A study of 99 pairs of twins with and without Parkinson's disease shows that those exposed to trichloroehylene (TCE) are prone to the risk of developing Parkinson's disease six times more than the other. Study shows exposure to perchloroethylene and carbon tetrachloride also increase the risk of developing the Parkinson's disease. No such evidence was found exposure to toluene, xylene and n-hexane. The data taken is less and requires more studies.
TCE is used as a degreasing agent though it is banned in food and pharma industries long time ago. TCE also results in chopped skin and tremors. Where its use is unavoidable, exposure to persons should be minimized by containment, ventilation, use of personal protective equipment (PPE). Excessive exposure may affect central nervous system, numbness, reduced heartbeat, unconsciousness and eventually death.
Heating of TCE can form phosgene that cause pulmonary edema.
Health effects of TCE: http://www.ccohs.ca/oshanswers/chemicals/chem_profiles/trichloroethylene/effects_trichloro.html