Exposure to chemical substances is common and comes from several sources (environmental, food, and occupational). It is often studied using a substance-by-substance approach. Although this method helps identify the determinants of exposure to a single chemical, it cannot accurately reflect exposure to multiple chemicals. In this study, we used the concept of exposure load (EL) to evaluate multi-chemical exposure in a representative sample of the general French population. EL corresponds to the number of substances (or metabolites) measured in body fluids above a defined concentration threshold. EL was calculated for adults and children separately for two groups of substances: those currently found in domestic environments (Group A) and pesticides (Group B). Although the EL does not assess the health impact linked to multi-chemical exposure, it does aid in the identification of particularly vulnerable populations. Accordingly, preventive actions specifically aimed at these subgroups could be useful.

In Group A, we found that multi-chemical exposure was generalized since all the adults and children had an EL greater than or equal to 13 (out of 22 substances studied) when the LOQ (limit of quantification) was considered as the discretization threshold. In adults, men, smokers and people of working age (i.e., people under 60 years old) had a higher EL. In Group B, multi-chemical exposure was also generalized, since all the adults (15 substances studied) and children (13 substances studied) had a mean EL almost equal to 6 when the LOQ was considered as the discretization threshold. In adults, persons with occupational exposure to pesticide dust had a higher EL when the P90 was considered as the discretization threshold.

This study highlights widespread multi-chemical exposure in adults and children in France, and the major impact of occupational exposure (Group B) and tobacco smoking (Group A) on EL.