Document 8Oabx7nX1mEnxd2vqvZ6yxkZo

ST0095MD3 THE DOW CH EiVIlCAL COMPANY' Midland, Viidii;:;in DOW C O N F I D F. N T 1 A L J uno 2-1, 1070 TO WHOM IT MAY CONCERN: It was my privilege to attend an intensive course on asbestos at Mount Sinai Medical School in Now York last week. In the accom panying report, a brief attempt has been marie to summarize this learning experience, I have innumerable references available, including 1 1 5 35-mrn slides, of all aspects of the course and would be pleased to discuss any aspect in detail with you or a group of your choice. Lists of the slides and references are attached. I have purposely kepi my summary short, but can enlarge on any particular area i: you arc mtercstca. '/ / Charles G. Kramer, M.D. Corporate Medical Department DOUJ 02791 ST009540U ASBESTOS AND I IE A I-Til Asbestos i/i nn extremely useful mineral in mir society--having ;/.or than 3,000 different application/!. Early in this century, a scarring diBcAfc of the called "Asbestosis" was discovered. Control standards were established and, to my knowledge, no ease of "classical" advanced a shew to sis has occurred at our Company. This disease brought early death, usually in less than 20 years after first exposure. Though there is no reason to believe we have ever exceeded the time* weighted average recommended for control of asbestos-containin',' dusts, it has now become: apparent that the se people exposed to the lower levels will develop various other forms of "asbestos disease" after a lapse period of 20 to 30 years. These diseases consist of (1) thickening of the pleura or lining of the lungs, (2) cancer of the lung, (3) cancer of the gastrointestinal tract, and, (4) malignant mesotheliomas --a deadly cancer of the lining of the lung or abdomen which ic extremely rare except following asbestos exposure, Studies by our Medical Department indicate that, though we thought our employees were exposed only to safe levels, the changing opinion of what constitutes a safe level has left us with a significant number of individuals who arc potential victims of asbestos disease. V/e should therefore (1) institute procedures to minimize future exposure, (2) institute medical surveillance of the individuals at risk, and, (3) institute a campaign among the previously exposed group to discontinue smoking, which habit vastly enhances the chances of developing cancer of the lung. Some Divisions have ongoing conLrol programs of excellent quality and I have no doubt their people will gladly share their experience with anyone who has not ycl established control. Continued public information on this topic could eventually result in another care of environmental hysteria--we hope if such occurs v.-c can say everything that can be done has been done. Let us he pure that, in addition to control ling our plant environment, wc also insure that wo arc adding no asbestos dust to the community environment. Corporate Medical Department July 17, 1970 S*- A CONFIDENTIAL DOLJ 02792 I' i /.*i / t W (>( j Ir.fi; f. c s' /iSHKSTOS 1111 roduct i on A shcr-tos is it generic term which includes a variety of fibrous materials. It has hern used in Scandinavia, particularly Finland, as early as 4500 years ago whore it was used as a binder in pottery. It is not, however, until the past 100 years that asbestos has come into significant commercial use, and its increase in use has been remarkably fast for the past 60 years. The recognition of the health hazards posed by the use of asbestiforn.e materials has been relatively recent. The first clear case of asbostosis was reported in 1907. The first association with respiratory cancer occurring in people with asbeslosis was in the 19'10's, It was not until 1955 that an association with respiratory cancer in the absence of asbestosis was recognize d The first pleural and peritoneal mesotheliomas began to be studied in 1955 and the study of this disease still requires much additional data. The possibility that asbestos material may be a hazard to the community, and not only the asbestos worker, first became of serious concern in 1960. (Often the level of concern has been higher than that justified by the known facts.) It is not until the past two years that sufficient evidence has developed to suggest that the presently "acceptable" levels of occupational exposure arc too high. It can be reasonably predicted that the present level of acceptable exposure will be decreased shortly and new methods of establishing ambient levels will be prescribed. Wc should very seriously keep in mind several potential types of exposure. (1) The exposure of the asbestos worker. (2) The exposure of other workers who do not work with asbestos, but arc exposed incidental to its use by the asbestos worker. (3) The family exposure through material carried home on clothing, et.r., and, (4) The potential for exposure to members of the community due to careless dissemination of airborne dust and careless disposal of asbestos-containing waste, A further point to consider is whether our technology can provide safe substitutes for this very useful material or find hinders that can make many of the asbestos products less likely to release dust during their use. DOW 02793 ST0095't05 ST0095U06 2- - Types and Bitdopic Prop< rt i<-h of A.1.!)!-s!o,s There are five main types of asbestos which fit into two separate types, according to Ihcir crystalline structure. Serpentine asbestos of which chrysotile is the only type, and, Ainphiboje asbestos of which there are amosite, crocidolitc, anthophyllite and tremolite. The most commonly used is chrysolite. The different types vary eheinically, depending on the source, and contain many associated impurities hath organic and inorganic, All types are assoeia:-' with many trace metals. It would he realistic to assume that even the same ty > of asbestos coming from different sources will show some variation in biologic activity, and there is some evidence to this effect but it is not yet conclusive. Some factors that may influence biologic effects arc: (1) chemistry; (2) trace mineral phases; (3) trace elements; (4) surface properties; (5) combination with other materials; (6) sorbed organics such as waxes and oils. Some of the "contaminating" materials may be present at the mine, but others may be added at the mill or become contaminants during the use of the materia., and the question of what part these contaminants play in the development of disease is not known. Uses of Asbestos There are over 3, 000 uses of asbestos presently listed. Of interest to The Dow Chemical Company is its use as insulation, diaphragm cells, and various types of filters. It should be mentioned that asbestos filters arc used in the pharmaceutical industry, and asbestos fibers h'>ve been noted in the end product which is often used intravenously, AnirnalToxicolog Various techniques for demonstrating the fibrogenic and tumorogenic properties of asbestos have been developed. The work of William lil. Smith of Farleigh Dickinson University is a good example. lie has demonstrated both the fibrogenic properties and the tumorogenic properties by intrapleural injection in hamsters. This route of administration will produce tumor:, with DOW 02794 - 3- Many materials; however, it. is of great i ntc re at that he produced swine fib ro:.: but no tumors by tin* use of int i.iplmral fibe rgl.iss. Intratracheal administration did not produce significant tumors unless benzpyrene w,is added, in which msc lie demons! rated a significant increase when the two substances were combined, an increase we}) above wliat would be expected from either tuibstasuc alone, Work of this type lends support to the possibility that contaminants, such a?; those associated with cigarette smoko, will enhance the ha.mful effects in a human population. Studies using cell cultures have tended to support Ihc hazardous potential of asbestos. Clinical Asbestos Disease Too many epidemiologic studies have been done to fjuote them alJ ben-, but they have produced convincing evidence of the hazard of asbestos exposure, Studi efi < (inducted by the Corporate Medical Department support the f,ict that previously considered "safe levels" are in fart too high and that we have a significant population at risk. Although we know of no classical eases of asbestos is, we have seen significant other manifestations of "asbestos disease," a term preferable to nsbestosis in indicating the broad range of pathology asso ciated with asbestos exposure. Unfortunately, the present state of knowledge would indicate that once an exposure has occurred, asbestos disease will occur in a significant number of individuals even though they do not continue the exposure. The disease occurs after a long lapse period of ?J) - 30 years and, therefore, unless a very careful history is conducted the possible association with asbestos exposure may be missed. The pathology produced by asbestos exposure is: (1) classical asbestosis; {Z) pleural placques and calcifications; (3) bronchiogenic nroplasms; (4) certain O, I, neoplasms; and, (5) mesotheliomas, both chest and abdominal. ST0095401 C o. * a iv *'^ i iAL E>0W 02795 ST0095U08 -4- The *,i; n:. nr symptom:; of asbestosis are initially basilar lair.,, followed by dyspnea and, eventually, cor pulmonale. Clubbiiip, of the fingers may on.nr, X-ray finding:; .show a fibrosis <*1' tin- lung field.', which is usually, hut not exclusively, basilar, mid-lung fi1 <_! adhesions, pleura) place} rii and calcifica tions, "porcupine" heart and various other miscellaneous findings. The signs and symptoms of malignancies are classical except that they more often begin peripherally am! the classical atelectasis seen with malignancy of a mainstem bronchus may not be noted. Establishment of the etiology is based on careful history to seek out asbestos exposure and Cite association with classical pleural plucques or calcifications. The incidence of mesothelioma, both pleural and peritoneal, is very low in the general population and its occur rence indicates the desirability of an extensive search for asbestos exposure in any such a patient. Employee Health Surveillance Recent studies just beginning to appear in the literature indicate that at physical exam careful attention should be given to the appearance of basilar raJcs. The timed vital capacity searching for evidence of restrictive pulmonary disease is very helpful. X-ray surveillance will be more effective if a regular iJA, an over-exposed PA, and both obliques arc performed. Frequency of chest >:-ray is open to considerable controversy, but six month intervals appear to be an adequate compromise. Many people l'cel three months is better, but others feel that development of signs over a threemonth period indicate such a highly malignant tumor that five-year cures arc almost unknown. The outlook is grave under any circumstance once malignancy has developed. Since there is a long lapse time, some individuals suggest a decreased frequency of surveillance for the young individual and the individual whose exposure has been recent. Smoking and Asbestos Disease Smoking vastly enhances the chances of developing a malignancy and, in view of the continued poor outlook following removal from exposure, the dis continuance of smoking is a paramount preventive measure. Fnvi ronmenl al Control The present level of 2 MPPCF is considered loo high by a factor of at least six and shortly a new limit will be announced. This will be in the neighborhood of 2 fibers nrr cc with a 1 to 3 aspect ratio and counted under phase microscopy DOW 02796 at rtand.i rd;magnifu .itioj;. *j i.e samp!ing meinod w:ij probe!,iy bo standardized to Inc use of the Casells po mount air sai;i;i'pri Additiona 1, more exact, information should be released soon. The establishment of a new industrial hygiene standard is based on the concept that there is a dose relationshiyj between exposure to asbestos ,>nd the development of malignancy. Though there is suggestive evidence that this is true, many still disagree with this concept. Community ambient air standards when developed can be expected to be much more stringent and, in exercising control of the work environment, extreme caution must be used to not inadvertently disperse asbcstos-r.ontair.ing dusts to the other workers or to the community air. The disposal of wastes must be such as to not increase the environmental hazn rd. Control Techniques The goal of all control techniques should be to avoid the exposure of all individuals to asbestos dust since the actual no effect level is still unclear. Enginecring Control Moihods (a) Substitution (b) Isolation of process (c) Local exhaust ventilation fei) General exhaust ventilation (e) Personal protective ccjuipmerit (re.spi rators should always bo a last re.w. Control methods should be such as to not increase the hazard to other individuals. Medic a 1 C on tr o 1 Methods (a) ^replacement exam (b) Periodic exams (c) Kotation of jobs (d) Limitation of time exposed Tire "A sbeston_ I'odjd^ This topic has not been broached until this point because it has so otter, bee,-. a red herring. Originally described ar. "curious bodies," these coat'-d containing iron have been called "asbestosis bodies." This is a cort.pbby improper term. These bodies may have cores made up of other ma'o :\.ib should be referred to ns ferruginous bodies or pseudo - a sbe . I bode-: the i ore content is aclunlly , nown. DOW 027^7 ST0095409 ST00954I0 - (, . There i:: Mime /i t bui ;< lo w J i 11 j < r the uuenaled .ubealoa fibre <>r fibril is m>`. the real culprit, These uncii.i'.c'! fiber:. < ,ui only be ivcn '^y hkji'c ti*r methods, such as electron mic roscopy, than arc available to the usual pathol ogist. Unless special techniques are used, the opinion of a pathologist rapidly scanning; a slide under ordinary light microscopy cannot be .cceplod .u; good evidence that no ferruginous bodies or asbestos fibers or fibrils are absent. The presence of these bodies must rai*u suspicion, but disease cannot be completely ruled ou! in their absence. (They are seldom identified in pleural placques or tumors.) Conversely, the presence of such bodies does not confirm the existence of asbestos disease. The general population is exposed to many fibers and to asbestos fibers front many sources. It is of interest that exposure to talc, used extensively in cosmetics, results in sonic exposure to associated asbestos fibers. Since talc is used in many insecticide formulations, we should remain aware that it also presents a hazard. Significance to The Dow Chemical Company (1) Occupational Health Control exposures. Maintain surveillance of previously exposed individuals. Discourage smoking. (2) Community Air Pollution Avoid insofar as possible. Make sure waste disposal is adequate. (3) R & D Consider the potential for the development of adequate substitutes, dust reducing binders, etc. New York City just last week discontinued, by regulation, certain uses of asbestos in all public buildings. Assure that any new products which produce respirable dusts are studied early in the course of their development. '/%) Production Departments Encourage a careful investigation of all potential hazards before attempting any new uses of asbesliforme materials or other dust producing materials. DOW 02798