Opinion ID: 326929
Heading Depth: 3
Heading Rank: 2

Heading: Level of Exposure Via Ingestion.

Text: 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