Exclusive: The same studies were submitted to US regulators and some are relevant to safety levels, the researchers say

Pesticide companies failed to disclose a series of studies assessing brain toxicity to European regulators, according to new research, despite the same studies having been submitted to US regulators.

When the EU authorities were made aware of the studies, between 14 and 21 years after they were conducted, new safety limits were applied in some cases and evaluation is still under way in other cases.

The researchers described the omissions as “outrageous”, concluding that “apparently non-disclosure is a problem that is not rare” and that there could be “no reliable safety evaluation of pesticides by EU authorities without full access to all performed toxicity studies”.

The new research is the first systematic assessment of non-disclosure and focused only on developmental neurotoxicity (DNT) studies. The researchers found 35 DNT studies submitted to the US Environmental Protection Agency as part of the pesticide approval process but found that nine of these had not been included in dossiers sent to the EU authorities for the same pesticides.

Among the findings in the undisclosed studies were changes in brain size, delayed sexual maturation and reduced weight gain in the offspring of laboratory rats exposed to a pesticide when pregnant. The pesticides identified in the new study include the insecticides abamectin, ethoprophos and pyridaben and the fungicide fluazinam. These are, or have been, used on a range of crops including tomatoes, strawberries, potatoes and aubergines. [...]

A spokesperson for the European Commission said: “There is a clear obligation to submit all available adverse data as part of applications since 2013, and there is an obligation to notify adverse data when they become available since 1991.”

The power to penalise companies if they unlawfully fail to disclose toxicity studies in Europe lies with national regulators. But no known penalty has been imposed on any pesticide company to date. The UK pesticides regulator, the Health and Safety Executive, did not answer a request for comment. [...]

The chemical companies said they had complied with the EU regulations, in some cases arguing they were not legally obliged to submit the studies. They also disagreed with the researchers’ conclusions that some of the studies had led to tighter regulation when the EU authorities had become aware of the studies’ existence, or that they could do so in the future. [...]

A spokesperson for Syngenta, which commissioned two DNT studies on abamectin in 2005 and 2007, as well as studies on two other pesticides, said: “Syngenta has complied with all EU data requests and provided relevant study data in accordance with regulatory requirements.”

The spokesperson said the abamectin DNT studies were not submitted to EU authorities in an application for approval that was completed successfully in 2008 because the studies had been conducted for its US regulatory application and were not a requirement in the EU at the time. He said these studies were not considered to provide any new toxicological information. [...]

A spokesperson for Bayer said: “At all times, we submitted the necessary studies required by the regulations at the time. For all three active ingredients [cited in the new research], the studies would not have changed the authorities’ risk assessment.”

Nissan Chemical Corporation said it had submitted the DNT study for its pesticide pyridaben, completed in 2007, to EU regulatory authorities in February 2023. Mie and Rudén said the study has the potential to impact the regulation of the chemical, which is still approved in the EU.

Japanese company ISK said it had submitted a 2005 DNT study on their pesticide fluazinam to EU authorities in 2020 and said it had not been required to do so beforehand. Efsa said the study was now being evaluated as part of the assessment of whether to renew the pesticide’s approval.

None of the companies said they had submitted justifications for exemption from the need to submit existing studies, though some said other DNT studies had been submitted. [...]