Tin disulphide

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of 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.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 2. Experiment, direct weight

Results with reference substance (positive control):

1. Experiment: EC50 = 12.3 mg/L
2. Experiment: EC50 = 7.3 mg/L

Percentage of activated sludge respiration inhibition for tested material (1st test):

Concentration [µg/L]	Inhibition [%]
11	-0.80
10	-6.63
9.1	-7.16
8.3	-7.69
7.5	-8.22

 

Percentage of activated sludge respiration inhibition for tested material (additional test, directly weighing in):

Concentration [mg/L]	Inhibition [%]
1000	14.98
500	9.41
250	3.14
125	12.20
62.5	9.76

 

The results are considered relevant for tin disulfide since both substances have the same metal moiety and have similar physico-chemical properties, e.g., they are almost insoluble in water. Further evidence is provided in the read across justification.

Validity criteria fulfilled:

yes

Conclusions:

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. In an additional experiment, no effects were observed at concentrations up to 1000 mg/L with directly weighing in.

Executive summary:

In the test for inhibition of respiration of microorganisms by tin sulfide according to OECD 209 no inhibition has been observed at any concentration, e.g., 11 µg/L and 1000 mg/L. Hence, tin sulfide has no inhibitoriy effect on the microorganisms up to the water solubility.

The results are considered relevant for tin disulfide since both substances have the same metal moiety and have similar physico-chemical properties, e.g., they are almost insoluble in water. Further evidence is provided in the read across justification.

Description of key information

Tin disulfide causes no inhibition of respiration of activated sludge. Determination of EC50 based on the obtained results was not possible. Based on the results obtained during additional test EC50 is above the highest nominal concentration – 1000 mg/L. This suspension was above water solubility level.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

Additional information

The endpoint was covered by read across from tin sulfide.

Tin sulfide, at used concentrations, caused no inhibition of respiration of activated sludge. Determination of EC50 based on the obtained results was not possible. Based on the results obtained during additional test EC50 is above the highest nominal concentration – 1000 mg/L. This suspension was above water solubility level.

Conclusion: Effects from tin sulfide were only observed at concentrations higher than the water solubility of tin sulfide (0.6 µg/L). Therefore, these effects are considered as not relevant. Read across from tin sulfide to tin disulfide was considered as possible (see Read Across justification document attached to the dossier). Hence it can be concluded that there is based on the read across data and the argumentation provided for the read across, there is no risk at the limit of water solubility of tin disulfide, i.e., at 0.67 µg/L.