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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms
Data waiving:
other justification
Justification for data waiving:
the study does not need to be conducted because the substance is found to be readily biodegradable and the applied test concentrations are in the range of concentrations that can be expected in the influent of a sewage treatment plant

Description of key information

for the influent of the sewage treatment plant was calculated according to the following formula:

water*106/EFFLUENT stp

al water was calculated to be 10.8 kg/d based on the assumption that a waste water stream saturated with Dodecane-12 -lactam is continuously released from the production site (water solubility 0.3 g/l), daily emission of waste water 36 m3; the effluent of the STP in Marl (Production site) is 11.3*106 l/d. The resulting influent concentration is thus 0.95 mg/l.

to the fact that the substance is readily biodegradable at this concentration (83% within 28 days, >60% in 10 day-window) it is assumed that the applied concentration is not inhibitory to bacteria and a possible exposure up to the amnt of the PEC poses no risk to sewage sludge bacteria.

The local PEC for STP was calculated according to chapter R.16.5.5.4 Modelling STP, Equation R.16-23. The calculated value was compared with the concentration used in the test on ready biodegradability (see chapter 5.2.1). The PEC is 20 times lower than the concentration used in the test on ready biodegradability. Since bacteria in this test degraded the substance by more than 60% in 10 days, it is assumed that the substance is not toxic to microorganisms.

Key value for chemical safety assessment

Additional information

The PEC for the influent of the sewage treatment plant was calculated according to the following formula:

C local influent = E local water*106/EFFLUENT stp

E local water was calculated to be 10.8 kg/d based on the assumption that a waste water stream saturated with Dodecane-12 -lactam is continuously released from the production site (water solubility 0.3 g/l), daily emission of waste water 36 m3; the effluent of the STP in Marl (Production site) is 11.3*106 l/d. The resulting influent concentration is thus 0.95 mg/l.

The concentration used for the ready biodegradability test (see 5.2.1.) was 20.9 mg/l. The calculated PEC is thus 20 times lower. Due to the fact that the substance is readily biodegradable at this concentration (83% within 28 days, >60% in 10 day-window) it is assumed that the applied concentration is not inhibitory to bacteria and a possible exposure up to the amount of the PEC poses no risk to sewage sludge bacteria.