Trichloroethylene (TCE), a century-old industrial chemical used in degreasing and dry cleaning, has contaminated groundwater and buildings across the US and is now linked by researchers to a 500% increased risk of Parkinson's disease through studies showing it damages dopamine-producing brain cells. The real concern is that most exposure is accidental—people inhale TCE vapor seeping into homes and offices from contaminated ground, or drink it in well water, often without knowing they're exposed. The Rochester attorneys study adds weight to this: four of 79 lawyers working near a former dry cleaning site developed Parkinson's at rates far above the general population, suggesting ordinary office buildings can pose hidden risks. What the reporting doesn't emphasize clearly: the 500% figure comes from a hypothesis paper proposing TCE as a cause, not yet from a randomized trial proving it—the epidemiological evidence is suggestive and compelling, but the causal mechanism is still being established.