Tin sulphide

Endpoint summary

Description of key information

No short-term or long-term effects on aquatic organisms were observed at or below the limit of water solubility of tin sulfide. Hence, there is no hazard identified.

Additional information

Under valid static test conditions according to OECD Guideline 203 the 96 h-LL50 of tin sulfide to Gobiocypris rarus is greater than nominal tested concentration of 100 mg/L WAFs (measured concentration 0.014 mg/L).

In the K1-study from Chen Guilan (2021) the effect of a 28 day exposure on the growth of Rare Minnow (Gobiocypris rarus) to tin sulfide was investigated in a semi-static test according to OECD 215. The test solutions were set up as saturated concentrations with nominal concentrations of 1.04 mg/L, 3.31 mg/L, 10.4 mg/L, 33.1 mg/L and 104 mg test item/L After the suspensions were stirred for about 24 h, the test suspensions were filtered with 0.22 μm water phase polyether sulfone (PES) filter membranes, the filtrates of the nominal concentrations of 1.04 mg/L, 3.31 mg/L, 10.4 mg/L, 33.1 mg/L and 104 mg/L saturated solutions were obtained respectively, and about 2000 ml filtrate from each test concentration group were measured as test solutions directly. The test solutions were exchanged on a daily basis. The time-weighted mean measured concentrations of Sn were 17.6 μg/L, 44.3μg/L, 107 μg/L, 145 μg/L and 149 μg/L, respectively. No mortality was observed in any of the test groups. In none of the test groups adverse effects were observed. The EC10 was greater than the the highest test concentration, i.e. greater 104 mg/L (nominal) or 149 µg Sn/L mean measured). I.e., there were no effects at the limit of water solubility.

The supporting 13–day short-term toxicity test on embryo and sac-fry stagese of Brachydanio rerio according to OECD Guideline 212 was studied under semi-static conditions with tin sulfide. 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 endpoint was weight, the NOEC being 7 µg/L (equals to 12.5% of filtrate from soluble fraction of 100 mg/L). This is about ten times above the limit of water solubility. No effects on the endpoints “mortality” or “hatchability” were shown.

 

The acute toxicity of tin sulfide to Daphnia magna was determined according to OECD 202 (2004). In a range-finding test 5 daphnids per treatment (no replicates) were exposed to nominal concentrations of 1.0, 10.0 and 100 mg test substance/L WAFs. No immobilization was observed. In the limit test 4 replicates with 5 daphnids per replicate each were tested at 100 mg/L WAF. A blank control was set up in parallel. After 48 h-test period all daphnids in control group and treated group were alive and appeared normal. A reference test with K2Cr2O7 under same conditions resulted in a 24h-LC50 of 1.,27 mg/L. All validity criteria were fulfilled. Under valid static test conditions the 48 h -EL50 of tin sulfide to Daphnia magna is greater than the nominal tested concentration of 100 mg/L WAF and greater than the measured concentration of 265 µg/L, which is greater than the water solubility of 0.6 µg/L. Therefore, it can be concluded that tin sulfide has no acute toxicity to Daphnia magna.

 

 

A chronic Daphnia study according to OECD 211 is in progress. This information will be submitted later based on ECHA decision number CCH-D-2114453316-51-01/F.

 

The supporting 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 values are higher than the solubility limit of the test item under test 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. However, the NOEC was 5 times higher than the limit of water solubility. This OECD 211 study is not relevant since the experimental conditions were not appropriate. Therefore, the study is considered to be not relevant for the PNEC derivation. In order to fill this data gap a new OECD 211 study is performed.

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. Therefore, the 72-hr EC50 is > 34 µg a.i./L and the 72-hr NOEC is >= 34 µg a.i./L. Hence the NOEC was a factor of at least 50 times higher than the limit of water solubility. From two read across substances supporting information is available. This information supports that SnS is not toxic to algae.

In the K1-study from Deng Guirong (2021), the effect of tin sulfide on the respiration of sewage sludge was investigated according to OECD 209. The 3h-EC50 of the test substance for the total oxygen uptake was higher than 1001 mg a.i./L, and NOEC was 1001 mg a.i./L, the highest test concentration. The results of that study are considered robust and reliable for the risk assessment of the registered substance.

In a second test on respiration inhibition of activated sludge according to OECD 209, Two tests were performed: 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. The later result is considered to be the relevant information.

Information from a well soluble read across substance (SnCl2) indicates that effects of Sn on sediment dwellers are not to be expected since the effect concentrations would be > 5000 times above the water solubility of tin sulfide.