Comprehensive analysis, comprehensive understanding: The benefit of widening the scope to uncover the complexity of human chemical exposome and tailor personalized risk assessment.

While biomonitoring approaches are frequently employed for assessing chemical exposure, many of them are constrained to a limited number of target chemicals, running counter to our current understanding of interactions within chemical mixtures and the growing evidence of multiple exposures within human populations. Although authors agree on the need for more comprehensive methodologies, literature provides insufficient evidence of the multifaceted nature of exposure and of the benefit of widening the analytical scope to improve exposure assessment. Moreover, although multiple exposures are generally admitted, very few are known on the scale of the human chemical exposome. Here, we illustrate how increasing the number of chemicals possibly captured improves the information on exposure. Through a literature review centered on studies utilizing hair analysis to assess exposure to anthropogenic organic pollutants, we provide here the first demonstration of how expanding the number of compounds analyzed in biomonitoring methods enhances our understanding of the chemical exposome. The results not only underscore the prevalence of multiple exposures but also reveal distinct exposure patterns within various demographic groups. Utilizing extrapolated biomonitoring data, we introduce a novel approach to estimate the number of chemicals to which humans can be simultaneously exposed. This biomonitoring-based approach is the first one relying on data derived from human samples rather than indirect metrics such as sales figures or registered chemicals. Eventually, we draw upon results from studies conducted in our team to illustrate local specificities in exposure among different populations, emphasizing the complexity of risk assessment while implemented in prevention strategies.