Associations of blood and urinary mercury with hypertension in U.S. Adults: The NHANES 2003–2006

Abstract

Background Few studies have examined the association between hypertension and mercury exposure in the general population. We examined cross-sectional associations between blood (mainly methylmercury) or urinary mercury (mainly inorganic mercury) and hypertension in representative U.S. adults and effect modifications by dietary omega-3 fatty acids and serum selenium. Methods We examined 6,607 adults aged 20 years or older, using the National Health and Nutrition Examination Survey (NHANES) from 2003/2004 to 2005/2006 (2,201 adults were available for urinary mercury from NHANES 2003–2006; 2,117 available for serum selenium from NHANES 2003–2004 aged 40 years or older). The average of omega-3 fatty acids from two 24-hour recalls was calculated. Results The weighted prevalence of hypertension was 32.2%. The geometric means (95% confidence intervals) of blood total and urinary mercury were 1.03 (0.95, 1.11) µg/L and 0.51 (0.47, 0.54) µg/L, respectively. The adjusted odds ratios for a doubling increase in blood mercury and urinary mercury were 0.94 (0.87 to 1.01) and 0.87 (0.78 to 0.99), respectively, after adjusting for potential confounders. The associations remained similar, even after adjusting for either omega-3 fatty acids or selenium or both. No significant effect modification by either omega-3 fatty acids or selenium was observed. Conclusions In this cross-sectional study of the U.S. general population, we found no association of hypertension with blood mercury but a suggestive inverse association with urinary mercury. Future prospective studies are warranted to confirm these findings.

Methyl mercury, but not inorganic mercury, associated with higher blood pressure during pregnancy

“…Several prior findings are inconsistent with our results, specifically: among the 2003-2006 NHANES study blood THg was associated with decreased SBP (Park et al, 2013); blood THg was associated with decreased DBP among 1,861 Inuit men from Greenland (Nielsen et al, 2012); and blood THg was associated with increased DBP, but not SBP among 2,114 healthy Korean adults (Eom et al, 2014). There are several possible explanations for these differences.…”

“…Urinary mercury concentrations, reflecting exposure to IHg, have been associated with a lower SBP among United States adults in the 2003-2006 NHANES (Park et al, 2013) and dental professionals (Goodrich et al, 2013); the latter study notes this was driven by associations among males. This is consistent with our observations that inorganic mercury was associated with a lower in PP.…”

“…There is substantial variation in the methods used to control for selenium and/or n-3 PUFAs. Several studies used fish consumption (Bautista et al, 2009; Choi et al, 2009; Eom et al, 2014; Mordukhovich et al, 2012; Mozaffarian et al, 2012), or dietary recall questionnaires (Park et al, 2013) instead of quantitative measures of Se or n-3 PUFAs, which may result in misclassification of these variables. Our study population Another potential contributor to differences in study results could be differences in underlying genetic, such as genetic susceptibility for cardiovascular disease, between the different populations studied.…”

“…Some studies have identified a link between total mercury in blood (Valera et al, 2009), hair (Yorifuji et al, 2010), or toenails (Choi et al, 2009) and worsening of cardiovascular risk factors such as blood pressure and heart rate variability; other studies using total whole blood (Nielsen et al, 2012) and urinary mercury (Park et al, 2013) have shown protective results. Of note is that none of the studies above focused on pregnant women.…”

Blood Mercury Can Be a Factor of Elevated Serum Ferritin: Analysis of Korea National Health and Nutrition Examination Survey (KNHANES 2008–2012)

“…You et al determined that blood mercury concentration is related to the waist-to-hip ratio, which is a central obesity index, in Korean men [20]. On the other hand, several studies have shown that there was no significant association between the level of mercury and chronic diseases, such as cardiovascular diseases [21] and hypertension [22,23]. It is interesting to note that the authors of these studies concluded that their results were due to the confounding factors such as lifestyle, diet, and exercise that could influence the clinically adverse effect of mercury on human health.…”