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Ecotoxicological information

Toxicity to soil microorganisms

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Reference
Endpoint:
toxicity to soil microorganisms
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
other:
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING
A study with calcium silicate has not been conducted as there are no concerns in regard to direct and indirect exposure of the soil compartment. The substance is considered to have no or very low toxicity based on a number of studies.

As the substance is poorly soluble, low concentrations are expected in the aquatic compartment. Low quantities which might be taken up are considered to have no or low bioavailability. Although ion exchange processes are possible, depending on the surrounding environment, the degree of hydrolysis involved in the dissolution of silicates in water is very limited and not quantifiable. Based on the chemical nature, inorganic structure and chemical stability of calcium silicate, phototransformation in air, water and soil is not expected.
The substance can be considered to have no/low toxicity based on the results of aquatic testing on three trophic levels. In each study the L(E)L50s were above 1000 mg/L, i.e. much greater than the solubility of the substance (11 mg/L). The ErL10 from the algal study was reported to be 41 mg/L, based on extrapolation from the available data. This value is also well in excess of the water solubility of calcium silicate. In addition, the interpretation of the algal toxicity ErL10 value must be carried out with caution, since it is well known that the growth-inhibiting effects of complexing agents and ion-exchanging materials, which are often observed in standard culture-media, result from the depletion of trace metals essential for algal growth. Thus, it can be concluded that the inhibitory effect observed in nutrient-poor or standard test media is without any practical relevance and not to be considered as a toxic effect.
A structurally related substance, silicon dioxide, was negative in an in vitro bacterial reverse mutation assay using Salmonella typhimurium TA 1538, TA1535, TA1537, TA98 and TA100 with and without metabolic activation. There was no evidence of cytotoxicity.
Finally a PBT assessment concluded that the substance should not be considered to be PBT.
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Description of key information

A study with calcium silicate has not been conducted as there are no concerns in regard to direct and indirect exposure of the soil compartment. The substance is considered to have no or very low toxicity based on a number of studies.

Key value for chemical safety assessment

Additional information