Foetal Exposure to Heavy Metals and Risk of Atopic Diseases in Early Childhood

Abstract

Early-life exposures to heavy metals have been associated with many adverse health outcomes in children. The purpose of this study was to investigate the association of fetal exposure to lead, cadmium, and manganese with the risk of developing asthma, allergic rhinitis, eczema, and food allergy in early childhood.In the study, researchers included 651 children who were part of a longitudinal birth cohort living in France.A total of 2002 mothers were recruited for the birth cohort in early pregnancy. They underwent an initial clinical examination and survey assessing their lifestyle and health between 24 and 28 weeks' gestation. Pregnancy, birth, and newborn characteristics were collected through standardized questionnaires and obstetric records. Measurements of lead, cadmium, and manganese were performed from the first consecutive 915 mother–children pairs from peripheral blood samples of mothers between 24 and 28 weeks' gestation as well as from cord blood at the time of delivery. A standardized parental-administered questionnaire used to assess the child’s health and environment was administered every 4 months for the first year, followed by every year until the age of 5 years and then, finally, at the age of 8 years. Asthma, allergic rhinitis, eczema, and food allergy were defined as positive responses for corresponding questions by using the International Study on Asthma and Allergies in Childhood questionnaire.A total of 915 children were enrolled for laboratory assessment of heavy metal exposure, and 845 completed this. Of these, 651 children had follow-up between 3 and 8 years of age and were included in this study. A total of 60% completed the final assessment at 8 years, and 52% were male. In this group, there was a lifetime prevalence of 17% for asthma, 22% for allergic rhinitis, 43% for eczema, and 11% for food allergy. There was a weak correlation between the concentrations of metals measured in maternal midpregnancy and cord blood samples. Comparing the quartiles of subjects with the lowest and highest exposure, there was a significant association between cord blood cadmium and food allergy (hazard ratio (HR): 3.17 [1.36–7.38]), cord blood cadmium and eczema (HR: 1.60 [1.09–2.35]), and maternal blood manganese and eczema (HR: 1.55 [1.05–2.28]), adjusted for sex, BMI, maternal education, parental history of atopy, maternal smoking in pregnancy, birth weight, gestational age, and type of delivery.In a prospective birth cohort, there was an association between fetal exposure to cadmium and manganese and the development of eczema and food allergy by 8 years of age.This may be the first prospective study in which researchers suggest an association between in utero exposure to heavy metals and risk for developing atopic diseases, although limited by parental report of these conditions. Further studies are needed to not only confirm this association but, also, to evaluate the effect of timing of in utero heavy metal exposure on the risk of developing atopic diseases in childhood, given the weak correlation between heavy metal concentrations in maternal midpregnancy and cord blood samples.