title: Exposure to Mixtures of Metals and Neurodevelopmental Outcomes: A Multidisciplinary Review Using an Adverse Outcome Pathway Framework.
abstract: Current risk assessment guidance calls for an individual chemical-by-chemical approach that fails to capture potential interactive effects of exposure to environmental mixtures and genetic variability. We conducted a review of the literature on relationships between prenatal and early life exposure to mixtures of lead (Pb), arsenic (As), cadmium (Cd), and manganese (Mn) with neurodevelopmental outcomes. We then used an adverse outcome pathway (AOP) framework to integrate lines of evidence from multiple disciplines based on evolving guidance developed by the Organization for Economic Cooperation and Development (OECD). Toxicological evidence suggests a greater than additive effect of combined exposures to As-Pb-Cd and to Mn with any other metal, and several epidemiologic studies also suggest synergistic effects from binary combinations of Pb-As, Pb-Cd, and Pb-Mn. The exposure levels reported in these epidemiologic studies largely fall at the high-end (e.g., 95th percentile) of biomonitoring data from the National Health and Nutrition Examination Survey (NHANES), suggesting a small but significant potential for high-end exposures. This review integrates multiple data sources using an AOP framework and provides an initial application of the OECD guidance in the context of potential neurodevelopmental toxicity of several metals, recognizing the evolving nature of regulatory interpretation and acceptance.
authors.affiliation: Harvard Center for Risk Analysis, Boston, MA, USA.|Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Katherine
authors.initials: K
authors.lastname: von Stackelberg
authors.affiliation: Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Guzy
authors.affiliation: Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Tian
authors.initials: T
authors.lastname: Chu
authors.affiliation: Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA.|Department of Environmental Health, Boston University School of Public Health, Boston, MA, USA.
authors.forename: Birgit
authors.initials: B
authors.lastname: Claus Henn
mesh_terms: D004781:Environmental Exposure; D059647:Gene-Environment Interaction; D006801:Humans; D008670:Metals / Q000633:toxicity*; D065886:Neurodevelopmental Disorders / Q000139:chemically induced*; D018570:Risk Assessment
chemical_list: D008670:Metals
keywords: Adverse outcome pathway; arsenic; cadmium; developmental; lead; manganese; metal mixtures; systematic review