Registration Dossier
Registration Dossier
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EC number: 939-692-2 | CAS number: 1474044-73-9
Endpoint summary
Administrative data
Description of key information
Additional information
General considerations
The ecotoxicological potential of the target substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanthiol’ (no CAS#, no EC#) and its short-chain homologue ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol’ (CAS# 91648-65-6) towards aquatic species was investigated in different experiments conducted with fish, daphnids and green algae to determine the toxicological effects in three different trophic levels. Both substances are UVCBs (Substances of Unknown or Variable composition, Complex reaction products or Biological materials) and their only difference is based on the diversity in the C-range of the used raw material alkanethiol: ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol’ requires a tert. C9-alkanethiol and ‘1,3,4 -Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol’ a tert. C12. Hence, due to the structural similarity of both substances it is obvious that the ecotoxicological properties are likely to be similar.
Based on the intrinsic properties of the used substances, Water Accommodated Fractions (WAFs) were prepared for testing. 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 may be present in the WAF. The "loading rate" is the mass to volume ratio of the mixture to medium used in the preparation. 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).
Toxicity to fish
Pimephales promelas was exposed to the supporting substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol’ (CAS 91648-65-6) in an experiment according to OECD Guideline 203. The LL50(96h) was determined to be > 1000 mg/L WAF. Additionally, the toxicity of the target substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol’ (no CAS#, no EC#) towards Leuciscus idus melanotus was investigated. The study was also conducted according to OECD Guideline 203 and revealed a LL50(96h) of 1900 mg/L WAF. Based on these observations and the chemical safety assessment (CSA), no long-term studies with fish are triggered in accordance to REACH, Annex IX, Section 9.1.6, column 2.
Toxicity to aquatic invertebrates
The closely related supporting substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol’ (CAS 91648-65-6) was found to be toxic against the freshwater invertebrate Daphnia magna in an experiment conducted according to OECD 202. The EL50(48h) value was determined as 41 mg/L WAF. Supporting data is given by the target substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol’ which was also exposed to Daphnia magna. It was considered adequate for assessment to use the afore-mentioned (most reliable) study on the closely related substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol’ as key study and the further available studies on the target substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol’ as supporting studies.Taking into account all observations for the CSA, the target substance needs to be classified as "Aquatic Chronic 3" (H412: Harmful to aquatic life with long lasting effects) and therefore, long-term toxicity investigations are waived in accordance to REACH, Annex IX, Section 9.1.5, column 2.
Toxicity towards aquatic algae
Vryenhoef (2012) exposed the green algae Pseudokirchneriella subcapitata towards the read-across substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol’ (CAS# 91648-65-6) for a time duration of 72 h. The test procedure was in accordance to OECD Guideline 201/EU Method C.3 and up to the maximum concentration tested (100 mg/L WAF), no effects were observed. Based on growth rate as well as on biomass, the EC10, EC20 and EC50 values will be > 100 mg/L WAF. The corresponding NOELr and NOELb are 100 mg/L WAF both. It was considered adequate for assessment to use the afore-mentioned (reliable) study on the short-chain homologue ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol’ as a stand alone study. The further two studies on the target substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol’ that have been provided were disregarded mainly due to their insufficient documentation.
Toxicity towards aquatic microorganisms
Ecotoxicological data regarding toxicity towards aquatic microorganisms is available for the target substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol’. The substance was used in an experiment according to German standard DIN 38 412 (part 8) with Pseudomonas putida as test organism; after 16 h, the EC10 as well as the EC50 was determined to be > 8000 mg/L.
Toxicity towards other aquatic organisms
No information is available regarding toxicity towards any other aquatic organisms, neither for the target substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol’ nor for the read-across substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol’. Based on the available data and the chemical safety assessment (CSA), no indication is shown to investigate further the fate and behaviour of the substances. Furthermore, it is no standard information requirement for a registration under REACH and thus no additional testing towards any other aquatic organisms is considered as necessary.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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