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One of the recurring issues as the hearings proceeded was the considerable gulf that existed between science and policy. Scientists accepted a degree of uncertainty, while legislators sought “proof” of threats to human health and safety before enacting laws restricting use. Occasionally members of the committee expressed their frustration over the failure of scientists to clarify the safety of DDT. As part of his prepared statement, Frank Princi, who was an associate professor of industrial medicine at the University of Cincinnati, endeavored to capture for the committee the scientific uncertainty related to DDT: “[DDT] has been subjected to more scientific investigation than any other organic material. Yet, despite this knowledge, there is still sharp disagreement concerning the hazard associated with its use. On the one hand, we are told that it is the safest of insecticides; and, on the other, it is suggested that its toxicity may have been underestimated and that it is probably responsible for such conditions as suicidal tendencies, aplastic anemia, pneumonia, leukemia, virus X, arteriosclerosis, and even cancer.”42 Princi’s comment reveals the wide range of conditions anecdotally associated with DDT, but he identified extrapolation from animal data to humans and real-life exposures as a critical element of scientific uncertainty: “Much of this controversy had developed because of attempts to translate the results of animal experimentation into human experience without appropriate consideration of the variability of animal species. Other diversities of opinion have developed because of a lack of understanding of the actual conditions of exposure which result from ordinary methods of use of the material. It is suggested that these questions cannot be resolved fairly and adequately by any single government agency.”43 Insofar as gaps existed between different scientific specialties, there were also fissures between government agencies. Regulation of problems that cut across different agencies proved particularly difficult.
It was however, Princi’s comment about the scientific uncertainty surrounding DDT that drew the ire of A. I. Miller. Miller initially requested from Princi a simple clarification: “You state, of course correctly, that there is sharp disagreement among the experts,” to which Princi responded, “Yes, sir.” At that point, Miller’s frustration boiled over and he responded sharply: “That does not help this committee. We are at sea when experts disagree. Why cannot we get some experts up here who can say DDT is or is not harmful under certain limitations? Have you any opinion, as an expert, on the question of DDT?”44 Princi replied, “In my opinion DDT, in the manner in which it is now used and in the quantities to which persons are presently exposed, is apparently innocuous.”45
Miller again returned to the problem of scientific uncertainty, when he asked if Congress would be on sound ground if it said to insecticide manufacturers that “[they] must prove to the satisfaction of either a group of scientists that might be set up that the chemicals are not harmful to the human being before they are to be used in commercial food for the public.” Princi took exception to the word “proof”: “It is difficult for me to answer that question since you have used the word ‘proof’ because …”46 Miller interrupted Princi: “Then let’s put it another way. Who should have the burden of proof that it is not harmful?” With the question framed in a way to avoid the issue of scientific uncertainty, Princi replied decisively with a concise iteration of the precautionary principle: “The burden of proof certainly should fall upon the supplier or manufacturer. I think there is no question on that.”47
Scientific uncertainty also proved challenging beyond the realm of human health effects. The problem of insects developing resistance to DDT arose in the testimony of Charles E. Palm, who was a professor of entomology at the New York State College of Agriculture at Cornell University. In his prepared statement, Palm underscored this problem, noting that DDT had become ineffectual against houseflies in New York dairy barns as a result of evolving resistance. He worried that houseflies were developing resistance to other insecticides too.48 When pressed, Palm noted that he had found flies resistant to the recommended dosage and even much higher dosages. Moreover, the Cornell entomologist noted that resistance to one chlorinated hydrocarbon conferred a measure of resistance to all chemicals in the class.49
Several of the members of the committee seemed to fully appreciate the implications of Palm’s statement; namely, that flies could develop resistance to all of the insecticides within the class of chlorinated hydrocarbons. The phenomenon was not restricted to New York but was a general difficulty across the United States. Palm indicated that resistance had developed in as little as three years.50 Congressman Walter Horan noted that such was the case in his home state of Washington.51 In response to further questioning regarding insecticide resistance, Palm introduced the committee to two concepts—the “balance of nature” and biological control—only to dismiss them in favor of DDT, which growers found more reliable.52
Like other witnesses, Palm argued that agricultural productivity in the United States depended on chemical insecticides. He also believed that insecticides were “chemical protectants used in the production and protection of food and not as chemical additives.” Entomologists could make recommendations concerning the type, quantity, and timing of particular insecticides to minimize residues and risks to consumers. As one example, Palm cited increased yields of Irish potatoes without evidence of DDT residues. He also noted that entomologists consulted with the FDA and the USDA regarding problems, but he stressed the difference between insecticides and drugs (also regulated by the FFDCA of 1938). Palm exhorted the committee to maintain existing distinctions between insecticides and drugs in order to provide farmers with insecticides quickly. Public health could be protected with the addition of research facilities, which would decrease the time to appraise health hazards while insuring “the use of pesticides in their beneficial roles of providing adequate supplies of food and fiber as well as essential roles in reducing insect vectors of pathogens causing diseases of man and animals.”53 With his final statement, Palm spoke for many, if not all, economic entomologists. Namely, chemical pesticides provided extraordinary benefits in the service of both public health and food production. Risks could be managed with additional research facilities at least in the theoretical sense.
Another economic entomologist, George C. Decker, who was head of the Economic Entomology Section at the Illinois Natural History Survey and the Illinois Agricultural Experiment Station, presented a view largely in accordance with Palm’s. Decker, however, underscored the general lack of evidence regarding health risks associated with insecticides. He noted that despite the use of millions of pounds of pesticides each year for the previous five years, there were very few recorded deaths attributable to insecticides and all were due to operations hazards or misuse. The general counsel, Kleinfeld, pressed Decker to acknowledge potential criteria of safety other than death, and he asked whether it was possible to say that no acute or chronic illnesses had been caused by the annual use of millions of pounds of insecticides. Decker answered the question in the abstract: “No one can answer that question with assurance and certainty. The circumstantial evidence would indicate that there is little, if any, of that, in my opinion. It seems to me, sir, that in studying accidents of any kind, the fatalities are an index of the other injuries.”54 Kleinfeld persisted in pressing the point that there could be illnesses in the absence of fatalities and that these illnesses might not register in vital statistics or even newspapers for a long time. Decker held his ground, arguing that any serious problems should have appeared in the media in the four to five years since the introduction of DDT.55 Still, Kleinfeld argued the subtler point regarding the possibility of chronic illnesses associated with the ingestion of very small amounts of an insecticide over a very long time, to which Decker finally acceded: “That is correct. I cannot deny that.”56
Up to this point, one can certainly understand why members of the Delaney Committee found themselves in a state of confusion regarding the risks of chemicals, particularly insecticides, in food products. In
point of fact, PHS toxicologists and economic entomologists demonstrated a considerable degree of agreement regarding the significant benefits and the relatively minor and, for the most part, manageable risks associated with insecticides. Thus the testimony of John Dendy, head of the Analytical Chemistry Division of the Texas Research Foundation in Renner, Texas, may have caught the committee off guard. Dendy concluded his brief prepared statement with four conclusions: there was widespread contamination of both animal and human foodstuffs with DDT and other chlorinated hydrocarbons, contamination was spread and intensified by the continued use of chemical insecticides, continued use of DDT and other chlorinated hydrocarbons posed an ever-increasing hazard to the public health, and existing laws and/or enforcement procedure were insufficient to prevent the development of this serious hazard to human health. He asserted that the Texas Research Foundation planned to continue its research into these conditions.57 E. H. Hedrick of West Virginia, expressed his appreciation for Dendy’s clear exposition: “For the record, that is about as forthright a statement on DDT, about the results of DDT on human beings as I have ever heard.”58 And yet, when Hedrick asked Dendy if the present law was sufficient, Dendy noted that he was not a lawyer (and by intimation unqualified to render an expert opinion on legislation), but he could comment on the law’s inadequacy in its original writing for allowing indiscriminate use of insecticides or in its enforcement for permitting contaminated products to be consumed by individuals.59
Just as he hesitated to give his opinion on legal matters, Dendy also deferred to doctors on matters concerning human toxicity. When Congressman Miller asked him what concentrations of DDT would be injurious to humans, Dendy noted his lack of medical credentials, but he then proceeded to elaborate on the implications of biomagnification: “Well, that puts me on a spot, not being a medical man, and to date no one yet has established the so-called LD-50 evidence in all these insecticides, because, first of all, in any specific species, whether they are rabbits, white mice, or human beings, each individual has a specific tolerance and it does not exactly correspond to its next-door neighbor, even its litter mate, so an LD-50 is difficult to establish, and men who are well qualified have not established that. Milk containing small concentrations of DDT has been found by most of the investigators in the field. Even though the intake is small, the fatty accumulation in the tissues as the result is magnified as high as 34 times the original intake. In other words, with a diet of 10 parts per million you could expect, in some instances 340 ppm.”60 By suggesting that LD50s had not been established for all insecticides and that they could vary across species and even individuals, Dendy turned the discussion back to scientific uncertainty, but he reframed the problem in terms of its implications for human health by explaining how DDT magnified within organisms, including humans, which meant that small exposures (10 ppm) could build up in tissues to levels as high as 340 ppm. Dendy’s testimony provides a very early example of a specific concern—biomagnification—regarding the environmental implications of the widespread use of DDT and other insecticides.61 In these comments, he anticipated one of Rachel Carson’s central arguments in Silent Spring.
Moreover, in another prescient statement, Dendy noted the gaps between professions, for example, between chemists and physicians. Specifically he wondered when the medical profession would indicate whether or not DDT produced death in human beings. Despite extensive research conducted on the detection of DDT, as a chemist, Dendy believed that he had struck a barrier in the medical profession. In Dendy’s opinion, lack of coordination contributed to the problem. He elaborated on this point: “Yes, remember, sir, there has been much work done on it, but the lack of coordination of the individuals doing the work, their unwillingness to share information with one another, has been the chief draw-back. There are only two sides of this fence. You have to talk relatively freely with those individuals who are on your side of the fence and those who are on the other side of the fence are rather hesitant, and this was our objective.”62
The benefit of insecticides to agricultural productivity was a consistent undercurrent during the hearings, but the Delaney Committee also heard from at least one farmer who wondered about the risks of the new insecticides. In his prepared statement, Louis Bromfield, the owner of Malabar Farms in Lucas, Ohio, argued that the effects of new insecticides on humans and animals were largely unexplored: “Certainly their use should raise grave doubts. Put in the simplest terms, what is poisonous to the organic structure of an insect must also be poisonous in sufficient immediate quantities or in sufficient accumulated quantities to other life as well.”63 Bromfield could testify to the benefits of insecticides, but he found the risks to be more worrisome, arguing that the nation had “plunged into the wholesale use of all these poisons with little or no research concerning their ultimate effects upon health, vitality, and the powers of reproduction” to the detriment of “virtually every citizen.”64
Unlike other farmers who testified, Bromfield spoke as someone who had used insecticides and as a citizen concerned about their rapid proliferation and potential health effects. He implicated the chemical manufacturers for their blind promotion of insecticides. Meanwhile, he was aware that insecticides could lose their effectiveness as insects developed resistance (or immunity). When Kleinfeld asked Bromfield whether an overuse of insecticides upset the natural balance of nature, Bromfield relayed the tendency of insecticides to kill all insects, harmful and beneficial alike. He noted that destroying ladybugs led to an explosion of aphids. Furthermore, it appeared that many birds and fish were dying as a result of spraying. As birds and beneficial insects died off, the insect population could double, triple, and even quadruple.
Despite his evident reservations regarding the overuse of DDT, Bromfield resisted its removal from the market or restrictions on its sale. Limited use of DDT in specific areas (feeding barns and loafing sheds) could be effective and safe, according to Bromfield. He extended the notion of specificity to target insects also. DDT, Bromfield acknowledged, was or had been in the past a “great fly killer,” but he had decided to shift to chlordane since DDT had become almost ineffective. Bromfield’s testimony clearly reflects his deep-seated ambivalence regarding DDT and other synthetic insecticides. The rapid development of resistance in flies and other target organisms seemed to necessitate application of greater concentrations with increasing frequency, both of which meant greater exposures. Bromfield attempted to minimize these risks by limiting his application of DDT to specific areas and by targeting specific pests (predominantly flies and lice).65
Members of the Delaney Committee must have found the wide disparity in testimony regarding DDT confusing. Many of the witnesses deferred to physicians and toxicologists to clarify what risks existed and their severity. Yet when individuals who studied human health effects testified, they couched their statements carefully. For example, Harold P. Morris of the nutrition unit at the National Cancer Institute at NIH noted the challenges to establish whether a particular compound induced cancer in animals. Morris concluded: “In summary, I have pointed out: (1) That a large number of chemical compounds induce cancer in animals. (2) That there is no way of predicting their cancer-inducing properties without a biological test. (3) That the careful testing of chemicals for cancer-producing properties in animals is exceedingly difficult to evaluate. Any test for cancer is influenced by a very large number of environmental and hereditary factors which the experimenter must seek to control and evaluate.”66 Despite the difficulties inherent to the analysis of compounds for carcinogenicity, Morris believed that any estimate of the possible injurious properties of chemicals added to nutrients should include testing for cancer-causing properties in several species of animals prior to approving their use in food. With that said, he sharply criticized a recent article in the British Medical Bulletin regarding the carcinogenic action of heated fats and lipoids on the grounds that the researchers used the rat as their model. Due to the nature of its stomach, the laboratory rat was u
nsatisfactory, and Morris discredited studies that used rats. As a result, Morris’s lab had never successfully reproduced the results of the British study. Such statements must have added to the committee’s growing sense of confusion in light of the fact that the vast majority of laboratory toxicity studies utilized rats, mice, rabbits, or dogs.
The committee heard from another expert on environmental cancer: Wilhelm C. Hueper, chief of the Cancerigenic Studies Section of the Cancer Control Branch of the National Cancer Institute and chief of the associated laboratory. More important, Hueper was widely regarded as a leading expert on occupational and environmental cancers (see chapter 2). But when asked in what capacity he was appearing before the committee, Hueper replied that he was testifying as a private citizen, basing his testimony on his experiences and training of the previous twenty-five years. In response to Miller’s questioning, Hueper noted that cancer incidence was rising in general due to the growing population and the increase of older age-groups in the population, but both lung cancer and leukemia had increased in recent years. Men seemed to be particularly vulnerable to lung cancer, presumably as a result of occupational exposures. Hueper proceeded to review specific dyes and other chemicals, including arsenic, that caused cancers. He noted that arsenical insecticides could be carcinogenic if levels rose to chronic arsenicism. Turning to chlorinated hydrocarbons, Hueper adopted a cautious tone. Kleinfeld asked, “What is the evidence, if any, that these chlorinated hydrocarbons may be carcinogenic?” Hueper replied: “I think we have to get away from the word ‘carcinogenic’ here. We have to use a more neutral term and say ‘tumor-producing,’ leaving it open whether the tumors produced are actually carcinomas or not, or cancers or not.”67 When Kleinfeld asked him to identify the lowest level of chlorinated hydrocarbons to cause tumors if ingested, Hueper stated: “I think I should emphasize that we have no record of human cancer from exposure to DDT, although we have evidence of cases of severe liver poisoning from exposure to other more powerful liver toxic agents like chloroform and carbon tetrachloride, but none of those chlorinated hydrocarbons so far, as far as we know, has caused cancer in men.”68