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Short-term toxicity to aquatic invertebrates

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Description of key information

Data is available on the acute toxicity of calcium sulfate to invertebrates. No short-term toxicity was observed at the concentrations tested.

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Additional information

A GLP guideline study was performed which assessed the acute toxicity of calcium sulfate dihydrate (NIER, 2003) to Daphnia magna in a limit test. The 48 h LC50 for calcium sulfate dihydrate was found to be >100 mg/L, which is equivalent to >79 mg/L for calcium sulfate anhydrous. No mortalities or adverse effects were noted at this concentration.

A further OECD guideline study (van Eijk, 2009), investigated the toxicity of flue gas desulphurisation gypsum on Daphnia magna.

The results showed that toxicity of the test material was low in all samples but some effects were noted in 3 of the 4 test samples. In one gypsum sample no effects were seen when the saturated solution was tested. The 48 h LC50 was 73% of the saturated solution which is equivalent to 1.533 g/L. The gypsum samples contained other trace metals in addition to Ca and it is therefore possible that the effects on Daphnia magna were caused by the other elements present in the test samples.

A literature study is available that quotes the 48 h LC50 values for calcium sulfate as >1970 mg/L for Daphnia magna and >1910 mg/L for Ceriodaphnia dubia (Mount et al, 1997).

Using a weight of evidence approach, the acute toxicity of calcium sulfate to invertebrates is generally greater than the highest concentration tested and is considered to be greater than the maximum solubility of calcium sulfate in water.

Calcium sulfate showed no short-term toxicity to aquatic invertebrates and is therefore not acutely toxic to invertebrates at the limit of its water solubility.