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Estimating Methylmercury Intake for the General Population of South Korea Using Physiologically Based Pharmacokinetic Modeling
Citation:
Lee, S., C. Tan, M. Phillips, J. Sobus, AND S. Kim. Estimating Methylmercury Intake for the General Population of South Korea Using Physiologically Based Pharmacokinetic Modeling. TOXICOLOGICAL SCIENCES. Society of Toxicology, RESTON, VA, 159(1):6-15, (2017).
Impact/Purpose:
Mercury (Hg) is a naturally occurring element and a ubiquitous contaminant of soil, air, foods, and other media. There are several forms of Hg in the environment; of these, organic forms, especially methylmercury (MeHg), have been extensively studied due to their ability to be highly absorbed, bioaccumulate, and cause neurotoxic, cardiovascular, reproductive, and carcinogenic effects (ARSDR, 1999; Hong et al., 2012). A recent study of Korean adults also reported a significant positive association between blood Hg levels and metabolic syndrome (Eom et al., 2014). Given the high level of concern surrounding Hg exposure and toxicity, regulatory agencies have promulgated health-related reference values and allowable exposure limits. Despite these efforts, certain populations are still exposed to relatively high levels of Hg through fish consumption, especially consumption of large, fatty fish, such as tuna (Minnesota Department of Health).
Description:
The Korean National Environmental Health Survey (KoNEHS 2009–2011) tracks levels of environmental pollutants in biological samples from the adult Korean population (age 19–88). Recent survey results for blood mercury (Hg) suggest some exceedance above existing blood Hg reference levels. Because total blood Hg represents both organic and inorganic forms, and methylmercury (MeHg) has been specifically linked to several adverse health outcomes, a need exists to quantify MeHg intake for this population. Gender, age, and frequency of fish consumption were first identified as important predictors of KoNEHS blood Hg levels using generalized linear models. Stratified distributions of total blood Hg were then used to estimate distributions of blood MeHg using fractions of MeHg to total Hg from the literature. Next, a published physiologically based pharmacokinetic (PBPK) model was used to predict distributions of blood MeHg as a function of MeHg intake; ratios of MeHg intake to model-predicted blood MeHg were then combined with KoNEHS-based blood MeHg values to produce MeHg intake estimates. These intake estimates were ultimately compared with the Reference Dose (RfD) for MeHg (0.1 µg/kg/day) and reported as margin of exposure (MOE) estimates for specific KoNEHS subgroups. The derived MOEs across all subgroups, based on estimated geometric mean intake, ranged from 1.6 to 4.1. These results suggest MeHg exposures approaching the RfD for several subgroups of the Korean population, and not just for specific subgroups (eg, those who eat fish very frequently).
