Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

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Additional information

SMBT is an organic salt of strong base NaOH and weak acid of MBT and it is solely marketed as aqueous solution. The presence of MBT determines the hazard profile of SMBT aqueous solution; and hence the environmental fate and behavior of MBT is used as read-across approach to support the risk assessment of SMBT.

In absence of light and oxygen 2-mercaptobenzothiazole is hydrolytically stable with no hydrolysis products observed and 85% recovery within 7 days. According to expert judgment MBT can be oxidized by atmospheric oxygen to 2,2`-dithiobisbenzothiazole (MBTS) in aqueous solution. Hansson & Agrup reported 60% conversion of MBT into MBTS in phosphate buffer at pH 6.5 within 2 hours with the presence of atmospheric oxygen.

The phothlytic breakdown of 2-mercaptobenzothiazole occures rapidly with a half-life under one hour. The calculated half-life was 27.4 minutes for synthetic humic water and 31.1 minutes for pure water. 2 -Mercaptobenzothiazole was classified as "photolabile".

In the atmosphere a half-life of 8.5 hours for SMBT due to reaction with photochemically produced hydroxyl radicals is estimated by AOPWIN v1.92 with a rate constant of 4.5 *10-11cm3/(molecule*sec), considering an OH-concentration of 500,000 radicals/cm³ as a 24-h average. The estimated half-life in air of SMBT is much shorter than 48 hours and hence no potential for long-range transport of SMBT in air is expected.