Document KGRLXDX5GGypJxr8p2p9ZX8oK

FILE NAME: Z,, DATE: DOC#: , OCUMENT DESCRIPTION>ZdZZ:W>Z h^,ZZ ! I.~ Addendum to the Testimony of J. P. Leineweber, Ph.D. lIouse of Representativcs Committee on Education and Labor -.. :-:. Subcommittee on Elementary, Secondary, and Vocational Education During my oral testimoney before the House Committee on Labor and Education, I deviated somcwhat.. from the wri tten testimony which had been submi tted to the Commi ttee. I felt that this was necessury to clarify certain points which had been made by those who had testified before me. The major points were: 1. Not all asbestos fibers in the environment can be . considered to be biologically active. 2. Not every fiber which is inhaled will remaIn forever entrapped in the lung. 3. Asbestos related diseases have been shown to follow a dose-response. 4. Concentrations of asbestos fiber as found in the general environment and inside public buildings arc below those occupational and para-occupational concentrations ~hich elicit a biological response. I believe that a consideration of these main points, which have been thoroughly documented in the scientific literature, sholiid serve to reduce the understandable inordinate concern Khich has been expressed by certain individuals with limited information. The following are more detailed explanations of these points incluuing the peTtincnt references to the articles in the sdentific and medical literature. :\ con sid era b I e a III 0 U 11 t 0 f res ear c h 11 ~l she c n car r i e <1 0 u t i II r ceo gil i zed 1:l b 0 rat 0 ric son the 1. 0 x i c () 1 0 g i c:1.1 p rt'i per tie s () r :Isb('stos and other fihers. By f::n the most thorough, :!I1d ]'chaps the most signi f:icant, :is the \;fol'k h'hich has been clone b y II r. rle r 1(' S. S tan ton 0 f the N;l t ion;l 1 C~l1l C C r 1II S tit tl t c . I Ie l1;lS studied the ability of a vClriety of fibrous mClterinls to jnuucc cancer in rats in t.hE' laboratory. His experimental ~~ ~:M ~, 2 technique involves implantation in the pleural cavity which is not at all representative of natural inhalation. Because. of its artificial nature it can only he used to screen materials for potential biological activity. lie has found that all fibers, regardless of their chemical composition, can be biologically active provided they meet two requirements; (a) they are durable in the biological system and (11) they fall within certain critical size limits. These size limitations, as defined by Dr. Stanton's latest work, are defined as fibers less than 1.5 ml~rometers in diameter and longer than 8-10 micrometers in l~ngth as the most biologically active. For your information, I am enclosing copies of two of Dr. Stanton's publications which describe his work in detail. The first (Exhibit 1) was a paper on asbestGs presented at a meeting of the International J\gency for Research on Cancer in Lyon, France in October of 1972. The second (Exhibit 2) was published in the March ]977 issue of the Journal of the National Cancer Institute. Although this paper refers strictly to the carcinogenicity of fibrous glass, it is pertinent in that it represents a most recent work refining the influence of fiber dimensions Several other studies have been published by other researchers which essentially confirm this work. These publications include those by George W. Wright, M.D., consultant; William E. Smith, M.I)., Director of the Health Research Institute, Fairley- Dickenson University, Madison, New Jersey; and J. C. Wagner, M.D., Pneumoconiosis Unit, Llandough Hospital, Penarth, Wales. J\n additional point in this regard is the fact that airborne fibers found in the general environment and in the air in commercial builcljngs are generaly extremely small, i.e. significantly less than ]0 m:icrometers in length. Thus, the vast majority of the small number of fibers which would be inhaled by the occupants of the builcling containing ashestos spray coatings cannot be con~.ic1erecl in the h:iologically active size range. This is one reason why I have ohjected strongly to thE: reporting of fiber concentrutions simply in terms of nanograms per cubic meter. This type of reporting tells nothing about the size range of the fibers encountered and, t 11 C' ref 0 r c, e] i min ate 5 a c r i tic a I pie ceo fin f 0 nn a. tj 0 nth a t is Jl('cess~1ry to evaluate the risk. ~Iost ()naJysts and hiolof:ical rcsc:nchcrs nOl'l' (q~rce that :it is important to report the sjzc distribution ()S Nell as the total mass of fibers. or Several the w:itnesses at t.he hcaril1~:5 attempted to leave t.he -impression that once an asbestos fiber is inhaled, it Tcmains ~[orever lodged in the lung where it cnn do its damage. This is patcntly false. It is truc that ashestos fihers are extremely durable and cannot be dissolved by the fluids present in the lung. It is also true, however, that the human lung has the ability to clear itself of foreign material, a fact which is known by everyone, even remotely associated with the biological sciences. Even if a foreign particle should reach the most distant portions of the lung where the muco-ciliary mechanism cannot operate, there is a ,&,?.oc1 probability that it will be ingested by a mohile cell called a macrophage. This cell can carry its burden out to the bronchi where the other clearance mechanisms can operate. Only those who wish to overdramatize environmental exposure to asbestos fiber choose to ignore this very important defense mechanism of the human body. ,For a very complete discussion of this subject, I call your attention to a book entitled, "Respiratory Defense Mechanisms, Vol. 2" edited by Joseph D. Brian, et aI, published by Marcel Dekker, Inc., New York, New York in 1977. Asbestos Related Diseases Have Been Sho'"n to Demonstrate A Dose Response Relationship The petition which was filed by the Environmental Defense Fund requesting immediate action from the Environmental Protection Agency includes the following statement, " ... once a qualitative presumption of carcinogenicity has been established for a substance, any exposure to that substance can be considered to be attended by risk when considering allY given popUlation. No exception to this point haS yet been demonstratecl. .. fI. This statement summarizes succinctly the feelings of those who would eliminate all possible exposure to asbestos fiber regardless of its intensity. There is ample evidence at the present time to demonstrate that asbestos related diseases do indeed exhibit a we]]-defined dose response effect. This effect would be manifested in two \\ays. At lo\\er doses, a smaller group of the exposed popu18tion ,,,ill be affected and the latency period will be longer. The latency period is defined as the time between the onset of exposure and appearance of disease. Tn support of this dose response hypothesis, T h:rve attached l"opit's or th'O p:lpcrs. The Cirst,which is ~ltt;lched ~l~~ rxhihit =.;, is by J. C. ~lc]lolla.1d, el a1, \\'110 studi.ed a l:ng<: pOpul:1Uon of people h'ho h;lve been employed in the Quebec a~bestos mining :industry. In this study, an attcmpt \v;1s llwc1c to quant:ify the exposure for each of the workers and relate it to the incidence or various diseases. 1:1.l,c)' round that. the overa] I mort;l).i ty \\'35 not siglll fiC[11)t.ly dl'Cfi..:,l'('n't from the general population for those (' x P0 S (' d t 0 1 0\" d u s t J C' \r e 1 s, but hi a s s i gIl j ric all tJ)' 11 i r. her (2 0':, ) for the group h'hich was exposed to the ltigher COllccntrat:iqns of ashestos fiher. -The next paper, \-Jld ch is attacllC'tl as Exhibi t 4, is hy F. WhitHcll, et aI, from the Department of Pathology, Broadgreen Hos pi tal, Li verpoo 1, Engl and. In th is study, the amount of asbestos fiber found in lung tissue was correlated with the incidence of mesothelioma. There is a clear cut conclusion that (a) there is a definite dose relationship between asbestos exposure and mesothelioma formation, and (b) levels of asbestos exposure that do not contribute to the formation of asbestosis are not implicated l~' the formation of lung cancer. The above citations are representative of several which establish beyond a reasonable doubt that all diseases normally associated with excessive asbestos exposure, i.e. asbestosis and mesothelioma, are subject to a dose response relationship. Bronchogenic cancer, which is very intimately associated with cigarette smoking, is also subject to a dose response relation~hip. Environmental Concentrations of Asbestos Fiber Are Below Those Which Elicit a Response In the previous section, evidence was cited to show that asbestos related diseases arc subject to a dose response relationship. As the concentration of fiber decreases, the incidence disease will decrease. There has been considerable debate in recent years as to whether or not a level exists below which there will be no incidence of disease. There is an increasing body of evidence that, in a very practical sense, such a level does exist. In the attached paper by Whitwell, et aI, (Exhibit 4), it is quite clearly indicated that those persons with low lung burdens of asbestos fiber are not at risk for development of mesothelioma. At the June 1978 meeting of the NeH York Academy of Sciences, Dr. Hallllllonc1and Dr. Selikoff presented a p<:tper \\'hich revie\Ved the mortality experiences of residents in the neighborhood of an asbestos plant. This paper, which is attached as ExhiDit 5, show quite clearly that the people who live.J in the immediate vicinity of this pJant but were not employed there, \\'crc at no greater risk for asbestos related diseases than a similar group \o/ho lived several miles from the "plant. It is most interesting to note that the first attempts to clcan this p~l1'ticllLn dirty p1<111t "Jere to bIo\\' the asbestos "dust around the' neighborhood Hith no filtration. SDmp1cs t<11\en in the Dt.tics of hOllses in the vicinity of the plant indicateth<1t the (lust concentrations must have been relatively high, very ]jke1;: hil;hel' than the concent.rations experienced in huildings ",here :lsbestos spr:l)' coatings are in usc. 5 .. I feel that be aware of it is extremely thc information lmportnnt thnt all concerncd should tha~ is discussed in the precceding paragraphs. Unfortunately, regarding the situation has all too ignored much of the discussion the existence of this body of literature. available from high What level hoacscubpeaetniondoanl e exispotsouretaskeandthefroimnformation relatively high level para-occupational exposures in an unwarranted manner, to the conditions which and extrapolate, exist in the ethnavtirothnme elnatyal psuibtluiactiiosn.incaTpheabolenlyof loagssicimfiOlTatitnhgissic~ietnhteifibcelief or technical data. I, however, believe that the opposite is true. If the educated given all layman is of the information in an objective manner, quite capable of assimilating the facts and all r~aching a logical conclusion. I of us who are concerned with tbis further believe that particular problem if craomulidfibceatigoinvesn inthetheoppproorpteurnietynvtiorondmisecnuts, s italwl ooufld thbee a simple malasottetro todetreeramchinea alograictiaolnacol nccoluusrsioenorfegaacrtdioinng. tIle facts and