Registration Dossier

Ecotoxicological information

Toxicity to microorganisms

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

In the available guideline studies, the EC50 values of C12-16 ADBAC for activated sludge ranged from 7.75 to 11 mg a.i./L. Furthermore, in another guideline study, a NOEC of 1.6 mg a.i./L and an EC10 of 4 mg a.i./L were determined.

Key value for chemical safety assessment

EC50 for microorganisms:
7.75 mg/L
EC10 or NOEC for microorganisms:
4 mg/L

Additional information

An activated sludge respiration inhibition test was performed according to OECD guidelines with the read-across substance C12-16 ADBAC. The respiration rate of activated sludge fed with a standard amount of synthetic sewage was measured. The respiration rate of the same activated sludge in the presence of various concentrations of the test substance under otherwise identical conditions was also measured. The inhibitory effect of the test substance at a particular concentration was expressed as a percentage of the mean respiration rates of the controls. The validity of the test was shown by two criteria. First, the control respiration rates were within 15% of each other and secondly, the EC50of the reference compound 3, 5-dichlorophenol (5.2 mg/L) was within the prescribed range of 5 to 30 mg/L. No analytical determination was performed for the test substance. The EC50 was 11 mg a.i./L. The EC10, EC20 and EC80were 4.0, 5.0 and 24 mg a.i./L, respectively. The test substance was therefore considered harmful to activated sludge (Geerts R and van Ginkel CG, 2004).

In another OECD guideline study, the effect of C12-16 ADBAC on activated sludge was determined. A mixture of activated sludge, synthetic sewage feed and a range of concentrations of the test substance or the reference substance were prepared in one liter glass beakers. The mixtures were aerated and after an incubation period of 3 hours at a temperature between 21.9 and 23°C, the decrease in the oxygen concentration in the mixtures was recorded during a period of 10 min. The inhibitory effect of the test substance at a particular concentration was expressed as a percentage of the mean respiration rates of the controls. The substance (50% pure) was tested at nominal concentrations of 0, 1, 3.2, 10, 32, 100, 320 and 1,000 mg/L. A control test with reference substance 3,5-dichlorophenol yielded an EC50 value of 5 mg/L, which is within the range of prescribed by guideline. The validity criteria of the guideline were fulfilled. No analytical determination was performed for the test substance. The EC50 was 7.75 mg a.i./L. The EC20 and EC80 were 3.4 and 17.8 mg a.i./L, respectively. The NOEC was 1.6 mg a.i./L. (Mayer Pet al.,2001).