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Toxicity to microorganisms

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Description of key information

3h-EC50 > 100 mg/L (nominal)
3h-EC50 > 0.078 mg/L (limit water solubility)

Key value for chemical safety assessment

Additional information

The toxicity of ethyl 3,5 -dichloro-4 -hexadecyloxycarbonyloxybenzoate (AF-366) to aquatic microorganisms was investigated by Caspers (2003). This test was conducted according to EU Method C11, under GLP conditions. Activated sludge collected from a domestic sewage treatment plant was exposed to test concentrations of 100, 1000 and 10000 mg/L (nominal) for 3 hours. Additionally, a physico-chemical oxygen consumption control was applied at 10000 mg/L (nominal). A positive control (3,5-dichlorophenol) was used in order to validate the test conditions. Analytical measurements of the actual test substance concentrations were not performed.

 

The results from the physico-chemical control showed that no O2-consumption is expected only due to chemical reactivity. Respiration inhibition was observed in all treatment groups, with values ranging from 9.5% (100 mg/L, nominal) to 14.3% (10000 mg/L, nominal). However, these values were not significantly different from those found in the controls and the 3h-EC50 was determined to be > 10000 mg/L (nominal).

 

Based on this information and the toxicity control results from the biodegradation test conducted by Hanstveit and Hemmink (1989, > 25% biodegradation within 14 days) it can be concluded that AF-366 does not have an inhibitory effect on the activity of aquatic microorganisms within the range of its water solubility (≤ 0.078 mg/L).