Tin disulphide

Endpoint summary

Description of key information

Tin disulfide causes no acute or chronic effects up to the limit of water solubility.

Additional information

For tin disulfide an algal study is available. This study demonstrated that the tin sulfide has no toxic effects at the limit of water solubility, i.e., at 0.67 µg/L. The other aquatic endpoints were covered using data from tin sulfide which has an almost identical water solubility, i.e., 0.6 µg/L. The algal study was used as bridging study since the WHO concluded in their report that alge are the most sensitive group. Furthermore, the WHO concluded that Sn II is more toxic than Sn IV. Hence, read across from tin sulfide (Sn II) to tin disulfide (Sn IV) was considered justified.

 

The acute toxicity of tin sulfide to Gobiocypris rarus was conducted in accordance with OECD Guideline 203. Under valid static test conditions the 96 h-LL50 is greater than nominal tested concentration of 100 mg/L WAFs (measured concentration 0.014 mg/L).

 

 

An ELS study for SnS2 is in progress.

To adress the long-term toxicity to fish, an OECD 215 is available for SnS (source substance). The test was performed well above the water solubility limit of SnS and also above the water solubility limit of SnS2. In the target substance SnS2, Sn(IV) will be present while the souce substance contains Sn(II). Toxicological studies show that SnS and SnS2 have a comparable toxicological profile. There is no information that Sn(IV) is more toxic when compared to Sn(II). No endocrine effects are described for one of the two substances. When SnS and SnS2 are dissolved also S2- gets into solution. Based on the results of the read across source study, there is no evidence that either S2- or one of the tin ions will cause long-term toxicity in fish at the concentrations which can be expected based on the water solubility of the source and target substance. Therefore, the results from this read across study, i.e., no long-term toxicity at the limit of water solubility, are considered relevant and reliable for the risk assessment.

 

The 13–day chronic toxicity of tin sulfide to early life stage of Brachydanio rerio was studied under semi-static conditions. Totally 60 embryos were exposed to measured tin sulfide concentrations up to 33 µg/L, which is the highest soluble fraction from a 100 mg/L (nominal) tin sulfide concentration. The test system was maintained at 23.9 to 25.8 ºC and a pH of 6.91 to 7.67.  The 13–day EC50value, based on mortality, was >33 µg a.i./L.  The sublethal effects included were hatching, weight and length of animals. The most sensitive end point was weight, the NOEC being 7 µg/L (equals to 12.5% of filtrate from soluble fraction of 100 mg/L).

 

The 21-day-chronic toxicity of tin sulfide to Daphnia magna was studied under semistatic conditions. The sublethal effects included were reproduction output, reduction of parent growth and intrinsic rate. The most sensitive end point was reduction of reproduction output, the NOEC was 3 µg/L (equals 12.5 % of maximum soluble fraction of nominal 20 mg/L).

EC50 (all endpoints): higher than 11.3 µg/L (equals to 100 % of maximum soluble fraction of nominal 20 mg/L).

 

In a 72-hour toxicity study, the cultures of Pseudokirchneriella subcapitata were exposed to Tin sulfide at a measured concentration of 34 µg a.i./L, which was the soluble fraction from a nominal 100 mg/L tin sulfide concentration, under static conditions in accordance with the OECD 201 Guideline. No effects were observed, neither on growth rate, biomass reduction or changes in cell morphology.

 

In a test on respiration inhibition of activated sludge according to OECD 209, no effects were observed at a nominal concentration of 11 µg/L, which was prepared from a saturated solution in deionized water from nominal 100 mg/L tin sulfide. In an additional experiment, no effects were observed at concentrations up to 1000 mg/L directly weighed in.

 

Based on this information and the read across information it can be concluded that tin disulfide results in no acute and chronic effects up to the limit of water solubility, i.e., 0.67 µg/L.