July’s Editor’s Choice article is "A review on the 40th anniversary of the first regulation of drinking water disinfection by-products" (https://onlinelibrary.wiley.com/doi/full/10.1002/em.22378) by David DeMarini.
Despite being considered one of the greatest achievements in protecting public health, disinfection of water by chlorination raised health concerns in the 1970s when certain disinfection by-products were found to be mutagenic and carcinogenic in animals and, possibly, in humans. Those concerns gave birth to the first regulation of disinfection by-products by the U.S. Environmental Protection Agency in 1979, initiating rich and educating research and regulatory activities that took place during the last 40 years. These activities, reviewed concisely by DeMarini, include, for example, the identification of over 600 disinfection by-products and the mechanisms of their formation, the accumulation of general toxicity and genotoxicity profiles of over 100 disinfection by-products, as well as cancer evaluation of 22 disinfection by-products. Interestingly, the genotoxicity of disinfection by-products found not only in drinking water but also in swimming pool and hot tub water is discussed. In addition, a detailed hypothesis for the induction of bladder cancer from certain disinfection by-products is thoroughly presented. Readers also learn that nowadays modern water-treatment methods used by most developed countries, in conjunction with regulations or guidelines, are likely responsible for a reduction, but not entire elimination (with some percent of bladder cancer cases attributable to drinking water exposure) of potential risk for the development of bladder cancer from chlorinated water. Further research needs, such as improved toxicological assays, including incorporation of cancer-related endpoints such as DNA damage and oxidative stress biomarkers, and additional epidemiological studies in swimmers, are also proposed. Overall, the review highlights many important lessons accumulated over the 40-year period of dedicated, cooperative research efforts conducted jointly by academic and government scientists, along with public and private water companies, to develop techniques and transfer knowledge to regulators for the betterment of public health.