Studies on Cape Cod have indicated that women who have been exposed to perchloroethylene (also called PCE or PERC pronounced "perk") through their water sources, have an increased risk for breast cancer (pdf). PERC is the most common chemical used at dry cleaning shops. It accumulates in our body fat and may therefore remain in our bodies for long periods of time. In addition to long-term effects on health, including cancer, shorter term exposures to air-borne PERC can skin irritation, as well as dizziness and headaches.
To decrease your exposure to PERC, try to buy clothes that don't require dry cleaning. Before buying clothes that may need dry-cleaning, find out more about the material from which the items are made, and see if dry-cleaning is really necessary. Manufacturers often put this on the label to prevent liability because they must accept the return if a garment shrinks or loses its shape. Gentle wet washing (even in cold water) and air drying may be sufficient to counter problems of shrinkage or damage.
If you are using a dry-cleaner, find out what kind of solvents they use. If they use PERC, try to find a cleaner that uses a different process such as wet-cleaning, liquid CO2, or silicone. Note however, that there is considerable controversy over how much safer some of the alternative process really are.
If you get your clothes dry cleaned with PERC or other organic substances, be sure to remove the plastic packaging from your clothes and air them out, preferably outside of your home. Also, many fabrics that say, "dry clean only" don't require it.
Also avoid spot removers or carpet cleaners that contain PCE.