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Long-term toxicity to aquatic invertebrates

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Description of key information

21-day aquatic toxicity study on Daphnia

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
11.7 mg/L

Additional information

To assess the chronic toxicity of 1,4-CHDM DGE, to the freshwater daphnid, Daphnia magna, a 21-day static-renewal reproduction study was conducted and endpoints included adult daphnid survival, reproduction (total young produced per surviving adult female), and growth (length and weight of surviving adults).

The study was conducted with ten daphnids (one individual per replicate with ten replicates per dose level) exposed to nominal concentrations of 0 (water control), 0.75, 1.5, 3.0, 6.0, and 12 mg 1,4-CHDM DGE/L. Test solutions were renewed three times weekly (Monday, Wednesday, and Friday) throughout the 21-day exposure. Daily observations were made and the number of surviving daphnids recorded. Reproduction was evaluated by counting and removing neonates on test solution renewal days (M, W, and F). Lengths and dry weights of all surviving adult daphnids were measured and recorded following termination of exposure.

Freshly prepared bulk test solutions were sampled at test initiation and on days 2, 5, 7, and 14 of the study for analytical verification of 1,4-CHDM DGE concentrations. Spent test solutions (10 replicates per dose level when applicable) were pooled and analyzed on days 2, 5, 7, 14, and at the end of exposure (day 21). The samples were analyzed for 1,4-CHDM DGE by liquid chromatography/mass spectrometry (LC/MS). The resulting mean measured test concentrations were 0.730, 1.44, 2.81, 5.72, and 11.7 mg/L. No 1,4-CHDM DGE was detected in the water control above the lowest level quantitated (LLQ) of 0.0103 mg/L.

Results from the analyses of the test solutions throughout the 21-day study yielded mean percent of target concentrations ranging from 93.5 to 97.5%. The chronic toxicity values for the freshwater daphnid (Daphnia magna) exposed to 1,4- CHDM DGE over a 21-day static-renewal exposure period and based on mean measured concentrations were as follows:

The LOEC and MATC for survival, reproduction, and length and weight (at study termination) were >11.7 mg/L;

The NOEC for survival, reproduction, and length and weight (at study termination) was 11.7 mg/L;