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Acute and chronic toxicity of high-grade chlordane (98%) and bioaccumulation were investigated in Daphnia magna at water soluble concentrations obtained without cosolvent. The measured effective concentrations immobilizing 50% of the microcrustacea (95% confidence interval) were 22.6 (19.7-26.1) microg/L at 24 h and 13.4 (11.3-15.8) microg/L at 48 h. This indicated an increase of chlordane toxicity with time of exposure as confirmed in chronic studies. After 21 d of exposure, significant effects on survival were recorded at a chlordane concentration greater than 2.9 microg/L, whereas reproduction (number of offspring per adult, brood size) and length of adults decreased at 0.7 microg/L or more in a concentration- and time-dependent manner. The production of male offspring and developmental abnormalities, consisting of underdeveloped second antennae and shell spines in live neonates, were recorded. The chlordane concentration tested with no significant adverse effect (NOEC) on reproduction of daphnids after 21 d compared with controls was 0.18 microg/L. The bioaccumulation factor of chlordane by daphnids exposed at a level of concentration close to the 21-d NOEC reached 10,600, wet weight, and 244,000, dry weight, after 40 d. The trans-chlordane bioaccumulated to a greater extent than the cis isomer in daphnids, whereas the cis isomer was predominant in the test medium. The results suggest a crucial role of the invertebrates in transfer of chlordane in aquatic food webs and can be used to derive a freshwater guideline for environmental protection accounting for bioaccumulation.

Chronic toxicity of chlordane, an organochlorine insecticide, was assessed on Ceriodaphnia dubia under standardized conditions of testing. Results were compared to Daphnia magna to determine the sensitivity of the two freshwater cladoceran species to this persistent organic pollutant (POP) and to explore the possibility of using the 7-day C. dubia test as an alternative to the 21-day D. magna test in chronic toxicity assessment of POPs. The NOEC-7d value of chlordane on reproduction of C. dubia (2.9 μg/L) was much higher than the NOEC-21d value of D. magna (0.18 μg/L), attesting that the 7-day test on C. dubia was less sensitive than the 21-day reproduction test on D. magna to chlordane. However, extending the period of exposure of C. dubia to chlordane from 7 to 14 days led to a NOEC-14d value similar to the NOEC-21d value in D. magna (0.18 μg/L). This study highlights the usefulness of prolonging the exposure time of the reproduction test in C. dubia from 7 to 14 days to increase the performances of the reproduction test on C. dubia for assessing chronic toxicity of POPs.

Fourteen series of toxic wastes from various origins (metallurgy, chemical industries, incinerators, industrial treatment plants, etc.) have been studied for their genotoxic properties with the Salmonella reversion assay. To consider realism of environmental impact, a strategy is proposed to assess genotoxicity of the water‐soluble fraction of the wastes. Water‐extractable micropollutants were further concentrated by liquid–liquid extraction or lyophilization prior to genotoxicity testing. None of the 14 crude aqueous fractions was shown to be mutagenic. On the contrary, positive responses were registered on the concentrated phases of two solid wastes derived from one chemical industry and from the treatment of organophosphorus wastewaters. Chemical analysis did not reveal the presence of known mutagens in the positive extracts. Interacting effects between micropollutants is thus hypothesized to explain genotoxicity.

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