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Short-term toxicity to aquatic invertebrates

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Description of key information

The 48-hour median effect concentration (EC50) for immobility, based on measured concentrations of volatile free 1592U89 was found to be 119 mg/L (with 95% confidence limits of 60.6 and 251 mg/L).

After 48 hours, the highest measured concentration at which no immobilisation occurred was 60.6 mg/L and the lowest at which there was 100% immobility was 251 mg/L. The no observed- effect concentration (NOEC) was 60.6 mg/L.

The results of chemical analysis indicated that intended exposure levels were adequately achieved and maintained during this 48-hour test.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
119 mg/L

Additional information

The study was carried out on one of the analogue materials. The analogue is considered to be sufficiently similar to the substance of interest (please see attached data matrix and justification in Section 13 for additional details) for it to be used for the purposes of health and environment risk assessments.

Introduction:

The purpose of this test was to determine the 48-hour median effect concentration (EC50) of 1592U89 for immobilisation of Daphnia magna. The test was conducted in accordance with US FDA Environmental Assessment Technical Assistance Handbook (March 1987) - Document 4.08 and, where possible, Procedure 202 ofthe OECD Guidelines (1984).

Method:

The test material (Batch number 94/5977-047-657), received on 12 April 1996, was stored at ambient temperature, protected from light. Test results are expressed in terms of volatile free 1592U89. Groups of twenty Daphnia were exposed to 1592U89 at nominal concentrations of 62.5 to 1000 mg/L (95 to 1520 mg/L as the succinate salt). The test media were prepared from a pH adjusted concentrated aqueous dispersion in which the test material had been added directly to dilution water (dechlorinated tap water).

Results:

The results of chemical analysis indicated that the intended exposures of the test material were adequately achieved and maintained during the test. After 48 hours, the highest measured concentration at which no immobilisation occurred (also the no-observed-effect concentration, NOEC) was 60.6 mg/L and the lowest concentration at which there was 100% immobility was 251 mg/L. The 24- and 48-hour EC50 values, based on measured concentrations of I592U89, were 176 and 119 mg/L respectively.

Conclusion:

The test material is considered to be of low toxicity to Daphnia magna.