To the Editor: Dr Navas-Acien and colleagues1 extended the observation of a diabetogenic effect of arsenic exposure from drinking water containing arsenic levels greater than 100 μg/L in Taiwan, Bangladesh, and Mexico to a fairly low exposure of approximately 0.1 μg/kg per day in the United States. This low exposure dosage is approximately 55 times lower than that observed in the arseniasis-endemic areas (assuming that a 55-kg adult drinks 3 L of water containing an arsenic level of 100 μg/L per day). The odds ratios comparing the 80th vs the 20th percentile of total urine levels of arsenic and the trend test for the tertile stratification were significant only in the models considering seafood intake (ie, with additional adjustment for arsenobetaine and blood mercury levels).
In addition to the limitations discussed by the authors, the study did not adjust for family history of diabetes, which is a strong risk factor for diabetes. It also did not consider the potential confounding of the use of hormone therapy and vitamin supplements. Estrogen2 and folate3 play important roles in the metabolism of arsenic. Furthermore, the source, forms, route, and duration of arsenic exposure were not clear in the study; therefore, urine arsenic levels might not be good surrogate markers for dosage of arsenic exposure.
There appears to be a link between an individual's methylation capacity and arsenic-related skin lesions, skin cancer, bladder cancer, and peripheral vascular disease or hypertension in persons living in arseniasis-endemic areas4 as well as those living far away from the endemic areas and with low exposure.5 Therefore, it would be interesting to know whether the methylation capacity, which can be expressed by the proportion dimethylarsinate level/total arsenic level or dimethylarsinate level/(total arsenic level − arsenobetaine level), was a risk factor for diabetes, even though total urine arsenic levels did not show significant association in some models and the evaluation for the association with levels of urine arsenite, arsenate, or methylarsonate was not feasible due to the detection limits of the assay. These additional analyses might strengthen the hypothesis of a diabetogenic effect of low-dose arsenic if consistent results were seen.
Financial Disclosures: None reported.
Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
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