Metal and metal mixture biomarkers across three U.S. cohorts: MASALA, MESA-LA, and Strong Heart Family Study.
BACKGROUND Low-dose metal exposure contributes to chronic disease, yet differences in metal exposure and metabolism across diverse U.S. populations remain poorly characterized. Geographic location, drinking-water sources, diet, lifestyle, and culturally specific product use may shape multi-metal exposure. OBJECTIVES To characterize urinary multi-metal biomarkers among Asian Indian adults, compare them with profiles with other western U.S. populations, and evaluate serum-urine relationships for these metals among Asian Indian adults to distinguish metal clearance from physiological regulation. METHODS We measured 19 urinary metals by inductively coupled plasma mass spectrometry (ICP-MS) in harmonized subsamples of Asian Indians in the Mediators of Atherosclerosis in South Asians Living in America (MASALA) pilot study (San Francisco Bay Area, 2010-2013; n = 111), White, Black, Hispanic/Latino, and Chinese in the Multi-Ethnic Study of Atherosclerosis, Los Angeles (MESA-LA, 2010-2012; n = 444), and American Indians in the Strong Heart Family Study (SHFS, 2006-2009; n = 111). Metals were creatinine-corrected and reported as µg/g creatinine. In MASALA, the same 19-metal panel was measured in serum. RESULTS Median age (years)/percent female were 56/50% (MASALA), 62/49% (MESA-LA), and 56/49% (SHFS). Compared with MESA-LA and SHFS, MASALA participants had the lowest urinary Zn (354 µg/g) and Mn (0.11 µg/g), and the highest Mo (66.5 µg/g) and Tl (0.26 µg/g). Median urinary Cs in MASALA (8.55 µg/g) was comparable to MESA-LA Chinese (9.38 µg/g), while Ba was highest in MASALA (2.57 µg/g) relative to both MESA-LA and SHFS. MASALA participants had higher As, Pb, and Cd than SHFS (As 7.60 vs 5.08 µg/g; Pb 0.88 vs 0.59 µg/g; Cd 0.51 vs 0.47 µg/g), but lower levels than MESA-LA Chinese (As 43.9 µg/g; Pb 1.12 µg/g; Cd 0.81 µg/g). In MASALA, serum-urine correlations were strongest for Mo (r = 0.83), As (r = 0.79), Co (r = 0.76), and Cs (r = 0.67); Zn, Cu, and Mn were weakly correlated. SIGNIFICANCE Multi-metal biomarker patterns differed across study populations, influencing exposure assessment and biomonitoring interpretation. Serum-urine analyses distinguish elements reflecting recent exposure versus physiological regulation and support population-specific metal mixtures linked to chronic disease risk. IMPACT Harmonized multi-metal biomarker data across diverse U.S. populations remain limited, which constrains interpretation of exposure patterns in epidemiologic research. This study provides one of the first cross-cohort comparisons of urinary metal profiles across diverse study populations in the western United States and includes paired urine-serum measurements for a broad 19-metal panel in MASALA adults, a population with elevated cardiometabolic disease risk but limited metal exposure data. The results support population-specific biomonitoring approaches and future studies evaluating metal mixtures and chronic disease.