TOPLINE:
Exposure to drinking water contaminated with arsenic below the current regulatory limit is associated with an elevated risk for type 2 diabetes (T2D) in urban US communities, with the correlation being stronger in women and individuals with a lower body mass index (BMI).
METHODOLOGY:
- US residents are exposed to inorganic arsenic exposure, a potential risk factor for T2D, through drinking water from both unregulated private wells and regulated community water systems (CWSs).
- This study relied on two cohorts — the Strong Heart Family Study (SHFS) and the Multi-Ethnic Study of Atherosclerosis (MESA) — to elucidate the prospective association between T2D and arsenic levels in federally regulated CWSs and unregulated private wells.
- Overall, 1791 participants (median age, 36 years) from SHFS and 5777 participants (median age, 62 years) from MESA whose water arsenic exposure data were available and who did not have T2D at baseline were included. The mean follow-up duration was 14.0 years in MESA and 5.6 years in SHFS.
- The association between water arsenic exposure and incident T2D was adjusted for BMI, sex, age at baseline, smoking status, and education.
- Arsenic exposure from drinking water obtained from private wells and regulated CWSs was estimated by clustering participants according to their baseline residential zip codes.
TAKEAWAY:
- In the MESA cohort, the T2D incidence rate was 11.2 cases per 1000 person-years, whereas in the SHFS cohort, it was 22.2 cases per 1000 person-years for CWS and 24.4 cases per 1000 person-years for private wells.
- Doubling of the arsenic levels in CWS increased the risk for incident T2D in the MESA cohort (hazard ratio [HR], 1.10; 95% CI, 1.01-1.20), particularly in women (HR, 1.19; 95% CI, 1.06-1.33) and in individuals with a BMI < 25 (HR, 1.24; 95% CI, 1.03-1.50).
- Doubling of the arsenic levels in private unregulated wells also increased the risk for T2D in individuals with a BMI < 25 in the SHFS cohort (HR, 3.05; 95% CI, 1.88-4.96).
- The risk for incident T2D increased with CWS arsenic concentrations > 1 µg/L vs ≤ 1 µg/L in the MESA cohort (HR, 1.34; 95% CI, 1.09-1.65).
IN PRACTICE:
“Because arsenic in drinking water can be prevented, through regulation and interventions, our findings support that further efforts are needed to assess whether the current (maximum contaminant level) for water arsenic in the United States is effective and sufficient in reducing arsenic-related risk of T2D and other cardiometabolic diseases,” the authors wrote.
SOURCE:
This study was led by Maya Spaur, Department of Environmental Health Sciences, Columbia University Mailman School of Public Health, New York City, and published online in Diabetes Care.
LIMITATIONS:
The study relied on zip code-level estimates of water arsenic, which may not accurately represent individual residential exposures. The study also lacked information on factors like bottled water use, water filters, and tap water consumption, which could affect individual arsenic exposure. The relatively short follow-up time and potential for residual confounding and measurement errors of exposure were other major limitations.
DISCLOSURES:
This study was supported by the National Institute of Environmental Health Sciences, the National Institutes of Health Office of the Director, and the National Institute of Dental and Craniofacial Research. No conflicts of interest were reported.
