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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

Three studies were selected for a weight of evidence approach. The most critical effect concentration from these studies was a 16-h EC50 of 15000 µg/L for growth inhibition of the bacterium Pseudomonas putida (Schmitz et al., 1998) obtained from a study in which SeO2 was used as test substance.

Key value for chemical safety assessment

EC50 for microorganisms:
15 000 µg/L

Additional information

For toxicity to aquatic microorganisms, 18 studies were identified as relevant (including 1 review publication). However, none of these studies turned out to be reliable. Three single-species tests with relevant species, but without analysis of the dissolved Se concentrations during exposure, were selected for a weight-of-evidence approach.

For the highly relevant ciliate Spirostomum ambiguum a 48-h LC50 of 32280 µg Se/L was obtained from a study with Na2SeO3 (Nalecz-Jawecki and Sawicki, 1998). Next to this value, two 16-h EC50 values were included for growth inhibition of the bacterium Pseudomonas putida. These values are reported in the same study (Schmitz et al., 1998), in which experiments were conducted with both SeO2 and Na2SeO3. The 16-h EC50 values for these substances are 15000 and 33400 µg Se/L, respectively.