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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Pseudomonas putida strain NCIB 8248, ISO 10712 "Determination of the inhibitory effect of water constituents on bacteria (Pseudomonas cell multiplication inhibition test)", EC50(16h) : 480 mg/L

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A study was performed to assess the effect of the test material on the growth of the bacteria Pseudomonas putida.The method followed that described in the German Water Hazard Classification Scheme (Bewertung Wassergefährdender Stoffe LTWS - Nr 10) and ISO 10712 "Determination of the inhibitory effect of water constituents on bacteria (Pseudomonas cell multiplication inhibition test)". The study is regarded as a valid guideline study with certificated GLP compliance. The validity criteria of the ISO guideline were fulfilled. Following a preliminary range-finding study, Pseudomonas putida was exposed to an aqueous dispersion of the test material at concentrations of 0.50, 1.0, 2.0, 4.0, 8.0, 16.0, 32.0, 64.0, 128.0, 256.0, 512.0 and 1024.0 mg/I (three replicate flasks per concentration) for approximately 16 hours, at a temperature of 25°C. Samples of the bacterial populations were removed after approximately 16 hours and absorbance values determined for each control and treatment group.

Exposure of Pseudomonas putida to the test material gave an EC10 of 180 mg/I and an EC50 of 480 mg/l. The EC10 of 180 mg/I (180 ppm = 1.8 x 10

-4 kg/l) corresponds to an evaluation number (Bewertungszahl, BWZ) for the German Water Hazard Classification Scheme of 3.7. Statistical analysis of the absorbance values was carried out for the control and all test concentrations using a Students t-test. There were no statistically significant differences between the control and 0.50, 1.0, 2.0, 4.0, 8.0, 16, 32, 64 and 128 mg/I test concentrations (p≥0.05), however all other test concentrations were significantly different (p<0.001) and, therefore the "No Observed Effect Concentration" (NOEC) is given as 128 mg/I.