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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

One reliable acute toxicity data point (Klimisch 1, GLP) for a freshwater fish species  -the carp Cyprinus carpio - has been identified. Based on measured Sr-level in the water column, a 96h-LC50 of >84.5 mg SrSO4/L (>40.3 mg Sr/L)  is reported by Tobor-Kaplon (2010), using  strontium nitrate as test substance.
One reliable acute toxicity data point (Klimisch 2) for a saltwater fish species -morone saxatilits - has been identified. Based on measured Sr-level, an umbounded 96h-LC50 of >193.9 mg SrSO4/L (>92.5 mg Sr/L) is reported by Dwyer, F.J., et al. (1992), using strontium chloride hexahydrate as test substance.

Key value for chemical safety assessment

LC50 for freshwater fish:
84.5 mg/L
LC50 for marine water fish:
193.9 mg/L

Additional information

Read-across statement:

In the aqueous and terrestrial environment, strontium sulfate dissolves in (pore) water releasing strontium cations and sulfate anions.

Sulfate:Sulfates are of low environmental toxicity (OECD SIDS for Na2SO4) as sulfate is essential to all living organisms and their intracellular and extracellular concentrations are actively regulated.

Strontium: No or few ecotoxicological data are available for strontium sulfate itself. For the assessment of the environmental fate and behaviour of strontium substances, a read-across approach is applied based on all information available for inorganic strontium compounds. This is based on the common assumption that after emission of metal compounds into the environment, the moiety of toxicological concern is the potentially bioavailable metal ion (i.e., Sr2+).This assumption is considered valid as the ecotoxicity is only affected by the strontium-ion and not by the counter (sulfate) ion.The speciation and chemistry of strontium is rather simple.

 

As reactive electropositive metal, strontium is easily oxidized to the stable and colourless Sr2+ion in most of its compounds, the chemical behaviour resembling that of calcium and/or barium (Wennig and Kirsch, 1988). In the environment, the element only occurs in one valence state (Sr2+), does not form strong organic or inorganic complexes and is commonly present in solution as Sr2+(Lollar, 2005). Consequently, the transport, fate, and toxicity of strontium in the environment are largely controlled by solubility of different Sr-salts (e. g., SrCO3, Sr(NO3)2, SrSO4, …).

These findings are sufficient justification for the implementation of a read-across strategy with ecotoxicity results obtained in tests that were conducted with different strontium compounds that generate free Sr2+-ions in solution, and this for all relevant environmental endpoints that were considered.

In sum, the environmental hazard assessment is based on strontium.

References:Wennig, R.; Kirsch, N. (1988): Chapter 57 Strontium, In: Seiler, U. G. et al.(eds), Handb. Tox. Inorg. Comp. NY, 631-638