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3-1 ECOLOGY-POLLUTION ASPECTS OF CHLOR-ALKAU PLANTS: ASBESTOS ANO HEALTH Charles G. Kramer, M.D. The Dow Chemical Company Midland, Michigan [Presented at The Chlorine Institute, Inc. Fourteenth Chlorine Plant Managers' Seminar New Orleans, Louisiana, February 3, 1971] 9 Asbestos is a generic term which includes a variety of fibrous min erals. It has been used in Finland as long as 4500 years ago as a binder in pottery. It was not, however, until the last 100 years that asbestos came into significant commercial use. There are, at present, at least 3000 uses for asbestos. Types of Asbestos There are five main varieties of asbestos which fit into two separate types, according to their crystalline structure. The two types are serpentine asbestos, of which chrysotile is the only variety, and amphibole asbestos of which there'are amosite, crocidolite, anthophyllite and tremolite. The most commonly used is chrysotile. The different asbestos fibers vary chemically depending on the source, and contain many associated impurities, both organic and in organic. All types are associated with various trace metals. It would be realistic to assume that even the same type coming from different sources will show some variation in biologic activity. There is some evidence to this effect, but it is not conclusive. There fore, at present, we must assume the same hazard for all varieties. Health Hazards The recognition of some of the more serious hazards associated with the inhalation of asbestos dust is relatively recent and, in some quarters, not adequately understood. < Asbestosis, the first recognized disease associated with the in halation of asbestos dust, is a scarring disease of the lung which often leads to early death. Though asbestosis still occurs, it has to a large extent been controlled where adequate Industrial hygiene stand ards have been followed. More recently, it has been recognized that individuals with as bestosis have an increased frequency of lung cancer. It has also been shown that there is a statistical increase in lung cancer in individuals exposed to lower amounts of asbestos dust which are not enough to pro duce asbestosis. Other abnormalities associated with asbestos exposure are cancer of the gastrointestinal tract, and cancer of the linings of the lung and abdominal cavities. DOW 04823 ST0312225 s 3-2 Table 1 ahowa the reaulta of a study of aabeatoa inaulatlon workers. No atudlea are available of aabeatoa vorkera In the chlor-alkall industry, but the reaulta of 8tudies of other vorkera indicate that ve oust be care ful to not over-expo8e any individual to asbestos dust. TABLE I Deaths Among 632 Asbestos Inaulatlon Workers Observed Prospectively January 1, 1943 To April 30, 19671*2 Cause of Death Cancer Of The Lung Cancer Of Lining Of Lung Cavity Cancer Of Lining Of The Abdominal Cavity Cancer Of The Gastrointestinal Tract All Other Cancers Asbestosis All Other Causes Total Deaths - All Causes Number Of Deaths Expected Observed 8.9 66 0.0 6 0.0 8 11.2 25.0 0.0 205.9 251.0 37 27 27 178 349 ^Sellkoff, I. J., Churg, J., and Hammond, E.C., JAMA, 188:22, 1964 2Selikoff, I. J., Hammond, E. C., and Churg, J., JAMA, 204:106, 1968 The cancers occurring after over-exposure to asbestos dust vere slow in being recognized because of a lapse period of 20 to 40 years betveen the beginning of asbestos exposure and the onset of the disease. Table II indicates the effect of regular cigarette smoking in con tributing to the development of lung cancer. The individual vho is over exposed to asbestos dust and regularly smokes cigarettes is far more likely to develop lung cancer. ST03I2226 DOW 04824 3-3 TABLE II Lung Cancer Deaths Among 370 Asbestos Insulation Workers January 1, 1963 to April 30, 1970* 1 2 Number Of Workmen Lung Cancers Lung Cancer Deaths No History Of Cigarette Smoking 87 1 1 History Of Regular Cigarette Smoking 283 38 33 It is estimated that the individual who is over-exposed to as bestos dust and also smokes cigarettes is 90 times more likely to devel op lung cancer than an individual not exposed to either of these factors. Control Methods If we are to avoid the consequences to the workman of over-expo sure to asbestos dust, we must control his exposure. Control methods should be such that they also eliminate any hazard to fellow workers and prevent contamination of the community atmosphere. Table III lists some methods of controlling asbestos-containing dusts in different processes. TABLE III Methods Of Controlling Dust Containing Asbestos Fiber 1. Wetting Down With Water Mixing Crushing Certain Textile Operations Demolition 2. Dust Collecting Equipment Cyclones - Multiclones Wet Collectors - Low And High Efficiency Scrubbers Electrostatic Precipitator Bag Houses Other Methods - Settling Chambers, Filters Construction Controls - Saw Pickup, Dust Containment ST0312227 OOU 04825 3-4 3. Modification Of Product Or Packaging Change In Formulation Substitution With Less Hazardous Materials Modification Of Material Handling Modification Of Production Line Asbestos In Plastic Bags (Can be wetted before unloading.) 4. Respiratory Protection--If Asbestos-Containing Dust Cannot Be Controlled. (Use only approved respiratory protective devices.) Medical control methods are of secondary importance to engineering control methods since, by the time a health problem is apparent, it is frequently too late for satisfactory treatment. Among medical control methods are programs to discourage cigarette smoking by asbestos workers and periodic exams to discover early evidence of disease. Community Air Pollution There has been considerable alarm about asbestos exposure of the general population. Some local governments have already established reg lations controlling asbestos contamination of the community atmosphere. It is expected that Federal criteria on airborne asbestos will be devel oped soon. ' Mot all investigators agree that there is reason for alarm. How ever, prudence should prompt us to avoid contaminating the community aii before we find ourselves in the midst of another environmental crisis. c/> CO ro ro ro (The tables and much of the material used in this presentation were ob tained by the author while attending the course on Asbestosis given by The Mount Sinai School of Medicine in June 1970. The help of all those presenting the course is gratefully acknowledged.) DOW 04826