Chemical exposome patterns in mothers and children across urbanisation levels in five European birth cohorts

Background: Urbanisation can be an important determinant of human exposure to synthetic chemical pollutants. The impact of contaminant exposures on health is of particular concern during susceptible periods of life, such as in utero and during childhood, when exposure may lead to adverse health effects in childhood and later adulthood. Objective: We aimed to examine how contaminant exposures vary between urban and non-urban areas across five different European birth cohorts in Spain, France, Greece, the UK, and Lithuania. Methods: Urine and blood samples were collected from a total of 1021 mother-child pairs during both pregnancy and childhood (6–11 years old). Concentration levels of forty metabolites—including PFASs, phenols, phthalates, metals, and organophosphate and persistent pesticide metabolites—were measured. We used a spatial indicator to define the participants’ degree of urbanisation. Linear Mixed-Effect Models were used to compare the distribution of exposures between urban and non-urban areas for the two life stages separately. Results: The concentrations of contaminants varied by degree of urbanisation and life stage. Overall, concentrations of phenols (GMRs; Geometric Mean Ratios, ranging from 1.06 to 1.56) and PCBs (GMRs ranging from 1.07 to 1.15) were higher among pregnant mothers living in urban areas compared to those in non-urban areas. Children showed more heterogeneous patterns of exposure across contaminant families. Children in urban areas had lower concentration levels of PFASs (GMRs ranging from 0.84 to 0.97) but higher concentration levels of phenols (GMRs ranging from 1.05 to 1.15) and phthalates (GMRs ranging from 1.05 to 1.17) compared to those in non-urban areas. Significance: Our study contributes to the understanding of how the degree of urbanisation characterises children’s exposure to hazardous substances. Our findings align with the existing literature, which shows varying profiles of environmental exposures based on different degrees of urbanisation. Impact: Our study provides important insights into how the degree of urbanisation can influence children’s exposure to hazardous substances during critical developmental windows, with potential implications for both immediate and long-term health outcomes. Specifically, phenols, phthalates, and PCBs were found to be more prevalent in individuals living in urban areas, with notable heterogeneity of PCB concentrations across European cohorts. In contrast, PFAS concentrations were higher in children residing in non-urban areas. Understanding the geographic variations in exposure to hazardous contaminants is useful for identifying areas with higher contaminant levels, which may have important implications for vulnerable populations.