1,3,4-Thiadiazolidine-2,5-dithione, reaction products with tert-dodecanethiol and hydrogen peroxide

Short-term toxicity to fish

Description of key information

- OECD 203, Leuciscus idus melanotus: LL50(96h): 1900 mg/L (nominal, WAF; moreover, based on the observed LL0 (96h) of 0.75g/L (nominal, WAF) it can be assumed that the test substance is non-toxic towards fish up to its limit of solubility in water [< 0.1 mg/L at 20°C];
- OECD 203, Pimephales promelas: LL50(96h) > 1000 mg/L (nominal) (read-across from supporting substance '1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol'; no toxicity observed even at highest concentration level tested)

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

1 000 mg/L

Additional information

In a 96-h acute toxicity study, Golden orfs (Leuciscus idus melanotus) were exposed to the UVCB substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol’ (no CAS#, no EC#) at nominal concentrations of 0.1, 0.25, 0.5, 0.75, 1.0, 1.5, 1.75, 2.0, 3.0 and 3.5 g/L under static conditions. The experiment was conducted in accordance with OECD 203 in principle and satisfies mostly the guideline requirements for an acute toxicity test onL. idus. As one deviation from the guideline the missing control must be mentioned. However, since nominal concentrations of the test substance up to 0.75 g/L did not induce lethal effects in fish (i.e. < 10 % as required in the guideline) and a nominal concentration of 3.5 g/L led to the death of all 10 fish within the test group, missing controls do not give rise to doubts on the validity of the test. Another deviation poses the missing analytics. Although not distinct mentioned in the study report, the test solutions were prepared as Water Accommodated Fractions (WAFs). Hence, the effect concentrations are listed as loading rate WAFs, although reported as concentrations in the study report. During a first test, mortality in the storage tanks was too high. Thus, the reported test is the repetition, when the mortality was appropriate. The 96-h LL50 was 1.9 g/L, the LL0 and LL100 values were determined as 0.75 g/L and 3.5 g/L respectively. Based on the observed LL0 (96h) of 0.75g/L (nominal, WAF) it can be assumed that the test substance is non-toxic towards fish up to its limit of solubility in water [< 0.1 mg/L (at 20°C, see IUCLID section 4.8)].

Moreover, an experiment was performed to assess the acute aquatic toxicity of the supporting substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol’ (CAS 91648-65-6). The method followed the OECD Guideline 203, with the exception that the nominal concentrations were not measured analytically for confirmation. The preliminary 96 h acute toxicity study was conducted with the Fathead minnow (Pimephales promelas) at nominal test concentrations of 1, 10 and 100 mg/L. Ten fish per test concentration were used in the preliminary and the definitive study. In the definitive study test concentrations of 100, 180, 320, 560 and 1000 mg/L were tested. In parallel a control, a solvent control and a positive control group were tested. No mortality occurred at any of the test concentrations. Under the conditions of the test the LL50 at 96 hours exposure was determined to be > 1000 mg/L (that should be also applicable for the long-chain homologue ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol’).