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Long-term toxicity to aquatic invertebrates

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Description of key information

NOEC (21 d) = 0.26 mg/L (measured) for Daphnia magna reproduction (OECD 2011), read across

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
0.26 mg/L

Additional information

Since no test regarding the long term aquatic toxicity of Zinc O, O, O', O'-tetrabutyl bis(phosphorodithioate) is available an analogy approach using the structural similar analogue substance Phosphorodithioic acid, mixed O, O-bis(1,3- dimethlybutyl and iso-Pr) esters, zinc salts (CAS 84605-29-8) has been applied. Further justification is given within the endpoint summary 6.1 and within the analogue justification section 13.

For the analogue substance one long term study on reproduction of the waterflea Daphnia magna is available (Keating, 2010). The study was carried out according to OECD guideline 211 under GLP conditions. Based on the results of an acute range finding test, the main test assessed the effect on daphnids over a 21 day period by observing survival, growth, and reproduction at the following nominal loading rates: 0, 0.05, 0.1, 0.2, 0.4 and 0.8 mg/L prepared from dilutions of a 100 mg/L WAF (water accomodated fraction). The measured concentrations differed by greater than 20% from the start of some exposure periods to the end, and therefore time-weighted means were calculated for each of the concentrations. The NOECs were 0.4 mg/L nominal (0.26 mg/L measured) for reproduction and 0.8 mg/L nominal (0.53 mg/L measured) for both daphnid length and daphnid weight. The LOECs were 0.8 mg/L nominal for reproduction and > 0.8 mg/L nominal for daphnid length and weight.