Published October 11, 2007
Ever since the World Health Organization reversed the environmentalist-promoted ban on DDT in 2006, eco-activists have scrambled to devise new ways to malign the life-saving insecticide in order to salvage their badly marred reputation.
Their latest effort involves touting a new study supposedly linking DDT exposure in adolescent girls with increased breast cancer risk in later life. The study was authored by researchers from the Mount Sinai School of Medicine — an institution infamous for alarmist research on asbestos and 9-11 rescue workers — and was published in Environmental Health Perspectives, a journal that seems to operate as a refuge for alarmist research.
The study first came to my attention via a letter by John Peterson Myers published in The Wall Street Journal (Aug. 25) entitled “Stop Pushing DDT.” Aficionados of health scares will recall that Myers was a co-author of the 1996 book “Our Stolen Future,” which fomented fears about chemicals in the environment causing every disease from cancer to attention deficit disorder.
A pro-DDT editorial by the Journal (Aug. 16) spotlighted new research countering the environmentalist claim that DDT is ineffective because mosquitoes can build resistance to the chemical’s toxic properties.
In taking exception to the Journal’s advocacy of DDT to combat the malaria — a disease that sickens 500 million per year, killing 1 million of them — Myers cited the Mount Sinai study and its claim that “women more exposed to DDT prior to puberty were five times more likely to develop breast cancer than those with lower exposure.” Myers pointed out that the authors concluded that “the public-health significance of DDT exposure is potentially large.”
I responded to Myers with a letter published in the Journal (Aug. 31) likening the study to statistical malpractice.
The study was small (including only 133 women with breast cancer), completely omitted data on key risk factors for breast cancer (such as genetics and family history) and only partially considered other potential risk factors (such as pregnancy and breast-feeding history). All of which amply explains the study’s internal contradictions and statistical flakiness.
The vast majority of the statistical correlations reported in the study were either zero or negative — meaning no relationship between DDT and breast cancer. Accepting the negative ones at face value, as Myers did the positive, would support the equally unlikely implication that DDT might actually prevent breast cancer. Moreover, the positive correlations were highly suspect.
The one cited by Myers — the five-fold increase in breast cancer risk — sports a wide margin of error, four times the size of the claimed correlation.
The Mount Sinai researchers responded with their own letter in the Journal (Sept. 22). Acknowledging that their study was small, their primary line of defense was that it was published in a reputable journal and was peer-reviewed by experts in the subject area, hardly a defense on the study’s merits, particularly given the particular journal in question.
While they acknowledged failing to consider genetic risk and family history of breast cancer in the study, they tried to excuse this lapse by glibly dismissing the two universally recognized breast cancer risk factors as being “unlikely to change the result.”
The final letter in this series (from Randall Dodd of Mill Creek, Wash., on Sept. 29) observed that the largest study on this subject found no link between DDT and breast cancer and that skepticism should be on “full alert status” whenever a small study contradicts all previous science done previously.
The Mount Sinai study reared its ugly head again this week in an Oct. 9 article by Rick Weiss on the front page of The Washington Post’s health section.
“A new study has found a significant link between women’s exposure to DDT as young girls and the development of breast cancer in later life,” Weiss begins. From there, he largely regurgitates the researchers’ results and views in uncritical fashion, including the denigration of the numerous previously published studies that found no link between DDT and breast cancer.
Although Weiss acknowledged to me that he had seen the exchange of letters in The Wall Street Journal, he inexplicably chose not to report that the study results had been so challenged.
Weiss closes his article with comments from Cornell University’s Suzanne Snedeker, a nutritionist by training who said that she had serious concerns about a DDT comeback in developing countries and would rather see funding for other approaches to malaria control.
Assuming purely for the sake of argument that DDT does increase the risk of breast cancer, do Snedeker’s concerns even make any sense?
Zimbabwe, for example, has about 2,000 cases of breast cancer per year, affecting about 0.016 percent of the population. In contrast, about 1.5 million cases of malaria occur there annually, affecting more than 12 percent of the population.
Avoiding the use of DDT to control malaria in Zimbabwe and other similarly afflicted areas because of concerns of breast cancer is clearly absurd — only made more so by the speciousness of the claim that DDT increases breast cancer risk.
As Randall Dodd concluded in his Wall Street Journal letter, “… in the context of the millions of people, principally children, who die from malaria every year, even if one suspends disbelief and grants the [Mount Sinai researchers] their findings, an elevated potential risk of the maladies they mention is outweighed exponentially by the certainty of millions of deaths, most of them avoidable, from malaria.”
Mr. Dodd’s point is so obvious and true that it ought to raise questions about the ulterior motives of those who dispute it.