Associations between mercury exposure with blood pressure and lipid levels: A cross-sectional study of dental professionals

Mercury (Hg) exposure is a public health problem worldwide that is now being addressed through the Minamata Convention on Mercury. Fish containing methylmercury and dental amalgam containing elemental Hg are the major sources of exposure for most populations. There is some evidence that methylmercury impacts cardiovascular and metabolic health, primarily in populations with high exposure levels. Studies of elemental Hg and these outcomes are relatively rare. We aimed to examine associations between Hg exposure (both elemental and methylmercury) and blood pressure, as well as cholesterol and triglyceride levels. In 2012, we recruited dental professionals attending the Health Screening Program at the American Dental Association (ADA) Annual Session in California. Total Hg levels in hair and blood samples were analyzed as indicators of methylmercury exposure and in urine as an indicator of primarily elemental Hg exposure (n = 386; mean ± sd age 55 ± 11 years). We measured blood pressure (systolic and diastolic) and lipid profiles (total cholesterol, high-density lipoprotein cholesterol [HDL], low-density lipoprotein cholesterol [LDL] and triglycerides). The geometric means (geometric standard deviations) for blood, hair, and urine Hg were 3.64 (2.39) μg/L, 0.60 (2.91) μg/g, and 1.30 (2.44) μg/L, respectively. For every one μg/L increase in specific gravity-adjusted urine Hg, LDL increased by 2.31 mg/dL (95% CI = 0.09, 4.54), in linear regression adjusting for BMI, race, sex, polyunsaturated fatty acid intake from fish consumption, smoking status, and use of cholesterol-lowering medication. No significant associations between Hg biomarkers and blood pressure or hair or blood Hg with lipid levels were observed. Results suggest that elemental Hg exposure may influence LDL concentrations in adults with low-level exposure, and this relationship merits further study in other populations.