Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Abiotic degradation

In general, phototransformation and hydrolysis are the main abiotic degradation pathways for a substance. 1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol (CAS 91648-65-6) is not susceptible for phototransformation in different environmental compartments (i.e. air, water and soil). Hydrolysis of the test substance was investigated in accordance to OECD Guideline 111, whereby significant hydrolysis was only observed at pH 7 (recovery after 11 days: 57 %; Rocchio, 1990).

Biotic degradation

1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol (CAS 91648-65-6) attained 2 % degradation after 28 days in a modified MITI test (OECD Guideline 301C) and can be considered as "not readily biodegradable" (Katsuura, 1990). The same applies to the read-across substances 1,3,4-Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-dodecanethiol (No CAS, no EC) and 5-(dodecyldithio)-1,3,4-thiadiazole-2(3H)-thione (CAS 50530-43-3).

Bioaccumulation

1,3,4 -Thiadiazolidine-2,5-dithione, reaction products with hydrogen peroxide and tert-nonanethiol (CAS 91648-65-6) 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 test substance possesses a logPow > 9.4 (Fox, 2012), thus no strong bioaccumulation is expected. This assumption is confirmed by the QSAR prediction with BCFBAF v3.01 which revealed an aquatic bioconcentration factor (BCF) of 15.7 L/kg (Chemservice S.A., 2013). Therefore, the substance can be considered as non-bioaccumulative and based on the chemical safety assessment (CSA), no further investigations are triggered.

Transport and distribution

The organic normalized adsoption coefficient (Koc) was determined as > 4.27 x 10E5 (logKoc > 5.63) in an experiment conducted according to OECD 121 (Fox, 2012). 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 (Rocchio, 1991).

The Henry´s Law constant was predicted as 2.98 E-2 Pa*m³/mol at 25 °C with the QSAR program HENRYWIN v3.20 (Chemservice S.A., 2013). This value 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-nonanethiol (CAS 91648-65-6).