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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Aquatic toxicity studies with zinc didocosanoate are not available. In the assessment of zinc didocosanoate, read-across to analogue substances and/or the assessment entities soluble zinc substances and docosanoic/behenic acid is conservatively applied since the ions of zinc didocosanoate determine its fate and toxicity in the environment.

The toxicity of an analogue substance fatty acids, C16-18, zinc salts to Pseudokirchneriella subcapitata is low (EL10= 3.31 mg/L WAF, EL50 > 100 mg/L WAF). A similar low potential is assumed for zinc didocosanoate, a longer-chained fatty acids (C22) with a lower zinc content and solubility.

Further, data available for soluble zinc substances and behenic acid indicate that the moiety of ecotoxicological concern are zinc cations. Aquatic toxicity data of behenic acid point to a low toxic potential to aquatic algae. The ecotoxic potential of the fatty acid chain, i.e. behenate, is assumed to be negligible. Fatty acids are generally not considered to represent a risk to the environment, which is reflected in their exclusion from REACH registration requirements (c.f. REACH Annex V (Regulation (EC) No 987/2008)).

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