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Long-term toxicity to aquatic invertebrates

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Description of key information

In a long-term study on Daphnia, the 21-day LC50-value of parents was determined to be higher than 1.45 mg test item/L (measured) and the 21-day reproduction EC50 value was calculated to be 1.42 mg test item/L (measured). 
The NOEC for reproductive effect was determined as 0.68 mg test item/L (measured).

Key value for chemical safety assessment

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

Additional information

A long-term study is available on Daphnia magna (2013) giving a NOEC of 0.68 mg/L. This study was selected as key study, and the NOEC was taken into account for the calculation of the PNEC.

In this study (2013), Daphnia magna were exposed in a semi-static test to aqueous test media containing the test item for 21 days, according to the OECD 211 guideline and realised under GLP conditions.

The Daphnids were exposed to the test item at the following nominal exposure concentrations:0.1, 0.2, 0.4, 0.8 and 1.6 mg/L.

 

Each exposure and control group comprised 10 Daphnids. The test animals were maintained individually, one per test vessel, with ~80 mL of test solution in each vessel.

As the measured concentrations deviated more than 20 per cent from the nominal in some cases, biological results are based on the measured geometric mean concentrations. The corresponding measured geometric mean test item concentrations were: 0.07; 0.16; 0.34; 0.68 and 1.45 mg/L.

The reproduction of the surviving parent animals in the highest test item treated group of 1.45 mg/L was not significantly different from the control group (Dunnett’s Test, α=0.05).

The body length of the surviving parent animals in the highest test item treated group was significantly different from the control group (Dunnett’s Test, α=0.05).

Statistically significant difference was also observed concerning the time to production of first brood between the highest test item treated group of 1.45 mg/L and the control group.

 

In this 21-days Reproduction test on Daphnia magna with Paramethoxyphenol:

-      the 21-day LC50-value of parents was determined to be higher than 1.45 mg test item/L (measured) and the 21-day reproduction EC50 value was calculated to be 1.42 mg test item/L (measured).

-      The NOEC for reproductive effect was determined as 0.68 mg test item/L (measured)

-      The LOEC was determined as higher than 1.45 mg test item/L (measured).

 

The NOEC and LOEC were determined based on the time to production of the first brood and based on the fact that, even if not statistically significantly different from the control, the effect on the reproductive output of the parent animals at the highest tested concentration is important.