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Environmental fate & pathways

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Ready biodegradability and inherent biodegradability studies are available for hexyl acetate. In an OECD 301D closed bottle test hexyl acetate was found to be 66% degraded after 28 days. In a closed bottle test it is considered that a 14-day window must be passed in order to conclude that a substance is readily biodegradable. However, no determination of dissolved oxygen was made until day 7, at which point 42% degradation had already occured. As such, it was considered necessary to determine if the 14 -day window had been met by statistical interpolation. A degradation curve indicated that 10% degradation had been achieved on day 3 and that the 60% pass level had been reached on day 17. As such, the 14 -day window had been achieved and the substance can be considered readily biodegradable.

An inherent biodegradability study provides further evidence that the substance will be rapidly degraded in the environment, as hexyl acetate was found to be 85% degraded by day 28.

In addition to this, a QSAR estimation of the biodegradation potential of hexyl acetate was made using Biowin v4.10. All of the modules within Biowin estimated that the substance would degrade quickly and as such the model predicted that hexyl acetate would be readily biodegradable. This indicates that the structure of hexyl acetate is likely to be available for microbial degradation and as such it can be expected that thte substance would be rapidly degraded in the environment. It is likely that biodegradation would proceed by cleavage of the ester group to yield acetic acid and hexanol. The latter would then be oxidised to hexanoic acid with subsequent breakdown of the chain via the beta-oxidation mechanism.

Based on the above evidence it is considered that hexyl acetate is readily biodegradable and will degrade rapidly in the environment.

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