Why Pesticides Could Be Even More Toxic – Adjuvants
September 6, 2018
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Writing in Frontiers in Public Health, Dr Robin Mesnage from King’s College London, suggests new regulations are needed to protect people and the environment from toxic pesticide ingredients that are not currently subject to safety assessments. With Dr Michael Antoniou, they published the first comprehensive review of gaps in risk assessments for “adjuvants” – ingredients added to pesticide formulations to enhance the function or application of the active ingredient.
Pesticides are a mixture of chemicals made up of an active ingredient — the substance that kills or repels a pest — along with a mixture of other ingredients that help with the application or function of the active ingredient.
“Exposure to environmental levels of some of these adjuvant mixtures can affect non-target organisms — and even can cause chronic human disease,” says Dr Mesnage. “Despite this, adjuvants are not currently subject to an acceptable daily intake and are not included in the health risk assessment of dietary exposures to pesticide residues.”
Regulatory tests for pesticide safety are currently only done on the active ingredient, which assumes the other ingredients have no effects. This means the full toxicity of a pesticide formulation — including those used in both agriculture and domestic gardens — is not shown.
“Currently, the health risk assessment of pesticides in the European Union and in the United States focuses almost exclusively on the active ingredient,” explains Dr Mesnage. “Despite the known toxicity of adjuvants, they are regulated differently from active principles, with their toxic effects being generally ignored.”
The researchers focused on glyphosate-based herbicides, the most used pesticide worldwide. They point out that this weed killer has so many different adjuvant formulations that a safety test of one weed killer does not test the safety of another.
“Studies comparing the toxicity of commercial weed-killer formulations to that of glyphosate alone have shown that several formulations are up to 1,000 times more toxic than glyphosate on human cells. We believe that the adjuvants are responsible for this additional toxic effect,” says Dr Mesnage.
The European Food Safety Authority is now reassessing the validity of pesticide risk assessment in the EU.