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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

EC50 = 865 mg/L (BASF AG, 1993)
EC10 = 499 mg/L (BASF AG, 1993)

Key value for chemical safety assessment

EC50 for microorganisms:
865 mg/L
EC10 or NOEC for microorganisms:
499 mg/L

Additional information

Key study

The inhibitory effect of the test substance on the growth rate of Pseudomonas putida were examined in a static test according to DIN 38412, part 8. Bacteria were cultivated under specific conditions and growth rate was determined under the influence of the test substance compared to blank controls. Therefore the optical density of the bacteria suspension was measured at 436 nm after incubation with a photometer. The grade of toxicity was determined in comparing the extinction values of the controls with the test samples.

Bacteria were exposed to the test substance at concentrations of 0 (control), 39.06, 78.13, 156.3, 312.5, 625, 1250, 2500, 5000 and 10000 mg/L for 16 hours. 4 replicates were performed for each concentration. At the four highest test concentrations a raise of pH was observed. Neutralization resulted in a reduction of harmful effects, i.e. a reduction of growth inhibition. No bacteriotoxic effects were observed at concentrations below 1250 mg/L. An EC50 of 865 mg/L and an EC10 of 499 mg/L were determined (BASF AG, 1993).

Supporting study

The inhibitory effects of the test substance on the respiration rate of aerobic waste water bacteria was examined in a static test according to OECD guideline 209 (BASF AG, 1993). Bacteria were cultivated under specific conditions and respiration rate was determined under the influence of test substance compared to blank and positive controls. As positive control substance 3,5-Dichlorophenol was used in concentrations of 0.5, 5 and 50 mg/L. An EC50 of 10 mg/L was determined for the positive control. The bacteria were incubated with the test substance at concentrations of 250, 500 and 1000 mg/L for 30 min and 3 hours. An EC50 of above 1000 mg/L was determined.

The results with Pseudomonas putida were chosen as key values due to the lower sensitivity and the shorter duration of the sludge respiration test.