Tall oil fatty acids are an alternate source to tallow fatty acids to synthesize surfactants used in various household, cosmetic and plant protection products.  Tall oil is a viscous liquid obtained as a by-product of the Kraft process of wood pulp manufacture. Recently a dry glyphosate-based formulation containing a tall oil fatty acid amidoamine ethoxylate surfactant has been developed and demonstrates low aquatic toxicity.  The purpose of this investigation was to evaluate the potential for estrogenic, anti-estrogenic, androgenic and impacts to steroidogenesis from a tall oil fatty acid amidoamine surfactants using a model aquatic vertebrate.  Based on the non-cyclic structure of tall oil based surfactants, they are not predicted to be ligands for the estrogen or androgen receptors or to disrupt steroidogenesis after exposure to concentrations that exceed worst case exposure scenarios.  Adult fathead minnows were tested following the OECD 230 endocrine screening test guideline at concentrations of 0.14, 1.4 and 14 mg/L in a flow-through system after 21-days of exposure. It was established in 14-day range-finding study that the highest test concentration did not result in significant overt toxicity.  Endpoints used to assess activity were secondary sexual characteristics (tubercle scores) and vitellogenin levels (VTG).  There were no effects on survival, growth, secondary sexual characteristics or VTG levels.  Based on the endpoints evaluated, these tall oil surfactants have been shown to not have estrogenic, anti-estrogenic, androgenic effects or produce aromatase inhibition in fish, which confirms initial predictions based on surfactant structure.  The no observed effect concentration (NOEC) was concluded to be 14 mg/L, a level that greatly exceeds predicted aquatic exposure concentrations.

Assessing the potential impact of a tall oil based surfactant blend on estrogenic, androgenic and aromatase endpoints in a fish endocrine screening assay

254th National Meeting (2017)

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