Nitrate in drinking water causes bladder cancer

Question: Have you looked into this paper specifically for any methodologic flaws or unsupported conclusions, or are you willing to concede that this is a solid paper that documents an increased risk of bladder cancer? 

Date: Tue, 27 Apr 2004 09:04:30 -0400

From: Alex Avery <aavery@rica.net>

Subject: Re: Nitrates/Bladder Cancer

Even the National Research Council at the National Academy of Sciences (which has a Committee on Nitrates and Nitrites that periodically reviews the science) doesn't believe in the cancer link. There are a couple of epidemiological studies "suggesting" a possible link, but the correlations were extremely weak (they included the null hypothesis) and many other epidemiological human studies show no association at all or even negative correlations. Bottom line: there isn't ANY good evidence for a cancer link to nitrates. The only way they've been able to cause cancer in lab animals with nitrates is to combine the nitrates with nitrosateable amines to make nitrosamines in a test tube and then feed the carcinogenic nitrosamines to the lab animals at high doses. Feeding the animals nitrates doesn't cause cancer, even when administered at high doses.

So the NRC Committee addressed this at length and has concluded that based on the high dietary exposures, endogenous nitrate production and exposure, and lack of connection between nitrate exposure and carcinogenicity that "The subcommittee concluded that exposure to the nitrate concentrations found in drinking water in the United States is unlikely to contribute to human cancer risk. Attempting to limit nitrate or nitrite exposure on the basis of carcinogenicity would implicate the diet, and vegetables in particular, as the primary source of risk for most of the U.S. population. But diets rich in vegetables have consistently been shown to reduce cancer risk. Any theoretical cancer risk should be weighed against the benefits of eating vegetables. Regulating exogenous nitrate exposure on the basis of carcinogenicity would also be inconsistent with endogenous nitrate formation." (page 5-6, of NRC's Nitrate and Nitrite in Drinking Water, National Academy Press, Washington DC 1995)

There is a whole small, subgroup of public health guys who have made a cottage industry fomenting public fears over nitrates and I've gone up against most. One in particular is Pete Weyer at U of Iowa Center for Health Effects of Environmental Contamination. He and I have gone at it professionally several times. He simply doesn't have the data to support his contentions, but he's got innuendo and that's all that's needed these days with newspapers shamelessly angling for the fear $$$$.

The EPA only regulates nitrates for the risks of blue baby. Same with the WHO, UK, EU -- all these regulatory agencies only regulate drinking water nitrate levels ONLY to prevent blue baby syndrome!  Miscarriages is another canard, based on two incidence reports of miscarraiges near areas with high nitrate levels in the MMWR. But these were only suspicions. Yet with the help of alarmist physicians and activism, these two simple case reports that included a "what if" about nitrates have become "Nitrates cause miscarraiges" in some circles. It's all too easy today to distort tiny kernals of truth into mass hysteria and alarmism.  Wastes lots of time and $$ for sure.

Hope this helps, let me know if there is anything else I can do.

Alex Avery