Quality of drinking water and associated health risks A new NIH study links arsenic in drinking water from private wells to bladder cancer The quality of water has an important impact on public health. Presence of contaminants, either microbial or chemical, puts health of people at risk. Water-borne diseases such as diarrhea, cholera, dysentery, typhoid, worm infestations are well-recognized and constitute a major cause of mortality and morbidity worldwide. It’s not only the surface water in rivers and lakes that is susceptible to contamination, groundwater or water in wells too is susceptible to contamination through poor management of industrial or agricultural waste. Groundwater may also be contaminated by naturally occurring chemicals. Drinking water requires appropriate treatment to remove the hazardous contaminants before it is fit for drinking. Water sources that are unprotected are at a great risk of contamination and become unfit for drinking. Arsenic is naturally present at high levels in the groundwater in many parts of the world. It is the only contaminant that has been shown to be the cause of human cancers following exposure through drinking water. In addition to occupational exposure, other important routes of arsenic exposure are oral intake of food and drinking-water. The goal for amount of arsenic in drinking water is usually less than 10 µg/L. But, in those areas in which drinking water contains arsenic levels greater than this, it becomes the major source of arsenic. Findings from a recent NIH study further support an association between low-to-moderate levels of arsenic in drinking water and bladder cancer risk in Maine, New Hampshire and Vermont in the United States, where most people use private wells for their drinking water. In the study published May 2, 2016, in the Journal of the National Cancer Institute, increasing cumulative exposure was found to be associated with an increasing risk of bladder cancer. Among study subjects who had used private wells, particularly wells that were dug during the first half of the last century, those who drank the most water had a 2-fold higher risk. These private wells are outside jurisdiction of federal regulations and are not maintained by municipalities. The water in these wells may contain low to moderate levels of arsenic due to use of arsenic containing pesticides. Dug wells are less than 50 feet deep, and potentially susceptible to contamination from man-made sources.