A new research report contributes to the increasing evidence that repeated occupational exposure to certain chemical solvents raises the risk for Parkinson's disease. Researchers analyzed the occupational histories of twins in which one of the pair developed the neurodegenerative disorder, and assessed that twin's likelihood of exposure to six chemicals previously linked to Parkinson's. Of the six chemicals investigated, researchers concluded that two common chemical solvents, trichloroethylene (TCE) and perchloroethylene (PERC), are significantly linked to development of this disease. This study,supported in part by the National Institute of Neurological Disorders and Stroke (NINDS), a part of the National Institutes of Health, appears in the Nov. 14, 2011 issue of Annals of Neurology.
The researchers, led by Samuel Goldman, M.D., M.P.H. and Caroline Tanner, M.D., Ph.D. at the Parkinson's Institute in Sunnyvale, Calif.,collected the histories of 99 pairs of twins in which one of the pair developed Parkinson's and the other twin did not. Since twins are so genetically similar, twin studies are especially useful in identifying environmental influences in disease. The twins were identified through the National Academy of Sciences/National Research Council World War II Veteran Twins Registry. Of the 99 pairs, half were genetically identical twins, and half were fraternal twins.
The study team assessed the twins' lifetime work and hobby activities, specifically inquiring about occupational tasks such as electrical work, industrial machinery repair, and dry cleaning, which would potentially expose people to chemicals previously linked to Parkinson's. The researchers also collected information on head injuries, which are suspected to increase Parkinson's risk, and smoking history, which is reported to decrease Parkinson's risk. Expert evaluators, unaware of which study subjects had Parkinson's, reviewed this information and calculated lifelong exposure to six chemicals: TCE,PERC, carbon tetrachloride, n-hexane, xylene and toluene. Of these, TCEand PERC posed a notable risk for developing Parkinson's.
By Nicole Garbarini
Source: http://www.eurekalert.org/pub_releases/2011-11/nion-nts111011.php