Analysis of the results of Inserm’s collective expert review on the health effects of pesticides
The adverse effects of plant protection products must be monitored and taken into account so that their uses and marketing authorisations can be adjusted where necessary. Through its phytopharmacovigilance scheme, ANSES analysed the results of a major scientific study: Inserm’s collective expert review on the links between pesticide exposure and human health, updated in 2021. Following this analysis, the Agency identified several health signals, including a strong signal concerning pyrethroids, which are used in plant protection products as well as in biocides and veterinary medicinal products. ANSES reiterates the importance of regularly reviewing the assessments of substances and products in light of new data.
Monitoring the adverse effects of plant protection products
Even though their safety is assessed before they are placed on the market, plant protection products can have unintended effects on health and the environment. ANSES’s phytopharmacovigilance scheme, which is unique in the European Union, monitors these effects under real conditions of use so that appropriate action can be taken.
To identify potential health signals, this vigilance scheme collects a large amount of data on the presence of pesticide residues in the environment, the exposure observed and the health impact on living beings and ecosystems. In addition to data from studies, surveys and measurements taken in the environment, scientific publications are also taken into account, with particular attention paid to epidemiological studies on human health. With this in mind, ANSES analysed the conclusions of Inserm’s 2013 collective expert review, updated in 2021, which provided an overview of current knowledge on the links between pesticide exposure and the occurrence of diseases.
The classes of ‘pesticide’ products and substances studied by Inserm included plant protection products for agricultural use as well as biocidal and veterinary products. ANSES focused its phytopharmacovigilance analysis on substances still approved in the European Union for plant protection uses. The numerous substances identified in Inserm’s collective expert review that are no longer authorised for use in agriculture, such as organochlorines, were therefore not considered in this analysis.
ANSES has already used the results of Inserm’s expert review on several occasions: for its expert appraisal on prostate cancer associated with occupational exposure to pesticides, including chlordecone, which led to the creation of a table of occupational diseases for the agricultural social security scheme, and for updating the toxicity reference values for succinate dehydrogenase inhibitor (SDHi) fungicides. Moreover, during the consultation phase of the European regulatory review of glyphosate, organised before the conclusions of the assessment were published, Inserm had submitted feedback from its own expert review.
Important signals to consider for pyrethroids
A group of independent experts was commissioned by ANSES to identify warning signals in the various results of Inserm’s collective expert review. To do this, the experts cross-referenced several types of data, including data on presumed links between pesticide exposure and human diseases as established by Inserm, data on authorised uses and data on the toxicity of various pesticides.
This analysis identified several signals. The most significant involved organophosphates, especially pyrethroids. These insecticides are still widely used, both in professional agriculture and for professional and amateur biocidal applications. The section of the Esteban study on pesticide contamination levels in the French population (Santé publique France, 2021) also showed high quantification frequencies for pyrethroids, which were higher in children than in adults.
The main signal for the pyrethroid class related to internalising behaviour disorders in children whose mothers had been exposed during pregnancy. Sperm damage was also identified in the general population (all sources of exposure combined), albeit with a lower level of presumption. Deltamethrin, a pyrethroid insecticide, was also associated with an increased risk of chronic lymphocytic leukaemia/lymphocytic lymphoma in connection with occupational exposure, with a moderate level of presumption.
To further investigate the conclusions of the Inserm report, the expert group on phytopharmacovigilance also analysed the results of a recent epidemiological study (Qi et al., 2022) on pyrethroids. This analysis confirmed that prenatal exposure to pyrethroids can have adverse effects on the neurodevelopment of very young children.
In order to implement public health prevention measures, ANSES recommends identifying the most significant sources of exposure to pyrethroids among all possible insecticide uses: medicinal products, plant protection products and biocides, including those used to treat building and furniture materials and textiles.
Regarding organophosphates, their use is currently very limited in France and products containing malathion are no longer authorised in the country. EFSA has been informed of the health signals identified by the phytopharmacovigilance scheme for this substance, while its European approval is currently under review.
Taking account of all the available scientific data for the assessment of plant protection products
The signals identified highlight the importance of regularly updating the risk assessment for each plant protection product and substance. This vigilance is all the more crucial for plant protection substances approved for long periods. ANSES points out that under the European regulations, the approval of an active substance can be reviewed when new scientific and technical knowledge calls it into question.
Furthermore, when reviewing products and substances and renewing decisions, the Agency emphasises the need to make use of all the available and relevant scientific literature, including epidemiological studies and signals and alerts from vigilance systems. The constant updating of assessment methodologies is also fundamental, and ANSES reaffirms its commitment to contributing to this, as part of the work harmonised by EFSA.
However, the interpretation of epidemiological data, and more generally of vigilance data, remains severely limited by difficulties in accessing detailed data on actual current and past uses of products. That is why ANSES is reiterating its recommendation that data on the use of plant protection products be made available and retained over the long term.
Lastly, the Agency points out that limiting use to what is strictly necessary is an essential part of risk management for biocidal, veterinary and plant protection products, whether in professional or domestic settings, due to their confirmed pharmacological and/or toxicological effects.