The National Geographic News interviewed Professor David Reckhow of the Civil and Environmental Engineering Department for an article that appeared on its web site April 29. Though shampoo may seem harmless, according to the article, it could be contributing to the formation of a mysterious, cancer-causing substance studied by new Yale University research. The substance, called nitrosamine, forms when shampoo or other household products interact with the disinfectant called chloramine, used in many wastewater treatment plants. Though inconclusive, the study suggests that "it's entirely possible that we're producing more problems—and maybe even worse problems—with chloramines," said Reckhow.
The story, about possible cancer-causing substances in our water supply, was part of a special series that explores the global water crisis.
Nitrosamines are found in a wide variety of sources, including processed meats and tobacco smoke, but what sparks their formation in drinking water has long baffled scientists. Past studies with cosmetics have hinted that substances called quaternary amines, which are also ingredients in household cleaning agents, may play a role in creating nitrosamines. Beyond treatment plants, nitrosamines can also form in other environments, such as swimming pools.
Yet no regulations exist so far in the United States, mostly because, as the National Geographic article noted, it's not unusual for regulations to lag behind scientific discovery. "There’s no way of getting around that,” said Dr. Reckhow, “and even the science isn’t really sure" about the consequences of combining chloramination at treatment plants with household products. (May 2010)