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Short-term toxicity to fish

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Description of key information

LC50 (96 h) Zebra fish > 300 mg/l

Key value for chemical safety assessment

LC50 for freshwater fish:
300 mg/L

Additional information

The short-term toxicity to fish was tested on CAS 67786-25-8, but only the test summary is available. The study was performed on Zebra fish at the dose concentration of 300 mg/l, following the OECD guideline 203 test procedures. No dead occurred, thus the LC50 was established as higher than 300 mg/l (Ciba-Geigy Ltd., 1992). Even if the reliability was set as 4, it is consistent and in agreement with the expected results for the category of Stilbene Fluorescent Whitening Agents and it supports the endpoint in a weight of evidence approach.

The overview of the category short-term toxicity to fish can be found in the data gap of the category, within the Category Justification Report attached to Section 13 of the dossier: eleven over fourteen registered substances were tested and for all of them the LC50 is greater than 100 mg/l.

The further tests here presented and following a weight of evidence approach, were performed on the analogous dihydroxyethyl derivative tetrasulphonated sodium salt (CAS 16470-24-9). This substance can be considered the best representative within the category, since it has the same sulphonation degree than CAS 67786-25-8, a very high structural similarity (Tanimoto distance > 0.9) and a very high water solubility (650 g/l Vs 1000 g/l of CAS 67786-25-8) (details in the category Justification Report, attached to the Section 13 of the dossier).

In all cases, the LD50 was recorded higher than 1000 mg/l.

Furthermore, a prolonged semistatic assay over 14 days was conducted with Brachydanio rerio. Endpoints were mortality, signs of intoxication, length and weight. The nominal concentrations 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 (Bayer AG., 1992).

Two fish acute toxicity tests are available (Ciba-Geigy, 1994 and 1998) on CAS 16090-02-1 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.

In conclusion, no fish acute toxicity is expected for CAS 67786 -25 -8 and its photodegradation products and the conservative value of LC50 (96h) greater than 300 mg/l, the maximum tested concentration on the substance, has been taken as a reference for the Chemical Safety Assessment.