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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

LC50 for freshwater fish:
100 mg/L

Additional information

The acute toxicity of the substance under registration (CAS 27344-06-5) on the fish Oncorhynchus mykiss was investigated over a period of 48 h, with the Modified Bioassay Method (n. a., 1976). Based on mortality data at 48 h of exposure the LC50 of the test item resulted higher than 1000 mg/l. The study is only a summary and the test duration was of 48 h instead than 96 h, therefore the study was considered as supporting and studies on similar substances belonging to the Stilbene Fluorescent Whitening Agents category were reported.

 

Testing results on the substance CAS 70942-01-7 were considered. CAS 70942-01-07 is the analogous dihydroxyethyl derivative, disulphonated, sodium / potassium salt.

Both the analogous and the substance under registration are disulphonated sodium salts with a very similar chemical structure. Tanimoto similarity is > 0,85. The difference is a carbamoyl terminal organic group for CAS 27344-06-5 instead than an hydroxyethyl group for CAS 70942-01-7. The salification with potassium has no environmental or toxicological relevant impact. Both CAS 27344-06-5 and CAS 70942-01-7 are very soluble substances in water, thus bioavailable (57.4 g/l vs 13.45 g/l, respectively).

Acute toxicity to Zebra fish was evaluated in the 96 hours screening test, according to the OECD guideline 203. A single dose was administrated at 100 mg/l (limit test) with no effect (Novartis Services AG., 1999).

Another study performed on the analogous substance CAS 16470-24-9 has been considered. The substance is chemically similar to CAS 27433-06-5: also in this case the substitution on the triazino moiety isan hydroxyethyl group for CAS 16470-24-9 instead a carbamoyl terminal organic group for CAS 27344-06-5; furthermore the sulphonation degree is higher in the analogous than in the substance under registration being a tetrasulphonated derivative. This makes this substance much more soluble in respect to CAS 27344-06-5 (650 g/l vs 54.7 g/l, respectively) and a more conservative example due to higher aquatic bioavailability.

The test on the acute toxicity to fish was conducted according to OECD 203, on Zebrafish (Brachydanio rerio) and the no abnormalities were recorded up to 1000 mg/l for the exposure period of 96 hours (Ciba - Geigy Ltd., 1992).

A further prolonged semistatic assay over 14 days was conducted with Brachydanio rerioon CAS 16470-24-9. 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 CAS27344-06-5.