Arsenic and Diabetes: Navas-Acien et al. Respond

Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
Environmental Health Perspectives (Impact Factor: 7.98). 03/2013; 121(3):a71-2. DOI: 10.1289/ehp.1206100R
Source: PubMed
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Available from: Ana Navas-Acien, Jul 03, 2014
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    ABSTRACT: The meta-analysis by Wang et.al1 examining the association of inorganic arsenic (iAs) exposure with Type-2 Diabetes Mellitus (T2DM) brings together the population studies considering water exposure and urine measurements in endemic areas. The evidence is convincing and the authors’ conclusion is that there is a collective association considering the findings. The inclusion criteria for this study included recent and complete articles comprising case-control or cross-sectional studies or cohort studies. The exposure of interest is iAs, with outcome being T2DM, with relative risk (RR) corresponding to 95% confidence interval. The meta-analysis for iAs in drinking water and in urine in endemic areas identified an association of iAs exposure with increased T2DM incidence. In addition the dose-response analysis suggested T2DM risk increase by 13% for every 100 µg/L increment of iAs in drinking water. Basic science research related to gene expression and cell mechanistic pathways has reported links to iAs exposure and T2DM. Future studies should combine the multiple populations and construct an epidemiological design to include confounders, polymorphisms, outcome assessment and longer chronic studies to ensure statistical power especially for low levels of iAs exposure.
    Full-text · Article · Feb 2014 · Journal of epidemiology and community health
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    ABSTRACT: The U.S. Environmental Protection Agency (EPA) is developing an integrated assessment of non-cancer and cancer risk assessment of inorganic arsenic (iAs). Cardiovascular disease (CVD) in association with iAs exposure has been examined in a number of studies and provides a basis for evaluating a reference dose (RfD) for assessing potential non-cancer health risks of arsenic exposure. In this systematic review of low-level iAs exposure (i.e., <100-150μg/L arsenic water concentration) and CVD in human populations, 13 cohort and case-control studies from the United States, Taiwan, Bangladesh, and China were identified and critically examined for evidence for derivation of a RfD. Eight cross-sectional and ecological studies from the United States were also examined for additional information. Prospective cohort data from Bangladesh provided the strongest evidence for determining the point of departure in establishing a candidate RfD based on a combined endpoint of mortality from "ischemic heart disease and other heart diseases." This study as well as the overall literature supported a no-observed-adverse-effect level of 100μg/L for arsenic in water, which was equivalent to an iAs dose of 0.009mg/kg-day (based on population-specific water consumption rates and dietary iAs intake). The study population was likely sensitive to arsenic toxicity because of nutritional deficiencies affecting arsenic methylation and one-carbon metabolism, as well as increasing CVD risk. Evidence is less clear on the interaction of CVD risk factors in the United States (e.g., diabetes, obesity, hypertension) with arsenic at low doses. Potential uncertainty factors up to 3 resulted in a RfD for CVD in the range of 0.003-0.009mg/kg-day. Although caution should be exercised in extrapolating these results to the U.S. general population, these doses allow a margin of exposure that is 10-30 times the current RfD derived by EPA (based on skin lesions in Southwest Taiwan). These findings suggest that the current EPA RfD is protective of CVD.
    Preview · Article · Jun 2014 · Toxicology