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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

LC50 (96 h) Zebra fish > 100 mg/l

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
100 mg/L

Additional information

The short-term toxicity to fish was tested on 3b-A in one reliable study (Bionomics Inc., 1971) with EC50 greater than 85 mg/l, but no analytical concentrations measures were performed. Based on the described physicochemical properties it can be expected that the substance is stable in the testing environment, therefore it is assumed that the nominal concentration will correspond to the measured. Furthermore, two summaries are available: both describe a test performed at 48 h on trout. In one case the LC50 was stated at 140 mg/l (Ciba-Geigy Ltd. 1978 and Ciba-Geigy Ltd., 1979), while in the second one the LC50 was stated at 45 mg/l (Ciba-Geigy Ltd. 1975 and Ciba-Geigy Ltd., 1989). Test procedures are scientifically acceptable, nevertheless many detail are missing; furthermore there are no evidence that the concentration of the substance being tested has been satisfactorily maintained throughout the test.

 

In general the studies performed on the substance under registration present some deficiencies, therefore studies performed on similar substances (3a-A(NaK) and 3a-A(Na) have been taken as main reference. Justification for Read Across is given in Section 13 of IUCLID.

In the case of 3a-A(NaK) the presence of potassium ion has no relevant toxicological influence for the endpoint. For all the analogous water solubility is higher from 3b-A, therefore they are more bioavailable in the water compartment and can be considered as conservative examples.

The chemical structures are very similar, with Tanimoto similarity higher than 95 %: the 3b-A has a methyl group where the analogues has a hydroxyethyl substituent on the nitrogen atom. Based on the OECD Toolbox modelling of the liver metabolisation, both structures share the same monohyroxy derivative as main metabolite. Biological reactivity for the substance under registration is therefore not expected higher that the considered analogues substances.

All analogues tested showed a LC50 > 100 mg/l on fish at 96h.