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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

One study examined the effect of the test substance disodium disilicate (delta-crystalline) on micro-organisms, by means of measuring the inhibitory effect in respiration (oxygen consumption) of micro-organisms in activated sludge taken from a domestic sewage. The EC50 value obtained in the study was 720 and 1000 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
720 mg/L

Additional information

The effect of the test substance disodium disilicate (delta-crystalline) on micro-organisms was assessed by measuring the respiration rate (oxygen consumption), according to OECD Guideline 209. The oxygen consumption of activated sludge (taken from a domestic sewage in Hildesheim, Germany) fed with synthetic sewage feed was measured after a contact time of 3 hours with 100, 180, 320, 580, 1000 mg/L disodium disilicate (delta-crystalline). A reference substance (potassium dichromate) and two controls (same inoculum and same synthetic sewage feed without the test substance) were used and fulfilled the validity criteria. The inhibitory effect of the examined test substance at a particular concentration was expressed as percentage of mean respiration rates of the two controls.

The EC50 (the concentration of test substance at which respiration rate is 50 per cent of control) was determined to be 720 mg/L.

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