Human biomonitoring of plasma trace elements in Brazilian adults: distribution patterns and sociodemographic determinants in the ELSA-Brasil cohort

Human biomonitoring (HBM) is essential for characterizing internal exposure to toxic and essential elements and for supporting environmental health risk assessment. However, comprehensive HBM data remain scarce in low- and middle-income countries, including Brazil. We characterized the plasma metallome of 9,949 adults aged 35-74 years participating in the baseline examination (2008-2010) of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). Plasma concentrations of 15 metals and metalloids, aluminum (Al), barium (Ba), cadmium (Cd), cobalt (Co), copper (Cu), iron (Fe), mercury (Hg), lithium (Li), manganese (Mn), nickel (Ni), lead (Pb), rubidium (Rb), selenium (Se), strontium (Sr), and zinc (Zn), were quantified by ICP-MS, and population distribution percentiles of plasma elemental concentrations were characterized. Associations with sociodemographic characteristics, lifestyle factors, and cardiometabolic conditions were systematically evaluated. Pronounced sex-specific differences were observed, with higher plasma concentrations of Al, Fe, Mn, Pb, Rb, Sr, and Zn in men, and Co, Cu, and Se in women. Median concentrations of Al, Cu, Se, and Zn were compared with those reported in large international HBM programs, revealing differences in background exposure and nutritional status. Plasma metal levels differ according to age, education, income, smoking, and alcohol consumption. Notably, hypertension, dyslipidemia, obesity, and smoking were associated with higher plasma copper concentrations. This study provides the first large-scale human biomonitoring assessment of the plasma metallome in a Brazilian adult population and represents one of the largest plasma-based HBM studies worldwide. By establishing reference distributions and identifying key sociodemographic and lifestyle determinants, these findings fill a critical data gap for Brazil and contribute valuable evidence for exposome-oriented research and environmental health risk assessment in Latin America and other low- and middle-income settings.