An older colleague of mine once suggested that the work product of an environmentalist is controversy. Fear and the threat of unseen, unchosen hazards enhance fund-raising for environmental political organizations and fund environmental research, he suggested. Though his view may be cynical, it was my introduction to the "politics" of the environment. Living Downstream is an environmental polemic and an unapologetic call to arms. Dr. Sandra Steingraber has analyzed an enormous volume of data with which she attempts to convince us first, that we are in the midst of a cancer epidemic and second, that chemical residues and pesticides in the environment are the cause of this deadly scourge.
Steingraber's first premise has not been supported by serious scientific analysis. In the February 1, 1995, Journal of the National Cancer Institute, Susan Devesa and colleagues reviewed cancer epidemiology in the United States extensively, comparing the five-year periods 1975 through 1979 and 1987 through 1991 ("Recent Cancer Trends in the United States." 1995;87:175-82). Although they note that age-adjusted incidence rates for all cancers increased by 18.6 percent among males and 12.4 percent among females, they conclude that these increases in cancer incidence are entirely explained by known factors. Early and improved detection of breast and prostate cancers, cigarette smoking as a determinant of lung cancer among women, and increases in non-Hodgkin's lymphoma and Kaposi's sarcoma as a result of acquired immunodeficiency account for the increases. Philip Cole and Warren Sateren, in an accompanying editorial, warn that causal interpretation of cancer statistics can "leave the unwary to see a rise in cancer where none has occurred." They go on to say that "it is only a small jump to the idea that this rise was due to environmental contamination." The ease with which such hypotheses may be developed, and their emotional charge, lead to "the prediction of an impending disaster of ever-increasing cancer rates." "In reality," they go on to say, "the disaster has remained impending for more than twenty years, and Devesa's findings suggest that it will not occur."
So obsessed is Steingraber with environmental pollution as the cause of cancer that she dedicates little more than a paragraph to dismissing high-fat diets and obesity as causes of breast cancer, despite the contention of the American Cancer Society that a 50 percent reduction in fat intake will help prevent breast and other cancers. She writes with indignation about environmental chemicals with estrogenic effects on the order of 1/10,000 the potency of estradiol but makes no mention of the possible contribution of estrogen-replacement therapy to the risk of breast cancer. She quotes data from in vitro studies suggesting dramatic synergistic effects of environmental estrogens that were originally published in Science but have since been withdrawn by the authors because the results could not be repeated. She casually applies the word "carcinogen" to a wide variety of industrial and agricultural chemicals, and although she speaks with authority about theoretical mechanisms of cancer, she fails to make mechanistic distinctions that would distinguish those few chemicals that cause genotoxic injury from those whose effects in animal models are clearly dose related. These are just a few examples of oversights and simplifications that can be found throughout her book.
Steingraber is otherwise a marvelous writer who combines the discipline of a scientist with the skill of a poet. She personalizes mundane statistics, and her book shifts easily from personal recollections and vivid descriptions of formerly pristine settings to the statistics of environmental pollution and the disease burden that she perceives is borne by the populace. In one chapter, she traces the MCF-7 cell line, widely used in cancer research, to a woman who died in Michigan in 1970 and from whom these cells originated. It is this human face that she places on cancer that gives her writing its poignancy and sense of urgency. Steingraber is a survivor of cancer diagnosed in her mid-twenties. In addition to making her passionate, her own cancer diagnosis seems to have resulted in her study of the field of cancer epidemiology from the perspective of a victim.
I read Living Downstream with a sense of sadness that this otherwise talented writer should have produced such a biased work. She has obviously put forth an enormous effort of scholarship in compiling this work; however, scholarship designed to prove a preconceived notion is notoriously poor scholarship. As Edward Campion in his July 3, 1997, editorial in the New England Journal of Medicine (1997;337:44), titled "Power Lines, Cancer, and Fear," concluded, "The 18 years of research [on the link between electromagnetic fields and cancer] have produced considerable paranoia, but little insight and no prevention. It is time to stop wasting our research resources." The focus on environmental pollution and agricultural chemicals to explain human cancer has simply not been fruitful nor given rise to useful preventive strategies.
None of us consciously wish for a contaminated environment, and many of Steingraber's calls for a new paradigm having to do with less chemical dependency in agriculture are unassailable. Nonetheless, Living Downstream frightens, at times misinforms, and then scorns genuine efforts at cancer prevention through lifestyle change. The objective of Living Downstream appears ultimately to be controversy.
Jerry H. Berke, M.D., M.P.H., 49 Windsor Ave., Acton, MA 01720
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