Document g2VLv0VnRgG5mvmZN2LRRevne

Epidemiology Before considering Che mortality studies of the various occupational groupa exposed to asbestos, it la uaeful to briefly consider the rolia the three important types of asbeitog, (aaoslte, crocldollte, and chrysotlle) have played In the commerce of North Azscrlca end Europe, the areas wherethe major epidemiological studies of asbestos workers were made. In Rorth America, chrysotlle entered the market In large quantities early In this century. Crocldollte was apparently first used In the United States in 1912 when 9 tonnes was imported, but it was not until Uorld Vsr I that Its use for high temperature Insulation became estab lished -- particularly In the ship building industry. By 1930 nearly 32,000 tonnes of crude crocldollte fiber had been Imported Into the United States (Mineral Reeourcce of the United States, 1907...1929, U.S. Dept. Interior, Washington, D.C.). It was not until the mid 1930's that amositc asbestos gained a market In Rorth America when it began to re place crocldollte for high temperature insulation. Crocldollte was milled in Bound Brook, New Jersey, in 1920, and in 1924 the operation ' moved to larger facilities in Millington, Mew Jersey. The many adver tisements in the trade Journal Aobeotoe during the period 1920 to 1945 indicate that crocldollte vae used in many products and particularly for Insulation of steam boilers, locomotives, end pipes. As an example, a product containing crocldollte asbestos and called "652 Magnesian Scc. tlonal Pipe Covering" was advertised monthly in Asbestos from 1920 to 1945 (see also McCullagh, 1980). Aaoslte, crocldollte, and chrysotlle vers almost universally used aboard shipa during World War II, amoslte for high temperature boilers and pipes, crocldollte for packings exposed to adds or salt water, and chrysotlls for low temperature and electric lneulatlon. The use of asbestos in Europe paralleled that in Rorth America, with one notable exception -- the extensive use In Europe of crocldollte asbestos as e sprayed-on coating to fireproof ships*, railroad cars. ^Mesothelioma is prevalent in the shipyard workers of Europe; at Walchcrcn, Vllhelmshaven, Plymouth, Trieste, Uamburg, Mantes, Rotterdam, and Malm8 (McDonald and McDonald, 1977). The extensive use of crocldo llte aboard European ships prior to and during World War II is suggested to* be an important factor In the etiology of thle disease. 304 8005 0063 buildings, etc. Sprayed-on coatings were also used in the United States after World War It, but the coatings contained, with few exceptions, chrysotlle rather than crocldollte. Sprayed-on asbestos coatings were not used on U.S. ships, the principal use being to fireproof steel building girders and as acoustical coatings in schools and offices. Aabcetoe trades uorkere. A very significant Increased Incidence, relative to the general male population, of lung cancer, aobeotosls, and mesothelioma Is found in men Who were employed in the "asbestos trades" -- the insulation of steam locomotives, boilers, ships, snd buildings; and the fabrication and Installation of asbestos-containing textiles, roofing materials, cement products, tiles, vallboards, brake linings, clutch facings, filters, packings, gaskets, etc. Those In the "trades" generally used several types of asbestos minerals during their working careers; most commonly these were chrysotlle, crocldollte, and amoslte, snd rarely anthophylllte. Significant exposures of any group of workera, at least for the past fifty years, to tremollte or ectlnollte asbestos dusts hoe probably not occurred. Thirteen major mortality studies of asbestos trades workers are presented in Table 4; five of these are of workers engaged in the asbes tos insulation trades, and eight ere of workers In the factory and tex tile trades. Most of the workers are male, a few are female. In all, 38,904 individuals were followed; of these, 5,450 have died. Including 998 (18.3 percent) who died of lung cancer and 327 (6.0 percent) who died of mesothelioma. In the thirteen studies the lung cancer mortality varied from 6.1 to 24.5 percent of all deaths; mesothelioma mortality varied from 0 to 9.5 percent of oil deaths. The workers Involved in studies nos. 1 through 12 vorked with more than one fern of asbestos; those in study no. 13 worked only with chrysotlle asbestos. Estimates of expected cancer mortality are, very difficult to pre dict, because cancer rates are modified by the individual's "lifestyle," s well as by occupation. The major "lifestyle" contribution to lung cancer Is cigarette use. To better assess the significance of these health studies. It le necessary to examine tba cancer mortality patterns of cigarette smokers Who wore not exposed to asbestos duets. Unless prevalence of smoking within the study group le carefully evaluated, it 305 PRODUCED BY FORD