Pesticides: breakthrough on cumulative risk assessment

EFSA and its European partners have taken a major step forward in their work on assessing the cumulative risks from exposure to pesticides. A software tool has been developed for carrying out exposure assessments of multiple pesticides. In a pilot study, consumer exposure assessments are now being performed with the tool on groups of pesticides that may affect the thyroid and nervous systems. 

The results of these assessments will be published by the end of this year, and will be considered by EFSA when it produces two scientific reports on cumulative risk assessments for the thyroid and the nervous systems in 2017.

In the longer term, EFSA hopes to start progressively incorporating high-level cumulative risk assessments into its annual analysis of the chronic and acute risks that pesticides pose to consumers. The analysis uses data collected by Member States.

The software – known as the Monte Carlo Risk Assessment (MCRA) tool – was initially developed through a project funded by the European Commission that involved researchers, scientists and regulators from 14 countries and was overseen by the National Institute for Public Health and the Environment for the Netherlands (RIVM).

In 2015, EFSA funded further development of the MCRA tool to allow the processing of cumulative assessment groups of pesticides containing up to 100 active substances and following the guidance of the EFSA Panel on Plant Protection Products and their Residues. This year EFSA will further support improvements to the tool regarding its accessibility by external users and data organisation and formatting.

Experience gained in the initial assessments will be used to optimise the tool to ensure its fitness for purpose in the context of regulatory decisions on applications concerning maximum residue levels (MRLs) of pesticides in food. This side of the project is being closely coordinated with the European Commission, which has established a working group to ensure that the project meets the needs of risk managers.

Luc Mohimont, from EFSA’s Pesticides Unit, said: “This is an exciting and significant development. Progress has been made in developing an approach for carrying out reliable exposure assessments of multiple pesticides, which takes us a step closer to our ultimate goal: to carry out comprehensive risk assessments of the combined effects on humans of pesticides, rather than just individual chemicals.”

The substances to be assessed in the pilot exposure assessments were identified by EFSA’s pesticide experts using a methodology specially devised for classifying pesticides into “cumulative assessment groups” (CAGs, see below). Over the coming years, CAGs will be defined for other organs, tissues and systems. Data is already being collected to define groups of pesticides that affect the liver, kidneys, eyes, and the reproductive and developmental systems.

Background

The EU regulation on MRLs in food stipulates that decisions on MRLs should take into account cumulative effects of pesticides as and when the methods to assess such effects become available. In addition, the regulation covering the placing of pesticides on the market stipulates that pesticides should have no harmful effects – including cumulative effects – on humans.

Cumulative assessment groups

In July 2013, EFSA’s Panel on Plant Protection Products and their Residues published a general methodology for classifying pesticides into cumulative assessment groups (CAGs). The methodology rests on the assumption that pesticides causing the same specific phenomenological effects, well defined in terms of site and nature, can produce joint, cumulative toxicity – even if they do not have similar modes of action.

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