America's drinking water supply comes from groundwater, reservoirs, rivers, lakes and rainwater. Rainwater collects air pollution, falls on our lawns, fields and parking lots and is collected in storm drains and funneled into the water supply. Household water and sewage is treated, then returned to the water supply. The sources of contamination, both natural and man-made, abound along the way.
When all the possible contamination sources are examined, it is actually amazing that our water is as good as it is. The debate over acceptable contamination levels will go on, but the 2008-2009 President’s Cancer Panel Report suggests that we should take a look at the contamination of our water supply and do as much as we can to remedy the situation now.
The Public Water Supply
Tap water undergoes water purification to remove contaminants, and is further treated to kill bacteria and microbes. It is not possible or economical to remove all contaminants, and small levels of contaminants remain. The EPA regulates 80 different chemicals, disinfection by-products, and nuclear particles, setting maximum contamination levels in our water supply. In a survey of tap water in 42 states, the President's Cancer Panel found 260 contaminants, 141 of which have no established safety standards.
The minimum clean water standards of the 80 regulated chemicals do not necessarily protect the public because of the way the standards are set. The EPA establishes a level that they estimate to be safe. The allowed levels are then negotiated upward from that number, taking cost and risk into consideration. Our minimum standards in many cases are far from ideal.
Private Well Water
Ten to fifteen percent of the American population relies on private well water. Water quality from these wells is regulated by differing state programs. The USGS reports that contaminants found in well water are often above recommended levels. Because most private wells are in rural areas, the levels of nitrates, arsenic, radon and uranium usually lead the contaminant list, but most levels are below the minimum contamination levels set by the EPA. Additionally, private wells may not be treated for bacterial contamination, avoiding the risks of chlorination by-products, but increasing the risk of bacterial disease.
Bottled Water
Bottled water users assume that is cleaner and undergoes more stringent testing. Actually, the reverse is often the case. Unlike public water districts, private bottlers do not have to release the contaminant levels or sources of their water.
The President's Cancer Panel notes that, of the ten brands tested, water quality was the same or worse than available tap water. On average each brand contained eight contaminants. Some brands contained two different carcinogens in levels exceeding local standards. Five of the ten samples contained bacterial contamination.
Contamination from caffeine, pharmaceuticals, arsenic, and fertilizer residues were also found in bottled water. Trace amounts of industrial chemicals, degreasers, propellants and solvents were found. Additional concerns are raised about the safety of compounds such as BPA leached from the plastic bottles.
Common Sources of Contamination- Chlorination By-Products
The chlorination process to kill bacteria and microbes produces by-products that may not be safe. While treatment is unquestionably needed to control the threat of disease in the water supply, there is strong evidence that some of these chemical by-products are carcinogenic and that long-term exposure to these chemicals increases risk of bladder and other cancers.
Federal standards for trihalomethanes (THMs), one group of these chemical by-products, is 80 parts per billion as an annual average. THM’s include chloroform, bromoform and other similar chemicals. Uncontrolled, THM levels can top several hundred parts per billion. The longer the water stays in the water system, the higher the level rises with customers at the extremities of the water supply system routinely experiencing levels higher than the recommended maximums.
Runoff of Agricultural Chemicals
Fertilizers and other lawn and garden care chemicals are a significant source of water contamination. Runoff carries these contaminants into the groundwater where they quickly find their way into the drinking water supply. Farm and landscaping workers exposed to these chemicals have increased cancer risks and it is reasonable to assume that their presence in the drinking water has implications on future cancer rates.
Pharmaceutical Contaminates
Pharmaceutical contaminants have become a source of concern to the US water supply. Medications excreted from patients join those flushed and dumped down drains to enter our rivers and lakes and ultimately our household water supply. Pharmaceutical contaminates are of increasing concern as the population ages and more medications are consumed. Currently water suppliers are not required to test for these contaminants and very little research has been done on the long term effects of the ingestion of low levels of these drugs.
Read the full President's Cancer Panel 2008-2009 Annual Report "Reducing Environmental Cancer Risk - What We Can Do Now". Deainfo.nci.nih.gov, Accessed May 2010
Diane Watkins - Diane is a writer and educator, an avid reader and researcher, a loving wife and the mother of 4 sons. Based in Tampa Bay, she enjoys ...
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