Chemical contaminants in foods

How do chemical contaminants get into our food? 

Our food is often the result of a complex chain of activities, including plant or animal production, processing, storage and distribution. Several types of substance used in these processes can thus contaminate foods: additives, substances from food contact materials, the residues of plant protection and veterinary medicinal products, etc.

These substances and the maximum levels allowed in foods are governed by regulatory limits. Substances that are used intentionally (veterinary medicinal products, biocides, preserving agents, additives, food-processing aids, etc.) undergo a risk assessment procedure before receiving marketing authorisation. The purpose of this assessment is to ensure, within the limit of available knowledge, that any substances potentially present in the foods concerned do not create an unacceptable risk for the consumer. In order to take into account the changing state of scientific knowledge, the risks related to these substances are reassessed on a regular basis and their marketing authorisation can be reviewed if necessary. At the same time, the levels of these substances in food are monitored by the national health authorities (Ministries of Agriculture, Consumer Affairs and Health regarding drinking water) and by the producers and processors themselves. 

Food can also become contaminated by substances found in the environment. These can be of natural origin, such as certain toxin-producing micro-organisms or fungi, or metals in the soil. They can also be the result of environmental pollution, for example by persistent organic pollutants, PCBs, Kepone, or metals.

In order to be certain that there is no unacceptable risk to consumers from the presence of these substances in food, the foods themselves also undergo risk assessment within the framework of the knowledge acquired and the information available. Based on the findings of the assessment, the Agency may make recommendations for reducing consumer exposure; for example, it may propose a maximum tolerable intake level for certain high-contribution foodstuffs. Levels of these substances in foods are monitored during production and processing; foods with levels in excess of these standards may not be marketed. This is the case of foods containing PCBs, methylmercury or cadmium, for example.

What does ANSES do about these substances?

ANSES plays a key role in the response to the possible presence of these substances in foods. 

Through the Regulated Products Department and the French Agency for Veterinary Medicinal products, the Agency participates in the assessment, before they can be placed on the market, of various products that may be used during the production and processing of foods (plant protection products, biocides, veterinary medicinal products, etc.).

In its research and reference laboratories, ANSES develops ever-more-accurate assaying methods to detect the presence of these substances in food and drinking water.

At the same time, the Agency’s Risk Assessment Department undertakes scientific risk assessments of products and the processes involved throughout the food production chain. It provides expert appraisals of chemical and microbiological pollutants in public water distribution systems. It also manages databases, such as the one for the French Observatory for Pesticide Residues, which collects all known data on the presence of contaminants in different environments, including food. 

Thanks to this cross-cutting approach and its unique structure combining laboratories with risk assessment units, ANSES is able to carry out studies, such as the French Total Diet Study or the Calipso Study, that enable it to monitor the exposure of the general population or of specific population groups to a large number of chemical substances. It undertakes studies to measure pollutants in water intended for human consumption. It analyses the data from monitoring campaigns carried out by the French health authorities in order to publish recommendations for projected plans regarding the dietary exposure of the French population and the results of previous monitoring campaigns. If necessary, these results can be exploited during assessments for marketing authorisations for regulated products.

What about the effects of simultaneous exposure to different substances?

It frequently occurs that several substances are found in the same food. As a result, in the course of a single meal, and more particularly in the course of a day, a subject may be exposed to several substances. The question of the potential effects of multiple exposure, or the “cocktail effect”, is currently a cause of some concern and is considered to be a challenge to both science and society at large in terms of knowledge and risk assessment.

Current methods for assessing the toxicity of substances are based on an assessment of each substance considered individually, usually without taking any potential combined effects into account. Only active substances with the same mechanism of toxic action and belonging to the same chemical class (triazoles, dioxins, etc.), are examined for a potential accumulated risk.

The problem of cocktail effects is consequently a key issue for ANSES. Since 2009, the Agency has been leading the Pericles project, designed to help answer these questions. Funded by the French National Research Agency (ANR), it aims to develop methods to determine the main mixtures of pesticides to which the French population is actually exposed through its diet and to understand the potential combined effects of substances occurring in mixtures. The Agency is currently in the opening stages of interpreting the results of these tests and discussing them in view of the different studies being carried out elsewhere in the world. However, this is a vast and complex task, requiring a huge effort of scientific input and collaboration on the part of the international community to contribute to possible future changes to the regulatory framework.