Visual impairment on dentists related to occupational mercury exposure

A detailed assessment of visual function was obtained in subjects with low-level occupational mercury exposure by measuring hue saturation thresholds and contrast sensitivity functions for luminance and chromatic modulation. General practice dentists (n = 15) were compared to age-matched healthy controls (n = 13). Color discrimination estimated by the area of Mac Adam ellipses was impaired, showing diffuse discrimination loss. There was also reduction of contrast sensitivity for luminance and chromatic (red-green and blue-yellow) modulation, in all tested spatial frequencies. Low concentrations of urinary mercury (1.97 ± 1.61 μg/g creatinine) were found in the dentists group. Color discrimination as well as contrast sensitivity function, assessed psychophysically, constitutes a sensitive indicator of subtle neurotoxic effect of elemental mercury exposure.