The Effect of Low-Level Environmental Arsenic Exposure on Obesity Risk

Abstract

As of 2019, arsenic ranks number one on the Agency for Toxic Substances and Disease Registries (A.T.S.D.R.) list of hazardous substances that will be the subject of toxicological profiles. Exposure to high levels of arsenic are known to cause skin lesions, cardiovascular disease, neurological effects, diabetogenic effects, and various forms of cancer. Arsenic exposure in lower concentrations remains controversial in the literature. Arsenic is a naturally occurring metalloid that is ubiquitous in the environment. Several states along the Mississippi Delta region contain the highest levels of soil arsenic concentrations in the U.S., one of which is Arkansas. From the 19th to the 20th century, Arkansas agriculture was heavily invested in apple orchards, cotton farming, and lignite mining, all of which used and produced arsenic compounds and byproducts. The majority of these practices were banned in the 1980’s, however Arkansas’ extensive history with arsenic use has contributed to the historic and a continuing addition to arsenic concentrations in the soil. Among women, Arkansas is ranked third in the nation for the highest prevalence of obesity compared to all other states, with no sign of a descending trend. While residing in the state, individuals are chronically exposed to low-levels of arsenic from local exposures, with the outcomes yet to be investigated. One possible outcome is obesity. Literature has identified that obesity results from the combination of multiple factors such as individual behavior and genetics. Genetic studies have identified that while obesity is a heritable disease, genetic variants only explain part of the variability. Investigation into arsenic within the soil and arsenic concentrations can identify if these century-long contaminations can still pose a threat to Arkansan health today, as well as generations to come. This study examines the effects of low-levels of arsenic on a female population, and contribute to the gap in variability. Furthermore, we hypothesized that the concentration of arsenic related to an individual’s residence is related to their salivary arsenic content, exposure to low-levels of arsenic will result in an increased risk for obesity, and arsenic results in transgenerational effects within families that can affect obesity status. This study has capitalized on subjects enrolled in an established rural community study with a cross-sectional study design that was created to examine potential breast cancer biomarkers from salivary samples. Low levels of arsenic were measured using inductively coupled plasma mass spectrometry (ICP-MS), which is capable of detecting concentrations as low as parts per trillion (ppt)) within the population. The aims of the study were to: 1) investigate if an individual’s residence, and length of time living in that location, have an association with the amount arsenic detected in their saliva; 2) examine the relationship between arsenic concentrations and obesity, and 3) to understand the transgenerational effects of arsenic and obesity. With a large variation of arsenic concentrations found in Arkansas soil, this study provides novel contributions to the understanding of chronic low-level exposures to arsenic. Knowledge gained from this study can aid in information used to set governmental limits and guidelines regarding appropriate levels of arsenic exposure.