1-(tert-dodecylthio)propan-2-ol

Endpoint summary

Additional information

General considerations for aquatic toxicity testing

The preparation of Water Accommodated Fractions (WAFs) was performed for all aquatic toxicity experiments since the test material possesses only a slight water solubility (4.84 mg/L at 20 °C, Woolley and Mullee, 2003). This procedure is in accordance with the OECD Guidance document on aquatic toxicity testing of difficult substances and mixtures (Series on testing and assessment - Number 23; OECD, 2000). The term WAF is applied to aqueous media containing only the fraction of multi-component substances that is dissolved and / or present as a stable dispersion or emulsion. These fractions are prepared individually and not by serial dilution of a single stock WAF. As the term indicates, only a fraction of the total mass of multi-component substances responsible for the composition of a WAF may be present in the WAF. The "loading rate" is the mass to volume ratio of the mixture to medium used in the preparation of a WAF. The obtained LL50 / EL50 values are comparable to LC50 / EC50 values, as well as the NOELR (No Observable Effect Loading Rate) to NOEL (No Observable Effect Concentration).

Acute toxicity to fish

Two experimental results are available, which are reliable without restrictions (Klimisch 1). The tests were conducted according to OECD Guideline 203 (EU Method C.1) with certificated GLP compliance. Rainbow trout (Oncorhynchus mykiss) were used as test organisms.

Considering the definitive test of the key study, the highest loading rate resulting in 0 % mortality was determined to be 0.56 mg/L loading rate WAF, the lowest loading rate resulting in 100 % mortality to be 1.0 mg/L loading rate WAF (Sewell, 2004). The LL50 was determined as 0.75 mg/L with 95 % confidence limits of 0.56 - 1.0 mg/L. The No Observed Effect Loading Rate (NOELR) was sought to be 0.56 mg/L loading rate WAF.

In the supporting study, at the the time point of 24 h all fish were dead testing the nominal loading rate of 10 mg/L (Sewell, 2004). The LL50 was determined as 0.42 mg/L with 95 % confidence limits of 0.32 - 0.56 mg/L. The No Observed Effect Loading Rate (NOELR) was thought to be 0.32 mg/L loading rate WAF.

Chronic toxicity to fish

No data on the long-term toxicity to fish are available for this substance. In short-term tests the water flea demonstrated equivalent sensitivity to the test substance as compared to the fish, and given that the chronic water flea study covers the complete life cycle of the organism it was deemed sufficient to characterize the long term endpoint for aquatic organisms along with the chronic algae results.The procedure is in accordance to Regulation (EC) 1207/2006 (REACH), Annex IX, Section 9.1.6, column 2.

Acute toxicity to aquatic invertebrates

Two reliable Guideline studies (OECD Guideline 202) with certificated GLP compliance can be reported concerning short-term toxicity towards Daphnia magna.

In the key study, the EC50 value was determined to be 0.58 mg/L loading rate WAF with 95 % confidence limits of 0.51 - 0.66 mg/L (Goodband and Mullee, 2011). The corresponding No Observed Effect Loading Rate (NOELR) is 0.32 mg/L.

The supporting study report gives an EC50 value of 1.3 mg/L loading rate WAF with 95 % confidence limits of 1.0 - 1.8 mg/L. The corresponding No Observed Effect Loading Rate (NOELR) is 1.0 mg/L.

In both cases, no evidence of undissolved substance was observed, since microscopic inspection of the WAFs showed no micro-dispersions or undissolved test item to be present. The solutions were not renewed during the exposure period. The differences were given in the used test concentrations, in the key study test concentrations of of 0.1, 0.18, 0.32, 0.56 and 1.0 mg/L nominal loading rate WAFs were used, whereas in the supporting study concentrations of 1.0, 1.8, 3.2, 5.6, 10, 18, 32, 56 and 100 mg/L nominal loading rate WAFs were tested.

Chronic toxicity to aquatic invertebrates

Daphnia magna was used as test organisms to investigated the chronic toxicty to aquatic invertebrates of the test material according to OECD Guideline 211(Wetton, 2003). The 14 and 21-Day EL50 (immobilisation) value, based on nominal loading rates, for the parental Daphnia generation (P1) was calculated to be 0.75 mg/L loading rate WAF with 95 % confidence limits of 0.56 – 1.0 mg/L loading rate WAF. The 21-Day EL50 (reproduction) value based on nominal loading rates was calculated to be 0.50 mg/L loading rate WAF with 95 % confidence limits of 0.39 – 0.63 mg/L loading rate WAF. The "Lowest Observed Effect Loading Rate" was considered to be 0.56 mg/L on the basis that at this test concentration significantly fewer live young per adult (P < 0.05) were produced when compared to the control. The "No Observed Effect Loading Rate " was considered to be 0.32 mg/L on the basis that at this test concentration there were no mortalities (immobilisation) observed in the parental generation (P1) and that there were no significant differences (P ≥ 0.05) between the control and the 0.32 mg/L loading rate WAF test group in terms of numbers of live young produced per adult by Day 21.

Toxicity to aquatic algae

The growth inhibition effect of the test substance to Desmodesmus subspicatus was investigated according to OECD Guideline 201with GLP compliance statement (Mead, 2004). An Effective Loading rate, EL50 greater than 100 mg/L loading rate WAF and the corresponding No Observed Effect Loading Rate of 100 mg/L is reported. It was considered unnecessary and unrealistic to test a loading rate in excess of this test concentrations.

Toxicity to microorganisms

Activated sludge was used in a static freshwater experiment with an exposure time to the test substance of 3 hours in accordance to OECD Guideline 209 (Goodrich, 1994). None of the test concentrations (1, 10, 100, 1000 and 10000 mg/L) produced an inhibition greater than 50 %, consequently an EC50 could not be calculated. Hence the EC50 is > 10,000 mg/L.