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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

There are no toxicity to microorganism studies with the test substance,tin bis(2-ethylhexanoate).

Key value for chemical safety assessment

Additional information

There are no toxicity to microorganism studies with the test substance,tin bis(2-ethylhexanoate). This endpoint is waived in accordance with column 2 of REACH Annex VIII, which states that the activated sludge respiration inhibition testing (Required in section 9.1.4) does not need to be conducted if the substance is found to be readily biodegradable. Tin bis(2-ethylhexanoate) is readily biodegradable and the concentrations which were tested in the biodegradation screening tests are orders of magnitude higher than could be realistically expected in a STP influent, based on known use scenarios. As no apparent inhibition of the inocula was observed in the biodegradation screening tests, it can be assured that concentrations equal to or lower than those tested in the biodegradation screening tests would have no adverse impact on respiration or viability of the STP microorganisms.

 

In order to calculate a PNECSTP, a sludge respiration inhibition test on 2-ethylhexanoic acid was considered, since the 2-ethylhexanoic acid is expected to be the component of the test substance that would be bioavailable to microorganisms. Thus, based on a respiration inhibition study with 2-ethylhexanoyl chloride using municipal sludge,the 30-min EC20 was reported as 650 mg/L. No EC50 for respiration inhibition was reported in this study, therefore the EC20 value was conservatively used as the EC50 for the calculation of the PNECSTP.