In Utero Exposure to Heavy Metals and Trace Elements and Childhood Blood Pressure in a U.S. Urban, Low-Income, Minority Birth Cohort.

BACKGROUND: In utero exposure to heavy metals lead (Pb), mercury (Hg), and cadmium (Cd) may be associated with higher childhood blood pressure (BP), whereas trace elements selenium (Se) and manganese (Mn) may have protective antioxidant effects that modify metal-BP associations. OBJECTIVES: We examined the individual and joint effects of in utero exposure to Pb, Hg, Cd, Se, and Mn on childhood BP. METHODS: We used data from the Boston Birth Cohort (enrolled 2002-2013). We measured heavy metals and trace elements in maternal red blood cells collected 24-72 h after delivery. We calculated child BP percentile per the 2017 American Academy of Pediatrics Clinical Practice Guideline. We used linear regression models to estimate the association of each metal, and Bayesian kernel machine regression (BKMR) to examine metal coexposures, with child BP between 3 to 15 years of age. RESULTS: Our analytic sample comprised 1,194 mother-infant pairs (61% non-Hispanic Black, 20% Hispanic). Hg and Pb were not associated with child systolic BP (SBP). Se and Mn were inversely associated with child SBP percentiles, which, on average, were 6.23 points lower with a doubling of Se (95% CI: -11.51, -0.96) and 2.62 points lower with a doubling of Mn (95% CI: -5.20, -0.04). BKMR models showed similar results. Although Cd was not associated with child SBP overall, the inverse association between Mn and child SBP was stronger at higher levels of Cd (p-interaction=0.04). Consistent with this finding, in utero exposure to cigarette smoke modified the Mn-child SBP association. Among children whose mothers smoked during pregnancy, a doubling of Mn was associated with a 10.09-point reduction in SBP percentile (95% CI: -18.03, -2.15), compared with a 1.49-point reduction (95% CI: -4.21, 1.24) in children whose mothers did not smoke during pregnancy (p-interaction=0.08). CONCLUSION: Se and Mn concentrations in maternal red blood cells collected 24-72 h after delivery were associated with lower child SBP at 3 to 15 years of age. There was an interaction between Mn and Cd on child SBP, whereby the protective association of Mn on child SBP was stronger among mothers who had higher Cd. The association of Mn and child SBP was also modified by maternal cigarette smoking-a source of Cd-during pregnancy. Optimizing in utero Se levels, as well as Mn levels in women who had high Cd or smoked during pregnancy, may protect offspring from developing high BP during childhood. https://doi.org/10.1289/EHP8325.

Trace Minerals, Heavy Metals, and Preeclampsia: Findings from the Boston Birth Cohort.

Background Preeclampsia is a leading contributor to maternal and perinatal morbidity and mortality. In mice experiments, manganese (Mn) and selenium (Se) are protective whereas cadmium (Cd) is promotive for preeclampsia. Epidemiologic findings on these chemical elements have been inconsistent. To confirm experimental findings in mice, we examined associations of trace minerals (Mn and Se) and heavy metals (Cd, lead [Pb], and mercury [Hg]) with preeclampsia in a birth cohort. Methods and Results A total of 1274 women from the Boston Birth Cohort (enrolled since 1998) had complete data on the exposures and outcome. We measured Mn, Se, Cd, Pb, and Hg from red blood cells collected within 24 to 72 hours after delivery. We ascertained preeclampsia diagnosis from medical records. We used Poisson regression with robust variance models to estimate prevalence ratios (PRs) and 95% CIs. A total of 115 (9.0%) women developed preeclampsia. We observed evidence of a dose-response trend for Mn (P for trend<0.001) and to some extent for Cd (P for trend=0.009) quintiles. After multivariable adjustment, a 1 SD increment in Mn was associated with 32% lower risk of developing preeclampsia (PR=0.68; 95% CI, 0.54-0.86), whereas a 1 SD increment in Cd was associated with 15% higher risk of preeclampsia (PR=1.15; 95% CI, 0.98-1.36). Null associations were observed for Se, Pb, and Hg. Conclusions Findings from our cohort, consistent with evidence from mice experiments and human studies, indicate that women with lower blood concentration of Mn or higher Cd are more likely to develop preeclampsia.