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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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According to the Regulation (EC) No 1907/2006 (REACH) Annex IX, 9.2.1.2, column 2 simulation testing in surface water is not required if the test substance is highly insoluble in water. As the water solubility of the Fatty acids, C18-unsaturated, trimers (CAS No. 68937-90-6) is < 0.37 mg/L, i.e. the limit of detection, a study does not need to be conducted for this particular endpoint.

As Fatty acids, C18-unsaturated, trimers (CAS No. 68937-90-6) has a very low water solubility (< 0.37 mg/L, detection limit) the concentration in water is expected to be low and consequently also the exposure to the aquatic environment, if occurring at all. Due the adsorption potential of the substance (log Koc > 5, log Kow > 4), adsorption to organic carbon in soils and sediments is expected. This adsorption is most likely to occur in the sewage treatment plant (STP) and hence the effluent from the STP to the rivers should, if at all, have insignificant or negligible quantities of the test substance. Thus, due to the very low water solubility of Fatty acids, C18-unsaturated, trimers (CAS No. 68937-90-6) sediments are not expected to be the compartment of highest exposure.

According to the Regulation (EC) No 1907/2006 (REACH) Annex IX, 9.2.1.4, column 2 a sediment simulation test does not have to be conducted if direct or indirect exposure to sediment is unlikely. Furthermore the “Guidance on information requirements and chemical safety assessment” Chapter R.7b states, that a simulation test will normally not be required for all environmental compartments. Only the compartments of highest exposure and risk should be tested first. As aforementioned, sediments are not expected to be the compartment of highest exposure for Fatty acids, C18-unsaturated, trimers (CAS No. 68937-90-6).