Two major agrochemical players, Bayer from Germany and Syngenta from Switzerland, face scrutiny over EU studies that reportedly reveal potential toxic effects on brain development. A recent scientific investigation published in Environmental Health highlights concerns about pesticide safety and how such findings are handled by regulators and industry alike.
Currently, the European Parliament has called for a hearing with leaders of both companies to seek clarification. Bayer and Syngenta maintain that they comply with all applicable laws and regulations.
The study examined 35 developmental neurotoxicity assessments conducted between 1993 and 2005. Interestingly, all but one of these studies were submitted to the United States Environmental Protection Agency, while nine were not submitted to European authorities, raising questions about compliance with EU requirements.
The most troubling aspect concerns seven of the nine non-submitted studies that involved researchers who identified concealing efforts related to pesticides. These findings have potential regulatory implications for how substances could affect brain development now or in the future.
Studies not entered into EU records included experiments on pregnant mice to determine whether offspring exposed to the compounds showed developmental issues. In seven cases, researchers noted reduced weight gain, delayed sexual maturation, impaired motor activity, and other adverse effects.
Among the nine pesticide compounds investigated, four have already been withdrawn from the EU market, while four are under review.
protect human health
Citing Bayer and Syngenta, the authors describe the lack of access to these studies as a serious flaw, arguing that it may bias regulatory risk assessments and hinder authorities from reliably identifying high-risk situations. Protecting human health as mandated by law hinges on full transparency in the data that inform safety decisions.
Without complete access to all toxicity testing, a robust EU safety assessment of pesticides cannot be completed, the researchers contend. They urge EU officials to cross-check datasets with counterparts in other jurisdictions, especially the United States.
They advocate that pesticide approval processes be cross-checked against lists of studies conducted under good laboratory practices to ensure all relevant data are submitted to authorities. They also propose shifting the testing obligations away from manufacturers and back to regulatory bodies to prevent commercial interests from shaping study design, performance, reporting, and distribution. The aim is that authorities remain informed and independent, minimizing conflicts of interest.
Additionally, the researchers call for a review of rules and procedures to deter non-disclosure of toxicity studies, noting the potential legal risks and penalties for companies that fail to comply with the law. They emphasize that serious consequences should apply to those who do not disclose relevant safety data.
The companies deny the allegations.
In the EU, the safety assessment for plant protection products largely relies on toxicity studies commissioned by the manufacturers. The law requires that all work conducted be included in the submission file for approval or renewal of the active substance.
Bayer and Syngenta, each cited as responsible for several undelivered studies, rejected the Swedish researchers’ conclusions. Bayer states that it always delivers the work required under community standards, while Syngenta claims it complies with EU and Swiss data requests and notes that additional studies are conducted to meet United States regulatory guidelines.
The European Food Safety Authority (EFSA) has observed that tighter rules took effect in the EU two years prior, mandating companies to share all safety-related work on their products.
While rat studies do not translate directly to humans, the focus remains on protecting brain development from chemicals that can affect attention, memory, coordination, learning, and IQ. The researchers stress that safeguarding children’s brains is a public health priority.
Pesticides play a key role in protecting crops from weeds, pests, and disease, but their approval is tightly regulated and requires extensive testing for efficacy, toxicity, and ecological impact.
Reference report: Phys.org coverage of pesticide toxicity and EU disclosure practices.
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