Parkinson's disease is the world's fastest growing brain disorder, and exposure to environmental toxicants is the principal reason. In this paper, we consider alternative, but unsatisfactory, explanations for its rise, including improved diagnostic skills, aging populations, and genetic causes. We t...
Interesting. One of the chemicals they reference is tetrachloroethylene. According to this Wikipedia article:
Perhaps the greatest use of TCE is as a degreaser for metal parts. It has been widely used in degreasing and cleaning since the 1920s because of its low cost, low flammability, low toxicity and high effectivity as a solvent. The demand for TCE as a degreaser began to decline in the 1950s in favor of the less toxic 1,1,1-trichloroethane. However, 1,1,1-trichloroethane production has been phased out in most of the world under the terms of the Montreal Protocol, and as a result, trichloroethylene has experienced some resurgence in use as a degreaser.[17]
My grandfather had Parkinson's. I would imagine that he had plenty of exposure in his work as a mechanic from about 1925 on.