Dry cleaning is a process of cleaning textiles without use of water, but using an organic solvent instead. This can help in dealing with some difficult to wash stains, but the process of cleaning itself is more hazardous that regular washing. Historically most commonly used solvent was tetrachloroethylene or perchloroethylene. It is relatively cheap and provides good stain-removal properties. However, increasing evidence suggests that this substance is carcinogenic – regular exposures to it may increase the risk of developing malignant tumours. As a result, it is phased out by the industry worldwide and replaced by less hazardous alternatives, such as liquid silicone and glycol ethers.