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Environmental fate & pathways

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The biodegradability potential of the members of Dimerised fatty acids and sub-category 2 members is evaluated based on standard biodegradation studies. These experimental results revealed a limited biodegradability potential for the members of the sub-category 2. As summarized in the category justification, the members of the fatty acids are divided into two sub-categories on the basis of their environmental fate properties. The first sub-category covers three monomeric (by-)products of the dimerization process, which are readily biodegradable. The second sub-category covers the predominately oligomers (dimeric and trimeric products) of dimerization based on their lack of ready biodegradability and other environmental fate characteristics.

Based on the results from the screening test on biodegradation in water (OECD Guideline 301 B, Ready Biodegradability: CO2 Evolution Test), Fatty acids, C18-unsaturated, dimers, hydrogenated (CAS No. 68783-41-5) is not readily biodegradable according to OECD criteria (<10 % biodegradation within 28 days).

This result is consistent with the complete data set for the sub-category 2 members of the Dimerised Fatty Acids and its derivatives as all available study reports for biodegradation in water (screening tests) for the sub-category 2 members, i.e Fatty acids, C18-unsaturated, dimers (CAS No. 61788-89-4), Fatty acids, C18-unsaturated, dimers, hydrogenated (CAS No. 68783-41-5), Fatty acids, C18-unsatd., trimers (CAS No. 68937-90-6) and Fatty acids, C16-18 and C18-unsatd., dimerised (CAS No 71808-39-4), observed a degradation of < 10 % within 28 days for the first three substances and 29.3 % within 28 days for the last mentioned substance, respectively.