Reference values for lead, cadmium and mercury in the blood of adults from the metropolitan area of Sao Paulo, Brazil

Human biomonitoring is an important tool for the evaluation of environmental exposure to contaminants. The data that are obtained from these studies might be compared to appropriate reference values (RVs) in a specific population. The RVs were derived from the rounded values of the upper limit of the 95th confidence interval of the 95th percentile for lead (Pb), cadmium (Cd) and mercury (Hg) in blood from adults in the metropolitan area of Sao Paulo (MASP), Brazil to investigate the association between blood metals and sociodemographic and lifestyle factors. Blood samples from 653 nonsmoking blood donors without occupational exposure to the studied metals were collected in 2006. Our evaluations distinguished a younger group (18–39 years) and an older group (40–65 years). RVs in the younger group were 60 μg Pb/L and 4 μg Hg/L for men and 47 μg Pb/L and 4 μg Hg/L for women. RVs in the older group were 80 μg Pb/L and 5 μg Hg/L for men and 63 μg Pb/L and 6 μg Hg/L for women. The RV for Cd was 0.6 μg/L for adults aged 18–65 years. Pb and Cd levels demonstrated a significant association with sex and age. Male blood contained 50% more Pb, and the older group exhibited 23% more Pb. Fish consumption and amalgam fillings were primarily related to Hg levels. RVs for lead were similar to the Czech Republic and Germany but higher than the US population. The RV for Cd in Brazil was well below the RVs of these countries. The RVs for Hg in Brazil were similar to the US but higher than Germany and the Czech Republic.