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Environmental fate & pathways

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Additional information

According to the REACH legislation Annex VIII 9.3.1 a study on the adsorption/desorption behaviour does not need to be conducted if the substance and its relevant degradation products decompose rapidly. Therefore, data on the adsorption/desorption behaviour of LAS-TEA are not required.

Assuming full and rapid dissociation of LAS-TEA in aqueous environments, data on the adsorption/desorption behaviour of LAS-Na and TEA can be used to describe the adsorption and desorption behaviour of LAS-TEA. Both LAS-Na and TEA decompose rapidly as well, and therefore no data on the adsorption/desorption behaviour of LAS-Na and TEA is required, however, the following information is available:

TEA:

Due to the calculated Koc of 17 and its rapid degradation, adsorption of TEA to the solid soil phase (e.g. clay) is not expected.

Due to the Henrys law constant, TEA will not evaporate from the water surface.

Regarding the environmental distribution (Mackay Level I), over time, TEA will preferentially distribute into the water.

LAS-Na:

The adsorption-desorption behaviour of LAS in activated sludge was determined in batch experiments. The Kp for commercial LAS was 2,500 L/kg, with a log Kp of 3.4.

Fugacity modeling of LAS was done using several different models: Mackay level I, II, and III, the ChemCAN model, and the WW-TREAT, GRiDS, and ROUT models.Based on these findings, the dominant fate processes are degradation rates in water and soil, and water-sediment transfer.

The HAZCHEM derived from Mackay type level III model was used to calculate the distribution of LAS in the environment. Results show that most of the LAS partitions to soil, with relatively little in water or air. However, the amount in soil may be overpredicted as the model did not take into account degradation in soil.