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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

High quality effects endpoints on micro-organisms are available for :  heterotrophic respiration inhibition, nitrification inhibition and effects on ciliated protozoa from sewage treatment plants.   The NOEC/L(E)C10  values from these studies are carried forward for the PNEC derivation in a WOE approach.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
0.23 mg/L

Additional information

NOECS for micro-organisms- STP

Data on the toxicity tests performed with aquatic bacteria and protozoa, reported as L(E)C50and NOEC values. The following high quality publications were selected for assessing the toxic effects of copper on bacterial populations: Dutka (1983), Waara (1992), Madoni et al. (1996), Milksch & Schürmann (1988), Almanza et al. (1996), Fiebig & Noack (2004) and the results from the Cha et al. (2003) research project. The date from Sauvant et al., 1997 ; Schäfer et al., 1994, Girling et al., 2000 were used for assessing the effects on protozoan populations

The exposure time among reports varied from short term batch exposures to continuous exposures. The effects endpoints on micro-organisms covered are: heterotrophic respiration inhibition, nitrification inhibition and effects on ciliated protozoa.

The bacterial studies using mixed population tests (e.g. activated sludge) representative for microbial degradation in STP, resulted in NOECvalues (reported as total or nominal concentrations) ranging from <0.5-1 and 5.4 mg/l for the heterotrophs and between 3.5 and >20 mg/l for the nitrifiers. The EC50values for the micro-organisms representative for microbial degradation in STP range from 2.1 to 26 mg/l Cu (as total or nominal copper) for the heterotrophs and between 9.9 and 49.1 mg/l for the nitrifiers (as total or nominal copper). Expressed as dissolved copper concentrations, a NOEC range for heterotrophs between 0.23 and 0.45 mg/l was observed. For the nitrifiers, a NOEC range between 0.26 and >0.92 mg/l was observed .

Protozoan tests resulted in NOEC/L(E)C50 values depending on the test species and test-set-up used. The short term tests withT. pyriformis, the species recommended by the TGD/REACH(1996, revisions 2003), resulted in NOEC and EC50(growth) values between, respectively, 3.6 - 3.8 mg/l and 8.0-10.2 mg/l nominal copper. These toxicity test results are based on short term experiments (between 2 and 4 days) performed in artificial media. The results obtained from protozoan communities were deemed to be more representative for the functioning of STPs and were therefore retained for the PNEC derivation. 

Accross endpoints/studies 0.23 mg dissolved Cu/L was considered as the most reliable NOEC