Seasonal and dietary determinants of metal and metalloid exposure in riverine communities of the Brazilian Amazon: A study on temporal variation

This study investigated the seasonal dynamics of the blood metallome and its relationship with environmental and dietary factors in riverine communities from the Tapajós River region, Brazil. A repeated cross-sectional biomonitoring study was conducted during the dry (October-November 2022) and rainy (April-May 2023) seasons across 13 communities, involving 110 participants assessed in both seasons. Nineteen metals and metalloids were determined in blood samples using inductively coupled plasma mass spectrometry (ICP-MS). Significant seasonal variations were observed, with median arsenic increasing from 3.73 μg/L to 6.95 μg/L, and mercury decreasing from 21.9 μg/L to 16.4 μg/L from the dry to the rainy season. Essential elements such as copper (997 μg/L to 783 μg/L) and zinc (5676 μg/L to 4436 μg/L) also exhibited notable differences. Selenium concentrations remained consistently elevated in both seasons, associated with Brazil nut consumption. Multiple regression analyses revealed significant associations between blood metal levels, dietary patterns, and sociodemographic factors. These findings underscore the importance of considering seasonal variability in biomonitoring studies and health policy development for Amazonian populations.