An occupational epidemiology study tracked the incidence of neurodegenerative disorders in relation to chemical solvent exposure using national industrial health registries over a 30-year period. The findings for individuals diagnosed with Early-Onset Dementia (EOD) or Parkinson's Disease (PD) by age 60 are shown in Table 1 below.
| Early-Onset Dementia (EOD) | Parkinson's Disease (PD) | |||
|---|---|---|---|---|
| Occupational Exposure Level | % of cohort diagnosed by age 60 | Number of individuals | % of cohort diagnosed by age 60 | Number of individuals |
| High Exposure (Direct daily handling) | 18.6 | 210 | 14.2 | 115 |
| Moderate/Low Exposure (Indirect contact) | 4.3 | 12,400 | 3.1 | 9,850 |
| No Exposure (Control group) | 0.8 | 1,250,000 | 0.5 | 1,250,000 |
To what extent can these findings be considered reliable?
