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Category name:
5-Mercapto-1,3,4-thiadiazol-2-thiol-benzoate and hydrolysis products

Justifications and discussions

Category definition:
5-Mercapto-1,3,4-thiadiazol-2-thiol-benzoate and hydrolysis products
Category rationale:
There is data available on the hydrolysis behaviour of the registered substance 5-Mercapto-1,3,4-thiadiazole-2-thiol-benzoate in unbuffered water at room temperature, hence posing the same conditions as test on aquatic toxicity. The hydrolytic degradation of 5-mercapto-1,3,4-thiadiazole-2-thiol-benzoate can be described as a pseudo-first order kinetic and the half-life of 5-mercapto-1,3,4-thiadiazole-2-thiol-benzoate was determined to be 1.91 h. 1,3,4-Dimercapto-thiadiazol (DMTD, CAS 1072-71-5) and benzoic acid (CAS 65-85-0) were identified as degradation products as expected by hydrolytical cleavage of the thioester group. It can be concluded that the substance hydrolyzes very rapidly in water, i.e. the half life is max. 1/25 of the test duration when put into aqueous test systems, e.g. daphnia or algae acute toxicity tests. Hence, the substance as such does not need to be tested in those systems, it is sufficient for hazard assessment to use data gained with 1,3,4-Dimercapto-thiadiazol (DMTD, CAS 1072-71-5) and benzoic acid (CAS 65-85-0).