Foetal exposure to heavy metals and risk of asthma and allergic diseases in early childhood: a population-based birth-cohort study

Abstract

Introduction: Heavy metal can affect the immune response and thus health. Birth cohort studies investigating the association between prenatal exposures to heavy metals and asthma and allergies diseases, however, are scarce. Aim: We investigated the relationship of maternal serum concentrations of lead (Pb), cadmium (Cd) and manganese to asthma and allergy in the child. Methods: Children from the French EDEN birth-cohort were followed-up with parental-standardized questionnaires administered yearly until the age of 5. Serum concentrations of lead (Pb), cadmium (Cd) and manganese (Mn) were assessed in maternal blood samples (n=706) collected during mid-pregnancy and in cord blood (n=658). Hazard ratios (HR) for the incidence of each health outcome at 5 years in relation to heavy metals were calculated using adjusted Cox models (sex, BMI, in utero and parental smoking, family allergy, education, center). Results: The incidence of asthma, allergic rhinitis, eczema and food allergy in our sample were: 27.2 [cases/person-years: 125/4,599], 38.7 [160/4,130], 95.1 [307/3,228] and 18.9 [80/4,224] per 1000, respectively. Elevated levels of Cd in cord blood were associated with a greater risk of asthma (HR [95% confidence interval] per 1 SD increase: 1.24[1.02-1.51]) and food allergy (1.44[1.13-1.83]), elevated levels of Mn in maternal serum were associated with eczema (1.14[1.04-1.26]), while cord blood Pb levels were inversely associated with allergic rhinitis (0.85[0.73-0.99]). Conclusions: Our results suggest that prenatal exposure to heavy metals may affect the development of asthma and allergic diseases in childhood.