Registration Dossier

Diss Factsheets

Ecotoxicological information

Toxicity to microorganisms

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

The inhibition of the degradation activity of activated sludge is not anticipated when introduced in appropriate low concentrations. 
2-Methylbutan-1-ol has an EC50 determined to be greater than 1000 mg/L and the EC10 was determined to be 470 mg/L. However, to be conservative, the EC10 value of 370 mg/L is used for PNEC determination..

Key value for chemical safety assessment

Additional information

A study according to OECD 209 (BASF 2010) was performed to determine the toxic effects of the test substance 2-methylbutan-1-ol (CAS 137-32-6) on the oxygen consumption rate of aerobic micro-organisms (activated sludge) after short-term exposure of 180 min, compared with the blank control. The nominal concentrations of the surrogate test substance were: 0 (control), 62.5 mg/L, 125, 250, 500 and 1000 mg/L. The inoculum was activated sludge from a municipal waste treatment plant. The sludge concentration was 1.5 g/L and a synthetic medium according to the guideline was used. A reference substance (3,5 dichlorophenol) was used as positive control. The EC50 was determined to be greater than 1000 mg/L and the EC10 was determined to be 470 mg/L.

In addition a study according to OECD 209 (BASF 2010) was performed to determine the toxic effects of the surrogate test substance pentanol, branched and linear (CAS 94624-12-1) on the oxygen consumption rate of aerobic micro-organisms (activated sludge) after short-term exposure of 180 min, compared with the blank control. The inoculum was activated sludge from a municipal waste water treatment plant. The sludge concentration was 1.5 g/L. A reference substance (3,5 dichlorophenol) was used as positive control. The EC50 was determined to be greater than 1000 mg/L and the EC10 was determined to be 370 mg/L.

Supplementary a study according to ISO 8192 (Test for Inhibition of Oxygen Consumption by activated sludge) (BASF 1989) was performed to determine the toxicity of the read across substance pentan-1-ol after 180 min of exposure. The EC20 was determined to be greater than 1000 mg/L. No EC10 and EC50 values are given. 

In conclusion, as the EC10 value determined with the read-across substance pentanol, branched and linear (CAS 94624-12-1) was lower than the EC10 value determined in the study with the target substance itself, the smaller value (3h-EC10 = 370 mg/L) was chosen as “key value” and also used for PNEC derivation, reflecting a worst case scenario.