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Environmental fate & pathways

Hydrolysis

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Description of key information

Hydrolysis may be a relevant degradation pathway for disulfiram in aquatic systems (half-lives 68.5 days, 3.5 days and 6.9 hours under acidic, neutral and alkaline conditions respectively)

Key value for chemical safety assessment

Additional information

No data on hydrolysis of disulfiram (CAS No. 97-77-8) are available. Therefore, a conclusion based on data from an analogue substance had to be drawn. Hydrolysis of tetramethylthiuram disulfide (CAS No.137-26-8), substance structurally and composition related to tetraethylthiuram disulfide, was investigated in one study. This test was conducted according to EPA’s Pesticide Assessment Guidelines, Series 161-1, Hydrolisis Studies (1988), under GLP conditions.14C-thiram was tested at pH 5, 7 and 9, and the half-lives determined, being 68.5 days, 3.5 days and 6.9 hours respectively. Hydrolysis in alkaline and neutral conditions took place at a faster rate than under acidic conditions. The main breakdown product was CS2.

The results from the HYDROWIN v2.00 program support these findings, as the hydrolysis of disulfiram is predicted to occur faster under neutral and alkaline conditions (less than one day to several days and less than one day, respectively).