The Topic of Cancer Sierra Magazine vs. Bruce Ames Bruce N. Ames, professor of biochemistry and molecular biology at the University of California, Berkeley, is a world-famous authority on cancer and carcinogens. In the fail of 1991, he was asked by Sierra, a publication of the Sierra Club, to contribute to a special, centennial issue devoted to the theme "If I Ruled the World." Ames wrote the piece, but Sierra chose not to run it. Here we reprint Ames's contribution, along with the letters of invita- tion and rejection from Sierra's editor-in-chief, Jonathan F. King. These documents first appeared in the autumn/winter 1992 issue of the Paris-based quarterly "Projections", which noted, "In our opinion, the point of view of such an authority as Bruce N. Ames deserves to be known even if it is nonconformist and attacks preconceived ideas." Letter of Invitation November 14, 1991 Bruce Ames Berkeley, CA 94709 Dear Professor Ames, Next year marks the Sierra Club's 100th anniversary. In May 1992, Sierra, the Club's national magazine, will publish a special Centennial issue that celebrates the past, surveys the present, and takes bets on the future. I am writing to ask if you would like to be pan of that effort. We plan to present the thoughts of a wide range of individuals whose knowledge, experience, and creativity qualify them to answer the following question: Given that our planet faces a future that appears bleak if not terrifying, what steps would you take to ensure our survival for the next 100 years? Consider this an opportunity to play "If I Ruled the World," an imaginative exercise whose goal is to achieve environmental serenity and security. You may assume that you have the ability to direct the course of governments and institutions, and that you have the wealth, brains, and political support of' the world's citizens at your disposal. As well as offering your general scenario for the future, please be as specific as possible: name those whom you would empower, and those whom you would have pay penance. Regulate industries, or set them free; draw geographical boundaries, or erase them; impose democracy on dictatorships, or vice versa; develop and distribute resources, or conserve them; plan our menus, our reading lists, and our births. Should you hold that our survival depends on successfully addressing just one or two key issues, feel free to offer your solutions in that light. If this exercise is something that appeals to you, and you'd like to take it on, we'll need your thoughts by January 1, 1992. Responses can be as long as 1,000 words--though we recognize that some very sensible prescriptions could be offered in as few as 100. Please include the biographical information you'd like to accompany your contribution. On behalf of our 600,000 readers across the United States and Canada, I hope we'll be able to include your vision in our Centennial issue. We look forward to heating from you. Sincerely, Jonathan F. King Editor-in-Chief ------------------------------------------------------------------ The Article: "Science and the Environment" It is popular these days to espouse an apocalyptic vision of the future of our planet. Pollution is being blamed for global warming and ozone depletion, pesticides for cancer. Yet these and many other environmental causes are based on weak or bad science. The reality is that the future of the planet has never been brighter. With the bankruptcy of Communism, the world is hopefully on the path to democracy, free markets, and greater prosperity. Science and technology develop in a free society, and free markets bring wealth, which is associated with both better health and lower birth rates. Scientific advances and free markets can also lead to technologies that minimize pollution for the lowest cost. A market for pollution rights is desirable-polluting shouldn't be free--and is much more effective than a bureaucratic monopoly. In my scenario for the future, I would like to see environmentalism based on scientific fact, directed at solving real problems rather than phantoms. An example of this problem is the public misconception that pollution is a significant contributor to cancer and that cancer rates are soaring. As life expectancy continues to increase in industrialized countries, cancer rates (unadjusted for age) also increase; however, the age-adjusted cancer death rate in the United States for all cancers combined (excluding lung cancer from smoking) has been staying steady or decreasing since 1950. Decreasing since 1950 are primarily stomach, cervical, uterine, and rectal cancers. Increasing are primarily lung cancer (which is due to smoking, as are 30 percent of all U.S. cancer deaths), melanoma (possibly due to sunburns), and non-Hodgkin's lymphoma. Cancer is fundamentally a degenerative disease of old age, although external factors can increase cancer rates (cigarette smoking in humans) or decrease them (eating more fruits and vegetables). A second misconception is that high dose animal cancer tests tell us the significant cancer risks for humans. Approximately half of all chemicals-whether natural or synthetic--that have been tested in standard animal cancer tests have turned out to be carcinogenic. These standard tests of chemicals are conducted chronically, at near-toxic doses--the maximum tolerated dose-and evidence is accumulating that it may be the high dose itself, rather than the chemical per se, that is the risk factor for cancer. (This is because high doses can cause chronic wounding of tissues or other effects that lead to chronic cell division, which is a major risk factor for cancer.) At the very low levels of chemicals to which humans are exposed through water pollution or synthetic pesticide residues, such increased cell division does not occur. Thus, they are likely to pose no or minimal cancer risks. The third misconception is that human exposures to carcinogens and other toxins are nearly all to synthetic chemicals. On the contrary, the amount of synthetic pesticide residues in plant foods are insignificant compared to the amount of natural pesticides produced by plants themselves. Of all dietary pesticides, 99.99 percent are natural: they are toxins produced by plants to defend themselves against fungi and animal predators. Because each plant produces a different array of toxins, we estimate that on average Americans ingest roughly 5,000 to 10,000 different natural pesticides and their breakdown products. Americans eat an estimated 1,500 mg of natural pesticides per person per day, which is about 10,000 times more than they consume of synthetic pesticide residues. By contrast, the FDA found that residues of 200 synthetic chemicals, including the synthetic pesticides thought to be of greatest importance, average only about 0.09 mg per person per day. The fourth misconception is that synthetic toxins pose greater carcinogenic hazards than natural toxins. On the contrary, the proportion of natural chemicals that is carcinogenic when tested in both rats and mice is the same as for synthetic chemicals--roughly half. All chemicals are toxic at some dose, and 99.99 percent of the chemicals we ingest are natural. The fifth misconception is that the toxicology of manmade chemicals is different from that of natural chemicals. Humans have many general, natural defenses that make us well buffered against normal exposures to toxins, both natural and synthetic. DDT is often viewed as the typically dangerous synthetic pesticide. However, it saved millions of lives in the tropics and made obsolete the pesticide lead arsenate, which is even more persistent and toxic, although all-natural. While DDT was unusual with respect to bioconcentration, natural pesticides also bioconcentrate if they are fat-soluble. Potatoes, for example, naturally contain fat-soluble neurotoxins detectable in the bloodstream of all potato eaters. High levels of these neurotoxins have been shown to cause birth defects in rodents. The sixth misconception is that correlation implies causation. The number of storks in Germany has been decreasing for decades. At the same time, the German birth rate also has been decreasing. Solid evidence that storks bring babies! Cancer clusters in small areas are expected to occur by chance alone, and there is no persuasive evidence from either epidemiology or toxicology that pollution is a significant cause of cancer for the general population. There are tradeoffs involved in eliminating pesticides. Plants need chemical defenses--either natural or synthetic--in order to survive pest attack. One consequence of disproportionate concern about synthetic pesticide residues is that some plant breeders are currently developing plants to be more insect-resistant and inadvertently are selecting plants higher in natural toxins. A major grower recently introduced a new variety of highly insect-resistant celery into commerce. The pest-resistant celery contains 6,200 parts per billion (ppb) of carcinogenic (and mutagenic) psoralens instead of the 800 ppb normally present in celery. The celery is still on the market. Synthetic pesticides have markedly lowered the cost of plant foods, thus making them more available to consumers. Eating more fruits and vegetables is thought to be the best way to lower risks of cancer and heart disease other than giving up smoking; our vitamins, antioxidants, and fiber come from plants and are important anticarcinogens. Thus, eliminating essential pesticides is likely to increase cancer rates. Huge expenditure of money and effort on tiny hypothetical risks does not improve public health. Rather, it diverts our resources from real human health hazards, and it hurts the economy. --Bruce N. Ames ------------------------------------------------------------------ Letter of Rejection March 27, 1992 Dr. Bruce N. Ames University of California Berkeley, CA 94720 Dear Dr. Ames, - I fear that you have yet to receive a response from us to your inquiry about the status of the essay you sent us in response to our invitation to contribute to our May/June feature, "If I Ruled the World." If that is so, I apologize; we have just sent that issue to press, and are now catching up with much postponed correspondence and other work. Your essay was not among those we chose to include, though we passed no judgment on its contents in making that decision. By that I mean, our concurrence with an author's ideas was not a prerequi- site to publication; there was no "litmus test" of ideological purity to be passed. Our problem with your piece was more stylis- tic: We found the focus on pollution and pesticides far narrower than the sweeping prescriptions other contributors were making, such that it seemed at times as though the question ("How would you solve the environmental crisis ff you ruled the world.'?") was in danger of being forgotten by the reader. In some cases we solved problems of focus by editing a contribution down, but in your case that clearly could not be done without doing damage to the arguments themselves. Space being at a premium--we received more contributions than we could possibly run, even when some were edited down--there was no question of running the piece uncut, at least in this format. Since we have long found your thinking provocative--it challenges some basic presuppositions of the environmental movement--we hope to be able to share your ideas with our readers in the future. But it simply wasn't feasible within the context we set for this special issue, and I wanted to be sure you understood the rationale behind our decision not to publish "Science and the Environment" at this time. Sincerely, Jonathan F. King Editor-in-Chief