Document 8RL4230vpXxNmV8rrM748MEDZ

G,'.r exposures Mix air pollution W. i. Ninim sow A. M. Lancia I. J. Srmorr Discussion 669 evidence that it is mort common in cities than in runt environments. They do nnt review the evidence which has been puhlivhed which liiggcsts that certain forms of axheitov art relatively harmleu. They do not inform the Trader it hat they consider to be the sourer of the asbestos in rite uihan atmosphere: is it from brake linings or construction materials, for example? I would lie grateful if the authors pointed up the nature of the risk to which they allude and stress, if possible, nays of distinguishing between more harmful and less harmful asbestos fibres. Veterans Administration Hospital, 10SS C"letmust Street, Center, Colorado 80220, U.S.A. Root* S. Mnnirii AUTHORS' REPLY mg' of persons in i of asbestos body n New York City, ami Brany W. T.) isN-stos in tissues, y Shawau H. A.) in. Arch. Environ. nal environmental Me and a reprodothc 49 other cities I was little eept when the -re is widespread niche at the meet ly report showed 'thtul no known ' '5rics. This indi; his cotblnsralnrs. j are present in thcT.-'x-'.' . every ease. T itr. sound of (he asbestos fibres in urban air is still a matter of speculation. Rome 3 million tons of the mateiial arc mined annually and nshesins has very many industrial applications so some perietal contamination of the air seems certain. Chrysolite is used in brake linings and brake linings ate being constantly disintegrated. However, the heat generated when brakes arc applied would alter tbc appearance of Ihc chrysoiilc fibre in the electron microscope. Some fibrils tn our samples appear to have been healed but most of the chtysotilc fibrils wc observed did not have this appearance and are mort likely to have been derived from building material. Photographs by Lumliv. 11 Atoms and O'Kelly (1971) iliusirate the production of dust from building materials. The individual fibrils seen in our samples probably have no pathological significance hut the appearance of large agglomerates in random samples is less reassuring. They suggest Ihc possible existence of localized sources where the conuiinuiaiion may he appreciable. Perhaps the titost disconcerting aspect of reports on Ihc incidence of a>l whwis and related diseases, and patiicularly mesothelioma, is tbc frequency with which a "neighbourbond hazard" nr "endemic asbcslosis" is mentioned, disease occurring in apparently innocent occupaimns or in members of an asbestos worker's family. Examples that may be quoted arc workers near luggers in Glasgow (Gold and CViiiiicrt, 19061. villagers near an asbestos mine in Italy (Vioiiani, 1 `Jt.'Z), finland (Klvu.uoio, I960) and South Africa (Waunf.r, 1959; SuJh'orf, 196}),in carpenters (Flf.khlr, 1971) and persons not occupationally exposed to asbestos in London (Nlwhoum and Tssompson, 1965) and Hamburg (DAbout i n. Daimf.kt and Hinz, 1970). The effects of asbestos may be due, in part, to the morphology of the fibres but, because it is more readily removed from She respiratory part of the lung, chrysolite the commonest form,pf asbestos M_._ "probeblylhe least harmful (Botham and Holt, 1971a). Submicron gists fibre is atso removeslilia^S similar me to chrysolite (Botham and Holt, 1971b). Chrysolite can be readily distinguished from other varieties of asbestos with the electron microscope. Gross fibrosis is prohahly produced only by very high concentrations of asbestos but the amount needed to produce a carcinoma is not known. Stanion and Wrench (1972) produced mesothelioma in rats with amosilc, crocidolitc and chrysoiilc. Department of Chemistry, University of Reading, . ... P. F. Holt D. 1C. Youno REFERENCES^, r. F. HoltJ: I :. z.-- v, - v 2 DothamTS'ICCT'aabivd Holt F7. F. (1971a) The devdopment of glatsfibm jbodie* wTneju tig**? pigs./Am*. 10J, 149-156. . jBotham S. K. and Holt F,. F. (1971b) Development of asbestos bodies oo tniosite, chrysoiilc and ciocidotite fibres in guinea-..pig.lun.gs. J. Path. 80S, 159-167. '" ; ' . * ' Dalouixn P,, Daralkt A. F. and Hinz 1. (1970) The epidemiology of pleural mesothelioma preliminary report on 119 eases from the Hamburg area. Gem. Med. Mon. 15 (2) 89-95. FinciirJi D. E. (1971) Asbestos-related chest disease In jointrs.Fruc. R. Soe. Med. M, (8) 817-8. Gold C and CiffMautT J. (1966) Asbestos--A hazard to the community. Dab. Health *0 (6) 261-70. ------- = "tioqju j YocotgtmoloelcaiRisW endemic - * kTlF.~S.','H aaaiw fhfc'.and O'Kkuv F.YTI971) ttundlngs msulatedwuh sprayed asbesloaV f'' ' ;a a potential hazard. Ann. Occup. Hyt. 14, 255-257. Ncw ikhikl M. L, and Thompson H. (1965) Mesothelioma of pleura and pentnm >m following expo- jure lojasbcifc* in (he London are*. Br.f. itsdust. Med. 22 (4) 261-9. .......... - 1 `^ j.*(1968) Asbeatog exposure, smoking and peopla^. ^lgvjiviir.'Sl^j':-. `: ..A-- -- - .^v.- . ... ' *' r d .... f". imwr ,n . yyr^.--Tryy\-rr - ' RQ8000 101; I PRODUCED BY FORD