Neurological abnormalities associated with remote occupational elemental mercury exposure

Area of Science:

• Occupational Health
• Neurotoxicology
• Environmental Medicine

Background:

• Elemental mercury exposure in occupational settings poses risks for long-term health.
• Neurological abnormalities may persist years after initial exposure.
• Understanding chronic mercury toxicity is crucial for worker safety.

Purpose of the Study:

• To investigate potential long-term neurological abnormalities in individuals with past occupational elemental mercury exposure.
• To correlate past mercury exposure levels with current neurological function.
• To identify specific neurological deficits associated with cumulative mercury exposure.

Main Methods:

• Study included 502 subjects, with 247 having documented occupational elemental mercury exposure 20-35 years prior.
• Neurological examinations assessed strength, coordination, sensation, reflexes, and tremor.
• Urine mercury levels from the exposure interval were used to quantify exposure, with peak levels analyzed.
• Multiple linear regression was employed to analyze correlations between exposure and neurological outcomes.

Main Results:

• Few significant differences were found between exposed and unexposed groups initially.
• Higher peak urine mercury levels (above 0.6 mg/L) correlated with decreased strength, coordination, sensation, increased tremor, and abnormal reflexes.
• Subjects with clinical polyneuropathy had significantly higher peak mercury levels compared to normal subjects.
• 28% of subjects with peak levels >0.85 mg/L showed polyneuropathy, versus 10% in others (p=0.005).

Conclusions:

• Occupational elemental mercury exposure can lead to persistent neurological abnormalities.
• Peak urine mercury levels are a significant predictor of neurological decline, including polyneuropathy.
• Age-mercury interactions suggest that aging may unmask prior subclinical mercury-induced neurological damage.