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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

Activated sludge (3 hr): EC50, EC20 and EC10: >1000 mg/l
Pseudomonas putida (5 hr): EC10> 1600 mg/l
Pseudomonas putida (30 min): EC10 >300 mg/l

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L
EC10 or NOEC for microorganisms:
1 000 mg/L

Additional information

Five studies are available where the toxicity of bis(2 -ethylhexyl) maleate to bacteria has been investigated. Three studies were conducted under aerobic conditions. One study according to OECD 209 using activated sludge, reports all relevant EC values above the highest test concentration of 1000 mg/l. The second study was conducted according a modification of OECD 209 using Pseudomonas putida as test organism and extending the exposure period to 5 -6 hours instead of 3 hours as recommended in the guideline. In this study, an EC10 of >1600 mg/l was reported. The third study was conducted according to the German DIN standard 38 412 using also Pseudomonas putida as test organisms. Here, the exposure time was limited to 30 min only. The EC10 was reported to be >300 mg/l. However, this value is based on the highest test concentration where a measurement of the oxygen respiration was possible. Due to technical reasons the oxygen respiration rate in the highest test concentration of 1000 mg/l could not be determined. However, it is reported that the oxygen consumption was increased in all of the measured test concentrations.

Two supporting anaerobic studies are available, both conducted according to the ETAD fermentation tube test over a test period of 24 hours and reporting an EC0 of > 74 mg/l and a toxicity threshold of 20 mg/l, respectively.

For the chemical safety assessment, the OECD study with activated sludge was selected as the key study. It represents the worst case of both OECD studies, was conducted with a sufficient exposure time, and a measurement of the oxygen consumption could be determined up to 1000 mg/l.