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

Endpoint summary

Additional information

Abiotic degradation

In general, phototransformation and hydrolysis are the main abiotic degradation pathways for a substance. The UVCB substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol’ (no CAS#, no EC#) is not susceptible for phototransformation in different environmental compartments (i.e. air, water and soil). Hydrolysis of the closely related substance ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol’ (CAS# 91648-65-6) was investigated in accordance with OECD Guideline 111, whereby significant hydrolysis was only observed at pH 7 (recovery after 11 days: 57 %).

Biotic degradation

The biodegradability of the target substance, `1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol´ (no CAS#, no EC#) and also of the read-across substances '1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol (CAS# 91648-65-6) and '5-(dodecyldithio)-1,3,4-thiadiazole-2(3H)-thione' (CAS# 50530-43-3) were tested in accordance with reliable guidelines and study methods. All substances were found to be "not readily biodegradable".

Bioaccumulation

The substance ‘1,3,4 -Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol’ (no CAS#, no EC#) is not expected to accumulate in organisms. Bioaccumulation in aquatic biota is expected for substances possessing a partition coefficient (logPow) in the range of 4.5 to 6 (ECHA REACH Guidance Chapter R.11 PBT Assessment). A higher logPow is probably more an effect of solubility than lipophilicity. The closely related substance '1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol' (CAS 91648-65-6) possesses a logPow > 9.4 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' (no CAS#, no EC#); thus no strong bioaccumulation is expected. This assumption is confirmed by the QSAR prediction with BCFBAF v3.01 (by US EPA) which revealed an aquatic bioconcentration factor (BCF) of 3.16 L/kg. Finally, the substance ‘1,3,4 -Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol’ can be considered as non-bioaccumulative and based on the chemical safety assessment (CSA), no further investigations are triggered.

Transport and distribution

The organic normalised adsorption coefficient (Koc) was determined to be > 4.27 x 10e5 (logKoc > 5.63) in an experiment conducted according to OECD 121. In another experiment conducted in accordance to OECD Guideline 106, the Koc values of three different soils were measured in a range from 45 - 473 at 23 °C. Although both studies were conducted on the supporting substance '1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol' (CAS# 91648-65-6) the results should be also applicable for the closely related substance '1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol' (no CAS#, no EC#).

The Henry´s Law constant was predicted as 0.163 Pa*m³/mol at 25 °C with the QSAR program HENRYWIN v3.20 (by US EPA). This value which was calculated for ‘1,3,4-Thiadiazole, 2,5-bis(tert-dodecyldithio)-‘ (CAS# 50530-43-3) [= one of the main constituents of the UVCB substance '1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol' (no CAS#, no EC#)] is used in the chemical safety assessment in order calculate the PNECsoil of ‘1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol’ (no CAS#, no EC#).