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

Maaike van Gerwen,Naomi Alpert,Eric Genden,Bian Liu,Peter Cooke,Kimia Ziadkhanpour,Wil Lieberman-Cribbin

doi:10.3390/ijerph17030712

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.

Highlights

IntroductionAside from these specific exposure scenarios, the general population is exposed to background radiation from uranium, which is a naturally occurring, radioactive element with a wide distribution in the soil and higher concentrations in certain rock formations, especially within North America, Africa and Australia [11]
Given that uranium is a ubiquitous, radioactive element, we proposed investigating the association between uranium exposure and thyroid health in the US, by (1) assessing the association between urinary uranium levels and thyroid-related antibodies, in particular thyroglobulin antibodies (TgAb), in the general population using the National Health and Nutrition Examination Survey (NHANES) and (2) performing an ecological study of thyroid cancer incidence and sources of uranium exposure
Thyroglobulin antibody levels were positively associated with urinary concentrations of uranium, suggesting that uranium exposure may affect thyroid health and potentially increase cancer risk as previous research has shown that TgAb positivity in patients with thyroid nodules was associated with an increased risk of suspicious cytology [33] and papillary thyroid cancer [34]

Summary

Introduction

Aside from these specific exposure scenarios, the general population is exposed to background radiation from uranium, which is a naturally occurring, radioactive element with a wide distribution in the soil and higher concentrations in certain rock formations, especially within North America, Africa and Australia [11]. Uranium has 17 known isotopes but only 234 U, 235 U, and 238 U are found in the environment due to the sufficient long half-lives of 235 U and 238 U; 234 U is present as the decay product of 238 U [11]. All uranium isotopes are known to be radioactive causing radiotoxicity. Public Health 2020, 17, 712; doi:10.3390/ijerph17030712 www.mdpi.com/journal/ijerph

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