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Toxicity to microorganisms

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Description of key information

The inhibition of the degradation activity of activated sludge is not anticipated when introduced in appropriately low concentrations.

Key value for chemical safety assessment

Additional information

Three short-term respiration inhibition tests according to ISO 8192B were performed using activated sludge from an industrial wwtp instead of activated sludge from a wwtp treating predominantly domestic sewage. The exposure duration was 30 minutes. The following effect values were determined for 1 -ethylpiperidine (CAS 766 -09 -6):

30 -min EC20: > 500 mg/L (BASF AG, 1988; 05 Feb 1988)

180 -min EC20: > 100, < 500 mg/L (BASF AG, 1988; 05 Feb 1988)

30 -min EC20: > 1510 mg/L (BASF AG, 1988; 04 Feb 1988)

30 -min EC20: > 1510 mg/L (BASF AG, 1988; 26 Jan 1988)

30 -min EC10: ca. 500 mg/L (BASF AG, 1988; 26 Jan 1988)

It can be concluded that the EC20 is significantly greater than 100 mg/L.

Since the respiration inhibition test with 1 -ethylpiperidine were performed with activated sludge from an industrial wwtp, experimental data from the structurally similar substance 1 -Methylpiperidine (CAS 626 -67 -5) were used to support the assessment and to derive the PNEC_STP.

Two short-term respiration inhibition tests were performed according to the OECD Guideline 209 (Activated sludge, Respiration Inhibition Test) using activated from a wwtp treating predominantly domestic sewage. The effect values were as follows:

- 30 -min EC20: > 996 mg/L (BASF AG, 1989; 01.89/1260)

- 30 -min EC10: > 1000 mg/L (BASF AG, 1991; 101.91/0271/08/1)

- 30 -min NOEC: 1000 mg/L (BASF AG, 1991; 101.91/0271/08/1)

In conclusion, the inhibition of the degradation activity of activated sludge is not anticipated when 1-ethylpiperidine is introduced in appropriately low concentrations.