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Scientists evaluate cancer risk of US drinking water

Carcinogens in drinking water could be the cause of more than 100,000 cases of cancer in the United States, according to a recent study. Researchers from the Environmental Working Group (EWG) in Washington, DC, used a new approach to analyze cumulative cancer risk due to cancer-causing chemicals in tap water across the U.S. They note that the study is the first to apply a "cumulative cancer risk framework" to the analysis of tap water contaminants for the whole of the U.S. The analysis drew on water quality data from 48,363 community water systems across the country. The dataset did not include private wells, which supply drinking water to around 14% of the U.S. population, or about 13.5 million households. The analysis revealed that the most significant impact on cancer risk came from arsenic, followed by byproducts of disinfection. "Drinking water contains complex mixtures of contaminants, yet government agencies currently assess the health hazards of tap water pollutants one by one," says first and corresponding study author Sydney Evans, an EWG science analyst. "In the real world," she adds, "people are exposed to combinations of chemicals, so it is important that we start to assess health impacts by looking at the combined effects of multiple pollutants." (Credits: ww.medicalnewstoday.com)

Why do we forget our dreams? Study sheds light

New research in mice identifies a group of neurons that helps reveal why and how the brain forgets dreams. When we sleep, our brains go through four stages. The initial three are non-rapid eye movement (non-REM) stages. The first stage includes the transition from wakefulness to sleep, when the body slows down from its daytime rhythm and "twitches" its way into sleep. The second stage, also of non-REM sleep, involves light sleep. The third stage of sleep is deeper, and it provides the profound kind of rest that one needs to feel refreshed in the morning. New research in mice suggests that the REM sleep stage also contains a period of "active forgetting." This most likely occurs to avoid information overload, according to the new study, and the neurons responsible for this forgetting are also the neurons that help control appetite. The new findings appear in the journal Science. Thomas Kilduff, Ph.D., the director of the Center for Neuroscience at the SRI International research institute in Menlo Park, CA, led the research in collaboration with Akihiro Yamanaka, Ph.D., from Nagoya University, in Japan. (Credits: ww.medicalnewstoday.com)