This study is important because it raises questions about drinking water standards. This study was referenced in Living Downstream by Sandra Steingraber
The exhaled breath of people who had recently showered contained elevated levels of volatile organic compounds. In fact, a ten-minute shower or a thirty minute bath contributed to a greater internal dose of these volatile compounds than drinking half a gallon of tap water. Showering in an enclosed stall appears to be contribute to the greatest dose, probably because of the inhalation of steam.
The particular route of exposure profoundly affects the biological course of the contaminant within the body. The water that we drink and use in cooking passes through the liver first and is metabolized before entering the bloodstream. A dose received from bathing is dispersed to many different organs before it reaches the liver. The relative hazards of each pathway depend on the biological activity of the contaminant and its metabolic breakdown product, as well as on the relative sensitivity of the various tissues exposed along the way.
The bathing studies raise additional questions about drinking water standards. Once again, we see how narrow the purview of these regulations is. The environmental scientists Clifford Weisel and Wan-Kuen Jo, the authors of the 1996 study, pointedly explained:
Traditional approaches for evaluating exposure to and adverse health effects from contaminants in tap water have assumed that ingestion is the major route of exposure….Furthermore, the ingestion of two liters of water has been used to estimate the health risk associated with waterborne chemical contaminants and the establishment of drinking water standards without quantifying the doses received from other routes. This practice can lead to an underestimation of the potential health risk.
Living Downstream by Sandra Steingraber