Predictors of urinary and blood Metal(loid) concentrations among pregnant women in Northern Puerto Rico

Abstract

Given the potential adverse health effects related to toxic trace metal exposure and insufficient or excessive levels of essential trace metals in pregnant women and their fetuses, the present study characterizes biomarkers of metal and metalloid exposure at repeated time points during pregnancy among women in Puerto Rico. We recruited 1040 pregnant women from prenatal clinics and collected urine, blood, and questionnaire data on demographics, product use, food consumption, and water usage at up to three visits. All samples were analyzed for 16 metal(loid)s: arsenic (As), barium (Ba), beryllium (Be), cadmium (Cd), cobalt (Co), chromium (Cr), cesium (Cs), copper (Cu), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), titanium (Ti), uranium (U), vanadium (V), and zinc (Zn). Urine samples were additionally analyzed for molybdenum (Mo), platinum (Pt), antimony (Sb), tin (Sn), and tungsten (W). Mean concentrations of most metal(loid)s were higher among participants compared to the general US female population. We found weak to moderate correlations for inter-matrix comparisons, and moderate to strong correlations between several metal(loid)s measured within each biological matrix. Blood concentrations of Cu, Zn, Mn, Hg, and Pb were shown to reflect reliable biomarkers of exposure. For other metals, repeated samples are recommended for exposure assessment in epidemiology studies. Predictors of metal(loid) biomarkers included fish and rice consumption (urinary As), fish and canned food (blood Hg), drinking public water (blood Pb), smoking (blood Cd), and iron/folic acid supplement use (urinary Cs, Mo, and Sb). Characterization of metal(loid) biomarker variation over time and between matrices, and identification of important exposure sources, may inform future epidemiology studies and exposure reduction strategies.

Keywords: Biomarkers; Blood; Exposure assessment; Metals; Pregnancy; Urine.

Figure 1.

Heat map of pairwise correlations between urine and blood GM concentrations among pregnant women in the PROTECT study^ab. ^a The correlation heat map was created using natural log-transformed urinary or blood metal(loid) concentrations; ^b All urinary concentrations were SG-corrected.

Figure 2.

Ratio of metal(loid) concentrations in urine and blood samples (n=509)^a. ^a All urinary concentrations were SG-corrected.

Figure 3.

Beta and confidence intervals extracted from individual linear mixed models for metal(loid) concentrations and potential predictors^ab. Δ Variables also selected as predictors of metal(loid) exposure from multivariable LMMLasso models; ^a In this figure, covariates that were not associated with any metal(loid) concentrations in the univariable and multivariable analysis were not included in the y-axis; ^b Drinking water source: bottle water (1) vs AAA public water (0).