Association between Uranium Exposure and Thyroid Health: A National Health and Nutrition Examination Survey Analysis and Ecological Study

Abstract

Besides specific, incidental radiation exposure, which has been associated with increased thyroid cancer risk, the effects of exposure to background radiation from uranium, a naturally occurring, radioactive, and ubiquitous element, on the thyroid gland has not been widely studied. We therefore investigated the association between uranium exposure and thyroid health in the US. Using the National Health and Nutrition Examination Survey (NHANES), we assessed the association between urinary uranium levels and thyroid-related antibodies, including thyroglobulin antibodies (TgAb) and anti-thyroid peroxidase (anti-TPO), in the general population. Secondly, we performed an ecological study of age-adjusted thyroid cancer incidence rates per state and sources of uranium exposure. We included 3125 eligible participants from the NHANES and found a significant association between increased TgAb and increased urinary uranium levels when analyzed as quartiles (p = 0.0105), while no association was found with anti-TPO. In addition, although no significant correlation was found in the ecological study, certain states had high age-adjusted thyroid cancer incidence rates and a high number of uranium activity locations and high uranium concentrations in water. The present study suggests that uranium exposure may affect thyroid health, which warrants increased sampling of soil and water in high-risk states.

Uranium Exposure in American Indian Communities: Health, Policy, and the Way Forward

“…Banning and Benfer (2017) have described weak yet statistically significant positive correlations between exposure to uranium through drinking water and an increase in the incidence rates of tumors and growths, in addition to liver disease, in Bavarian residents (Banning and Benfer 2017). In addition, a recent study by van Gerwen et al (2020) stated that although there was no evidence of a significant correlation within the described ecological study, certain states evidenced high ageadjusted thyroid cancer incidence rate in geographic areas that were within close proximity to known uranium-contaminated sites (van Gerwen et al 2020).…”

“…In addition, a recent study by van Gerwen et al. ( 2020 ) stated that although there was no evidence of a significant correlation within the described ecological study, certain states evidenced high age-adjusted thyroid cancer incidence rate in geographic areas that were within close proximity to known uranium-contaminated sites ( van Gerwen et al. 2020 ).…”

“…Last, van Gerwen et al. ( 2020 ), specifically noted that a higher uranium concentration in drinking water may affect thyroid health.…”

The correlation between small papillary thyroid cancers and gamma radionuclides Cs-137, Th-232, U-238 and K-40 using spatially-explicit, register-based methods

“…Uranium has 17 known isotopes but only U-234, U-235, and U-238 are found in the environment due to their long half-lives (250 thousand, 700 million and 4.5 billion years respectively) (23). U-238 is released into the environment through wind and water erosion, as well as mining, milling or other forms of uranium processing (9). U-238 can be absorbed into the body through ingestion of contaminated food or drink, or inhalation of uranium-containing dust particles or aerosols (23).…”

“…All uranium isotopes are radioactive, emitting alpha particles causing radiotoxicity (23). Therefore, chemical toxicity is the limiting factor determining the current US Environmental Protection Agency (EPA) maximum allowable contaminant level of 30 µg/L in drinking water (9). Increased thyroid cancer incidence has been documented in volcanic regions where increased urinary uranium concentrations have been found, although the underlying mechanism is still not clearly understood (9).…”