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Environmental fate & pathways

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2,5-Xylenol is an organic solid with avapourpressure of 4.24 Pa at 25 °C (QSAR, modified Grain method). The substance is soluble in water (3.543 g/L at 25°C) and has a log Pow of 2.6 at 25 °C and pH3 (undissociated form; OECD TG 117, HPLC method). A dissociation constant (pKa) of 10.41 at 25 °C was determined for 2,5-Xylenol. The pKa indicates that the substance mainly exists in the undissociated form at environmentally relevant pH values (pH 4-9). Based on the low log Pow bioaccumulation was well as adsorption of the substance to soil, sediment and suspended matter is not expected. The assumption is supported by a QSAR calculation performed for the neutral molecule. The estimated log Koc value was 2.53 using the experimentally determined log Pow of 2.6 as input parameter (KOCWIN v2.00).

2,5-Xylenol is not readily biodegradable (2% after 28 d, OECD 301C). Inherent biodegradability was demonstrated in a study similar to OECD guideline 302B conducted with adapted activated sludge as inoculum (94.5% COD removal after 5 d).

The substance will be mainly present in water if released to the environment. Accumulation in air and the subsequent transport to other environmental compartments is not likely due to the low vapour pressure.