External Scientific Report
External Scientific Report
External Scientific Report
Chemical mixtures
People, animals and the environment can be exposed to multiple chemicals from a variety of sources. EFSA has already developed some approaches for assessing combined exposure to multiple pesticides and contaminants in humans and multiple pesticides in bees. Our scientists are further developing new approaches and tools for harmonising how we assess risks to humans and the environment from combined exposure to multiple chemicals in the food chain: “chemical mixtures” and their effects, sometimes called “cocktail effects”.
Latest
EFSA publishes a scientific report that expedites its work in the field of cumulative risk assessment of pesticides: Prioritisation of pesticides and target organ systems for dietary cumulative risk assessment based on the 2019-2021 monitoring cycle
The report analyses 350 substances and 16 organs, identifying:
- Low priority substances, expected to contribute only marginally to cumulative risk;
- High priority organs for future cumulative risk assessments.
The report concludes that for 70% of organs considered, there is no need for additional risk assessments: combined exposure to pesticide residues is not likely to pose a health risk to consumers for those organs. In addition to the nervous system and the thyroid, for which EFSA has already carried out cumulative risk assessments, the report prioritises the following organs for future cumulative risk assessment: reproductive function, foetal development, liver, kidney, male reproductive system, and hematopoietic system (the system producing blood cells).
The milestones of EFSA’s work to assess combined exposure to multiple pesticides in humans are outlined in this timeline.
Milestones
2023
June
Two external scientific reports explain how to use the updated methodology of a new release of the Monte Carlo Risk Assessment (MCRA) web platform for cumulative risk assessment of pesticides and other chemicals. This release came out with improved transparency, accessibility, and interoperability for risk assessors. The MCRA is a central plank in EFSA’s and Member States’ efforts to assess how combined exposure to multiple chemicals can affect humans over time.
June
A technical workshop on risk assessment for plant protection products (PPPs) is attended by some 80 participants from 25 Member States, the European Commission, ECHA and EFSA who share experiences and current practices for assessing pesticide formulations, with the overall purpose of harmonising assessments at Member State and EU level.
2022
October
EFSA assesses the risks to pregnant women from dietary cumulative exposure to pesticide residues that have acute effects on embryo development. The assessment focuses on two types of craniofacial malformations: alterations due to abnormal skeletal development, and head soft tissue alterations and brain neural tube defects. The conclusion is that, with varying degrees of certainty, exposure is below the threshold that triggers regulatory action.
2021
December
Following a public consultation and an international workshop, EFSA publishes new guidance from its Scientific Committee providing a framework for grouping chemicals for human risk assessment of combined exposure to multiple chemicals, and methods for identifying low priority chemicals to reduce the number of chemicals in assessments. For more details see FAQ (Q5).
October
EFSA holds an international workshop on scientific criteria for grouping chemicals into assessment groups and future challenges in risk assessment of chemical mixtures. Scientific advisory bodies from across the globe take part.
June - September
EFSA meets French MEPS to clarify the methods and data used to establish the safety of representative formulations of herbicides and pesticides. This follows a letter co-signed by more than 100 political leaders – MEPs, French deputies and French senators – to EFSA concerning its role in considering cumulative effects of substances in pesticide formulations under EU regulations on plant protection products.
- Letter by MEPs and EFSA’s reply
- Technical Meetings with MEPs:
May
EFSA consults publicly on a draft guidance document (‘MixTox 2’) for grouping chemicals across the food safety area and prioritisation of groups of chemicals for human health risk assessment.
February
The European Commission and EFSA publish an action plan to accelerate development of the methodology for cumulative risk assessment (CRA) of pesticides, with a view to gradually implementing CRA into regulatory practice.
- EFSA publishes an assessment of the risks to consumers from dietary cumulative exposure to pesticide residues that have chronic effects on the nervous system (chronic erythrocyte acetylcholinesterase [AChE] inhibition). The overall conclusion is that, with varying degrees of certainty, exposure does not exceed the threshold for regulatory consideration established by risk managers.
- EFSA also issues a statement comparing cumulative exposure to pesticides that have chronic effects on the thyroid system and acute effects on the nervous system for the periods 2014-2016 and 2016-2018. The results of the analysis show that consumer exposure patterns over the two periods did not change significantly and suggests that repeating cumulative risk assessments every three years can adequately address potential changes to exposure.
2020
April
EFSA publishes the results of its first two pilot assessments on the risks posed to humans by residues of multiple pesticides in food. The assessments – one considering chronic effects on the thyroid system and the other acute effects on the nervous system – are the culmination of a multi-year collaboration between EFSA and the Dutch National Institute for Public Health and the Environment (RIVM).
The overall conclusion for both assessments is that consumer risk from dietary cumulative exposure is, with varying degrees of certainty, below the threshold that triggers regulatory action for all the population groups covered.
2019
March
EFSA finalises its ‘MixTox’ guidance document following a public consultation. The guidance equips its scientists with methodologies and tools to assess combined exposure to multiple chemicals. Related advice comes out on how to assess the genotoxicity of substances in chemical mixtures.
An EFSA research study from 2018 shows that overall in the EU awareness of chemical mixtures among the general public is quite low.
2018
April
EFSA’s partners the Dutch National Institute for Public Health and the Environment (RIVM) and Wageningen University, publish data model for probabilistic cumulative dietary exposure assessments of pesticides.
2017
January
Launch of “OpenFoodTox” database reporting summary chemical hazards information and linking to the OECD eChemPortal. Step-by-step approaches for human and ecological risk assessment of chemical mixtures using OpenFoodTox data provide alternatives to animal testing in toxicological assessments.
2016
October
Public consultation on proposed MixTox guidance scope and objectives.
May
January
An RIVM-EFSA pilot study tests the Monte Carlo Risk Assessment software tool for carrying out exposure assessments of multiple pesticides.
2015
March
Finalisation of data collection on toxicokinetic and toxicodynamic interactions of chemical mixtures for human risk assessment and combined toxicity of multiple chemicals for animal health and ecological risk assessment.
2014
September
2013
July
EFSA presents cumulative assessment group methodology for pesticides.
Scientific report on international frameworks dealing with human risk assessment of combined exposure to multiple chemicals, reviewing current approaches and setting out future priorities.
2008
May
2006
November
Cumulative risk assessment of pesticides
2030
Target date for the completion of all needed cumulative risk assessments for pesticides residues.
2024
A scientific report is published which enables EFSA to speed up its work in the field of cumulative risk assessment of pesticides. The report identifies pesticides that need to be considered in the context of cumulative risk assessment and prioritises the organs and the human body functions and systems for which a cumulative risk assessment is needed. In addition to the nervous system and the thyroid, for which EFSA has already performed cumulative risk assessments, those are: reproductive function, foetal development, liver, kidney, male reproductive system, and hematopoietic system (the system producing blood cells).
EFSA’s production of cumulative risk assessments for pesticides intensifies. EFSA is currently performing cumulative risk assessments on the kidneys, the liver and the reproductive function.
2022
EFSA assesses the risks to pregnant women from dietary cumulative exposure to pesticide residues that have acute effects on embryo development. The conclusion is that, with varying degrees of certainty, exposure is below the threshold that triggers regulatory action.
2021
The European Commission and EFSA publish an action plan to accelerate development and implementation of the methodology for cumulative risk assessment (CRA) of pesticides.
EFSA publishes an assessment of the risks to consumers from dietary cumulative exposure to pesticide residues that have chronic effects on the nervous system (chronic erythrocyte acetylcholinesterase [AChE] inhibition). The overall conclusion is that, with varying degrees of certainty, exposure does not exceed the threshold for regulatory consideration established by risk managers.
2020
EFSA carries out two pilot cumulative risk assessments of pesticide residues: one considering two chronic effects on the thyroid system and another looking at two acute effects on the nervous system. The overall conclusion for both assessments is that consumer risk from dietary cumulative exposure is, with varying degrees of certainty, below the threshold that triggers regulatory action for all the population groups covered.
2006 - 2019
In collaboration with its stakeholders, EFSA develops approaches for assessing combined exposure to multiple pesticides in humans. For more detailed information, please see the complete timeline.
EFSA's role
EFSA’s Scientific Committee develops harmonised risk assessment methodologies on cross-cutting scientific matters in EFSA's areas of activities where EU-wide approaches are not already defined. The Scientific Committee considers development of guidance for harmonised methodologies for combined exposure to multiple chemicals a priority for EFSA.
EFSA’s Panel on Plant Protection Products and their Residues is responsible for the general methodology for classifying pesticides into cumulative assessment groups. The methodology developed by the Panel uses broad criteria for inclusion of pesticides in groups to maximise consumer protection.
EFSA undertakes and/or supports research activities to contribute to the implementation of guidance in this area:
- Data collection and analysis of combined toxicity of multiple chemicals of relevance to EFSA in the area of human, animal and environmental toxicology.
- Development of tools for modelling (tiered approaches, population dynamics, human variability) for human and ecological risk assessment for single and multiple chemicals.
FAQ
For a single chemical, scientists review available toxicity data to set a safe level for human health or the environment. They compare this with exposure (for example through food) to predict potential risks. For multiple chemicals, scientists have developed methods which use the same principles. They assess the toxicity of the group of chemicals identifying how these substances are metabolised in the body and how they might express their toxicity, often referred to as “mode of action”. Then, the toxicity information is combined with exposure information to assess potential health risks using assumptions about the combined toxicity. The most common assumptions are dose addition, response addition and interaction.
Dose addition means that the individual chemicals in the mixture have a similar toxicity and the doses are added up and combined with exposure for the risk assessment.
For response addition, scientists consider the independent toxic effects of each substance in the mixture and include these together when carrying out the risk assessment.
Interactions are more complex. Some chemicals can become more toxic when combined. This is called “synergism”. On the other hand, other chemicals when combined can be less toxic when combined, which is known as “antagonism”. The mechanisms behind synergism and antagonism are complex. Two important ones are: an increase or decrease in the body’s ability to detoxify and eliminate the compounds, and an increase or decrease in toxicity of the chemical(s). If there is evidence of such interactions, scientists collect the information to take these effects into account in the risk assessment.
In its 2021 guidance document, EFSA’s Scientific Committee provides a framework for grouping chemicals for human risk assessment of combined exposure to multiple chemicals and methods for identifying low priority chemicals to reduce the number of chemicals in assessments. The framework proposes:
- to apply hazard-driven criteria for the grouping of chemicals, using mechanistic information (how chemicals behave) on toxicity as the gold standard, i.e. a common mode of action or adverse outcome pathway, where available
- to group chemicals using a common adverse outcome, e.g. EFSA’s approach to the cumulative risk assessment of pesticides, when mechanistic data are not available
- to use toxicokinetic data (what happens to chemicals in an organism) for grouping, particularly for compounds that share common toxicologically relevant metabolites (breakdown products resulting from metabolism)
- to use risk-based approaches for combined or single chemicals, and exposure-driven approaches as prioritisation methods
- to follow a structured weight of evidence approach in all cases