Reprinted from the Florida Specifier November 2014
High nitrate levels in Floridan Aquifer may have cancer implications
By SUSAN TELFORD
Robert Knight, PhD, director of the Howard T. Odum Florida Springs Institute in Gainesville, has been studying water most of his life and knows a bit about the state’s springs and natural resources.
There’s one ugly piece of information that he is aware of about the Floridan Aquifer that he wants all of us to know.
“Existing elevated nitrate concentrations throughout much of the Floridan Aquifer may be harmful to humans in addition to their deleterious effects on the
ecology of springs,” Knight said. “The concerned public and their elected officials should demand that the federal, state and local public health organizations conduct a comprehensive epidemiological study of the effects of groundwater nitrate levels on human health in Florida.”
Knight has good reason for his concern. A study released in 2001 indicated that drinking water contaminated with nitrates from fertilizers or human and animal wastes may cause bladder cancer in women—nitrates at levels far below current government ceilings.
The U.S. Environmental Protection Agency states that nitrate levels are safe below 10 parts per million. However, the study showed that levels as low as 2.46 parts per million may nearly triple the risk of bladder cancer.
“There have been a few studies that looked at nitrate in drinking water and a variety of cancers,” said Peter Weyer, PhD, associate director of the University of Iowa’s Center of the Health Effects of Environmental Contamination and author of the study. “And while some have found an association with such diseases as non-Hodgkin’s lymphoma, there has only been one study done in Spain, published in 1993, that showed an association between nitrate, a municipal water supply and an increased risk for bladder cancer.”
Bladder cancer is the sixth most common cancer in the country.
Weyer and his colleagues used data from more than 41,000 women, aged 55 or older, in the Iowa Women’s Health Study.
“We were looking at women who were using the same water supply for more than 10 years. That turned out to be about 22,000 women. 16,500 of them were using the municipal water supplies from 400 municipalities,” he said.
The level of exposure to nitrate was based on data collected from municipal water suppliers. No nitrate data was available for women using private wells. The research team checked the cancer incidence data from the Iowa Cancer Registry from 1986 to 1998.
“What we found was a positive association for an increased risk of bladder cancer in women who used municipal water supplies,” wrote Weyer in the study. “For women on municipal-supplied (water), if the nitrate level was greater than 2.5 parts per million, those women had an almost three-fold risk for bladder cancer compared to a group of women who we used as reference who were exposed to less than 0.4 parts per million.”
The 2001 study was adjusted for risk factors such as smoking, nitrate in the diet and vitamins E and C that impact how nitrate is reduced in the body. According to Weyer, nitrates are reduced to carcinogenic N-nitroso compounds in the body. And nitrates are found everywhere. “It’s present naturally in the soil. It can seep into groundwater from nitrogen-based fertilizers, from both agricultural and farming, as well as from the single family home-owner,” wrote Weyer. “Nitrates are a by-product of livestock facilities, human waste, municipal wastewater treatment plants and septic tanks.”
According to the American Cancer Society, the findings from the 2001 study are potentially important. Harmful concentrations of nitrate are substantially lower than what the government claims will prevent toxicity. In its 2008-09 Annual Report of the President’s Cancer Panel, “Reducing Environmental Cancer Risk - What We Can Do Now,” published in 2010 by the U.S. Department of Health and Human Services, National Institutes of Health, National Cancer Institute, authors Dr. LaSalle Leffall Jr. and Dr. Margaret L. Kripke implored President Obama to take action by warning the public about everyday exposure to carcinogens.
In 2009 alone, approximately 1.5 million American men, women and children were diagnosed with cancer and 562,000 died from the disease. With the growing body of evidence linking environmental exposure to cancer, the public is becoming increasingly aware of the unacceptable burden of cancer resulting from environmental exposures that could be prevented through appropriate national action.
Of particular concern to the research panel was that the true burden of environmentally induced cancer has been grossly underestimated. With nearly 80,000 chemicals on the market in the U.S., many of which are used by millions of Americans on a daily basis, exposure to potential carcinogens is widespread. And children are far more vulnerable to environmental toxins and radiation than adults.
The panel expressed concern that significant harm from cancer-causing products had not been addressed adequately by the National Cancer Program and that the American people, before they are even born, are bombarded continually with myriad combinations of these dangerous exposures.
The panel implored the president to use the power of the office to remove carcinogens and other toxins from our food, water and air that needlessly increase health care costs, cripple our nation’s productivity and devastate American lives.