Abstract
ObjectiveThe objective of this study was to evaluate the association between measures of body composition and patterns of urine arsenic metabolites in the 1989–1991 baseline visit of the Strong Heart Study, a cardiovascular disease cohort of adults recruited from rural communities in Arizona, Oklahoma, North Dakota and South Dakota.MethodsWe evaluated 3,663 Strong Heart Study participants with urine arsenic species above the limit of detection and no missing data on body mass index, % body fat and fat free mass measured by bioelectrical impedance, waist circumference and other variables. We summarized urine arsenic species patterns as the relative contribution of inorganic (iAs), methylarsonate (MMA) and dimethylarsinate (DMA) species to their sum. We modeled the associations of % arsenic species biomarkers with body mass index, % body fat, fat free mass, and waist circumference categories in unadjusted regression models and in models including all measures of body composition. We also considered adjustment for arsenic exposure and demographics.ResultsIncreasing body mass index was associated with higher mean % DMA and lower mean % MMA before and after adjustment for sociodemographic variables, arsenic exposure, and for other measures of body composition. In unadjusted linear regression models, % DMA was 2.4 (2.1, 2.6) % higher per increase in body mass index category (< 25, ≥25 & <30, ≥30 & <35, ≥35 kg/m2), and % MMA was 1.6 (1.4, 1.7) % lower. Similar patterns were observed for % body fat, fat free mass, and waist circumference measures in unadjusted models and in models adjusted for potential confounders, but the associations were largely attenuated or disappeared when adjusted for body mass index.ConclusionMeasures of body size, especially body mass index, are associated with arsenic metabolism biomarkers. The association may be related to adiposity, fat free mass or body size. Future epidemiologic studies of arsenic should consider body mass index as a potential modifier for arsenic-related health effects.
Highlights
IntroductionInorganic arsenic (iAs) is a known human carcinogen [1]. Major sources of exposure to inorganic arsenic for the general population include contaminated water and food [2,3,4,5]
Inorganic arsenic is a known human carcinogen [1]
In addition to evaluating each measure of body composition separately, we contrasted the four measures of body composition in models with multiple measures of body composition. Because both arsenic metabolism and adiposity differ by sex, we evaluated the association between % arsenic species and measures of body composition stratified by sex, with consistent findings
Summary
Inorganic arsenic (iAs) is a known human carcinogen [1]. Major sources of exposure to inorganic arsenic for the general population include contaminated water and food [2,3,4,5]. IAs is methylated [6] and eliminated in urine as iAs (~10-30%), monomethylarsonate (MMA, ~10-20%) and dimethylarsinate (DMA, ~60-80%) [7,8,9,10,11,12]. Increased body mass index has been related to higher %DMA and lower %MMA in urine in populations from Northern Mexico, Central Europe, and Bangladesh [10,38,39], other studies in Bangladesh have been inconsistent [13,40]. Studying the relationships of arsenic metabolism with other measures of adiposity and body composition, such as waist circumference (a measure of central adiposity), body fat and fat free mass, might help to distinguish whether associations are with adiposity or with fat free body mass
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