Blood mercury concentrations are associated with decline in liver function in an elderly population: a panel study

Abstract

Background: Mercury is a toxic heavy metal and is known to affect many diseases. However, few studies have examined the effects of mercury exposure on liver function in the general population. We examined the association between blood mercury concentrations and liver enzyme levels in the elderly. Methods: We included 560 elderly participants (60 years or older) who were recruited from 2008 to 2010 and followed up to 2014. Subjects visited a community welfare center and underwent a medical examination and measurement of mercury levels up to five times. Analyses using generalized estimating equations model were performed after adjusting for age, sex, education, overweight, alcohol consumption, smoking, regular exercise, high-density lipoproteins cholesterol, and total calorie intake. Additionally, we estimated interaction effects of alcohol consumption with mercury and mediation effect of oxidative stress in the relationship between mercury levels and liver function.

Mercury Exposure in Association With Decrease of Liver Function in Adults: A Longitudinal Study

“…In previous epidemiological studies, blood Hg showed a significant positive association with ALT in NHANES 2003-2004 [ 11 ], and with AST and ALT in KNHANES 2008-2012 [ 12 ]. A recent study [ 13 ] reported significantly higher AST levels in the highest quarter of blood Hg levels than in the lowest quarter, and the odds of high ALT levels (>35 IU/L) were 3.10 times higher in the highest quarter of blood Hg levels than in the lowest quarter in a repeated-measures study of Koreans over 60 years old. However, other studies have reported no association [ 9 , 10 ], and conflicting results have been reported depending on whether liver dysfunction was defined as a continuous or dichotomous variable within the same study [ 13 ].…”

“…A recent study [ 13 ] reported significantly higher AST levels in the highest quarter of blood Hg levels than in the lowest quarter, and the odds of high ALT levels (>35 IU/L) were 3.10 times higher in the highest quarter of blood Hg levels than in the lowest quarter in a repeated-measures study of Koreans over 60 years old. However, other studies have reported no association [ 9 , 10 ], and conflicting results have been reported depending on whether liver dysfunction was defined as a continuous or dichotomous variable within the same study [ 13 ]. Significantly higher GGT levels were found in the second-highest and highest quarters of blood Hg levels than in the lowest quarter [ 13 ], and the odds of high GGT (>47 IU/L for men and >21 IU/L for women) were 2.59 times higher for men and 2.03 times higher for women in the highest quarter of blood Hg levels than in the lowest quarter [ 14 ].…”

“…However, other studies have reported no association [ 9 , 10 ], and conflicting results have been reported depending on whether liver dysfunction was defined as a continuous or dichotomous variable within the same study [ 13 ]. Significantly higher GGT levels were found in the second-highest and highest quarters of blood Hg levels than in the lowest quarter [ 13 ], and the odds of high GGT (>47 IU/L for men and >21 IU/L for women) were 2.59 times higher for men and 2.03 times higher for women in the highest quarter of blood Hg levels than in the lowest quarter [ 14 ]. The differences in results among studies may be explained by various factors, such as differences in the adjusted confounding variables, study design, sample size, and whether effect modifiers such as alcohol consumption and gender were considered.…”

“…Previous epidemiological studies have mostly analyzed cross-sectional data [ 10 - 12 , 14 ] and did not consider fish consumption as a potential confounder, although fish are a major source of Hg exposure [ 10 , 11 , 13 , 14 ]. In addition, no studies have examined the possibility of a nonlinear relationship between blood Hg and liver function indices, or the possible role of gender.…”

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“…Mercury primarily metabolized in the liver. Due to its accumulation in the liver, resultant severe hepatic damages 9 , including histopathological and ultrastructural lesions evidenced by periportal fatty degeneration and cell necrosis 10 , whereas, the kidney is the primary organ of elimination. Being recognized mercury as a hazardous environmental pollutant 11 , and has efficacy to produce several adverse effects on human health, achieve considerable attention and need to investigate through about the toxicity.…”