Registration Dossier

Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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The assessment entity “tall oil” is a mixture of different saturated and unsaturated C16 -C18 fatty acids. Therefore, the endpoint is addressed with publicly available data on fatty acids with the same or similar structure, including conservatively fatty acids with a shorter chain(i.e. C14) if relevant and appropriate in accordance with previously applied read-across approaches (U.S. EPA Fact Sheet, 2008).

A registration dossier shall contain information on the environmental hazard assessment (Regulation 1907/2006, Article 10). For the environmental hazard assessment of tall oil, the standard testing regime set out in Annexes VII to IX is adapted in accordance with Section 1.2 and 1.3 of Annex XI so that “testing does not appear to be scientifically necessary” as follows:

(I) The ecotoxic potential of the fatty acid (tall oil) is assumed to be negligible. Fatty acids are generally not considered to represent a risk to the environment, which is reflected in their exemption from the obligation to register (Annex V, Section 9 and Regulation (EC) No 987/2008).

(II) Half-live times of salts of C8- C18 fatty acids in soil were determined with < 3 days (U.S. EPA Fact Sheet, 2008, Health Canada, 2017) and the salts are thus broken down readily by soil microorganisms (Health Canada, 2017). A similar biodegradation rate may be expected in aerobic sediments. Hypothetically, the aerobic degradation pathway of fatty acids constitutes a sequential elimination of C2 fragments, meaning that major soil metabolites of a given fatty acid would be other fatty acids with shorter chains (U.S. EPA Fact Sheet, 2008). Fatty acids are, “therefore, not expected to be persistent in the environment” (Health Canada, 2017).

 

In summary,fatty acids are not expected to be persistent in sediment due to a quick microbial degradation and are indistinguishable from naturally occurring fatty acids present in sediment as a result of plant, animal and microbial metabolism.Thus,performing further sediment simulation tests of tall oil is from a scientific point of view not expected to provide more insight into the environmental fate and is not considered necessary for the environmental hazard assessment.

 

References:

 

Health Canada’s PMRA, Pest Management Regulatory Agency (2017). Ammonium Salt of Fatty Acid Proposed Registration Decision PRD2017-04, p. 36

U.S. Environmental Protection Agency, U.S. EPA (2008). Ammonium nonanoate (031802) Fact Sheet, OPP Chemical Code: 031802, p. 2

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