Co-formulants in pesticides

“Co-formulants” are part of the mixtures contained in pesticide products, serving to enhance product efficiency and usability. These are for instance surfactants, anti-foaming agents, solvents or wetting agents. The regulatory framework considers co-formulants as “biologically inactive” components of pesticide products. This in contrast to the declared “active ingredient”, the component that is declared as acting against the targeted 'harmful' organism. For instance, glyphosate kills weeds and imidacloprid kills insects but in order to be effective, co-formulants are added to the product. The co-formulants can make up more than 50% of a product formulation. Many of them are very toxic and others increase the toxic effect of the active ingredient in the pesticide formula.

According to EU pesticide Regulation 1107/2009, the European Commission is supposed to regulate co-formulants since 2016. Just as for active substances, they shall have “no harmful effect on human and animal health and no unacceptable effect on the environment”. However, no proper regulation is in place. In a new proposal presented in November 2022, the Commission suggests a less strict risk assessment. They propose to let each individual member state to do the job, without any obligation for the industry to provide the necessary toxicity data to properly assess the toxicity of the product.

A large number of co-formulants used in pesticide products were confirmed as being harmful to health and the environment, by public authorities and researchers. In 2021, a first list of “unacceptable co-formulants” was adopted by the EU Commission, containing 144 substances to be banned due to their inherent hazardous properties[1].

For instance, while they were considered "safe" for decades, POE-tallowamines were banned as co-formulants, now confirmed as highly toxic and having powerful effects against plants[2], just like an active substance[3]. According to the pesticide regulation, it is up to the pesticide producers to disclose if a component of a pesticide is an active substance or a co-formulant. The misclassification of POE-tallowamines by the pesticide industry did not lead to any kind of legal redress on behalf of Member States or the European Commission. This example highlights the necessity to assess in a stricter way the environmental and health risks posed by these substances the moment they are sprayed into our environment.

Still, which co-formulants are used in pesticides is unknown. The composition of the products are not publicly available. Furthermore, and contrary to claims by the Directorate General for Health from the European Commission (DG Sante), a significant proportion of the co-formulants are currently not assessed under the chemical regulation REACH. For those that are assessed, the risk assessment is highly superficial, especially with regards to environmental toxicity. Many independent studies found clear evidence where co-formulants pose grave risks to human health, the environment and/or non-target organisms[4].

For this reason it is important that the use of co-formulants is regulated. PAN Europe reacts to the public consultation and presents a position paper on this topic.

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[1] Regulation (EC) 2021/383 amending Annex III to Regulation (EC) No 1107/2009 

[2] Defarge, N., Spiroux de Vendômois, J., & Séralini, G. E. (2018). Toxicity of formulants and heavy metals in glyphosate-based herbicides and other pesticides. Toxicology Reports, 5, 156–163.

[3] Mesnage, R., Benbrook, C., & Antoniou, M. N. (2019). Insight into the confusion over surfactant co-formulants in glyphosate-based herbicides. Food and Chemical Toxicology, 128, 137–145.

[4] Mesnage, R., & Antoniou, M. N. (2018). Ignoring Adjuvant Toxicity Falsifies the Safety Profile of Commercial Pesticides. Frontiers in Public Health, 5.; A., & Brown, M. J. F. (2021). Co-formulant in a commercial fungicide product causes lethal and sub-lethal effects in bumble bees. Scientific Reports, 11(1), 21653.;  Mullin, C. A. (2015). Effects of ‘inactive’ ingredients on bees. Current Opinion in Insect Science, 10, 194–200.; Mesnage, R., Bernay, B., & Séralini, G.-E. (2013). Ethoxylated adjuvants of glyphosate-based herbicides are active principles of human cell toxicity. Toxicology, 313(2), 122–128.; Straw, E. A., & Brown, M. J. F. (2021). Co-formulant in a commercial fungicide product causes lethal and sub-lethal effects in bumble bees. Scientific Reports, 11(1), 21653.; Straw, E. A., Thompson, L. J., Leadbeater, E., & Brown, M. J. F. (2022). ‘Inert’ ingredients are understudied, potentially dangerous to bees and deserve more research attention. Proceedings of the Royal Society B: Biological Sciences, 289(1970), 20212353.

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Pesticide Action Network Europe (PAN Europe) gratefully acknowledges the financial support from the European Union, European Commission, DG Environment, LIFE programme. Sole responsibility for this publication lies with the authors and the funders are not responsible for any use that may be made of the information contained herein.