Diabetes has rapidly moved to the forefront of health problems in 21st century America. Understanding the vast number of risk factors that contribute to the quickly increasing number of individuals who develop this disease is crucial to applying appropriate public health measure to combat it. The majority of attention tends to be on lifestyle risk factors however, it is also important to investigate potential environmental hazards members of the population might be exposed to. Recently, a group of researchers including Water Institute Faculty Working Group Member, Ana Navas-Acien, MD, PhD and her former student Chin-Chi Kuo, MD, PhD investigated the potential links between arsenic exposure and diabetes in their paper Arsenic Exposure, Arsenic Metabolism, and Incident Diabetes in the Strong Heart Study. Their study followed 1,694 initially diabetes-free patients from approximately 1989 to 1999, observing their diabetes status and the proportions of inorganic arsenic (iAs), monomethylarsonate (MMA), and dimethylarsinate (DMA) used as biomarkers of arsenic metabolism. The metabolism of arsenic is crucial because unbound arsenic can accumulate in cells, leading to skin, bladder, kidney, liver, lung, or prostate cancer over time.
The Strong Heart Study (SHS) is a population-based, prospective, cohort study of cardiometabolic diseases in American Indian communities rural Arizona, Oklahoma, North Dakota, and South Dakota. The study’s population ranged in age from 40 to 74 years old from communities with high existing burdens of obesity and diabetes.
Individuals can be exposed to inorganic arsenic, a naturally occurring element and human carcinogen, through drinking water, food and ambient air. Above average arsenic concentrations in groundwater wells can be traced back to the erosion of natural deposits, runoff from orchards, and runoff from glass and electronics production waste, among other sources. For example, North Dakota, one of the sites investigated by the study, faces widespread arsenic contamination in their shallow ground water aquifer as a result of the use of arsenic-laced bait in the 1930s and 1940s.
The study found that arsenic metabolism, but not iAs exposure, was prospectively associated with an increased incidence of diabetes in the population. The results showed that individuals with a lower MMA%, and the higher iAs and DMA percentages that result, were associated with a higher diabetes incidence. This indicates that lower arsenic metabolism patterns may be a predisposing factor for diabetes. The associations found in the study held up after adjustment for sociodemographic factors, kidney function, and lifestyle risks such as alcohol and smoking. While the results of the study were novel and indicated an interesting potential association, the researchers made it clear that more research is necessary in order to understand the scope of the impact of arsenic methylation on the development of diabetes.
Faculty Working Group Member, Ana Navas Acien, MD, is a physician and epidemiologist with a specialty in Preventative Medicine and Public Health. Her work focuses on the health consequences of widespread environmental exposures.
Kuo, CC, Howard, BV, Umans, JG, Gribble, MO, Best, LG, Francesconi, KA, Goessler, W, Lee, E, Guallar E, Navas-Acien, A. Arsenic Exposure, Arsenic Metabolism, and Incident Diabetes in the Strong Heart Study, Diabetes Care, 2015 Jan 12. pii: dc141641.