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Ecotoxicological information

Long-term toxicity to fish

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Description of key information

Long-term toxicity to fish: NOEC = 2.5 mg/L  for the zebrafish, 14 d-prolonged toxicity, flow-through  (OECD TG 204); study Röderer (1990)

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater fish:
2.5 mg/L

Additional information

The value for the key parameter is based on the lowest observed value in a study considered to be reliable (key study: Röderer, 1990) using zebrafish Brachydanio rerio in a 14 -day prolonged toxicity test using a flow-trough system. This protocol is not considered as a true chronic test but rather a subchronic one.

The second study (Black, 1982) using rainbow trout and fathead minnow in short term toxicity tests on embryo and sacfry stages is regarded unreliable. According to Eurochlor assessment, this study has been criticised for testing widely spaced concentrations and giving few details of control performance (UK Department of the Environment, 1994) and the methods were non-standard and not well validated. However, they were conducted under flow-through conditions, with control of volatile loss and with analysis. Therefore, the long-term LC50 values quoted can be used with care. The 9 day-LC50 (4 days post-hatch) for P. promelas was 4 mg/l; for S. gairdneri, the 27 day-LC50 (4 days post-hatch) was 1.97 mg/l. A NOEC (which is required for the PNEC calculation) is not cited in the paper. The lowest concentration tested which had no discernible effect on survival of S. gairdneri (0.07 mg/l) is not valid as a NOEC, because of the wide interval between concentrations. The conclusion is that the apparent NOEC was within the range 0.07 to 1.1 mg/l. However, the lower end of this range is approximately the same as the NOEC for freshwater algae. Therefore, the S. gairdneri study is sufficient to demonstrate that fish are no more sensitive than other trophic levels and the study can be used for that purpose without needing to define a NOEC for PNEC calculation.