Opinion ID: 326929
Heading Depth: 3
Heading Rank: 1

Heading: Ingestion of Fibers as a Danger to Health.

Text: 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