Does chloroform exposure while showering pose a serious public health concern?

The problem of organic chemicals in drinking water has been well known since 1974-1975 when the National Organics Reconnaissance Survey (NORS) and the National Organics Monitoring Survey (NOMS) showed that drinking water contaminated by organics could be found throughout the nation. Of special concern are the trihalomethanes (THMs) one of which, chloroform, is a suspected human carcinogen, and has been proven to be carcinogenic in test animals. In addition to chloroform exposure from drinking water, inhalation of chloroform from air while showering may constitute an additional source of exposure. Since the EPA has not included exposure to airborne chloroform in their risk-assessment calculations, the actual cancer risk to the population due to chloroform in drinking water may be significantly higher than the EPA estimated. It is suggested that a major research effort be directed at the determination of airborne chloroform levels in the domestic shower environment. Effort should also be made to determine what variables affect the magnitude of the chloroform levels if present. Once these variables are known it may be possible to educate the public about the potential hazard and ways to eliminate or reduce it.