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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

It was a  report for microbial inhibition test.   The IC50 was determined to be 784 mg/l.

Key value for chemical safety assessment

EC50 or LC50 for microorganisms:
784 mg/L

Additional information

There was a report for about microbial inhibition test. The report did not include information on dissolved oxygen concentrations, inhibition rates for controls or reference substance or duration of the study. Dates for the start and end of the study indicated that the test duration may have been up to 2 days. No inhibition curve was presented in the translated report, although it is indicated that this was included in the original. Although the IC50 for the reference substance was not included in the original report, a supplementary document was provided indicating that the validity criterion was satisfied. Dissolved oxygen concentrations and respiration rates of controls were not reported. Despite some limitations in the test report, the test was conducted to GLP and according to ISO guidelines, therefore it is considered acceptable for determining the PNEC for microorganisms. The IC50 was determined to be 784 mg/l.

As part of a monitoring study (Guzzella and Galassi, 1993; see section 3.1.4.2.2), water was extracted from the River Po at a site in Ferrara, at the closing section of the river basin. A bacterial assay using the Vibrio fischeri photobacterium (also known as Photobacterium phosphoreum) was used to determine toxicity of the samples; chemical analysis was performed using GC with a N/P-selective detector. The detection limit for organophosphorus compounds in water was 1 ng/l. A LUMIStox bacteriological assay was used. The micropollutants were removed from the water and redissolved. Over a 15-minute exposure period, the EC50 for TCPP was found to be 171.5 ppm (95% confidence interval of 149.0-197.0). Due to this study was not conducted with a standard method, it can only be defined as a supporting study.