A multiple sclerosis cluster associated with a small, north-central Illinois community

Area of Science:

• Environmental epidemiology
• Neurology
• Toxicology

Background:

• DePue, Illinois, has a history of significant environmental heavy metal exposure due to a zinc smelter.
• Soil and water contamination with zinc and other metals was documented during the study period.
• A cluster of multiple sclerosis (MS) cases was reported to the Illinois Department of Public Health in the mid-1990s.

Purpose of the Study:

• To investigate the validity and statistical significance of a reported multiple sclerosis (MS) incidence cluster in DePue, Illinois.
• To determine if environmental factors, specifically heavy metal exposure, are associated with the observed MS cases.
• To assess the incidence rate of MS in DePue and compare it to expected rates.

Main Methods:

• Reviewed available medical records of purported MS cases.
• Examined living individuals diagnosed with MS.
• Conducted statistical analyses on clinically definite MS cases, determining onset dates by first symptom.
• Calculated incidence rates using published epidemiologic studies for comparison.

Main Results:

• Nine new cases of clinically definite MS were identified among DePue residents between 1971 and 1990.
• The computed incidence rate for MS in DePue Township was statistically significantly higher than expected.
• Significant exposure to mitogenic trace metals, including zinc, was documented in the DePue population during the same period.

Conclusions:

• A statistically significant excess of multiple sclerosis (MS) cases occurred in DePue, Illinois, between 1971 and 1990.
• The findings suggest a potential link between the observed MS cluster and significant environmental heavy metal exposure in the community.
• Further research is warranted to explore the specific mechanisms and causal relationships.