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Environmental fate & pathways

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ZMBT is an organic complex, in which MBT structure is present. The dissolution of MBT determines the hazard profile of ZMBT aqueous solution; and hence the environmental fate and behavior of MBT is used as read-across approach to support the risk assessment of ZMBT.

MBT is not readily biodegradable with a biodegradability of 2.5% observed in 14 days and also not inherently biodegradable with only 2% biodegradability observed during 35 days exposure to adapted bacterial inoculum. The described main metabolites of MBT are also not readily biodegradable and only certain level of degradation was observed for BT, BTon and MeSBT when the microorganisms used adapted under special conditions. Such processes are expected in biological treatment plant, but not in the environment.

According to the negligible biodegradation of MBT and its described metabolites, no better biodegradability can be expected to be observed in simulation test and hence to carry out such tests are scientifically unjustified. MBT and its described metabolites are expected to be non-biodegradable and hence persistent in surface water, sediment and soil.