Maddison Couch
Mentor: Walter Smith, PhD
Current Status: Undergraduate
Instititution: UVa-Wise
Presentations: Student Research Symposium, UVA-Wise, Virginia
NCUR, University of Kentucky, Lexington
Potential Environmental Causes for Central Appalachia's Thyroid Hotspot
The Central Appalachian region is widely known as a hotspot for many thyroid disorders, including hypo- and hyperthyroidism, thyroid cancer, and goiter (enlarged thyroid). The high incidence of goiter in Appalachia is of particular interest since this hotspot occurs in an iodine-sufficient region and presently lacks any known environmental cause – a fact that has led to a wide discussion in the literature of potential causes of this Appalachian “Goiter Belt” (Hollingsworth et al. 1977, Gaitan et al. 1991, Pearce 2007).
Previous research has investigated the potential role of chemical compounds present in the native environment as goitrogens, or compounds that can act to induce abnormalities in thyroid tissue upon exposure and thus lead to thyroid disorders. One class of compounds, phenols, have been shown to exhibit goitrogenic properties in vitro and in vivo (Cooksey et al. 1985, Gaitan 1990). Phenols are a class of compounds encompassing molecules that contain a hydroxyl group bonded directly to an aromatic hydrocarbon group. Phenolic compounds may be widely substituted and vary in function in natural systems, yet a wide variety of goitrogenic phenols have been extracted from coal-bearing strata, such as those found in central Appalachia (Lindsay et al. 1992).
This information has led researchers to hypothesize that goitrogenic phenols may be present in Appalachian surface and groundwater and therefore serve as an environmental cause of Appalachia’s goiter hotspot, particularly for those residents who rely on private water supplies such as wells, cisterns, or piped springs (Gaitan 1989, Lindsay et al. 1992, Gaitan et al. 1993). However, no large-scale, comparative study currently exists to determine if, in fact, phenols are present in higher concentrations in waters underlain by coal bearing strata versus waters outside of this region, and no demographic survey has been performed to determine if goiter patients obtain water from private supplies (as opposed to highly purified bottled water or public/municipal supplies) at a greater frequency relative to the general population as would be expected if native phenols are a source of goitrogenesis.
We performed a multidimensional study to fill this knowledge gap in the central Appalachian region. The first dimension of this study used standard phenolic assays to survey regional surface waters for the presence of phenols. We specifically sampled 45 regional streams to test for the presence and concentration of phenolic compounds in coal-bearing regions relative to undisturbed streams within the coalfields region and those without coal-bearing strata (control). We predicted that streams in areas with exposed coal-bearing strata (abandoned surface mines) would have higher concentrations of phenols than nearby undisturbed streams or those outside of the coalfields, as hypothesized by previous studies (Gaitan 1989, Lindsay et al. 1992, Gaitan et al. 1993)
The second dimension of this study involved a demographic survey of patients at a regional pathologist’s office receiving treatment for thyroid-related disorders. The purpose of this survey was to ascertain the general location of residence for thyroid patients (within or outside the coalfields region), obtain information on the type and history of thyroid disorders for each patient, and obtain information related to the patients’ primary source of drinking water (private or public). A copy of this survey is available in Appendix 1. If phenols were indeed found to be present in the regional surface and groundwater as has been previously predicted, this survey would help to shed light on whether thyroid patients in Appalachia obtain water from private supplies at a higher rate than is reported for general population of the region by the Appalachian Regional Commission (Hughes et al. 2005). These results would then help us focus future, more intensive research into the status and/or role of phenolic compounds in private water supplies as a source of Appalachia’s thyroid disorder hotspot.
