Low-level mercury exposure and peripheral nerve function

Abstract

Background: Mercury is known to be neurotoxic at high levels. There have been few studies of potential peripheral neurotoxicity among persons with exposure to elemental mercury at or near background levels.

Objectives: The present study sought to examine the association between urinary mercury concentration and peripheral nerve function as assessed by sensory nerve conduction studies in a large group of dental professionals.

Methods: From 1997 through 2006 urine mercury measurements and sensory nerve conduction of the median and ulnar nerves in the dominant hand were performed, and questionnaires were completed, on the same day in a convenience sample of dental professionals who attended annual conventions of the American Dental Association. Linear regression models, including repeated measures models, were used to assess the association of urine mercury with measured nerve function.

Results: 3594 observations from 2656 subjects were available for analyses. Urine mercury levels in our study population were higher than, but substantially overlap with, the general population. The only stable significant positive association involved median (not ulnar) sensory peak latency, and only for the model that was based on initial observations and exclusion of subjects with imputed BMI. The present study found no significant association between median or ulnar amplitudes and urine mercury concentration.

Conclusions: At levels of urine mercury that overlap with the general population we found no consistent effect of urine mercury concentration on objectively measured sensory nerve function.