Copper iodide

Toxicity to microorganisms

Additional information

COPPER IODIDE

The environmental hazard associated with copper iodide is assessed in terms of the toxicity of copper and iodide ions released during dissociation of the compound in the aqueous phase.

 

Summary information on the toxicity of copper and iodide ions to microorganisms is presented below.

COPPER

Short 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/LC10 or NOEC: 0.23 mg/l

Discussion:

NOECS for micro-organisms- STP

Data on the toxicity tests performed with aquatic bacteria and protozoa, reported as L(E)C50 and 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 NOEC values (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.

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

IODINE:

Short description of key information:

The EC10 for iodine (3 hours contact time) is 110 mg/L and the EC50 (3 hours contact time) is 280 mg/L.

Key value for chemical safety assessment:

EC50/LC50: 280 mg/L.

EC10/LC10 or NOEC: 110 mg/L.

Discussion:

This study investigated the ability of iodine to adversely affect aerobic microbial treatment plants. The source of test organisms is activated sludge freshly obtained from a municipal sewage treatment plant receiving predominanty domestic sewage. As this study was conducted to OECD Guideline 209: Activated Sludge, Respiration Inhibition Test this is considered to meet the Klimisch reliability criteria of 1 - reliable without restriction. The EC10 for iodine (3 hours contact time) is 110 mg/L and the EC50 (3 hours contact time) is 280 mg/L.