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Toxicity to microorganisms

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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) Fatty acids are a natural component of soil and water, produced in the cells of plants and animals. Fatty acids will be rapidly degraded in soil and water via the β-oxidation pathway (e.g. essential process in the citric acid cycle) and thus not expected to accumulate in the environment (EU RAR zinc distearate, 2008). Hence, an accumulation in the environment and long-term effects are not expected (Health Canada, 2017).

(III) Earlier assessments indicate that solubility and bioavailability of fatty acids decreases in the water column with increasing chain length (> 12C) (OECD SIDS, 2014; HERA, 2003). “For chain lengths > C12, solubility decreases to a degree where an adverse effect would not be expected in the environment due to reduced bioavailability […] Data for longer chain lengths have been generated using solvents which makes interpretation more difficult” (HERA, 2003). However, HERA (2003) does not specify if effect concentrations were derived from tests in which the fatty acid was applied with a solvent.

(IV) “Given that fatty acids are readily biodegradable a low risk to sewage treatment organisms was concluded” (EFSA, 2013). Data on activated sludge respiration inhibition tests with fatty acids are rather limited. According to Madsen et al. 2001, “monitoring conducted in the Netherlands showed that the concentrations of soap in the effluent of six representative municipal sewage treatment plants varied between 0.091 and 0.365 mg/L with an average value of 0.174 mg/L (Madsen et al. 2001 and references therein).“Two available tests with bacteria resulted in NOEC values of 1000 and 1560 mg zinc distearate/L” and were derived in a test with Pseudomonas putida and a Microtox test (DIN 38412, part 34), respectively (EU RAR zinc distearate, 2008 and references therein), both values being ≥ OECD test limit of 1000 mg/L (§ 40, OECD 209, 2010). “In the latter study an EC20 of 6250 mg zinc distearate/L was calculated, with the remark that an EC50 could not be derived because of the low effect response” (EU RAR zinc distearate, 2008). HERA (2003) provides an EC10 of 10,000 mg decanoic acid (C10 fatty acid)/L for P. putida (DIN 38412-part 27), which according to the authors can be directly related to the criteria specified by OECD 209 (HERA, 2003 and references therein).

(V) Meat or vegetable extracts are added to the synthetic sewage feed at a concentration of 11 g /L according to the “activated sludge respiration inhibition test (Carbon and Ammonium Oxidation)” (OECD TG 209, 2010). Meat, including beef, pork or chicken, contain C14-C22 saturated and unsaturated fatty acids. Thus, fatty acids as substrate for microbial growth are expected to have a very low potential for toxicity to aquatic microorganisms.

In sum, available data indicate a low toxic potential of fatty acids to microorganisms. Fatty acids as contained in plant and animal tissue are a natural component of the environment, are rapidly degraded by microorganisms and therefore not expected to accumulate in the environment. It is thus from a scientific point of view not required to perform additional tests on the toxicity of tall oil to aquatic microorganisms since further tests are not expected to provide more insight into the environmental toxicity and are not considered necessary for the environmental hazard assessment.



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

EFSA (2013). Conclusion on the peer review of the pesticide risk assessment of the active substance Fatty acids C7 to C18 (approved under Regulation (EC) No 1107/2009 as Fatty acids C7 to C20), European Food Safety Authority, Parma, Italy, Vol 11(1):3023

OECD 209(2010). OECD Guideline for Testing of Chemicals, Adopted 22 July 2010, Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation), p. 18.

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

OECD SIDS initial assessment profile- aliphatic acids (2014), CoCAM 6 September 30-October 3, Italy/ICCA, p. 41

HERA (2003). Human & Environmental Risk Assessment on ingredients of European household cleaning products. Fatty Acid Salts (Soap) Environmental Risk Assessment

EU Risk Assessment Report, RAR - Zinc distearate (2008), CAS No. 557-05-1 & 91051-01-3. PART 1 Environment, p. 63


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