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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

A key study is available that assesses the toxicity of the reaction mass of calcium carbonate

and calcium dihydroxide and calcium peroxide to microorganisms. The resulting 3h-EC50 is 170 mg/L, the 3h-NOEC is 30 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
170 mg/L
EC10 or NOEC for microorganisms:
30 mg/L

Additional information

The toxicity of the reaction mass of calcium carbonate and calcium dihydroxide and calcium peroxide to microorganisms has been assessed in a recent GLP activated sludge respiration inhibition study according to OECD guideline 209 (Desmares-Koopmans, 2012).

In this reliable study, activated sludge of predominantly domestic sewage were exposed to nominal concentrations of 10, 30, 100, 300 and 1000 mg/L for 3 hours. The initial pH of these test solutions was 7.3 (control) - 7.6 (10 mg/L) - 8.0 (30 mg/L) ) - 8.6 (100 mg/L) - 8.7 (300 mg/L) - 10.5 (1000 mg/L). A 3h-EC50 of 170 mg/L (confidence intervals: 100-290) and a NOEC of 30 mg/L were calculated.

In a supporting study by Wang (2019), it was found that CaO2 caused - to some extent - inhibitions to all the tested microbes. Its inhibition to hydrogen consumers was found to be much more severe than that to hydrolytic microbes and hydrogen producers.