The prestigious President's Cancer Panel is releasing a new report today, Reducing Environmental Cancer Risk: What We Can Do Now. The press release heralding the report notes:
Even with the growing body of evidence linking environmental exposures to cancer in recent years, a report released today by the President's Cancer Panel finds that the true burden of environmentally-induced cancer is greatly underestimated.
Environmental exposures in this report are largely confined to exposures to man-made chemicals, medical radiation, and household radon. Perhaps the burden is underestimated, but glancing through the report, I have not yet found any new overall estimates for the incidence of cancer associated with environmental exposures. I will keep looking. In any case, the report recites the now canonical claim:
With nearly 80,000 chemicals on the market in the United States, many of which are used by millions of Americans in their daily lives and are un- or understudied and largely unregulated, exposure to potential environmental carcinogens is widespread.
If trace exposures to increasing numbers of synthetic chemicals is a cause of cancer, then one might reasonably think that cancer incidence rates must be going up, but that's not so. A fact that the report acknowledges from at its beginning:
Despite overall decreases in incidence and mortality [emphasis added], cancer continues to shatter and steal the lives of Americans. Approximately 41 percent of Americans will be diagnosed with cancer at some point in their lives, and about 21 percent will die from cancer. The incidence of some cancers, including some most common among children, is increasing for unexplained reasons.
This statement is in line with the Centers for Disease Control's (CDC) most recent report on cancer incidence which notes:
Overall incidence was on the rise from 1975 to 1989, with non-significant changes in rates from 1989 to 1999. From 1999 to 2006 incidence has significantly declined.
The President's Cancer Panel focuses its attention on recent increases in childhood cancers which is as it should be. Cancer is terrible at any age, but especially so in young people. So how alarmed should we be? The report doesn't cite an actual number, but eyeballing the graph on page 4 indicates an increase from about 13 per 100,000 in 1975, to just over 15 per 100,000 in 2006. The CDC's 2007 report on childhood cancer trends noted:
The findings in this report indicate that, during 1990–2004, overall childhood cancer death rates declined significantly among boys and girls, children and adolescents, Hispanics and non-Hispanics, most racial groups, and all U.S. Census regions. Incidence rates for all childhood cancers increased by 0.6% per year during 1975–2002 (emphasis added). The overall decreasing trend in childhood cancer mortality in the United States likely reflects advances in cancer treatment in this population.
This rate yields about the same increase in incidence as reported by the President's Cancer Panel. The panel is also concerned about occupational exposures of farming families and workers to pesticides. As evidence for this concern, the panel cites a 2005 study which found that pesticide applicators had higher rates of prostate and ovarian cancer. However, the report fails to mention this additional result from the report.
The overall cancer incidence among farmers [SIR 0.88, 95% confidence interval (95% CI) 0.84-0.91] and their spouses (SIR 0.84, 95% CI 0.80-0.90) were significantly lower than expected.
Both results are interesting and a balanced report would have cited them. After all, the study concluded:
Low overall cancer incidence rates seem to be a result of low overall smoking prevalence and other lifestyle factors, while excess cancer of the prostate and ovaries among applicators may be occupationally related.
May be related. Or maybe not.
Of course, most Americans are not agricultural pesticide applicators, thus the relevant concern would be just how much danger do exposures to trace amounts of pesticides pose to consumers? One gets a sense of the carefully alarmist way the report is written by reading this section:
A key concern regarding pesticide use is whether, and to what extent, food products are contaminated with these chemicals. To estimate pesticide contamination of foods purchased by consumers, the Department of Agriculture's Pesticide Data Program (PDP)224 samples more than 80 types of fruits, vegetables, nuts, meat, grains, dairy products, and other foods to identify and quantify residues from insecticides, herbicides, fungicides, and growth regulators. The foods, including processed and imported products, are collected from 10 states representing all regions of the country; the samples are collected as close to the point of consumption as possible. In its most recent report, PDP analyzed 11,683 samples, conducting an average of 105 tests on each sample (more than 1.22 million analyses in total). Only 23.1 percent of samples had zero pesticide residues detected, 29.5 percent had one residue, and the remainder had two or more.224 The majority of residues detected were at levels far below EPA tolerances[emphasis added] (limits on pesticide residues on foods; referred to as maximum residue limits, or MRLs, in many other countries) but the data on which the tolerances are based are heavily criticized by environmental health professionals and advocates as being inadequate and unduly influenced by industry.
Well, environmental health professionals and advocates would criticize those EPA tolerances, wouldn't they? But what does the science say about exposure to trace amounts of synthetic pesticides? The panel reaches back to cite a 1993 National Research Council report on childhood exposures to synthetic carcinogens to bolster its case. Fair enough. But oddly, the panel overlooks the 1996 National Research Council report, Carcinogens and Anticarcinogens in the Human Diet. The press release for that report noted:
Cancer-causing chemicals that occur naturally in foods are far more numerous in the human diet than synthetic carcinogens, yet both types are consumed at levels so low that they currently appear to pose little threat to human health.
Again, I am still combing through the panel's report, but preliminarily I fear that the President's Cancer Panel has ignored President Barack Obama's promise to "restore science to its rightful place."
There is at least some good news for cell phone users, the panel finds no convincing evidence that they cause cancer.