Before a plant protection product is authorised, the risk to the consumer from exposure to residues of that plant protection product via food shall be assessed and maximum residue limits (MRLs) shall be set. The risk to the consumer is also investigated after authorisation, within the framework of control and monitoring (see, for example, our recent notification about the European annual report).

At present, this risk assessment is carried out separately for each substance. However, work at EU level has been ongoing for several years to develop a scientific methodology for estimating the health risks to consumers exposed via food to different plant protection products, which may have similar effects and thus together may pose a higher (cumulative) risk.

To make such a cumulative risk assessment possible, all active substances should be grouped on the basis of their common toxicological effects on a specific organ or system. Only substances within such a group can contribute to the same cumulative effect. For effects on the nervous system and thyroid gland, existing substances have already been classified into groups, while for other organs/systems (e.g. liver, eye, adrenal gland and reproductive system) the grouping is still under development.

On 29 April, the European Food Safety Authority (EFSA) published the results of a pilot study in which a cumulative risk assessment was carried out for the two groups already defined, of substances with (short-term) effects on the nervous system on the one hand and substances with possible (long-term) effects on the thyroid gland on the other. Residue monitoring results collected by several EU Member States in the 2014-2016 period were used.

On the basis of these first cumulative risk assessments, it appears that an adaptation of MRLs for individual substances or an adaptation of existing authorisations is not yet necessary. More information can be found in the FAQ on EFSA's website.

Additional cumulative risk assessments will be carried out in the coming years, e.g. for other toxicological effects. In the meantime, work continues on optimising the methodology and the software needed to perform such complex calculations efficiently, as well as collecting as much data and information as possible in a structured manner, in order to be able to estimate with greater certainty the cumulative risk in the future.