Solving the Solvent Question

This past month, a study on Parkinson Disease raised some disturbing questions about the role that certain common chemical solvents may play in leading to this potentially devastating neurological disease. The chemical solvents in question, trichloroethylene and perchloroethylene, are used commonly in a number of workplaces. They are also allowed on the market in household consumer products.
The research study, "Solvent Exposures in Parkinson Disease Risk in Twins," was published in November by the medical journal Annals of Neurology and has been widely noted since, including a prominent posting by the Parkinson's Disease Foundation (http://www.pdf.org/en/science_news/release/pr_1321655549). The investigators took advantage of U.S. military veterans registry of twins, focusing on cases where only one of the pair had develop Parkinson's Disease. Through detailed questioning about job duties and hobbies, the study was able to ascertain who was likely to exposure to certain solvents and who was not. The results indicated that if a twin was exposed to perchloroethylene (commonly called PERC), this led to a more than 10-fold increased risk of Parkinson's. Exposure to trichloroethylene (also known as TCE) carried a 6-fold risk.
The research paper listed a number of jobs or hobbies that could involve such exposures, including work as an electrician, dry cleaner or as an artist; it also alluded to a variety of consumer product types with past or current inclusion of PERC or TCE. Not surprisingly, brand names were not provided - this is a practice rarely done in medical publications. It turns out, though, that there is a rich and easy to use resource for such information provided by the U.S. government via that National Institute of Health's National Library of Medicine
(http://householdproducts.nlm.nih.gov/). It is a database that allows anyone to search consumer products by type or by ingredient.
This site currently lists 30 PERC-containing products including in the categories of arts and crafts and home maintenance, but dominated by auto products. As disturbing, the most common delivery form for these products was as aerosol sprays, a very efficient method for putting PERC into the air and thus allowing it be breathed into the body. For TCE the current list is shorter at only 12 products. Of these are, 9 are from the same company, Sprayway, which has the distinction of appearing on both lists (3 for PERC).Of course none of this excludes older products that may still be on the shelf, for example a hold-over user of old typewriter correction fluid. Nor is it clear that the National Library of Medicine database, although regularly updated, is all inclusive.
It is also important to remember that PERC and TCE are just two chemicals linked to Parkinson's Disease. A far bigger threat may be posed by the potential addition of the manganese additive MMT to gasoline. That additive, manufactured by Afton Chemical Corporation (formerly known as the Ethyl Corporation, the makers of the U.S< banned gasoline additive tetraethyl lead), is still under review by the U.S. EPA (http://www.epa.gov/otaq/regs/fuels/additive/mmt_cmts.htm) and there is no guarantee MMT won't get a green light. So even if we solve the solvent problem, we may still be awash in other toxins.