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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

LC50 96h > 100 mg/l

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
100 mg/L

Additional information

Acute toxicity assays were performed on several species: Brachydanio rerio, Lescidus idus, Ictalurus lacustries, Salmo gairdnerii.

The most reliable studies set an LC50 higher than 100 mg/l. The assay with a LC50 value of 7.1 mg/l (Ciba-Geigy, 1991) showed flocculation and as a consequence, the recovery was only approx. 26 % and the study has been disregarded. The limited solubility and resulting precipitation is probably due to the formation of insoluble Ca++ and other salts, which may impair oxygen exchange at the gills. The results with purified Z- and E-isomers are reliable with good recovery rates and no flocculation observed.

A prolonged semistatic assay over 14 days was conducted on Brachydanio rerio. Endpoints were mortality, signs of intoxication, length and weight and the nominal concentrations tested were 100, 316 and 1000 mg/l. There was no mortality and no difference in body weight at nominal concentrations of 100 and 316 mg/l. Only at 316 mg/l one fish showed slackening in movement. Many data with low reliability about the acute toxicity to fish are available for the test substance (Bayer AG, 1993).

Many reports not completed of all information required to perform a scientifically valid study evaluation were found in the archives of the companies: most of them are old studies, which did not follow a recognized testing method; in some cases details on procedures, test conditions and results are not available; in other cases the procedures are in accordance with the international accepted testing procedures, but only a summary of the results is available.

Further two fish acute toxicity tests are available (Ciba-Geigy, 1994 and 1998) on the substance pre-treated with light in order to obtain a high percentage of photodegraded products and verify their impact on aquatic toxicity. Both tests resulted in a LC50 > 100 mg/l, demonstrating that those degradation products are no more dangerous for the environment than the parent compounds.


As a conclusion, based on the most reliable studies, the tested substance and his photodegradation products are considered as not acutely harmful to fish, with LC50 96h higher than 100 mg/l.