Fatty acids, tall-oil, manganese salts

Biodegradation in soil

Description of key information

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) Fatty acids are not persistent in soil since they are broken down quickly by soil microorganisms (Health Canada, 2017). Half-live times of C8- C18 fatty acids in soil were determined with < 3 days (U.S. EPA Fact Sheet, 2008, Health Canada, 2017). Hypothetically, the degradation pathway of fatty acids constitutes a sequential elimination of C2 fragments, meaning that the 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 persistent in soil since they are broken down quickly by soil microorganisms and are indistinguishable from naturally occurring fatty acids present in soil as a result of plant, animal and microbial metabolism. Thus, performing further soil 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