposure assessment [ECHA Guide R.20].
Exposure assessment	Exposure assessment aims to make a quantitative or qualitative estimate of the dose or concentration of the substance to which humans and the environment are or may be exposed. Exposure assessment under REACH consists of two steps: (i) development of exposure scenarios; and (ii) exposure estimation; which have to be iterated until it can be concluded that the resulting Exposure Scenarios would ensure adequate control of risks upon implementation [ECHA Guide R.20]. See also: chemical safety assessment.
Exposure scenario (ES)	The set of conditions, including operational conditions and risk management measures, that describe how the substance is manufactured or used during its life-cycle and how the manufacturer or importer controls, or recommends downstream users to control, exposures of humans and the environment. These exposure scenarios may cover one specific process or use or several processes or uses as appropriate [REACH Regulation, 1907/2006]. The ES in the context of the CSR and in context of the SDS have a different purpose, and thus the content may differ. For example, the ES in the CSR will contain justifications and comments, the ES in the SDS annex will not. However the CSR chapters and their content must be consistent with the content of ES in the SDS [ECHA Guide R.20]. See: use and exposure category. See also: final exposure scenario. See also: generic exposure scenario. See also: initial exposure scenario.
Eye irritation	The production of changes in the eye following the application of test substance to the anterior surface of the eye, which are fully reversible within 21 days of application [CLP Regulation, 1272/2008]. See also: serious eye damage.

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Fate	Pattern of distribution of an agent, its derivatives, or metabolites in an organism, system, compartment, or (sub)population of concern as a result of transport, partitioning, transformation, or degradation [IPCS Risk Assessment Terminology].
Final exposure scenario	The final exposure scenario (ES) is developed from the initial ES, and describes the operational conditions and risk management measures suitable to the control risk in an identified use (or a group of uses) of a dangerous substance [ECHA Guide R.20].
Flammable gas	A gas or gas mixture having a flammable range with air at 20 °C and a standard pressure of 101.3 kPa [CLP Regulation, 1272/2008]. See also: chemically unstable gas.
Flammable liquid	A liquid having a flash point of not more than 60 °C [CLP Regulation, 1272/2008].
Flammable liquid	A liquid having a flash point of not more than 93 °C [GHS Rev 8, 2019].
Flammable solid	A flammable solid means a solid which is readily combustible, or may cause or contribute to fire through friction [CLP Regulation, 1272/2008]. See also: readily combustible solid.
Flash point	The lowest temperature (corrected to a standard pressure of 101.3 kPa) at which the application of an ignition sources causes the vapours of a liquid to ignite under specified test conditions [GHS Rev 8, 2019]. See: flammable liquid.
Form placed on the market	This is the form or physical state in which a substance or mixture is placed on the market, which can affect its hazard classification. Common examples are particle size (eg granules vs fine powder), which can affect the physico-chemical and toxicological hazards, or viscosity (gel vs mobile liquid), which can affect classification as a flammable liquid.
Fragrance	Chemical substances used to impart control odours or impart pleasing odours. Fragrance compounds are molecules that stimulate the human olfactory chemical senses [REACH Use Descriptors (R.12)].
Fuel	Chemical substance used to create mechanical or thermal energy through chemical reactions; used to evolve energy in a controlled combustion reaction [REACH Use Descriptors (R.12)].
Fuel additive	Substances added to a fuel for the purpose of controlling the rate of reaction or limiting the production of undesirable combustion products; provide other benefits such as corrosion inhibition, lubrication, or detergency [REACH Use Descriptors (R.12)].
Full study report	A complete and comprehensive description of the activity performed to generate the information. This covers the complete scientific paper as published in the literature describing the study performed or the full report prepared by the test house describing the study performed [REACH Regulation, 1907/2006]. See also: robust study summary. See also: study summary.

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Gas	A substance which: (i) at 50 °C has a vapour pressure greater than 300 kPa (absolute); or (ii) is completely gaseous at 20 °C at a standard pressure of 101.3 kPa [CLP Regulation, 1272/2008].
Gases under pressure	Gases which are contained in a receptacle at a pressure of 200 kPa (gauge) or more at 20 °C, or which are liquefied or liquefied and refrigerated. They comprise compressed gases, liquefied gases, dissolved gases and refrigerated liquefied gases [CLP Regulation, 1272/2008].
Generic concentration limit	Generic concentration limits are concentrations assigned to substances with a specific hazard classification above which it leads to the classification of the mixture as hazardous. These are set for the relevant hazard classes in the CLP Regulation 1272/2008, Annex I, Parts 3, 4 and 5. See also: specific concentration limit.
Generic exposure scenario	Exposure scenario(s) for the typical conditions of use(s) of a certain type of substance (e.g. solvents, pigments, resins, detergents) within a certain sector industry (area of use), suitable to control risks for substances with a certain generic hazard profile (eg low toxicity, low volatility). Such GES aims to cover the whole life cycle of the type of substance [ECHA Guide R.20].
Genotoxic and genotoxicity	Apply to agents or processes which alter the structure, information content, or segregation of DNA, including those which cause DNA damage by interfering with normal replication processes, or which in a non- physiological manner (temporarily) alter its replication. Genotoxicity test results are usually taken as indicators for mutagenic effects. [These are more general terms than mutagen and mutagenicity]. See: mutation.
GESTIS	The information system on hazardous substances of the German Social Accident Insurance. Contains a useful substance search (GESTIS Substance Database) and occupational exposure limit search (GESTIS International Limit Values).
GHS	The Globally Harmonized System of Classification and Labelling of Chemicals [GHS Rev 8, 2019].
GLP	Good Laboratory Practice. [A managerial quality control system from the OECD, and established in the EU under Directive 2004/9/EC, required for testing by most regulatory authorities, ensuring the generation of high quality and reliable data, and promoting mutual acceptance of data].
Grandfathering	Transitional provision in UK REACH that recognises GB-based EU REACH Registrations in UK REACH at the point the Transition Period ends [ie 31 December 2020; UK HSE Glossary]

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Harmonised classification	These are mandatory hazard classifications and labelling listed in Annex VI to the CLP Regulation and should be applied to the listed substances by all actors in the supply chain. These harmonized classifications, agreed at EU level, are intended for hazards of highest concern (CMRs and respiratory sensitisers) but other hazards may be included. The harmonised classification is therefore often incomplete, and the classifier should check other hazard classes to obtain the correct hazard classification. Annex VI contains many ‘minimum hazard classifications’ (denoted by *), particularly for acute toxicity and STOT RE, that should be more severe if warranted by available data. See also: hazard classification. See also: labelling.
Hazard	The intrinsic property of a chemical agent with the potential to cause harm [Chemical Agents Directive, 98/24/EC].
Hazard assessment	A process designed to determine the possible adverse effects of an agent or situation to which an organism, system, or (sub)population could be exposed. The process includes hazard identification and hazard characterization. The process focuses on the hazard, in contrast to risk assessment, where exposure assessment is a distinct additional step [IPCS Risk Assessment Terminology].
Hazard category	The division of criteria within each hazard class, specifying hazard severity [CLP Regulation 1272/2008]. See also: differentiation.
Hazard class	The nature of the physical, health or environmental hazard [CLP Regulation 1272/2008]. [eg flammable liquid, skin sensitisation, hazardous to the aquatic environment].
Hazard classification	This involves identifying the hazards of the substance or mixture and comparing the hazard information with the criteria for hazard classes laid down in the CLP Regulation. The classification is based on the intrinsic hazardous properties of a substance or mixture and not on the likelihood of exposure and risk considerations. Hazard classification aims to determine whether a substance or mixture has physical, health or environmental hazards. The hazard classification determines the labelling required to communicate the hazard. See also: harmonised classification.
Hazard identification	The identification of the type and nature of adverse effects that an agent has an inherent capacity to cause in an organism, system, or (sub)population. Hazard identification is the first stage in hazard assessment and the first of four steps in risk assessment [IPCS Risk Assessment Terminology].
Hazard not otherwise classified (HNOC)	An adverse physical or health effect identified through evaluation of scientific evidence during the classification process that does not meet the specified criteria for the physical or health hazard classes addressed in this section [ie hazard classification] [US HazCom 2012].
Hazard pictogram	A graphical composition that includes a symbol plus other graphic elements, such as a border, background pattern or colour that is intended to convey specific information on the hazard concerned [CLP Regulation 1272/2008].
Hazard statement	A phrase assigned to a hazard class and category that describes the nature of the hazards of a hazardous substance or mixture, including, where appropriate, the degree of hazard [CLP Regulation 1272/2008].
Hazardous chemical agent	(i) any chemical agent which meets the criteria for classification as hazardous within any physical and/or health hazard classes laid down in [the CLP Regulation], whether or not that chemical agent is classified under that Regulation; (iii) any chemical agent which, whilst not meeting the criteria for classification as hazardous in accordance with point (i) [above] may, because of its physico-chemical, chemical or toxicological properties and the way it is used or is present in the workplace, present a risk to the safety and health of workers, including any chemical agent that is assigned an occupational exposure limit value [EU IOELV, BOELV or BLV] [Chemical Agents Directive, 98/24/EC].
Hazardous to the ozone layer	See: substance hazardous to the ozone layer.
Health surveillance	The assessment of an individual worker to determine the state of health of that individual, as related to exposure to specific chemical agents at work [Chemical Agents Directive, 98/24/EC].

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IARC	The International Agency for the Research on Cancer [GHS Rev 8, 2019].
Identified use	A use of a substance on its own or in a mixture, or a use of a mixture, that is intended by an actor in the supply chain, including his own use, or that is made known to him in writing by an immediate downstream user [REACH Regulation, 1907/2006].
Import	The physical introduction into the customs territory of the Community [CLP Regulation, 1272/2008 and REACH Regulation, 1907/2006].
Importer	Any natural or legal person established within the Community who is responsible for import [CLP Regulation 1272/2008 and REACH Regulation 1907/2006]. [Importers generally have the same responsibilities under REACH and CLP as do manufacturers, as they are responsible for ‘placing on the market‘ in the EU].
Impurity	An unintended constituent present in a substance as manufactured. It may originate from the starting materials or be the result of secondary or incomplete reactions during the manufacture process. While it is present in the final substance it was not intentionally added [REACH Substance ID].
In vitro	Latin for ‘in glass’, ie in the laboratory. Not using intact animals or animal tissues. See: ex vivo. See: in vivo.
In vivo	Latin for in the living body. Usually refers to using intact animals for testing. See: ex vivo. See: in vitro.
Inhalable particulate fraction	The fraction of a dust cloud that can be breathed into the nose or mouth [WHO]. See also: respirable particulate fraction and thoracic particulate fraction.
Initial boiling point	The temperature of a liquid at which its vapour pressure is equal to the standard pressure (101.3 kPa), ie the first gas bubble appears [GHS Rev 8, 2019].
Initial exposure scenario	The initial exposure scenario (ES) describes the current conditions of use based on information readily available to M/I when starting the Chemical Safety Assessment for the identified use (or groups of uses) for a substance. The initial ES forms the starting point for the exposure estimate and risk characterisation. An initial ES is a set of assumptions (using the determinants of exposure) on how a process is conducted and which risk management measures are used or should be implemented. The tentative ES may have to be adapted during the iterative Chemical Safety Assessment until it is shown that risks are controlled. The resulting ESs shall be implemented for own manufacture/use and/or communicated to Downstream Users (DU) as annex to the Safety Data Sheet [ECHA Guide R.20]. See: exposure scenario.
Intentional explosive	A substance, mixture or article which is manufactured with a view to producing a practical, explosive or pyrotechnic effect [CLP Regulation, 1272/2008].
Intermediate	A substance that is manufactured for and consumed in or used for chemical processing in order to be transformed into another substance (hereinafter referred to as ‘synthesis’) [CLP Regulation 1272/2008 and REACH Regulation 1907/2006]. See also: non-isolated intermediate. See also: on-site isolated intermediate. See also: transported isolated intermediate.
Intermediate packaging	Packaging placed between inner packaging, or articles, and outer packaging.
IOELV	Indicative occupational exposure limit values, as given in Commission Directive 2000/39/EC, as amended, and established by the Chemical Agents Directive, 98/24/EC.
ISO	International Standards Organisation. [a non-governmental international organization with a membership of 164 national standards bodies, such as the BSI in the UK].
IUCLID	International Uniform Chemical Information Database. IUCLID is a database and management system for the administration of data on chemical substances [REACH Substance ID]. [IUCLID is used by the registrant to compile dossiers for REACH Registration].
IUPAC	The International Union of Pure and Applied Chemistry. [IUPAC publishes systematic nomenclature guides for chemicals that are widely adopted by regulatory agencies for identifying chemicals, ie the ‘IUPAC name’].

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Koc	Organic carbon to water partition coefficient, a key parameter in environmental fate modelling of substances, indicating sorption to organic carbon in soils, sediment, and sludge. Used for example in calculating the removal of organic chemicals in waste treatment plants, or the migration of substances in soil.
Kow	See: octanol – water partition coefficient.
Kinematic viscosity (mm2/s)	Dynamic viscosity (mPa s) divided by density (g/cm3) [CLP Regulation, 1272/2008]. [Used to determine aspiration hazard: substances, (mainly hydrocarbons) with kinematic viscosity ≤ 20.5 mm2/s at 40 °C are Hazard Category 1].
Klimisch score	A score of the quality of data, such as test report or scientific paper, based on relevance, reliability, and adequacy. 1. Reliable without restrictions: studies or data generated according to valid or internationally accepted testing guidelines, eg OECD (preferably including GLP); 2. reliable with restrictions: studies or data, in which the test parameters do not totally comply with the specific testing guidelines, but are sufficiently well documented and scientifically acceptable; 3. not reliable: studies or data in which there were generated according to a method which is not acceptable, the documentation of which is not sufficient for assessment and which is not convincing for an expert judgment; 4. not assignable: studies or data which do not give sufficient experimental details (eg listed in short abstracts or reviews). [See ECHA Guide R.20].

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Label	An appropriate group of written, printed or graphic information elements concerning a hazardous product, selected as relevant to the target sector(s), that is affixed to, printed on, or attached to the immediate container of a hazardous product, or to the outside packaging of a hazardous product [GHS Rev 8, 2019]. See: labelling.
Label element	One type of information that has been harmonized for use in a label, eg pictogram, signal word [GHS Rev 8, 2019].
Labelling	The CLP Regulation defines the content of the label and the organisation of the various label elements, based on the hazard classification of the substance or mixture. The label should be firmly attached to the packaging and should include: (a) name, address and telephone number of the supplier; (b) the nominal quantity if made available to the general public; (c) product identifers; (d) applicable hazard pictograms, signal words, hazard statements, precautionary statements and supplemental information .
LC50 (50% lethal concentration)	The concentration of a chemical in air or of a chemical in water which causes the death of 50% (one half) of a group of test animals [GHS Rev 8, 2019].
LD50 (50% lethal dose)	The amount of a chemical, given all at once, which causes the death of 50% (one half) of a group of test animals [GHS Rev 8, 2019].
L(E)C50	LD50 or EC50.
Letter of access (LoA)	An original document, signed by the data owner or its representative, which states that the data may be used for the benefit of a third party by competent authorities, the Agency, or the Commission for the purposes of this Regulation [Biocidal Products Regulation, 528/2012].
LEV	Local exhaust ventilation.
Liquid	A substance or mixture which: (i) at 50 °C has a vapour pressure of not more than 300 kPa (3 bar); (ii) is not completely gaseous at 20 °C and at a standard pressure of 101.3 kPa; and (iii) which has a melting point or initial melting point of 20 °C or less at a standard pressure of 101.3 kPa [CLP Regulation, 1272/2008].
LOAEL	Lowest-observed-adverse-effect level. [A value from repeated-dose toxicity studies that can be used in the Chemical Safety Assessment to derive safe use levels, eg DNELs].
Long-term (chronic) hazard	For classification purposes the hazard of a substance or mixture caused by its chronic toxicity following long-term exposure in the aquatic environment [CLP Regulation, 1272/2008]. See also: chronic aquatic toxicity. Cf: acute aquatic toxicity.
Lubricating agent	Product introduced between two moving surfaces or adjacent solid surface to reduce the friction between them, improve efficiency, reduce wear, and reduce heat generation; enhance the lubricity of other substances. These lubricating films are designed to minimize contact between the rubbing surfaces and to shear easily so that the frictional force opposing the rubbing motion is low [REACH Use Descriptors (R.12)].

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M-factor	A multiplying factor. It is applied to the concentration of a substance classified as hazardous to the aquatic environment acute category 1 or chronic category 1, and is used to derive by the summation method the classification of a mixture in which the substance is present [CLP Regulation 1272/2008]. [Substances that are Hazard Category 1 in acute aquatic toxicity or chronic aquatic toxicity are given an M-factor depending on the LC50 or EC50, with higher M-factors (eg 10, 100) for lower L(E)C50 values, ie more toxic substances, for calculation of the classification of mixtures].
Main constituent	A constituent, not being an additive or impurity, in a substance that makes a significant part of that substance and is therefore used in substance naming and detailed substance identification [REACH Substance ID].
Manufacturer	Any natural or legal person established within the Community who manufactures a substance within the Community [CLP Regulation 1272/2008 and REACH Regulation 1907/2006].
Manufacturing	Production or extraction of substances in the natural state [CLP Regulation 1272/2008 and REACH Regulation 1907/2006].
Medical personnel	A registered medical practitioner, or a person working under the direction of a registered medical practitioner, acting to provide patient care, make a diagnosis or administer treatment, and who is bound by professional confidentiality [Detergents Regulation, 648/2004].
M/I	Manufacturer/importer. [These roles have the same obligations as registrants for REACH].
Minimum ignition energy (MIE)	Lowest electrical energy stored in a capacitor, which upon discharge is sufficient to ignite the most sensitive dust/air mixture under specific test conditions [GHS Rev 8, 2019].
Mist	Liquid droplets of a substance or mixture suspended in a gas (usually air) [GHS Rev 8, 2019].
Mixture	A mixture or solution composed of two or more substances [CLP Regulation 1272/2008 and REACH Regulation 1907/2006].
Mono-constituent substance	As a general rule, a substance, defined by its composition, in which one main constituent is present to at least 80% (w/w) [REACH Substance ID]. See also: multi-constituent substance. [Substances are usually categorised as mono-constituent substances, multi-constituent substances, or UVCB substances for the purposes of REACH Registration].
Monomer	A substance which is capable of forming covalent bonds with a sequence of additional like or unlike molecules under the conditions of the relevant polymer-forming reaction used for the particular process [CLP Regulation 1272/2008 and REACH Regulation 1907/2006]. See also: polymer.
Monomer unit	In the context of this definition a ‘monomer unit’ means the reacted form of a monomer substance in a polymer [CLP Regulation 1272/2008]. See: polymer.
Montreal Protocol	Montreal Protocol on Substances that Deplete the Ozone Layer. Implemented in the EU as Regulation 1005/2009 of the European Parliament and of the Council of 16 September 2009 on Substances that Deplete the Ozone Layer.
Multi-constituent substance	As a general rule, a substance, defined by its composition, in which more than one main constituent is present in a concentration ≥ 10 and < 80 wt% [REACH Substance ID]. [Substances are usually categorised as mono-constituent substances, multi-constituent substances, or UVCB substances for the purposes of REACH Registration].
Multiplying factor	See: M-factor.
Mutagenic and mutagen	Agents giving rise to an increased occurrence of mutations in populations of cells and/or organisms. See: mutation.
Mutagenicity	The process of forming mutations in a normal cell. See: mutation.
Mutation	A permanent change in the amount or structure of the genetic material in a cell. The term ‘mutation’ applies both to heritable genetic changes that may be manifested at the phenotypic level and to the underlying DNA modifications when known (including specific base pair changes and chromosomal translocations). The term ‘mutagenic’ and ‘mutagen’ will be used for agents giving rise to an increased occurrence of mutations in populations of cells and/or organisms. See also: genotoxic.

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Nanoform	A form of a natural or manufactured substance containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50 % or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm-100 nm, including also by derogation fullerenes, graphene flakes and single wall carbon nanotubes with one or more external dimensions below 1 nm [REACH Regulation, 1907/2006].
Nanomaterial	A natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50 % or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm-100 nm. In specific cases and where warranted by concerns for the environment, health, safety or competitiveness the number size distribution threshold of 50 % may be replaced by a threshold between 1 and 50 % [Nanomaterial Definition, 2011/696/EU].
Natural or legal person	A natural person is an individual person, also including self-employed people, sole traders or people in partnerships. A legal person is not a specific individual but something with a legal personality such as limited companies, trusts, charities etc. [UK HSE Glossary]
NLP	See: no-longer-polymers.
NOAEL	No-observed-adverse-effect level. [A value from repeated-dose toxicity studies that can be used in the Chemical Safety Assessment to derive safe use levels, eg DNELs].
NOEC	See: no-observed-effect-concentration. [A value from repeated-dose toxicity studies that can be used in the Chemical Safety Assessment to derive safe use levels, eg DNELs and PNECs].
NOEL	No-observed-effect level. [A value from repeated-dose toxicity studies that can be used in the Chemical Safety Assessment to derive safe use levels, eg DNELs].
No longer polymer (NLP)	The definition of polymers was changed in April 1992 in 67/548/EEC, with the result that substances previously considered to be polymers (and thus exempt from notification under) were no longer excluded from regulation. Thus the No-longer Polymers (NLP) list was drawn up, consisting of such substances that were commercially available between 18 September 1981 and 31 October 1993. The ‘No-longer-polymers’ list contains EC numbers for certain substances, important for the definition of phase-in substances.
Non-isolated intermediate	An intermediate that during synthesis is not intentionally removed (except for sampling) from the equipment in which the synthesis takes place. Such equipment includes the reaction vessel, its ancillary equipment, and any equipment through which the substance(s) pass(es) during a continuous flow or batch process as well as the pipework for transfer from one vessel to another for the purpose of the next reaction step, but it excludes tanks or other vessels in which the substance(s) are stored after the manufacture [CLP Regulation, 1272/2008 and REACH Regulation, 1907/2006].
Non-phase-in substance	A substance requiring registration which does not benefit from the transitional regime provided for phase-in substances under REACH [REACH Substance ID].
NONS	Notification of New Substances Regulations, Directive 67/547/EEC (also called NONS) formed part of the old EU chemicals regulatory framework which was replaced by REACH. [UK HSE Glossary]
No observed effect concentration (NOEC)	The test concentration immediately below the lowest tested concentration with statistically significant adverse effect. The NOEC has no statistically significant adverse effect compared to the control [CLP Regulation, 1272/2008]. [A value from repeated-dose toxicity studies that can be used in the Chemical Safety Assessment to derive safe use levels, eg DNELs and PNECs].
Normal conditions of use (of an article)	Conditions of use associated with the main function of an article. They are frequently documented in the form of user manuals or instructions for use. Normal conditions of use for articles used by industrial or professional users may differ from conditions that are ‘normal’ for consumers, eg regarding frequency and duration of use. It is explicitly not a ‘normal condition of use’ if the user uses an article in a way that the supplier of the article has clearly recommended against. See also: reasonably foreseeable conditions of use.
Not chemically modified substance	A substance whose chemical structure remains unchanged, even if it has undergone a chemical process or treatment, or a physical mineralogical transformation, for instance to remove impurities [REACH Regulation, 1907/2006]. See also: substances which occur in nature.
Notified substance	A substance for which a notification has been submitted and which could be placed on the market in accordance with Directive 67/548/EEC [ie the Dangerous Substances Directive] [REACH Regulation, 1907/2006]. [The DSD was the forerunner of REACH. Notified substances were treated as though registered under REACH].
Notifier	The manufacturer or the importer, or group of manufacturers or importers notifying to the Agency [CLP Regulation, 1272/2008].

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Occupational exposure limit value (OEL)	Unless otherwise specified, the limit of the time-weighted average [TWA] of the concentration of a chemical agent in the air within the breathing zone of a worker in relation to a specified reference period [Chemical Agents Directive, 98/24/EC].
Octanol–water partition coefficient (log Kow or log Pow)	A measure of the lipophilicity of a substance. As such, log Kow is a key parameter in the assessment of environmental fate. Many distribution processes are driven by log Kow, eg sorption to soil and sediment and bioconcentration in organisms [GHS Rev 8, 2019]. [Log Kow is derived from the equilibrium concentration of a substance in each layer of the two liquids, so indicates if a substance will migrate to ‘fatty tissues’ (as modelled by the octanol) or reside in the aqueous environment].
OECD	The Organization for Economic Cooperation and Development. [The OECD publishes Guidelines for the Testing of Chemicals, which have been widely adopted by regulatory agencies worldwide].
OEL	See: occupational exposure limit value.
Only representative (OR)	A natural or legal person established in the Community to fulfil the obligations on importers for registration under REACH. The OR is appointed (by mutual agreement) by a natural or legal person established outside the Community who manufactures a substance on its own, in mixtures or in articles, formulates a mixture or produces an article that is imported into the Community. A non-EU company may appoint an EU-based OR to take on the REACH Registration responsibilities for its EU-based importers.
On-site isolated intermediate	An intermediate not meeting the criteria of a non-isolated intermediate and where the manufacture of the intermediate and the synthesis of (an)other substance(s) from that intermediate take place on the same site, operated by one or more legal entities [REACH Regulation, 1907/2006].
Operational conditions (OC)	Operational conditions include eg physical appearance of mixture, duration and frequency of use/exposure, amount of substance, room size and ventilation rate. More general: the operational conditions include any action, use of tool or parameter state that prevails during manufacture or use of a substance (either in a pure state or in a mixture) that as a side effect might have an impact on exposure of humans and/ or the environment [ECHA Guide R.20].
Organic peroxides	Liquid or solid organic substances which contain the bivalent -O-O- structure and may be considered derivatives of hydrogen peroxide, where one or both of the hydrogen atoms have been replaced by organic radicals. The term organic peroxide includes organic peroxide mixtures (formulations) containing at least one organic peroxide. Organic peroxides are thermally unstable substances or mixtures, which can undergo exothermic self-accelerating decomposition. In addition, they can have one or more of the following properties: (i) be liable to explosive decomposition; (ii) burn rapidly; (iii) be sensitive to impact or friction; (iv) react dangerously with other substances. Organic peroxides are classified by definition based on their chemical structure and on the available oxygen and hydrogen peroxide contents of the mixture. [CLP Regulation, 1272/2008].
Oxidising gas	Any gas or gas mixture which may, generally by providing oxygen, cause or contribute to the combustion of other material more than air does [CLP Regulation, 1272/2008].
Oxidising liquid	A liquid substance or mixture which, while in itself not necessarily combustible, may, generally by yielding oxygen, cause, or contribute to, the combustion of other material [CLP Regulation, 1272/2008].
Oxidising solid	A solid substance or mixture which, while in itself is not necessarily combustible, may, generally by yielding oxygen, cause, or contribute to, the combustion of other material [CLP Regulation, 1272/2008].

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Package	The complete product of the packing operation, consisting of the packaging and its contents [CLP Regulation 1272/2008].
Packaging	One or more receptacles and any other components or materials necessary for the receptacles to perform their containment and other safety functions [CLP Regulation 1272/2008]. See also: intermediate packaging.
Particle	A minute piece of matter with defined physical boundaries [Nanomaterial Definition, 2011/696/EU].
PBT	Persistent, bioaccumulative, toxic. [Criteria are given in the REACH Regulation, Annex XIII]. See also: vPvB, PMT, vPvM. More information: persistent organic pollutants.
PEC	Predicted environmental concentration. [An estimated environmental concentration of a substance, usually derived from default values for release and distribution into the environment from a use of the substance, as part of the Chemical Safety Assessment].
Per year	Per calendar year, unless stated otherwise, for phase-in substances that have been imported or manufactured for at least three consecutive years, quantities per year shall be calculated on the basis of the average production or import volumes for the three preceding calendar years [REACH Regulation, 1907/2006].
pH	Measure of of the acidity or alkalinity of a solution. The pH scale ranges from around 0 to 14, with pH 7 as neutral, pH < 7 are acidic, pH > 7 are basic or alkaline. At pH 7.0, the concentration of H3O+ equals the concentration of OH−.
pH regulating agent	Substance that maintains the desired pH range of a product; used to alter, stabilize, or control the pH (hydrogen ion concentration) [REACH Use Descriptors (R.12)].
Phase-in substance	A substance which meets at least one of the following criteria: (a) it is listed in the European Inventory of Existing Commercial Chemical Substances (EINECS); (b) it was manufactured in the Community, [or in the countries acceding to the European Union], but not placed on the market by the manufacturer or importer, at least once in the 15 years before the entry into force of this Regulation, provided the manufacturer or importer has documentary evidence of this; (c) it was placed on the market in the Community, [or in the countries acceding to the European Union], by the manufacturer or importer before the entry into force of this Regulation and it was considered as having been notified in accordance with [Directive 67/548/EEC], but it does not meet the definition of a polymer as set out in this Regulation [see no-longer polymer], provided the manufacturer or importer has documentary evidence of this, including proof that the substance was placed on the market by any manufacturer or importer between 18 September 1981 and 31 October 1993 inclusive [REACH Regulation, 1907/2006]. [Phase-in substances were subject to delayed registration obligations during the transition phase of REACH].
Pigment	Any substance, usually in the form of a dry powder, that imparts colour to another substance or mixture by attaching to the surface of the substrate through binding or adhesion; may contribute towards opacity, durability, and corrosion resistance. Pigments differ from dyes in that they are insoluble in the vehicle and exist as dispersed compounds in paint rather than as a solute [REACH Use Descriptors (R.12)]. See also: dye.
Placing on the market	Supplying or making available, whether in return for payment or free of charge, to a third party. Import shall be deemed to be placing on the market [CLP Regulation 1272/2008 and REACH Regulation 1907/2006].
Plasticizer	An organic compound that softens synthetic polymers; added to a polymer to facilitate processing and to increase flexibility, plasticity, fluidity and toughness of the final product by internal modification (solution) of the polymer molecule. Plasticizers may be added internally or externally. A rigid polymer can also be externally plasticized by addition of a plasticizer, which imparts the desired flexibility but is not chemically changed by reaction with the polymer [REACH Use Descriptors (R.12)]. See also: polymer.
PMT	Persistent, mobile and toxic. An emerging hazard in the EU, that may become recognised as a ‘substance of very high concern‘ (SVHC) according to Article 57 of REACH. A hazard to remote aquatic environments and sources of drinking water. May include perfluoroalkyl and polyfluoroalkyl substances (PFAS). See also: vPvM, PBT, vPvB.
PNEC	Predicted no effect concentration. [A key parameter from the Chemical Safety Assessment giving a ‘safe’ level for environmental exposure, usually derived from aquatic toxicity studies].
Polymer	A substance consisting of molecules characterised by the sequence of one or more types of monomer units. Such molecules must be distributed over a range of molecular weights wherein differences in the molecular weight are primarily attributable to differences in the number of monomer units. A polymer comprises the following: (a) a simple weight majority of molecules containing at least three monomer units which are covalently bound to at least one other monomer unit or other reactant; (b) less than a simple weight majority of molecules of the same molecular weight. In the context of this definition a ‘monomer unit’ means the reacted form of a monomer substance in a polymer [CLP Regulation 1272/2008 and REACH Regulation 1907/2006].
log Pow	See: octanol – water partition coefficient.
PPE	Personal protection equipment. [EU PPE Regulation gives general information. Details are given in Standards produced by CEN, and published by national bodies such as the BSI in the UK. See: PPE Regulation.
PPE Regulation	Regulation (EU) 2016/425 of the European Parliament and of the Council of 9 March 2016 on Personal Protective Equipment.
PPORD	Product and process orientated research and development.
Precautionary statement	A phrase that describes recommended measure(s) to minimise or prevent adverse effects resulting from exposure to a hazardous substance or mixture due to its use or disposal [CLP Regulation 1272/2008].
Primary biodegradation	The structural change (transformation) of a surfactant by micro-organisms resulting in the loss of its surface-active properties due to the degradation of the parent substance and consequential loss of the surface-active property as measured by test methods listed in Annex II [of the Detergents Regulation, 648/2004].
Process category (PROC)	Element of the use descriptor system describing the type of technical processes applied during manufacturing and use (PROCs). In other categorisation systems for occupational conditions, the term operation unit (OU) is used [ECHA Guide R.20]. [PROCs are part of the use descriptor system (UDS) used in the Chemical Safety Assessment for the exposure assessment of a substance for particular uses].
Producer of an article	Any natural or legal person who makes or assembles an article within the Community [CLP Regulation 1272/2008 and REACH Regulation 1907/2006]. See also: article.
Product and process orientated research and development (PPORD)	Any scientific development related to product development or the further development of a substance, on its own, in mixtures or in articles in the course of which pilot plant or production trials are used to develop the production process and/or to test the fields of application of the substance [REACH Regulation, 1907/2006]. See also: Scientific research and development.
Product category (PC)	Element of the use descriptor system characterizing the type of chemical product in which the substance is (finally) used. Includes also intermediates and single substances marketed as chemical product [ECHA Guide R.20]. [PCs are part of the use descriptor system (UDS) used in the Chemical Safety Assessment for the exposure assessment of a substance for particular uses].
Product identifier	The name or number used for a hazardous product on a label or in the SDS. It provides a unique means by which the product user can identify the substance or mixture within the particular use setting eg transport, consumer or workplace [GHS Rev 8, 2019]. [For a substance, the product identifier usually consists of the name and and identification number (eg EC number); for a mixture it usually consists of the trade name and the identification of ingredients that contribute to the health-hazard classification of the mixture (details in Article 18 of the CLP Regulation].
Pyrophoric liquid	A liquid substance or mixture which, even in small quantities, is liable to ignite within five minutes after coming into contact with air [CLP Regulation, 1272/2008].
Pyrophoric solid	A solid substance or mixture which, even in small quantities, is liable to ignite within five minutes after coming into contact with air [CLP Regulation, 1272/2008].
Pyrotechnic article	An article containing one or more pyrotechnic substances or mixtures [CLP Regulation, 1272/2008].
Pyrotechnic substance or mixture	A substance or mixture of substances designed to produce an effect by heat, light, sound, gas or smoke or a combination of these as the result of non-detonative self-sustaining exothermic chemical reactions [CLP Regulation, 1272/2008].

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QSAR	Quantitative structure–activity relationships. [Eg Quantitative computation, calculation, functional group analysis, or read-across or grouping of chemicals in order to generate data on substances in the absence of direct laboratory testing].

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RAC	The EU Risk Assessment Committee, that prepares the opinions of ECHA, eg for harmonised classification, restriction, authorisation, and occupational exposure limits. The final decisions are taken by the European Commission.
Rapidly biodegradable	A substance is considered rapidly degradable in the environment if one of the following criteria apply. (a) in 28-day ready biodegradation study: (i) tests based on dissolved organic carbon, >70% degradation; (ii) tests based on oxygen depletion or carbon dioxide generation, > 60% of theoretical maximum. [a 10-day-window condition may apply to non-UVCB sustances] (b) if, in those cases where only BOD and COD data are available, when the ratio of BOD 5 /COD is ≥ 0.5; or (c) if other convincing scientific evidence is available to demonstrate that the substance can be degraded (biotically and/or abiotically) in the aquatic environment to a level > 70 % within a 28-day period. [Biodegradation is the complete mineralisation of organic parts of a substance to carbon dioxide and water. Primary degradation is the initial transformation of the substance to other products, and does not constitute rapid biodegradation unless the assessor can demonstrate these products do not meet the criteria for classification as hazardous]. See also: readily biodegradable.
REACH Regulation 1907/2006	Regulation (EC) No 1907/2006 of the European Parliament and of the Council of 18 December 2006 concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) (as amended).
Read-across	A type of structure–activity relationship (SAR), including grouping of substances, that is a common alternative to testing for filling data gaps in REACH registrations. This approach uses information from an analogous (‘source’) substance to predict the properties of a ‘target’ substance.
Readily biodegradable	Meeting the criteria for biological degradation as defined in the OECD Test Guidlines No. 301. [Readily biodegradable is a more specific type of ‘rapid biodegradability’]. See: rapidly biodegradable.
Readily combustible solids	Powdered, granular, or pasty substances or mixtures which are dangerous if they can be easily ignited by brief contact with an ignition source, such as a burning match, and if the flame spreads rapidly [CLP Regulation, 1272/2008].
Reasonably expected use (of a substance or mixture)	Any process, including production, handling, maintenance, storage, transport or disposal: • technical activities, eg spraying • consumer contact, eg through household chemicals and their disposal • professional and non-professional uses including reasonably foreseeable accidental exposure, but not abuse such as criminal or suicidal uses.
Reasonably foreseeable conditions of use (of an article)	Conditions of use that can be anticipated as likely to occur because of the function and physical form of the article (even though they are not normal conditions of use). For example when a small child does not know the function of an article but uses it for any purpose he associates with it, such as biting or licking it
Recipient of a substance or a mixture	A downstream user or a distributor being supplied with a substance or a mixture [REACH Regulation, 1907/2006].
Recipient of an article	An industrial or professional user, or a distributor, being supplied with an article but does not include consumers [REACH Regulation, 1907/2006].
Registrant	The manufacturer or the importer of a substance or the producer or importer of an article submitting a registration for a substance under Regulation (EC) No 1907/2006 [ie REACH Regulation] [CLP Regulation 1272/2008 and REACH Regulation (1907/2006)].
Registrant’s own use	An industrial or professional use by the registrant [REACH Regulation, 1907/2006]. See also: identified use.
Registration	A completed application to ECHA required before a substance may be placed on the market, unless exemptions apply, under the ‘no data, no market’ principle. See: registration dossier. More information: REACH Registration.
Registration dossier	A registration dossier is the information supplied to ECHA, in IUCLID format, that allows a supplier to place a substance on the market. The registration dossier comprises: Technical Dossier: (i) applicant information; (ii) substance identification; (iii) manufacturing process and uses; (iv) hazard classification and labelling; (v) human exposure; (vi) recommendations for safe use; (vii) properties (physico-chemical, toxicological, and ecotoxicological) according to the lists given in REACH Annexes VII to X. Chemical Safety Report: A chemical safety report is required for substances marketed at > 10 t/a. It comprises: (i) hazard classification; (ii) assessment of the substance as persistent, bioaccumulative and toxic (PBT) and very persistent and very bioaccumulative (vPvB); (iii) for all hazardous, PBT, or vPvB substances, exposure scenarios and risk characterisation are required for for all identified uses during the lifecycle of the substance. More information: REACH Registration.
Registration number	An 18-digit number assigned by the European Chemicals Agency (ECHA), after the successful submission of registration dossier by a legal entity. Format is: xx-xxxxxxxxxx-xx-xxxx, and is usually communicated via SDSs.
Reproductive toxicity	Includes adverse effects on sexual function and fertility in adult males and females, as well as developmental toxicity in the offspring. Adverse effects on or via lactation are also included in reproductive toxicity, but for classification purposes, such effects are treated separately [CLP Regulation, 1272/2008].
Respirable particulate fraction	The fraction of inhaled airborne particles that can penetrate beyond the terminal bronchioles into the gas-exchange region of the lungs [WHO]. See also: inhalable particulate fraction and thoracic particulate fraction.
Respiratory sensitisation	Respiratory sensitisation describes asthma and other related respiratory conditions, irrespective of the mechanism (immunological or non-immunological) by which they are caused. There is an induction phase that renders the airways unusually sensitive (hypersensitive), so that subsequent inhalation exposure gives an asthmatic response (airway narrowing, chest-tightening and bronchial restriction).
Respiratory sensitiser	A substance that will lead to hypersensitivity of the airways following inhalation of the substance [CLP Regulation, 1272/2008]. See also: respiratory sensitisation. See also: skin sensitiser.
Responsible person [for inclusion in an SDS]	Any person that the supplier from one Member State may have chosen to appoint in a different Member State to deal with any enquiries concerning SDSs which arise in that different Member State [Guidance on the compilation of safety data sheets, Version 4.0]
Restriction	Any condition for or prohibition of the manufacture, use or placing on the market [REACH Regulation, 1907/2006].
RID	The Regulations Concerning the International Carriage of Dangerous Goods by Rail.
Risk	The likelihood that the potential for harm will be attained under the conditions of use and/or exposure [Chemical Agents Directive, 98/24/EC].
Risk assessment	A process intended to calculate or estimate the risk to a given target organism, system, or (sub)population, including the identification of attendant uncertainties, following exposure to a particular agent, taking into account the inherent characteristics of the agent of concern as well as the characteristics of the specific target system. The risk assessment process includes four steps: (i) hazard identification, (ii) hazard characterization, (iii) exposure assessment, and (iv) risk characterization. It is the first component in a risk analysis process [IPCS Risk Assessment Terminology]. See also: Chemical Safety Assessment. See also: risk characterisation.
Risk characterisation	The risk characterisation consists of: (i) a comparison of the exposure of each human population known to be or likely to be exposed with the appropriate DNEL, (ii) a comparison of the predicted environmental concentrations (PECs) in each environmental sphere with the PNECs, and (iii) an assessment of the likelihood and severity of an event occurring due to the physicochemical properties of the substance. [REACH Regulation, 1907/2006].
Risk management measures (RMM)	Measures that control the emission of a substance and/or exposure to it, thereby controlling the risks to human health or the environment. RMM include eg containment of process, local exhaust ventilation (LEV), gloves, waste-water treatment, exhaust air filters. More general: RMM include any action, use of tool, change of parameter state that is introduced during manufacture or use of a substance (either in a pure state or in a mixture) in order to prevent, control, or reduce exposure of humans and/or the environment [ECHA Guide R.20]. See: risk.
Robust study summary	A detailed summary of the objectives, methods, results and conclusions of a full study report providing sufficient information to make an independent assessment of the study minimising the need to consult the full study report [REACH Regulation, 1907/2006]. See also: study summary. See also: Klimisch score.

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Safety	Practical certainty that adverse effects will not result from exposure to an agent under defined circumstances. It is the reciprocal of risk [IPCS Risk Assessment Terminology].
Safety data sheet (SDS)	The SDS is the primary hazard communication document for suppliers of a hazardous substance or mixture to enable users to take the necessary risk management measures to protect workers, and the environment, and includes information on safe storage, handling and disposal. The SDS is used by employers to determine whether any hazardous chemical agents are present in the workplace and to assess any risk to the health and safety of workers. [In the EU, requirements for the SDS are given in Article 31 and Annex II of the REACH Regulation] More information: safety data sheets.
SAR	See: structure–activity relationship.
Scaling	A mathematical approach to check if operational conditions and risk management measures in a downstream user (DU) workplace, which differ from those prescribed in the supplier exposure scenario in the Annex of an SDS, can be still covered by it. In practice, the conditions of use at the DU’s site may differ from those in the exposure scenario, yet the risk can be shown to be adequately controlled, by compensating one variable with another in a calculation of risk. This process is called scaling.
Scientific research and development	Any scientific experimentation, analysis or chemical research carried out under controlled conditions in a volume less than one tonne per year [REACH Regulation, 1907/2006]. See also: PPORD.
SDS	See: safety data sheet.
Sector of Use (SU)	Element of the use descriptor system describing the sector of economy (industry, professional service, private) a substance is used in, as such or in a mixture [ECHA Guide R.20]. [SUs are part of the use descriptor system (UDS) used in the Chemical Safety Assessment for the exposure assessment of a substance for particular uses].
Self-accelarating decomposition temperature (SADT)	The lowest temperature at which self-accelerating decomposition may occur with the substance as packaged [GHS Rev 8, 2019].
Self-heating substance or mixture	A liquid or solid substance or mixture, other than a pyrophoric liquid or solid, which, by reaction with air and without energy supply, is liable to self-heat; this substance or mixture differs from a pyrophoric liquid or solid in that it will ignite only when in large amounts (kilograms) and after long periods of time (hours or days). Self-heating of a substance or a mixture is a process where the gradual reaction of that substance or mixture with oxygen (in the air) generates heat. If the rate of heat production exceeds the rate of heat loss, then the temperature of the substance or mixture will rise which, after an induction time, may lead to self-ignition and combustion [CLP Regulation, 1272/2008].
Self-ignition temperature	The minimum ambient temperature expressed in °C at which a certain volume of a substance will ignite under defined conditions of this method [Test Method Regulation, 440/2008]. The test method is described for solids. Cf: auto-ignition temperature for liquids and gases.
Self-reactive substances or mixtures	Thermally unstable liquid or solid substances or mixtures liable to undergo a strongly exothermic decomposition even without participation of oxygen (air). This definition excludes substances and mixtures classified […] as explosives, organic peroxides or as oxidising [CLP Regulation, 1272/2008].
Sensitisation	See: skin sensitisation. See: respiratory sensitisation.
Serious eye damage	The production of tissue damage in the eye, or serious physical decay of vision, following application of a test substance to the anterior surface of the eye, which is not fully reversible within 21 days of application [CLP Regulation, 1272/2008]. See also : eye irritation.
Seveso III	The EU Seveso Directive: Directive 2012/18/EU of the European Parliament and of the Council of 4 July 2012 on the Control of Major-accident Hazards Involving Dangerous Substances. The main EU legislation on the control of on-shore major accidents involving dangerous substances. The UK implement this Directive through the COMAH Regulations 2015. Requires industry to take measures to prevent major accidents involving dangerous substances, and limit the consequences to people and the environment of any major accidents which do occur.
Short-term (acute) hazard	For classification purposes the hazard of a substance or mixture caused by its acute toxicity to an organism during short-term aquatic exposure to that substance or mixture. See also: acute aquatic toxicity.
SIEF	Substance information exchange forum. [The SIEF for a substance were the potential registrants, downstream users and third parties who pre-registered phase-in substance, and exchanged information to avoid duplication of studies for REACH registration purposes under REACH, and agreed hazard classification and labelling. SIEFs officially became defunct on 1 June 2018].
Signal word	A word that indicates the relative level of severity of hazards to alert the reader to a potential hazard; the following two levels are distinguished: (a) ‘Danger’ means a signal word indicating the more severe hazard categories; (b) ‘Warning’ means a signal word indicating the less severe hazard categories [CLP Regulation, 1272/2008].
Simple asphyxiant	See: asphyxiant.
Site	A single location, in which, if there is more than one manufacturer of (a) substance(s), certain infrastructure and facilities are shared [REACH Regulation, 1907/2006].
Skin corrosion	The production of irreversible damage to the skin; namely, visible necrosis through the epidermis and into the dermis, following the application of a test substance for up to 4 hours. Corrosive reactions are typified by ulcers, bleeding, bloody scabs, and, by the end of observation at 14 days, by discolouration due to blanching of the skin, complete areas of alopecia, and scars. Histopathology shall be considered to evaluate questionable lesions [CLP Regulation, 1272/2008].
Skin irritation	The production of reversible damage to the skin following the application of a test substance for up to 4 hours [CLP Regulation, 1272/2008].
Skin sensitisation	An allergic response in the skin of susceptible individuals following contact with a skin sensitiser which causes adverse effects via immunological mechanism of allergic contact dermatitis or atopic dermatitis. There are several ex vivo or in vitro tests for skin sensitisation (notably the local lymph node assay, LLNA) that have superseded the in vivo maximisation and Buehler tests.
Skin sensitiser	A substance that will lead to an allergic response following skin contact [CLP Regulation, 1272/2008]. See also: respiratory sensitiser. See also: skin sensitisation.
SME	Small and medium-sized enterprises as defined in the Commission Recommendation of 6 May 2003 concerning the definition of micro, small and medium-sized enterprises [Commission Implementing Regulation (EU) 2015/864 of 4 June 2015] [REACH Regulation, 1907/2006].
Solid	A substance or mixture which does not meet the definitions of liquid or gas [CLP Regulation, 1272/2008].
Solvent	Any substance that can dissolve another substance (solute) to form a uniformly dispersed mixture (solution) at the molecular or ionic size level; provides dissolving capability required for a stable formulation; dissolves certain components of the formulation to aid dispersion of components; aids oil cleansing power and controls film drying rate; allows the product to solubilize soils on surfaces and facilitate removal; used to dissolve, thin, dilute, and extract [REACH Use Descriptors (R.12)].
Specific concentration limits	Specific concentration limits are concentrations (different from generic concentration limits) assigned to a specific substance above which it leads to the classification of the mixture as hazardous. These are given in the CLP Regulation 1272/2008, Annex VI, or can be set by the manufacturer or importer where reliable information shows that the hazard of a substance is different (usually higher) than generic concentration limits provide for.
Specific target organ toxicity (repeated exposure) (STOT RE)	Specific, target organ toxicity arising from a repeated exposure to a substance or mixture. All significant health effects that can impair function, both reversible and irreversible, immediate and/or delayed are included. However, other specific toxic effects that are specifically addressed in sections [on acute toxicity, skin corrosion/irritation, serious eye damage/eye irritation, respiratory or skin sensitisation, germ cell mutagenicity, carcinogenicity, reproductive toxicity, STOT SE, and aspiration toxicity] [CLP Regulation, 1272/2008].
Specific target organ toxicity (single exposure) (STOT SE)	Specific, non lethal target organ toxicity arising from a single exposure to a substance or mixture. All significant health effects that can impair function, both reversible and irreversible, immediate and/or delayed and not specifically addressed in sections [on acute toxicity, skin corrosion/irritation, serious eye damage/eye irritation, respiratory or skin sensitisation, germ cell mutagenicity, carcinogenicity, reproductive toxicity, and aspiration toxicity] [CLP Regulation, 1272/2008].
Stabilizing agent	A substance that tends to keep a compound, solution, or mixture from changing its form or chemical nature; renders or maintains a solution, mixture, suspension, or state resistant to chemical change; used to prevent or slow down spontaneous changes in and ageing of materials [REACH Use Descriptors (R.12)].
Structure–activity relationship	Computation, calculation, functional group analysis, or read-across or grouping of chemicals in order to generate data on substances in the absence of direct laboratory testing. See also: QSAR.
Study summary	A summary of the objectives, methods, results and conclusions of a full study report providing sufficient information to make an assessment of the relevance of the study [REACH Regulation, 1907/2006]. See also: robust study report.
Substance	A chemical element and its compounds in the natural state or obtained by any manufacturing process, including any additive necessary to preserve its stability and any impurity deriving from the process used, but excluding any solvent which may be separated without affecting the stability of the substance or changing its composition [CLP Regulation, 1272/2008 and REACH Regulation, 1907/2006]. [Substances are usually categorised as mono-constituent substances, multi-constituent substances, or UVCB substances for the purposes of REACH Registration].
Substance hazardous to the ozone layer	A substance which, on the basis of the available evidence concerning its properties and its predicted or observed environmental fate and behaviour may present a danger to the structure and/or the functioning of the stratospheric ozone layer. This includes substances which are listed in Annex I to Regulation (EC) No 1005/2009 [implementing the Montreal Protocol] [CLP Regulation, 1272/2008].
Substance of very high concern (SVHC)	Substances with severe hazards that may be subject to authorisation, or other restriction, including: (i) Substances meeting the criteria for classification in the following hazard classes: Carc 1A or 1B, Muta 1A or 1B, Repr 1A or 1B. These substances are expected to cause cancer, transmissible genetic defects, or reproductive or developmental effects in humans, and are collectively known as CMRs. (ii) Substances meeting the criteria for classification as PBT or vPvB substances. These are long-lasting chemicals that accumulate in animal tissues. (iii) Other substances of equivalent level of concern to the above, with endocrine disruptors being specifically mentioned. [Adapted from REACH Regulation, 1907/2006, Article 57]. More information: Candidate List of SVHCs.
Substances or mixtures which, in contact with water, emit flammable gases	Solid or liquid substances or mixtures which, by interaction with water, are liable to become spontaneously flammable or to give off flammable gases in dangerous quantities [CLP Regulation, 1272/2008].
Substances which occur in nature	A naturally occurring substance as such, unprocessed or processed only by manual, mechanical or gravitational means, by dissolution in water, by flotation, by extraction with water, by steam distillation or by heating solely to remove water, or which is extracted from air by any means [REACH Regulation, 1907/2006]. See also: not chemically modified substance.
Substitution	Replacement of a substance, or physical appearance of a mixture or a technique with an alternative (less hazardous or lower exposure potential). The registrant of a substance under REACH will usually not recommend the substitution of that substance as a risk management measure. However he can advise against a certain use of the substance or limit the uses covered in his exposure scenario. In this way he may initiate substi-tution further down the supply chain [ECHA Guide R.20].
Supplemental label element	Any additional non-harmonized type of information supplied on the container of a hazardous product that is not required or specified under the GHS. In some cases this information may be required by other competent authorities or it may be additional information provided at the discretion of the manufacturer/distributor [GHS Rev 8, 2019]. The EU specifies several types of supplemental information, such as: (i) EUH hazard phrases specified in the CLP Regulation, Annex II [eg EUH208 ‘contains (name of sensitising substance). May produce an allergic reaction’]; (ii) the unique formula identifier (UFI); and (iii) a statement for hazardous plant protection products [regulations other than the CLP Regulation may require additional phrases, eg ‘Restricted to professional users’ for CMRs in the REACH Regulation; also the authorisation number, if applicable]. The statements for the percent of the product with unknown acute toxicity and aquatic toxicity should also be given (CLP Regulation, Annex I, Sections 3.1.3.6.2.2. and 4.1.3.6.1.). See also: labelling.
Supplier (of a substance or mixture)	Any manufacturer, importer, downstream user or distributor placing on the market a substance, on its own or in a mixture, or a mixture [CLP Regulation, 1272/2008 and REACH Regulation, 1907/2006].
Supplier of an article	Any producer or importer of an article, distributor or other actor in the supply chain placing an article on the market [REACH Regulation, 1907/2006].
Surfactant	Any organic substance and/or mixture used in detergents, which has surface-active properties and which consists of one or more hydrophilic and one or more hydrophobic groups of such a nature and size that it is capable of reducing the surface tension of water, and of forming spreading or adsorption monolayers at the water–air interface, and of forming emulsions and/or microemulsions and/or micelles, and of adsorption at water–solid interfaces [Detergents Regulation, 648/2004]. Surfactants are generally classified by their ionic (electrical charge) properties in water and can be categorised as being anionic (negative), non-ionic (neutral), cationic (positive) or zwitterionic (amphoteric, ‘double ion’).
SVHC	See: substance of very high concern.
Synthesis	Manufacture or use for chemical processing resulting in transformation into another substance [adapted from CLP Regulation, 1272/2008]. See: intermediate.

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Technical name	A name that is generally used in commerce, regulations and codes to identify a substance or mixture, other than the IUPAC or CAS name, and that is recognized by the scientific community. Examples of technical names include those used for complex mixtures (eg petroleum fractions or natural products), pesticides (eg ISO or ANSI systems), dyestuffs (Colour Index system) and minerals [GHS Rev 8, 2019].
Third party representative	Appointed by a manufacturer, or importer, or downstream user, they play a part in the negotiations between the (potential) registrants, while the appointing company retains full responsibility for complying with its registration obligations. [UK HSE Glossary]
Thoracic particulate fraction	The fraction that can penetrate the head airways and enter the airways of the lung [WHO]. See also: inhalable particulate fraction and respirable particulate fraction.
Threshold	Dose or exposure concentration of an agent below which a stated effect is not observed or expected to occur [IPCS Risk Assessment Terminology].
Transported isolated intermediate	An intermediate not meeting the criteria of a non-isolated intermediate and transported between or supplied to other sites [REACH Regulation, 1907/2006].
TWA	Time-weighted average. See: Occupational exposure limit value.

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UFI	See: Unique Formula Identifier
Ultimate aerobic biodegradation	The level of biodegradation achieved when the surfactant is totally used by micro-organisms in the presence of oxygen resulting in its breakdown to carbon dioxide, water and mineral salts of any other elements present (mineralisation), as measured by test methods listed in Annex III, and new microbial cellular constituents (biomass) [Detergents Regulation, 648/2004]. See also: rapidly biodegradable.
UN RTDG	The United Nations Recommendations on the Transport of Dangerous Goods
Unique Formula Identifier (UFI)	Code with 16 alpha-numerical characters separated by hyphens into four blocks, eg VDU1-414F-1003-1862. The UFI is required in the poison centre notification, which is being introduced in the EU, and on the label of your products. You can generate the UFI using the UFI Generator tool available from ECHA’s Poison Centre Website. For more information, see: poison centre notification.
Unstable explosive	Explosive substance or mixture which is thermally unstable and/or too sensitive for normal handling, transport and use [CLP Regulation, 1272/2008].
Use	Any processing, formulation, consumption, storage, keeping, treatment, filling into containers, transfer from one container to another, mixing, production of an article or any other utilisation [CLP Regulation, 1272/2008 and REACH Regulation, 1907/2006]. See: identified use. See: registrant’s own use.
Use and exposure category	An exposure scenario covering a wide range of processes or uses, where the processes or uses are communicated, as a minimum, in terms of the brief general description of use [REACH Regulation, 1907/2006].
Use descriptor system (UDS)	Set of 5 descriptors which can be used (i) to briefly describe identified uses in a brief general way and (ii) to build the short title of an exposure scenario. The descriptors are: • Sectors of use (SU) • Chemical product category (PC) • Process category (PROC) • Article category (AC) • Environmental release category (ERC) [ECHA Guide R.20]. [The UDS is used in the Chemical Safety Assessment for the exposure assessment of a substance for particular uses. Details are given in ECHA Guidance R.12: Use Description].
UVCB substance	Substances of unknown or variable composition, complex reaction products or biological materials. [Substances are usually categorised as mono-constituent substances, multi-constituent substances, or UVCB substances for the purposes of REACH Registration].

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Validation	Process by which the reliability and relevance of a particular approach, method, process, or assessment is established for a defined purpose. Different parties define ‘Reliability’ as establishing the reproducibility of the outcome of the approach, method, process, or assessment over time. ‘Relevance’ is defined as establishing the meaningfulness and usefulness of the approach, method, process, or assessment for the defined purpose [IPCS Risk Assessment Terminology]. [Often used in the context of whether a test method, QSAR, or calculation to determine a chemical property (eg for REACH Registration) is reliable and suited to a particular substance]. See also: Klimisch score.
Vapour	The gaseous form of a substance or mixture released from its liquid or solid state [GHS Rev 8, 2019].
Vapour pressure (Vp)	The saturation pressure above a solid or liquid substance [Test Method Regulation, 440/2008]. A key parameter, particularly for liquids, to determine their propensity to form vapours, thus determining the likelihood of inhalation exposure, and flammable or explosive atmospheres. Vp is inversely related to the initial boiling point.
Very persistent, very mobile (vPvM)	An emerging hazard in the EU, that may become recognised as a ‘substance of very high concern‘ (SVHC) according to Article 57 of REACH. A hazard to remote aquatic environments and sources of drinking water. May include perfluoroalkyl and polyfluoroalkyl substances (PFAS). See also: PMT, PBT, vPvB.
Very persistent, very bioaccumulative (vPvB)	Very persistent and very bioaccumulative. [Criteria are given in the REACH Regulation, Annex XIII]. See also: PBT. More information: persistent organic pollutants.
Viscosity	A measure of a fluid’s resistance to flow, often referred to as the fluid’s thickness. Water has a low viscosity compared to honey. A high viscosity liquid has stronger molecular interaction, increasing the internal friction of the moving fluid.

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Washing	The cleaning of laundry, fabrics, dishes and other hard surfaces [Detergents Regulation, 648/2004].
Waste	Any substance or object in the categories set out in Annex I to Directive 2006/12/EC which the holder discards or intends or is required to discard [Directive 2006/12/EC]. Examples include products that are: off-specification, expired, spilled or contaminated, non-performing, unusable, unwanted or are residues from processing.
WEL	Workplace exposure limit. UK OELs published in EH40/2005, as amended.
WGK	German Wassergefährdungsklassen (water-hazard class). A designation prescribed in the German Regulation: Verwaltungsvorschrift wassergefährdende Stoffe (VwVwS). Substances are classified as WGK 1, 2, or 3 (or non-hazardous to water, nwg), and can be searched for at the UBA Rigoletto website, which also gives guidance on mixture classification.
WHO	World Health Organisation.

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