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Does One Size Fit All? Revisit of the Hair-to-Blood Concentration Ratio for Evaluation of Mercury Exposure-Poster
Citation:
Lin, Y., S. Ramasamy, J. Xue, AbdelRazak Kadry, D. Segal, AND L. Kopylev. Does One Size Fit All? Revisit of the Hair-to-Blood Concentration Ratio for Evaluation of Mercury Exposure-Poster. 2019 SOT, Baltimore, MD, March 10 - 14, 2019.
Impact/Purpose:
Estimation of body burden of mercury (Hg) based on biological monitoring of hair and blood Hg levels is important in assessing Hg toxicity. A better understanding of causes that reflect the uncertainty and variability in the ratio could inform the adoption of dose conversion parameters for advancing Hg exposure assessment.
Description:
Background: Mercury (Hg) is considered by the World Health Organization (WHO) as one of the priority chemicals that affect human and ecologic health worldwide. Although WHO recommends a constant concentration ratio (250:1) of hair-to-blood Hg for assessing mercury exposure, the mechanisms underlying variability in that ratio remain to be elucidated. Objective: To identify key determinants of the hair-to-blood ratio of total mercury in US women. Methods: The data were obtained from 1306 women aged 16-49 years, each of whom provided valid measurements of blood and hair Hg, in the National Health and Nutrition Examination Survey 1999-2000. The impact on the hair-to-blood ratio of factors, such as age, race, body mass index, socioeconomic status, seafood consumption, liver function (assessed by serum levels of alanine aminotransferase [ALT] and aspartate aminotransferase [AST]), hair treatment, and smoking, are examined by linear regression analysis. Logarithmic transformations were applied when necessary. Results: Although hair Hg level is well correlated with blood Hg concentration (Spearman correlation=0.71, p < 0.05), there is a great deal of variability in the hair-to-blood Hg ratio in the study population (mean= 282; median [interquartile range] = 215 [129-330]). Of the physiological and sociodemographic parameters investigated, race is the leading factor followed by smoking in determining the hair-blood Hg ratio and while African-American women had the lowest estimated ratio, women in “All Other Races (including Asians)” have the highest hair-blood Hg ratio. Moreover, the hair-blood Hg ratio is approximately 13% higher among current and former smokers than their counterparts after covariate adjustment. On the other hand, the hair-blood Hg ratio among subjects with impaired liver function is 16% lower (p=0.08) than that in subjects with normal liver enzyme levels. Conclusions: Conclusions: While this study generally supports the WHO recommendation of using a hair-to-blood Hg ratio of 250 for mercury assessment, there is a range of interindividual variation in the ratio. As dose metric conversion of Hg biomonitoring data is important in estimating body burden of Hg exposure, further research is warranted to confirm our findings.