Adjuvants and Safety Profile of Commercial Pesticides

From the report «Ignoring Adjuvant Toxicity Falsifies the Safety Profile of Commercial Pesticides», of Robin Mesnage and Michael N. Antoniou, published at Frontiers in Publih Health.

Commercial formulations of pesticides are cocktails of chemicals, composed of a designated pesticidal “active principle” and “other ingredients,” with the latter collectively also known as “adjuvants.” These include surfactants, antifoaming agents, dyes, etc.

The health risk assessment of pesticides in the European Union and in the United States focuses almost exclusively on the stated active principle. Nonetheless, adjuvants can also be toxic in their own right with numerous negative health effects having been reported in humans and on the environment. Numerous toxic effects have been reported in humans and the environment. However, adjuvants are regulated differently than active principles, and their long-term toxic effects are generally ignored and thus missing from pesticide risk assessment procedures.

The major adjuvants are surfactants. The most common are non-ionic surfactants such as ethoxylated alkylphenols. Surfactants are added to pesticides to form micelles, which increase the solubility of the active ingredient and protect it from degradation. This increases the half-life of the active ingredient and improves its pesticidal activity.

A total of 750 different formulations of glyphosate-based herbicides are marketed worldwide. Indeed, each name of a given formulation represents a different mixture of active principle and co-formulants. Séralini and colleagues have conducted the most extensive study on the composition and toxicity of the different ingredients that constitute glyphosate-based herbicides. They have compared the toxicity of different brands of glyphosate-based herbicides in tissue culture cell assays and showed that several commercial formulations were up to 1,000 times more toxic than glyphosate alone, the regulated active ingredient.

Regarding the neonicotinoid insecticides, organosilicon surfactants are a class of silicon-based polymers used to modify the surface tension of plant cells and insect cuticles to increase the penetration of pesticide active ingredients and can constitute up to 2% of the spray tank mix. A series of publications by Mullin and colleagues have revealed their profound effects on honeybees. This ranged from acute toxic effects to olfactory learning impairments.