ECHA - Guidance of the application of CLP criteria [November 2012]

Guidance on the Application of the CLP Criteria Version 3.0 - November 20121.3.2.2 Environmental hazardsThe hazard classification for the aquatic environment is based on the three elements aquatictoxicity, bioaccumulation and degradation. The measurement of toxicity to aquatic organismsand its use within a hazard classification system introduces a number of compoundingproblems. The substance is not dosed directly into the organism but rather into water in whichthe organism lives. While this reflects more accurately the manner in which the organism willreceive the dose in the environment, it does not allow the direct control of the dose which isan important part of much mammalian toxicity testing. The dose is limited by thebioavailability of the substance, the maximum dose being determined by the level of watersolubility.It is usually assumed that toxic effects are only measured following exposure to the dissolvedfraction, i.e. organisms are exposed to substances dissolved in water. It is assumed that thesubstances will either be absorbed by the organisms through passive diffusion or taken upactively by a specific mechanism. Bioavailability may, therefore, vary between differentorganisms. In the case of bioaccumulation, oral exposure could also be considered forsubstances with high Log K ow . Further guidance of the impact of bioavailability caused by thesize of the molecule and how this is considered for aquatic hazard classification can be foundin Annex III to this document.In general, there are no specific environmental test methods developed to measure biologicalavailability of substances or mixtures. This aspect is built into the testing methodology fortoxicity and if adverse effects are identified the substance should be classified accordingly.Substances which lack bioavailability would not be absorbed by the exposed organisms andtherefore due to lack of toxic effects these substances would not be classified, unless they areknown to degrade or transform to hazardous products. For example see the strategy for metalsclassification in Annex IV to this document.1.4 USE OF SUBSTANCE CATEGORISATION (READ ACROSS ANDGROUPING) AND (Q)SARS FOR CLASSIFICATION AND LABELLINGArticle 5(1) Manufacturers, importers and downstream users of a substance shall identify the relevantavailable information for the purposes of determining whether the substance entails a physical, healthor environmental hazard as set out in Annex I, and, in particular, the following:[…](c) any other information generated in accordance with section 1 of Annex XI to Regulation (EC) No1907/2006;Article 6(1) Manufacturers, importers and downstream users of a mixture shall identify the relevantavailable information on the mixture itself or the substances contained in it for the purposes ofdetermining whether the mixture entails a physical, health or environmental hazard as set out in AnnexI, and, in particular, the following:[…](c) any other information generated in accordance with section 1 of Annex XI to Regulation (EC) No1907/2006 for the mixture itself or the substances contained in it;Section 1 of Annex XI to REACH provides a list of data that can be used instead of testingwhen standard data are missing. This Annex specifies the conditions under which results of(Q)SARs, read across and grouping may be used for the classification of substances. It statesthat results of (Q)SARs may be used instead of testing when the (Q)SAR models have beenscientifically validated, “the substance falls within the applicability domain”, the "results areadequate for the purpose of classification and labelling" and “adequate and reliable46