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Long-term toxicity to aquatic invertebrates

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Description of key information

NOEC (21d) = 46.2 mg a.i./L  (Daphnia magna) 

Key value for chemical safety assessment

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No experimental data investigating the chronic effects of sodium 2,4-dichlorophenoxyacetate (CAS No. 2702-72-9) to aquatic invertebrates are available. Thus, conclusions on this endpoint had to be drawn based on data from analogue substances. The chronic effects of dimethylammonium 2,4-dichlorophenoxyacetate (CAS No. 2008-39-1) to aquatic invertebrates were investigated by Mark and Hantink-de Rooy (1989), in a test conducted according to Draft 4, EEC XI 681/86 (1986) and UBA (1984), under GLP conditions. Daphnids (Daphnia magna) were exposed for 21 days to the test substance and effects on survival and reproduction were reported at the highest concentrations tested (100 and 215 mg/L). The resulting NOEC was determined to be 46.2 mg a.i./L.

Sodium 2,4-dichlorophenoxyacetate is highly soluble and it is rapidly dissociated in water, being 2,4-dichlorophenoxyacetic acid (CAS No. 94-75-7) its main product. This substance was tested in a study by Fochtman (2003) according to OECD Guideline No. 211, Daphnia magna Reproduction test (1998), under GLP conditions. After 21 days of exposure to the test item in a semi-static water regime, no effects on daphnids reproduction were observed an a NOEC = 100 mg test substance/L was determined.