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4.1.1.: Definitions and general considerations

4.1.1.1. Definitions
(a) ‘acute aquatic toxicity’ means the intrinsic property of a substance to be injurious to an aquatic organism in a short-term aquatic exposure to that substance.
(b) ►M12  short-term (acute) hazard ◄ ’ means 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.
(c) ‘availability of a substance’ means 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).
(d) ‘bioavailability’ or ‘biological availability’ means 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.
(e) bioaccumulation’ means 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).
(f) bioconcentration’ means the net result of uptake, transformation and elimination of a substance in an organism due to waterborne exposure.
(g) chronic aquatic toxicity’ means 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.
(h) degradation’ means the decomposition of organic molecules to smaller molecules and eventually to carbon dioxide, water and salts.
(i) ‘ECx’ means the effect concentration associated with x% response.
(j) ►M12  long-term (chronic) hazard ◄ ’ means for classification purposes the hazard of a substance or mixture caused by its chronic toxicity following long-term exposure in the aquatic environment.
(k) no observed effect concentration (NOEC)’ means 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.
4.1.1.2. Basic elements
4.1.1.2.0.

►M12  Hazardous to the aquatic environment is differentiated into:

 short-term (acute) aquatic hazard

 long-term (chronic) aquatic hazard. ◄

4.1.1.2.1.

The basic elements used for classification for aquatic environmental hazards are:

 acute aquatic toxicity,

 chronic aquatic toxicity,

 potential for or actual bioaccumulation, and

 degradation (biotic or abiotic) for organic chemicals.

4.1.1.2.2.

Preferably data shall be derived using the standardised test methods referred to in Article 8(3). In practice data from other standardised test methods such as national methods shall also be used where they are considered as equivalent. Where valid data are available from non-standard testing and from non-testing methods, these shall be considered in classification provided they fulfil the requirements specified in section 1 of Annex XI to Regulation (EC) No 1907/2006. In general, both freshwater and marine species toxicity data are considered suitable for use in classification provided the test methods used are equivalent. Where such data are not available classification shall be based on the best available data. See also Part 1 of Annex I to Regulation (EC) No 1272/2008.

4.1.1.3. Other considerations
4.1.1.3.1.

Classification of substances and mixtures for environmental hazards requires the identification of the hazards they present to the aquatic environment. ►M12  The aquatic environment is considered in terms of the aquatic organisms that live in the water, and the aquatic ecosystem of which they are part. The basis, therefore, of the identification of short-term (acute) and long-term (chronic) hazards is the aquatic toxicity of the substance or mixture, although this shall be modified by taking account of further information on the degradation and bioaccumulation behaviour, if appropriate. ◄

4.1.1.3.2.

While the classification system applies to all substances and mixtures, it is recognised that for special cases (e.g. metals) the European Chemicals Agency has issued guidance.