Be wary. There is no legal definition of "organic" when it comes to dry cleaning, therefore oftentimes dry cleaners call themselves organic but are just using an alternative hydrocarbon. One such solvent is made by Exxon-Mobil called DF-2000 which is safer than perc but the EPA still lists it as a neurotoxin. There's also EcoSolv which is a mixture of isoparrafins. Little is known about EcoSolv yet. Another method touted as more environmentally friendly than perc is a silicone-based solvent called GreenEarth. However, GreenEarth also has come under scrutiny as a possible carcinogen, a claim that could harm its prospects among consumers concerned about their health.
The safest alternative is carbon dioxide cleaning, which uses liquid carbon dioxide (when under high pressure) to carry biodegradable soaps. The carbon dioxide is then turned back into a gas, therefore the clothes dry instantly.
This list is "clean":
Dry cleaning involves washing clothes in liquids other than water. As it's done at 90 percent of cleaners in the U.S., it uses a liquid form of perchloroethylene (PERC), a chemical believed to cause cancer. As it evaporates, PERC can contaminate nearby air and groundwater, and reportedly can be absorbed through the skin from soil or from dry-cleaned clothes. California is phasing out its use by 2011..