Occupational Mercury Exposure and Neurological Disease Prevalence In US Dentists

Background: The neurologic effects of chronic low-level occupational exposure to elemental mercury (Hg0) in dentists are largely unknown. The objective was to examine occupational Hg0 exposure and multiple sclerosis (MS) and tremors. Methods: The study included 13,906 dentists who attended the American Dental Association’s annual meeting in 23 years (1986–2007, and 2011–2012). Participants reported MS and tremor via questionnaire and provided urine specimens for mercury analysis. We estimated cumulative Hg0 exposure and used logistic regression to assess the association between Hg0 exposures and disease. Results: Urinary Hg0 exposure in US dentists has decreased dramatically over the last three decades and is now approaching that of the general population. The prevalence of MS (1.36%) was found to be substantially higher than what has been reported in surveys of the general population. Cumulative Hg0 exposure was not associated with MS [odds ratio [OR] =.85 (95% CI, 0.39, 1.85)]. In younger dentists (<51 years), a mean cumulative Hg0 exposure significantly increased the risk of tremor by 13% [OR=1.13 (95% CI, 1.04, 1.22)]. Conclusion: Our results suggest a possible association between cumulative mercury exposure and increased risk of tremors and an unusually high prevalence of MS among dentists. Our study has many limitations that preclude drawing strong conclusions.