摘要：Background: Metal exposure alters neurodevelopmental outcomes; little is known about critical windows of
susceptibility when exposure exerts the strongest effect.
Objective: To examine associations between dentine biomarkers of manganese (Mn), zinc (Zn) and lead (Pb) and
later childhood behaviors.
Methods: Subjects enrolled in a longitudinal birth cohort study in Mexico City provided naturally shed deciduous
teeth. We estimated weekly prenatal and postnatal dentine Mn, Zn and Pb concentrations in teeth using laser
ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and measured behavior at ages 8–11 years
of age using the Behavior Assessment System for Children, 2nd edition (BASC-2). We used distributed lag models
and lagged weighted quantile sum regression to identify the role of individual and combined dentine biomarkers
of Mn, Zn and Pb on behavioral outcomes controlling for maternal education and gestational age.
Results: Among the 133 subjects included in this study, prenatal and early postnatal dentine Mn appeared
protective against childhood behavioral problems, specifically hyperactivity and attention. Postnatal dentine Mn
was associated with increased reporting of internalizing problems, specifically anxiety. At 6 months, a 1-unit
increase (unit = 1 SD of log concentration) in Mn was associated with a 0.18-unit (unit = 1 SD of BASC-2 score)
increase in internalizing symptoms score and a 0.25-unit increase in anxiety. Postnatal Pb was associated with
increasing anxiety symptoms; at 12 months, a 1-unit increase in Pb was associated with a 0.4 unit increase in
anxiety symptoms. When examined as a metal mixture, we observed two potential windows of susceptibility to
increased anxiety symptoms: the first window (0–8 months) appeared driven by Mn, the second window
(8–12 months) was driven by the metal mixture and dominated by Pb. A 1-unit increase in the mixture index was
associated with a 0.7-unit increase in SD of anxiety symptoms.
Conclusions: Childhood behaviors may demonstrate postnatal windows of susceptibility to individual and mixed
metal concentrations measured in deciduous teeth. Prenatal dentine Mn may be protective, while excessive early
postnatal Mn may increase risk for adverse behaviors. In combination, higher concentrations of Mn, Zn and Pb
may have an adverse impact on behavior.
