The SDHI class includes 11 fungicidal substances that prevent the development of fungi and moulds affecting crops by blocking an enzyme involved in cellular respiration: succinate dehydrogenase (SDH). In April 2018, in an article published in the press, several scientists warned of the potential risks of these substances to human health. ANSES then convened a group of independent experts to assess this signal. On the basis of their work, it concluded that there was no health alert justifying the withdrawal of marketing authorisations for these fungicides.
Launch of specific research and expert appraisal work
With a view to examining the warning signal in greater depth, ANSES identified several research projects that respond to the independent expert group's recommendations to improve knowledge, issued in early 2019.
ANSES is currently providing nearly 450,000 euros of funding for work to explore data from the national register of hereditary paraganglioma associated with a mutation in one of the SDH genes, in order to explain the trend in the incidence of this type of disease and carry out a case-control study based on the national register.
Two other research projects are in progress, with funding of around 600,000 euros from the Ecophyto plan and ANSES's National Research Programme for Environmental and Occupational Health, for toxicological and mechanistic studies to further investigate the mechanisms of action of SDHI fungicides.
ANSES also asked Inserm to consider the issue of the health effects of SDHIs as part of the ongoing collective expert appraisal aimed at updating knowledge of the health effects associated with pesticides. This update will take into account recent scientific publications, including the article published on 7 November 2019 in the scientific journal PLOS One referring to the toxicity of SDHI fungicides to cells cultured in vitro.
Moreover, ANSES is continuously improving its methods for assessing the risks associated with the use of plant protection products. In addition to the work in progress, in 2019 it issued an internal request to examine the question of cumulative dietary exposure to the various SDHIs, and will be publishing its report in the end of 2021.
Monitoring for possible health effects
ANSES also remains vigilant regarding all adverse effects on human health and continues to collect field data through its multi-year national phytopharmacovigilance (PPV) programme. Ongoing and future studies on monitoring pesticide contamination of ambient air, soil and food will take the study of SDHIs into account.
Sharing knowledge with health authorities responsible for substance assessment
Lastly, as with all plant protection products, active substances are assessed at European level under the aegis of EFSA and the European Chemicals Agency (ECHA). The commercial products containing them undergo a specific assessment for each use by the Member States, with a view to obtaining marketing authorisation. Active substance approvals and marketing authorisations are regularly reviewed in light of advances in the available knowledge.
As early as 2018, ANSES had informed the European authorities, Member States and its North American counterparts of the warning signal concerning SDHI fungicides and of its internal request to address the matter. In early 2019, ANSES forwarded its conclusions to EFSA, ECHA and the Member States for their consideration and to ask them to pay particular attention to any new data during ongoing assessment and re-assessment processes, such as the re-assessment of boscalid, the most widely used active substance in the SDHI class.
To date, no new evidence has been provided to confirm the existence of a health alert justifying the withdrawal of the marketing authorisations in force, in accordance with national and European regulations on plant protection products.