Parkinson's Disease is a brain disorder that causes tremors and difficulty with movement and walking.  Several studies have reported that exposure to solvents may increase risk of Parkinson’s.  Used extensively worldwide, trichloroethylene (TCE) is a common agent in dry-cleaning solutions, adhesives, paints, and carpet cleaners. Widely used today as a degreasing agent, waste remnants of TCE are discharged in to the environment and contaminate the soil, groundwater, and air.  TCE  is the most common organic contaminant found in ground water, detected in up to 30% of drinking water supplies in the country. Samuel Goldman, from The Parkinson's Institute (California, USA), and colleagues investigated exposure to TCE, and two other solvents, on the risk of developing Parkinson's Disease. The team interviewed 99 twin pairs from the National Academy of Sciences/National Research Council World War II Veteran Twins Cohort in which one twin had PD and one didn't, inquiring about lifetime occupations and hobbies. Lifetime exposures to six specific solvents previously linked to PD in medical literature -- n-hexane, xylene, toluene, CCl4, TCE and PERC -- were inferred for each job or hobby.  The researchers revealed that exposure to trichloroethylene (TCE) significantly associates with increased risk of Parkinson's disease (PD). As well, the team observed that the possibility of developing this neurodegenerative disease is also linked to perchloroethylene (PERC) and carbon tetrachloride (CCI4) exposure.  Concluding that: “Exposure to specific solvents may increase risk of [Parkinson's Disease], the study authors warn that: “[Trichloroethylene]  is the most common organic contaminant in groundwater, and [perchloroethylene] and [carbon tetrachloride] are also ubiquitous in the environment.”