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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

In an activated sludge respiration inhibition test (OECD 209, EU C.11, limit test, according to GLP) the toxicity of Single super phosphate to bacteria was tested. At the nominal concentration of 100 mg/L 11% inhibition of respiration was observed. In the duplicate measurement no significant inhibition of respiration rate of the sludge was recorded. Therefore, no further testing was needed. Hence, the EC50 of Single super phosphate was >100 mg/l.
Supportive data on the bacterial toxity of other components support the conclusion of absence of toxicity to sewage sludge:
In a test with potassium humate according to EU method C11 no inhibtion of activated sludge respiration was found in concentrations up to 1000 mg/L EC50 > 1000 mg/L).
In an activated sludge respiration inhibition test (OECD 209, according to GLP) the toxicity of Calcium sulfate, dihydrate to bacteria was tested. At the nominal concentration of 1000 mg/L no significant inhibition of respiration was observed.

Key value for chemical safety assessment

Additional information

The following information on constituents of the submission substance and components of the humate-complexed superphosphate are available:

Single Superphosphate:

In an activated sludge respiration inhibition test (OECD 209, EU C.11, limit test, according to GLP) the toxicity of Single Superphosphate to bacteria was tested. At the nominal concentration of 100 mg/L 11% inhibition of respiration was observed. In the duplicate measurement no significant inhibition of respiration rate of the sludge was recorded. Therefore, no further testing was needed. Hence, the EC50 of Single Superphosphate was >100 mg/l.

Potassium humate:

In a test according to EU method C11 no inhibtion of activated sludge respiration was found in concentrations up to 1000 mg/L EC50 > 1000 mg/L).

Ca sulfate:

In an activated sludge respiration inhibition test (OECD 209, according to GLP) the toxicity of Calcium sulfate, dihydrate to bacteria was tested. At the nominal concentration of 1000 mg/L no significant inhibition of respiration was observed. Therefore, the EC50 of Ca-sulfate dihydrate was >1000 mg/l.