Barium sulphide

Short-term toxicity to fish

Description of key information

Reliable acute toxicity data for fish are available for sulfide, sulfate and barium. Barium and sulfide are released upon dissolution of BaS in the aqueous environment. Sulfide is rapidly oxidised under natural environmental conditions. Thus, only acute but not long-term effects due to sulfide exposure are expected. Further, the acute toxicity of sulfate was considered. However, sulfate is of low toxicity. Regarding toxic effects of dissolved Ba, a reliable 96h-LC50 of >3.5 mg Ba/L was determined by Egeler and Kiefer (2010) for Danio rerio corresponding to a 96h-LC50 of > 4.3 mg BaS/L (dissolved). Comparing acute toxicity levels of Ba and S in freshwater, it can be concluded that the acute toxicity of BaS is driven by sulfide resulting in a 96h-LC50 of 0.013 mg BaS/L.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

13.4 µg/L

Additional information

Egeler and Kiefer (2010) conducted an acute toxicity test withDanio rerio(test substance: soluble BaCl₂*2H₂O). No effects (mortality) were observed at the nominal test concentration of 100 mg Ba²⁺/L. The dissolved and total fractions were measured. A white precipitate was observed upon dissolution of BaCl₂, presumbably the formation of poorly soluble barium sulfate. However, at a nominal concentration of 100 mg Ba²⁺/L, the dissolved and total barium concentrations amounted to 3.5 and 97.5 mg/L, respectively. Reading-across the latter value to BaS, a 96h-LC₅₀of > 120.3 mg BaS/L is derived based on the total barium concentration. Further, the 96h-LC₅₀of > 3.5 mg dissolved Ba/L corresponds to an LC₅₀of > 4.32 mg BaS/L.

The lowest reliable acute effect concentration for fish with regard to sulfide was reported by Yussoff et al. (1998) for the Javanese carpPuntius gonionotus, i.e. the 96h-LC₅₀of 0.0027 mg H₂S/L corresponding to 0.013 mg BaS/L. In oxic environments, however, sulfide released from BaS is oxidized to sulfate, and the hazard of the released sulfur should be evaluated by reading-across the toxicity of sulfate. The study by Mount et al (1997) was identified in the OECD SIDS for Na₂SO₄(i.e., the most relevant substance for assessing the hazard of sulfate) as key study with regard to acute toxicity of sulfate to fish. This study reports a 96h-LC₅₀of 7960 mg Na₂SO₄/L for the fathead minnowPimephales promelascorresponding toa 96h-LC₅₀of 9493 mg BaS/L.