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Environmental fate & pathways

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Although MBS is not readily biodegradable with a biodegradability of 0% observed in 28 days, it is abiotically unstable in aquatic environment with a hydrolysis half-life of ca. 24 hours at pH 7.0 and 25°C and with a half-life of direct photolysis in water of 0.78 hour. The hydrolysis products were identified to be mercaptobenzothiazole (CAS: 149-30-4), benzothiazole (CAS: 95-16-9) and morpholine (CAS: 110-91-8). The identified breakdown products are also not readily biodegradable. MBS is not bioaccumulative with an estimated BCF of 81.34 l/kg. The hydrolysis products of MBS, such as MBT, BT and morpholine, also have no bioaccumulation potential with the experimentally determined BCFs all below 10. At environmentally relevant pH and 25°C the logKoc of MBS is determined to be 2.84, which indicates a moderate adsorption potential. The hydrolysis products, such as MBT and BT, also have a moderate adsorption potential in soil/sediment with the log Koc of 2.51 – 3.55 and 3.0, respectively. Morpholine however has only a low affinity to adsorption with a logKoc of 0.867. MBS is essentially non-volatile with the calculated Henry's law constant lower than 5.52*10-7 Pa m3/mol at 25°C. The estimated half-life in air of MBS is much shorter than 48 hours; and hence no potential for long-range transport of MBS in air is expected. The distribution of MBS in a "unit world" was calculated according to the Mackay fugacity model level I based on the physico-chemical properties. The main target compartment for MBS is water of 71.3 % and sediment of 14.32 %, followed by soil of 14.16 %.