A 15-year old high school student's science fair project got the ball rolling. Alexa Dantzler wondered what chemicals remained in clothing after dry cleaning. She called around and got a willing chemistry department from Georgetown on board. They tested cotton, wool, polyester and silk from one to six cleanings. Their results were published in Environmental Toxicology & Chemistry, and can be found here.
So what did they find? As can be expected, there were elevated levels of known dry cleaning solvents left on the fabric tested. One of the more concerning is perchloroethylene, also known as PCE or perc. This chemical is associated with cancer and neurological damage, though no toxicity has been proven by (or for) the FDA, so it is not highly regulated (OSHA regulates amounts found in the air of related businesses such as dry cleaners, but no regulations for consumers).
Where was the PCE found in highest concentrations? In the wool fabrics, increasing after each subsequent dry cleaning. Other fabrics such as cotton and polyester leveled off in terms of their PCE after a few washes. And silk did not appear to take any PCE home with it.
How about "Green Cleaners?" Well, some use hydrocarbons instead of PCE. Hydrocarbons are petroleum based, like a relative to kerosene and gasoline. For this research two "green cleaners" were tested, both negative for PCE, one with and one without hydrocarbons. What was the last one using, if not PCE and not hydrocarbons? This industry really isn't regulated near enough for a consumer to understand all the chemicals being used and their potential health implications.
Some conclusions and suggestions implied from this research is that wool adheres the most chemicals and silk the least, amounts of washing has a cumulative effect on chemical exposure and that green cleaners may be better options but this is unknown. As an aside to their research, dry cleaned wool left in a car was found to release a lot of its chemicals into the air- so avoid leaving dry cleaned garments in a closed air space for long.
Any additional information you may have on this topic is greatly appreciated. I personally rarely make use of dry cleaning services, and am inherently skeptical of how "green" the "green ones" are- so let me know if you are knowledgeable on this subject. Thank you for reading.