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Sediment toxicity

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Description of key information

28-d NOEC >= 100 mg/kg sediment

Key value for chemical safety assessment

Additional information

The sediment organism Chironomus sp. was exposed to Triclosan and the number of emerged animals as well as signs of intoxication of the animals was recorded during a test period of 28 days. The test was set up according to OECD guideline 218 with artificial sediment. A NOEC >= 100 mg/kg sediment was determined (Ciba Specialty Chemicals 2006).

Dussault (2008) performed toxicity tests with spiked sediment with Chironomus tentans and Hyalella azteca similar to US EPA guideline EPA/600/R-99/064. Deviating from the guideline a larger test vessel and a higher animal density were used. Due to analytical difficulties sediment concentrations were not verified, therefore effect values are based on nominal concentrations. Based on mortality a 10 -d LC50 of 397.6 mg/kg sediment for C. tentans and 198.8 mg/kg sediment for H. azteca were determined.

These studies confirm the results of the OECD 218 study by Ciba Specialty Chemcials (2006).

Two further studies were performed by Dussault (2008) with spiked-water exposing C. tentans and H. azteca for 10 -d under semi-static conditions. The studies were performed to the above mentioned US EPA guideline. The test concentrations were analytically verified. The 10 -d LC50 for C. tentans was 0.4 mg/L, the EC50 (growth) was 0.28 mg/L. For H. azteca, the 10 -d LC50 was 0.20 mg/L and the EC50 was 0.25 mg/L. Regarding the low environmental relevance of exposure only via water and the availability of the three spiked-sediment studies mentioned above, the results of these studies are not considered for the risk assessment.

The study by Ciba Specialty Chemicals (2006) was selected as key study since it is a long-term study and a NOEC was derived. In addition the study was performed according to GLP.