Pregnant women are exposed to numerous contaminants via their diet, including pesticides, furans, heavy metals, additives, and more. To study their “mixture” effect on fetal development, an Inserm team has been working with Anses (the French Agency for Food, Environmental and Occupational Health & Safety) to develop a methodology that has resulted in the identification of eight standard mixtures and their composition.
The French Agency for Food, Environmental and Occupational Health & Safety (Anses), assisted by researchers from an Inserm unit*, is now focusing on studying the exposure of pregnant women to mixtures of substances, rather than to each individual substance, as was previously the case, in order to assess the effects on fetal development.
In recent years, numerous studies have examined the impact of certain endocrine disruptors, pesticides and heavy metals. However, individuals are not exposed to just one of these substances, but to dozens of them at the same time. The doses of each substance may be very low – below the limits recommended by the health authorities – but, ultimately, they accumulate in the body. And, above all, these mixtures imply interactions between the various substances and the body, which could result in their negative effects being potentiated. This is what needs to be verified!
Eight mixtures of 25 substances
Anses therefore worked with Inserm to develop a methodology leading to the identification of eight mixtures of 25 substances to which pregnant women are exposed in France via their diets. To achieve this, the researchers used data on dietary habits provided by pregnant women included in two Inserm cohorts – Eden (2003-2006) and Elfe (2011) – as well as data from the EAT2 study (Total diet study). This Anses study indicates the average concentration of 441 contaminants (food additives, environmental pollutants, pesticide residues, mycotoxins, phytoestrogens, acrylamide, heavy metals, etc.) in 212 standard foods, depending on their preparation method (raw meat versus cooked meat, for example). One of the mixtures identified is higher in pesticides, another in furans, etc., and some substances are obviously common to different mixtures. The authors were surprised to discover the extent to which certain foods contributed to contaminant exposure compared to others, such as apples due to how often they are eaten and their impregnation with pesticides, or fish, for instance.
What is the impact on fetal health?
The objective is now to correlate exposure to these mixtures with fetal growth and development data in these women. This work is under way in the lab run by Marie-Aline Charles*: “The first step was to manage to differentiate between the various mixtures pregnant women were exposed to,” explains the researcher. “Now we need to determine whether they are innocuous or whether they have an effect on fetal health. This research is extremely complex because we need to systematically verify that it is the contaminant mixture that is to blame rather than the nutrients supplied by the foods making the greatest contribution to this mixture. In addition, it is necessary to take into account the expected benefits of these foods – for example the high fiber and vitamin content of apples – in order to reliably assess their effect on health,” she explains.
Pending more information, the methodology developed in this study can now be used by other teams to carry out the same sort of studies on other populations. “It was useful to study pregnant women as a priority since developing fetuses are more sensitive to contaminants. But these women’s diets are generally modified, to take into account risks of infection in particular. Consequently, they often eat less unpasteurized cheese and seafood and more dairy products, for example. The substance mixtures that might be identified in the general population would certainly be different,” stresses the researcher.
*Inserm unit 1153/Université Denis Diderot/Université Paris Nord/Inra, ORCHAD team, Center of Research in Epidemiology and Statistics Sorbonne Paris Cité (CRESS), Paris
T. Traoré et al. To which mixtures are French pregnant women mainly exposed? A combination of the second French total diet study with the EDEN and ELFE cohort studies. Food Chem Toxicol, online edition of November 11, 2017