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Chemical mixtures and children's health

Claus Henn, Birgita; Coull, Brent A.a,b; Wright, Robert O.c

Current Opinion in Pediatrics: April 2014 - Volume 26 - Issue 2 - p 223–229
doi: 10.1097/MOP.0000000000000067

Purpose of review Humans are routinely exposed to multiple chemicals simultaneously or sequentially. There is evidence that the toxicity of individual chemicals may depend on the presence of other chemicals. Studies on chemical mixtures are limited, however, because of the lack of sufficient exposure data, limited statistical power, and difficulty in the interpretation of multidimensional interactions. This review summarizes the recent literature examining chemical mixtures and pediatric health outcomes, with an emphasis on metal mixtures.

Recent findings Several studies report significant interactions between metals in relation to pediatric health outcomes. Two prospective studies found interactive effects of early-life lead and manganese exposures on cognition. In two different cohorts, interactions between lead and cadmium exposures were reported on reproductive hormone levels and on neurodevelopment. Effects of lead exposure on impulsive behavior and cognition were modified by mercury exposure in studies from Canada and Denmark. However, there is little consistency related to exposure indicators and statistical approaches for evaluating interaction.

Summary Several studies suggest that metals interact to cause health effects that are different from exposure to each metal alone. Despite the nearly infinite number of possible chemical combinations, mixtures research represents real-life exposure scenarios and warrants more attention, particularly in the context of uniquely vulnerable children.

aDepartment of Environmental Health, Harvard School of Public Health

bDepartment of Biostatistics, Harvard School of Public Health, Boston, Massachusetts, USA

cDivision of Environmental Health, Mt. Sinai School of Medicine, New York, New York, USA

Correspondence to Birgit Claus Henn, Department of Environmental Health, Harvard School of Public Health, Landmark Center East, 3rd floor, 401 Park Drive, Boston, MA 02215, USA. Tel: +1 617 684 5721; e-mail:

© 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins