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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
the study does not need to be conducted because the substance and its relevant degradation products decompose rapidly
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING
In accordance with column 2 of REACH Annex VIII, information requirement 9.3.1., a study does not need to be conducted if the substance and its relevant degradation products decompose rapidly.

Description of key information

Waived: Testing is technically not feasible.

Key value for chemical safety assessment

Additional information

In accordance with Column 2 of REACH Annex VIII, the study does not need to be conducted if the substance and its relevant degradation products decompose rapidly. The substance decomposes upon contact with water, making measurement of adsorption/desorption impossible by either batch equilibration or HPLC methods.

The adsorption coefficient (Koc) of the test substance was determined by calculation using valid modelling software (EPIWIN). The calculated Koc was 2.87 x 10E+8 L/kg. The corresponding log Koc was 8.46. This high Koc value suggests that the test substance is highly hydrophobic and has a high potential to be adsorbed in soils and sediments.

However, the adsorption/desorption of the parent substance may be regarded as irrelevant, as the substance rapidly decomposes upon contact with water which would occur in soil, sediments, or wastewater biosolids. The organic carbon-normalised adsorption coefficient was estimated for the expected daughter product, 2 -ethylhexylthioglycolate, using the QSAR based on first order molecular connectivity index. The estimated log Koc is 2.56 (Koc = 359.5 L/kg) for this daughter product. Thus, the relevant component/degradation product of the substance will have low affinity for adsorption to soil, sediment, and wastewater biosolids.