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Ecotoxicological information

Long-term toxicity to aquatic invertebrates

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Description of key information

One reliable chronic toxicity study was identified.
Biesinger and Christensen reported a 21d-EC16 of 42 mg Sr/L (nominal values), which can be used for the estimation of a NOEC-value of 21 mg Sr/L (i.e., EC16/2; ECHA-guidance). The value re-calculated to strontium sulfide resulted in an NOEC-value of 29 mg SrS/L.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
29 mg/L

Additional information

Reliable chronic toxicity data for freshwater/marine invertebrates are available for strontium but not for sulfate. Toxic effects of released sulfide from SrS are not relevant for the chronic hazard assessment of SrS as it is oxidized to sulfate, and thus the toxicity of sulfate should be assessed. In freshwater, however, sulfate appears to be of low toxicity to invertebrates with acute LC/EC50 values far above 1000 mg/L. Sulfate is essential to all living organisms, their intracellular and extracellular concentrations are actively regulated and thus, sulfates are of low toxicity to the environment (OECD SIDS for Na2SO4). The solubility product constant of strontium sulfate of ~3×10–7 indicates that once sulfide released from SrS is oxidized to sulfate, and that celestite (SrSO4) precipitates. Therefore, it may conservatively be assumed that the toxicological moiety of concern for the long-term toxicity of SrS to invertebrates (if any) is strontium and further that the contribution of sulfate to the overall toxicity of SrS may be neglected.

Biesinger and Christensen (1972) reported a nominal 21-EC16of 42 mg Sr/L for the water fleaDaphnia magna. Measured concentration levels were not reported. According to ECHA Guidance, a NOEC can be estimated by dividing a reliable ECXby 2 when X refers to an effect between 10 and 20%. The 21d-EC16of 42 mg Sr/L is compliant with this criterion. Thus, a NOEC of 21 mg Sr/L is derived for the reproduction ofDaphnia magnain freshwater corresponding to the 21d-NOEC of 29 mg SrS/L.

It is concluded that the chronic toxicity of SrS under normal environmental conditions is determined by the release of strontium, and the21d-NOEC of 29 mg SrS/Lis considered in the CSA.