Opinion ID: 326929
Heading Depth: 1
Heading Rank: 2

Heading: health issue

Text: 43 The initial, crucial question for our evaluation and resolution focuses upon the alleged hazard to public health attributable to Reserve's discharges into the air and water. 44 We first considered this issue on Reserve's application for a stay of the district court's injunction pending a determination of the merits of its appeal. We noted the usual formulation of the applicable standards to be met by the party seeking a stay. One of those standards addresses the likelihood of success by the moving party on the merits of the appeal. In applying this standard we made a preliminary assessment of the merits of Reserve's appeal from the trial court's injunction order. We noted that the rather drastic remedy ordered by the district court    was a response to the finding of a substantial danger to the public health, and that our preliminary assessment of whether such a substantial danger was presented should control our action as to whether to grant or deny a stay. 498 F.2d at 1076-1077. 45 In this preliminary review, we did not view the evidence as supporting a finding of substantial danger. We noted numerous uncertainties in plaintiffs' theory of harm which controlled our assessment, particularly the uncertainty as to present levels of exposure and the difficulty in attempting to quantify those uncertain levels in terms of a demonstrable health hazard. As we stated then,     it is not known what the level of fiber exposure is, other than that it is relatively low, and it is not known what level of exposure is safe or unsafe. 498 F.2d at 1082. In confirmation of our view, we noted the opinion of Dr. Arnold Brown, 18 the principal court-appointed expert, that no adverse health consequences could be scientifically predicted on the basis of existing medical knowledge. Additionally, we noted the district court's conclusion that there is  '    insufficient knowledge upon which to base an opinion as to the magnitude of the risks associated with this exposure.'  498 F.2d at 1083. We thought one proposition evident: 46 (A)lthough Reserve's discharges represent a possible medical danger, they have not in this case been proven to amount to a health hazard. The discharges may or may not result in detrimental health effects, but, for the present, that is simply unknown. (Id.) 47 On the basis of the foregoing we forecast that Reserve would likely prevail on the merits of the health issue. 19 We limited this forecast to the single issue before us whether Reserve's plant should be closed immediately because of a substantial danger to health: 48 While not called upon at this stage to reach any final conclusion, our review suggests that this evidence does not support a finding of substantial danger and that, indeed, the testimony indicates that such a finding should not be made. In this regard, we conclude that Reserve appears likely to succeed on the merits of its appeal on the health issue. 498 F.2d at 1077-1078. (Emphasis added). 49 We reached no preliminary decision on whether the facts justified a less stringent abatement order. 50 As will be evident from the discussion that follows, we adhere to our preliminary assessment that the evidence is insufficient to support the kind of demonstrable danger to the public health that would justify the immediate closing of Reserve's operations. We now address the basic question of whether the discharges pose any risk to public health and, if so, whether the risk is one which is legally cognizable. This inquiry demands separate attention to the discharge into the air of Silver Bay and the discharge into Lake Superior. 20 51
52 As we noted in our stay opinion, much of the scientific knowledge regarding asbestos disease pathology derives from epidemiological studies of asbestos workers occupationally exposed to and inhaling high levels of asbestos dust. Studies of workers naturally exposed to asbestos dust have shown excess cancer deaths 21 and a significant incidence of asbestosis. 22 The principal excess cancers are cancer of the lung, the pleura (mesothelioma) and gastrointestinal tract (gi cancer). 53 Studies conducted by Dr. Irving Selikoff, 23 plaintiffs' principal medical witness, illustrated these disease effects. Dr. Selikoff investigated the disease experience of asbestos insulation workers in the New York-New Jersey area, asbestos insulation workers nationwide, and workers in a New Jersey plant manufacturing amosite asbestos. Generally, all three groups showed excess cancer deaths among the exposed populations, as well as a significant incidence of asbestosis. With respect to cancer generally, three to four times the expected number of deaths occurred; with respect to lung cancer in particular, five to eight times the expected number; and with respect to gastrointestinal cancer, two to three times that expected. Dr. Selikoff described the increase of gastrointestinal cancer as modest. (A.10:286-287.) 54 Several principles of asbestos-related disease pathology emerge from these occupational studies. One principle relates to the so-called 20-year rule, meaning that there is a latent period of cancer development of at least 20 years. (A.10:284-285.) Another basic principle is the importance of initial exposure, demonstrated by significant increases in the incidence of cancer even among asbestos manufacturing workers employed for less than three months (although the incidence of disease does increase upon longer exposure). (A.10:279-280.) Finally, these studies indicate that threshold values and dose response relationships, 24 although probably operative with respect to asbestos-induced cancer, are not quantifiable on the basis of existing data. 25 (A.10:280, 317-19.) 55 Additionally, some studies implicate asbestos as a possible pathogenic agent in circumstances of exposure less severe than occupational levels. For example, several studies indicate that mesothelioma, a rare but particularly lethal cancer frequently associated with asbestos exposure, has been found in persons experiencing a low level of asbestos exposure. 26 Although Dr. Selikoff acknowledged that these studies of lower-level exposure involve certain methodological difficulties and rest on much less firm ground than the occupational studies, 27 he expressed the opinion that they should be considered in the assessment of risks posed by an asbestos discharge. 56 At issue in the present case is the similarity of the circumstances of Reserve's discharge into the air to those circumstances known to result in asbestos-related disease. This inquiry may be divided into two stages: first, circumstances relating to the nature of the discharge and, second, circumstances relating to the level of the discharge (and resulting level of exposure). 57
58 The comparability of the nature of Reserve's discharge to the nature of the discharge in known disease situations raises two principal questions. The first is whether the discharged fibers are identical or substantially identical to fibers known to cause disease; the second is whether the length of the fibers discharged is a relevant factor in assessing pathogenic effect. The district court found that Reserve's discharge includes known pathogenic fibers and that a lower risk to health could not be assigned to this discharge for reasons of fiber length. 59 On the first question the issue of the identity of the fibers the argument focuses on whether the ore mined by Reserve contains (and yields wastes during processing consistent with) amosite asbestos. The inquiry is critical because studies demonstrate that amosite, at least in occupational settings, may serve as a carcinogenic (cancer-producing) agent. A principal dispute concerns the precise composition of the mineral cummingtonite-grunerite found in Reserve's taconite ore: Reserve maintains that the cummingtonite-grunerite present in its Peter Mitchell Mine at Babbitt is not asbestiform and is not chemically consistent with amosite asbestos; plaintiffs argue that much of the cummingtonite-grunerite mined by Reserve is substantially identical to amosite asbestos. 60 As a general scientific proposition, it is clear that cummingtonite-grunerite embraces a range of chemistries, including the chemistry of amosite asbestos. The mineral also embraces a range of morphologies, from asbestiform, needle-like fibers to block-shaped, crystal aggregates. The crucial factual determination is, thus, whether the particular cummingtonite-grunerite mined by Reserve contains asbestiform fibers consistent with the properties of amosite asbestos. 61 The trial court heard extensive evidence as to the chemistry, crystallography and morphology of the cummingtonite-grunerite present in the mined ore. This evidence demonstrated that, at the level of the individual fiber, a portion of Reserve's cummingtonite-grunerite cannot be meaningfully distinguished from amosite asbestos. Reserve attempted to rebut this testimony by showing that the gross morphology of the two minerals differed and that characteristics of the two minerals varied when considered in crystal aggregations. Since, according to the opinions of some experts, the individual fiber probably serves as a carcinogenic agent, the district court viewed the variations in mineralogy as irrelevant and determined that Reserve discharges fibers substantially identical and in some instances identical to fibers of amosite asbestos. 62 The second question, that of fiber length, reflects a current dispute among scientists as to whether short fibers (i.e., fibers less than five microns in length) have any pathogenic effect. Most of the fibers detected in Reserve's discharges may be termed short. 28 The evidence adduced at trial included conflicting scientific studies and diverse opinions on this question. Several Reserve witnesses testified concerning animal studies which seem to demonstrate that short fibers are nontumorigenic. 29 Plaintiffs offered opposing evidence based on contrary studies. 30 Dr. Brown noted his general criticism of the studies on fiber size, stating that the researchers typically did not use electron microscopy to properly size the fibers, and thus it cannot be said that the animals are in fact being exposed to only short or only long fibers. (A.23:338-40.) 63 Presented with this conflicting and uncertain evidence from animal experimentation, and the fact that there are no human epidemiological studies bearing on the issue, the district court concluded that short fibers could not be assigned a lower relative risk than long fibers. 31 This conclusion comports with the uncertain state of scientific knowledge. Furthermore, Dr. Brown and the National Academy of Sciences reached the same conclusion. 32 64
65 The second major step in the inquiry of the health aspects of Reserve's air emissions is an assessment of the amount of the discharge and the resulting level of exposure. Two principal issues are raised: first, what in fact is the level of exposure; second, does that level present a cognizable risk to health? The district court found the level significant and comparable to the levels associated with disease in nonoccupational contexts. 380 F.Supp. at 48. 66 The first issue was addressed at length in our stay opinion. We noted there the great difficulties in attempted fiber counts and the uncertainties in measurement which necessarily resulted. 498 F.2d at 1079-1080. Commenting on these difficulties, Dr. Brown stated that the fiber counts of the air and water samples could establish only the presence of fibers and not any particular amount, i. e., such a count establishes only a qualitative, and not a quantitative, proposition. The district court recognized these difficulties in counting fibers and observed that (t)he most that can be gained from the Court (ordered) air study is the very roughest approximation of fiber levels. 380 F.Supp. at 49. 67 A court-appointed witness, Dr. William F. Taylor, 33 made the most sophisticated attempt to use the fiber counts in a quantitative manner. By taking the average fiber count of five testing sites in Silver Bay, Dr. Taylor concluded that the burden of fibers in the air of Silver Bay exceeded that present in St. Paul, Minnesota, (used as a control) by a margin which could not be attributed to chance. 34 (A.23:117.) 68 The experts indicated that the counting of fibers represents a scientifically perilous undertaking, and that any particular count can only suggest the actual fiber concentration which may be present. Nevertheless, Dr. Taylor's computation indicating some excess of asbestiform fibers in the air of Silver Bay over that of the control city of St. Paul appears statistically significant and cannot be disregarded. Thus, as we indicated in the stay opinion and as the district court concluded, 35 while the actual level of fibers in the air of Silver Bay is essentially unknown, it may be said that fibers are present at levels significantly higher than levels found in another Minnesota community removed from this air contamination. 69 Given the presence of excess fibers, we must now assess the effects of this exposure on the public. We note first, as we did in the stay opinion, that the exposure here cannot be equated with the factory exposures which have been clearly linked to excess cancers and asbestosis. 36 Our inquiry, however, does not end there. Asbestos-related disease, as noted earlier, has been associated with exposure levels considerably less than normal occupational exposure. The studies indicating that mesothelioma is associated with the lower levels of exposure typical of residence near an asbestos mine or mill or in the household of an asbestos worker are of significance. 37 Although these studies do not possess the methodological strengths of the occupational studies, they must be considered in the medical evaluation of Reserve's discharge into the air. 70 Of course, it is still not possible to directly equate the exposure in Silver Bay with the exposure patterns in these nonoccupational studies. The studies typically do not attempt to quantify the level of exposure and, as noted above, it is not possible to assess with any precision the exposure level in Silver Bay; thus, exposure levels may be compared only on the most general basis. Furthermore, it is questionable whether Reserve's operations may be equated with those of an asbestos mine or mill; for, while we concur in the trial court's finding that Reserve discharges fibers similar, and in some cases, identical to amosite asbestos, it is also true, as testified by plaintiffs' own witnesses, that only a portion of Reserve's discharge may be so characterized. 38 Additionally, it is also true that at least some of the fiber counts reported to the court reflect all amphibole fibers present, thereby including fibers inconsistent with amosite asbestos. 39 Even if all the amphibole fibers inconsistent with amosite could still be attributed to Reserve's discharge, it remains uncertain whether the disease effects attributable to amosite may be extended to these other fibers, or whether the varying forms of asbestos possess differing pathogenic properties. 40 3. Conclusion. 71 Plaintiffs' hypothesis that Reserve's air emissions represent a significant threat to the public health touches numerous scientific disciplines, and an overall evaluation demands broad scientific understanding. We think it significant that Dr. Brown, an impartial witness whose court-appointed task was to address the health issue in its entirety, joined with plaintiffs' witnesses in viewing as reasonable the hypothesis that Reserve's discharges present a threat to public health. Although, as we noted in our stay opinion, Dr. Brown found the evidence insufficient to make a scientific probability statement as to whether adverse health consequences would in fact ensue, he expressed a public health concern over the continued long-term emission of fibers into the air. We quote his testimony at some length. 72 (Dr. Brown). Based on the scientific evidence, I would be unable to predict that the number of fibers in the air of Silver Bay, as seen on four days in October, that I would be unable to predict that cancer would be found in Silver Bay. 73 Now, going beyond that, it seems to me that speaking now in general terms, where it has been shown that a known human carcinogen, sir, and I make that distinction and I shall make it again, I suspect, a human carcinogen is in the air of any community, and if it could be lowered I would say, as a physician that, yes, it should be lowered. And if it could be taken out of the air completely, I would be even more happy. 74 But the presence of a known, human carcinogen, sir, is in my view cause for concern, and if there are means of removing that human carcinogen from the environment, that should then be done. (A.23:207-08.) He explained further: 75 As a physician, I take the view that I cannot consider, with equanimity, the fact that a known human carcinogen is in the environment. If I knew more about that human carcinogen, if I knew what a safe level was in the air, if I knew what a safe level was in the water, then I could draw some firm conclusions and advise you in precise terms. That information is not available to me and I submit, sir, it's not available to anyone else. And that until that information is developed in a scientific way, using techniques that would be acceptable to the medical community, until that time has arrived, then I take only the view that I have expressed. (A.23:211.) 76 But with asbestos,    we're dealing with a different situation, we're dealing with a material which is known to cause cancer not only in animals but in humans. (A.23:212.) 77 Finally, in a post-trial deposition taken December 6, 1974, which the parties have stipulated may be considered by this court, Dr. Brown further testified: 78 Q (Mr. Bastow, attorney for the United States). (I)s there any question in your mind that the people living on the North Shore are being exposed to a human carcinogen in the air and water? 79 A (Dr. Brown). Court studies demonstrated to my satisfaction that similar (asbestiform) fibers are present in the air of Silver Bay and since I am convinced that asbestiform fibers are carcinogenic for humans, my answer to your question would be yes. He added: 80 I took some pains to also say that it was my medical opinion that the presence of a human carcinogen in the air and water was not to be taken lightly   . 81 Until I know what the safe level is I therefore could not, as a physician, consider with equanimity the fact that they are being exposed to a human carcinogen. (Brown dep. at 8-12.) 82
83 The claim that Reserve's discharge of tailings into Lake Superior causes a hazard to public health raises many of the same uncertainties present with respect to the discharge into air. Thus, the previous discussion of fiber identity and fiber size is also applicable to the water discharge. In two respects, however, the discharge into water raises added uncertainties: first, whether the ingestion of fibers, as compared with their inhalation, poses any danger whatsoever; and second, should ingestion pose a danger, whether the exposure resulting from Reserve's discharge may be said to present a legally cognizable risk to health. 84
85 All epidemiological studies which associate asbestos fibers with harm to health are based upon inhalation of these fibers by humans. Thus, although medical opinion agrees that fibers entering the respiratory tract can interact with body tissues and produce disease, it is unknown whether the same can be said of fibers entering the digestive tract. If asbestos fibers do not interact with digestive tissue, they are presumably eliminated as waste without harmful effect upon the body. 86 The evidence bearing upon possible harm from ingestion of fibers falls into three areas: first, the court-sponsored tissue study, designed to measure whether asbestos fibers are present in the tissues of long-time Duluth residents; second, animal experiments designed to measure whether, as a biological phenomenon, fibers can penetrate the gastrointestinal mucosa and thus interact with body tissues; third, the increased incidence of gastrointestinal cancer among workers occupationally exposed to asbestos, and the hypothesis that this increase may be due to the ingestion of fibers initially inhaled. 87
88 Recognizing the complete lack of any direct evidence (epidemiological or otherwise) on the issue of whether the ingestion of fibers poses a risk, the trial court directed that a tissue study be conducted to determine whether the tissues of long-time Duluth residents contain any residue of asbestoslike fibers. 89 The study sought to analyze by electron microscope the tissues of recently deceased Duluth residents who had ingested Duluth water for at least 15 years; that is, approximately since the beginning of Reserve's operations. As a control check on results, tissue samples were obtained from the deceased residents of Houston, Texas, where the water is free of asbestos fibers. Although this study was necessarily expedited, plaintiffs' principal medical witness, Dr. Selikoff, testified to the sound design of the study and expressed his belief that it would yield significant information. 90 One of the court-appointed experts, Dr. Frederick Pooley, 41 in explaining the results of the study, stated that he found that the tissues of the Duluth residents were virtually free of any fibers which could be attributed to the Reserve discharge. Dr. Brown said of this study: 91 It is my conclusion, from the tissue study, that residents of Duluth have not been found to have asbestiform fibers in their tissues when compared with Houston. (A.23:208.) 92 As we noted in the stay opinion, the parties dispute the significance to be attributed to the results of this study. Dr. Selikoff, prior to the conclusion of the study, expressed this view: 93 Now, our feeling was that no matter what air samples show or water samples show or anything else, unless it is found that asbestos is in the tissues of people who have drunk this water    if we do not find it in the tissues in appreciable quantities, then I would risk a professional opinion that there is no danger, at least up to this point, to the population no matter what our samples show or water samples. (A.11:95.) 94 After negative results had been actually obtained, however, plaintiffs argued, and the district court agreed, that because the specimens of tissue represented only a microscopically minute body area, the actual presence of fibers may have been overlooked. 42 95 We note that this limitation had not seemed dispositive prior to the study when Dr. Selikoff commented: 96 I would think we should find some fibers there. We're looking for needles in a haystack, but that's all right, we should find needles in the haystack with all the difficulties of the study, the technical difficulties, if we examine sufficiently large numbers of samples in some instances we should find some fibers there. (A.11:77.) 97 The district court decided, and we agree, that the study cannot be deemed conclusive in exonerating the ingestion of fibers in Lake Superior water as a hazard. The negative results must, however, be given some weight in assessing the probabilities of harm from Reserve's discharge into water. The results also weigh heavily in indicating that no emergency or imminent hazard to health exists. 43 Thus, while this study crucially bears on the determination of whether it is necessary to close Reserve down immediately, the negative results do not dispose of the broader issue of whether the ingestion of fibers poses some danger to public health justifying abatement on less immediate terms. 98
99 At a somewhat more theoretical level, the determination of whether ingested fibers can penetrate the gastrointestinal mucosa bears on the issue of harm through ingestion. If penetration is biologically impossible, then presumably the interaction of the fibers with body tissues will not occur. 100 This medical issue has been investigated through experiments with animals which, unfortunately, have produced conflicting results. For example, Reserve witness Dr. Davis reported on his experiment in feeding crocidolite and chrysotile asbestos to rats for varying periods of up to six months. He killed the rats at the end of the period and examined their gastrointestinal tissues for evidence of fibers. At the time of trial, light and electron microscopy had so far revealed no evidence of fibers in the tissues. (A.16:143-59.) 101 Plaintiffs, however, cited contrary studies. Research by George Westlake, in which rats were fed a diet including chrysotile fibers, indicated that fibers had traveled through the colon wall and accumulated in the area of the mesothelium. 44 (A.11:23-25.) Pontrefact, who injected chrysotile fibers into the stomachs of rats, found that fibers had dispersed throughout the body tissues. 45 (A.11:37-41.)On this conflicting scientific evidence, Dr. Brown testified that the Westlake and Pontrefact studies provide some support for the hypothesis that asbestos fibers can penetrate the gastrointestinal mucosa. 46 102
103 The affirmative evidence supporting the proposition that the ingestion of fibers poses a danger to health focuses on the increased rate of gastrointestinal cancer among workers occupationally exposed to asbestos dust. Plaintiffs' experts attribute this excess incidence of gastrointestinal cancer to a theory that the asbestos workers first inhaled the asbestos dust and thereafter coughed up and swallowed the asbestos particles. 104 The attribution of health harm from ingestion rests upon a theoretical basis. As Dr. Selikoff explained, there are several possible explanations for the increased evidence of gastrointestinal cancer, some of which do not involve ingestion. (A.11:41-43.) Moreover, as noted previously, the excess rates of gastrointestinal cancer are generally modest (A.10:220, 223, 226, 279.), and substantially lower than the excess rates of mesothelioma and lung cancer associated with inhalation of asbestos dust. Also, the experts advised that an analysis of a small exposed population may produce statistically unstable results. (A.10:278-80.) 105 The existence of an excess rate of gastrointestinal cancer among asbestos workers is a matter of concern. The theory that excess cancers may be attributed to the ingestion of asbestos fibers rests on a tenable medical hypothesis. Indeed, Dr. Selikoff testified that ingestion is the probable route accounting for the excess in gastrointestinal cancer. (A.11:44.) 47 The occupational studies support the proposition that the ingestion of asbestos fibers can result in harm to health. 106
107 The second primary uncertainty with respect to ingestion involves the attempt to assess whether the level of exposure from drinking water is hazardous. Of course, this inquiry is handicapped by the great variation in fiber counts, and Dr. Brown's admonition that only a qualitative, and not a quantitative, statement can be made about the presence of fibers. 48 108 In spite of these difficulties, the district court found that the level of exposure resulting from the drinking of Duluth water was comparable to that found to cause gastrointestinal cancer in asbestos workers. 380 F.Supp. at 48. The court drew this finding from an elaborate calculation by Dr. Nicholson in which he attempted to make a statistical comparison between the fibers probably ingested by an asbestos worker subject to an excess risk of gastrointestinal cancer with the probable number of amphibole fibers ingested by a Duluth resident over a period of 18 years. (A.22:228-229.) To make this calculation, Dr. Nicholson computed what he believed to be the level of exposure in a typical occupational environment and multiplied this figure by the total amount of air inhaled by the worker over a four-year period (taken to be the relevant period in which a risk of excess gastrointestinal cancer was posed), thereby obtaining total fibers inhaled. A percentage reduction was then applied to obtain the number of fibers brought up the respiratory tract and swallowed. For Duluth residents, Dr. Nicholson calculated the number of fibers ingested over an 18-year period, assuming a daily intake of two liters of water and a fiber concentration of 25 million fibers/liter. From these assumptions, Dr. Nicholson opined that a Duluth resident over a period of 18 years ingested about two-thirds of the amount of asbestos fibers swallowed by an asbestos worker in four years. As is evident, this calculation is beset by several uncertainties. The assumptions as to fiber concentration in occupational settings and the resulting percentage of fibers ingested involve margins of error. Furthermore, in assuming that the relevant fiber concentration in Duluth water was 25 million fibers/liter, Dr. Nicholson used a figure twice that found by the court as the mean concentration of all amphibole fibers. 49 Reserve witness Dr. Gross performed a calculation similar to Dr. Nicholson's, but using somewhat different assumptions, and concluded that Duluth water would have to contain several hundred million fibers/liter and be ingested for 60 years before an exposure comparable with occupational levels would be reached. (A.17:37-51.) 109 The comparison has other weaknesses, for without regard to the comparability of the gross exposure levels, the dynamics of the exposure process are markedly different. The vagaries attendant to the use of assumptions rather than facts result in comparisons which are of dubious accuracy. Thus, Dr. Brown testified that, if Nicholson's calculations were correct, he would conclude only that the risk was non-negligible. (Brown dep. at 20.) 110 The Nicholson comparison, although evidentially weak, must be considered with other evidence. The record does show that the ingestion of asbestos fibers poses some risk to health, but to an undetermined degree. Given these circumstances, Dr. Brown testified that the possibility of a future excess incidence of cancer attributable to the discharge cannot be ignored: 50    I would say that it is conceivable that gastrointestinal cancers can develop from the ingestion of asbestos, and what I don't know, Your Honor, is just how low that level of ingestion must be before the likelihood of GI cancer becomes so remote as to be, for all intents and purposes, ignored as a real live possibility. (A.23:157.) 111 We quote at length Dr. Brown's testimony expressing the medical concern appropriate to the continued discharge of asbestos fibers into Lake Superior: 112 (Dr. Brown). After some degree of exposure to the literature and to the testimony given in this trial I would say that the scientific evidence that I have seen is not complete in terms of allowing me to draw a conclusion one way or another concerning the problem of a public health hazard in the water in Lake Superior. 113 Q. (The court). Would you define the difference between what you say is scientific proof and medical proof, and then maybe I will give you another kind of proof that I have to live with here and we will see where we are going? A. Well, science requires a level of proof which is pretty high. That is, we do not accept as truth things that seem to be casually associated, a cause casually associated with an effect. We have erected certain statistical barriers which force us to come to conclusions based on probability, and Dr. Taylor used those terms. He used .05 per cent, he used things like .01 per cent, criteria which generally are accepted in the scientific community as levels which are consistent with or from which you can conclude that there is some cause and effect relationship. 114 Q. All right. Now, scientific proof for what purpose? Doesn't the quantum of proof vary with the purpose? Now, I haven't really asked you this before, but wouldn't scientists be satisfied for one purpose and not another, or is that when you stop and put on your medical hat then, after you get a certain quantum of proof? 115 A. Well, as a scientist, sir, I would say that there are many questions which have been raised in this trial which would provide me with a hypothesis which I would like to see pursued. This is in the abstract scientific sense of an interesting intellectual question for which there is suggestive evidence. 116 Now, when I turn, however, to the medical side of things, Your Honor, I am faced with the fact that I am convinced that asbestos fibers can cause cancer, I am faced with the fact that I have concluded that the size of the fibers is not particularly helpful in allowing me to decide whether a given fiber is or is not carcinogenic. 117 As a medical person, sir, I think that I have to err, if err I do, on the side of what is best for the greatest number. And having concluded or having come to the conclusions that I have given you, the carcinogenicity of asbestos, I can come to no conclusion, sir, other than that the fibers should not be present in the drinking water of the people of the North Shore. (A.23:202-203.) 118
119 The preceding extensive discussion of the evidence demonstrates that the medical and scientific conclusions here in dispute clearly lie on the frontiers of scientific knowledge. Industrial Union Department, AFL-CIO v. Hodgson, 162 U.S.App.D.C. 331, 499 F.2d 467, 474 (1974). The trial court, not having any proof of actual harm, was faced with a consideration of 1) the probabilities of any health harm and 2) the consequences, if any, should the harm actually occur. See Carolina Environmental Study Group v. United States, 510 F.2d 796 at 799 (D.C.Cir., filed Jan. 21, 1975). 120 The District of Columbia Circuit was recently confronted with a problem analogous to the one now before us in Ethyl Corporation v. Environmental Protection Agency, --- F.2d --- (D.C.Cir., filed Jan. 28, 1975). The court, faced with a regulation of the Environmental Protection Agency 51 requiring the phased reduction of the lead content in motor vehicle gasoline promulgated pursuant to a statute authorizing a restriction only if the emission product of a fuel or fuel additive will endanger the public health or welfare, rejected the EPA regulation stating that the case against auto lead emissions is a speculative and inconclusive one at best. Id. at 6-8. The majority reasoned that in the absence of past harm, no potential consequences can be considered: 121 If there can be found potential harm from lead in exhaust emissions, the best (and only convincing) proof of such potential harm is what has occurred in the past, from which the Administrator can logically deduce that the same factors will produce the same harm in the future. (Id. at 14.) 122 Judge J. Skelly Wright, in dissent, approached the problem of potential harm as encompassed within the statutory term of will endanger differently. He discussed this concept of danger to the public health in terms of separate but reciprocal evaluations of both risk and harm: 123 While risk and harm are separate concepts that cannot be compared and ranked    there is a reciprocal relationship between them, and they may not really be assessed in isolation   . The significance of the risk    can only be ascertained through knowledge of the threatened harm, and it is the total risk of harm that must be sufficient to endanger the public health. This relationship does not, however, invalidate the separate analysis   , for the parameters of each term must be identified before their interaction can be studied. (Id. at 14 n. 14 of dissenting opinion.) 124 Judge Wright, believing the EPA regulations valid, concluded that the low probability of harm (greater than a remote possibility) shown by the EPA coupled with the potentially dire consequences which could result from lead emissions justified the EPA regulations. See id. at --- - --- of dissenting opinion. 125 These concepts of potential harm, whether they be assessed as probabilities and consequences or risk and harm, necessarily must apply in a determination of whether any relief should be given in cases of this kind in which proof with certainty is impossible. The district court, although not following a precise probabilities-consequences analysis, did consider the medical and scientific evidence bearing on both the probability of harm and the consequences should the hypothesis advanced by the plaintiffs prove to be valid. 126 In assessing probabilities in this case, it cannot be said that the probability of harm is more likely than not. Moreover, the level of probability does not readily convert into a prediction of consequences. On this record it cannot be forecast that the rates of cancer will increase from drinking Lake Superior water or breathing Silver Bay air. The best that can be said is that the existence of this asbestos contaminant in air and water gives rise to a reasonable medical concern for the public health. The public's exposure to asbestos fibers in air and water creates some health risk. Such a contaminant should be removed. 127 As we demonstrate in the following sections of the opinion, the existence of this risk to the public justifies an injunction decree requiring abatement of the health hazard on reasonable terms as a precautionary and preventive measure to protect the public health.