Abstract
OBJECTIVE: To study color discrimination impairment in workers exposed to elemental mercury (Hg) vapor. SUBJECTS: Twenty-four male workers from a chloralkali plant exposed to Hg vapor, aged 42+/-9.8 years, duration of exposure 14.7+/-9.7 years, were examined.
The 8h TWA air-borne Hg concentration in workplace was 59 microg/m(3); mean Hg urinary excretion (HgU) was 20.5+/-19.3 microg/g creatinine; mean Hg urinary excretion after the administration of a chelating agent, sodium 2,3-dimercapto-1-propane-sulfonate (DMPS), was 751.9+/-648 microg/48h. Twenty-four age- and gender-matched control subjects were compared.
Visual acuity, alcohol intake, smoking habits, and history of diseases or drugs potentially influencing color vision were registered. METHODS: The Lanthony 15-Hue desaturated test (L-D15-d) was used to assess color vision.
The results were expressed quantitatively as Bowman's Color Confusion Index (CCI), and qualitatively according to Verriest's classification of acquired dyschromatopsias. This effect was observed at an exposure level below the current biological limit for occupational exposure to mercury.
This raises doubts on the actual protection afforded by this limit concerning the effect of mercury on color vision.