Document k9bkqyvLVmKr1XoLRD7Dpb9ZB

i'SO t'AXt'lM ix AsaiiSTOS AttXhHS *> ? , no reliable eriteriiiu by which mw cun siitiiiate carcinogenicity ami, a* is wdl 1 | gown, relatively minute changes in the '! itucture of a chemical carcinogen are suffi i:cient to diminish or eliminate carcinogenic ition. "3 If asbestns is indeed to lie regarded as a jyjrriiiogvn, Uk- ueeil is fell to demonstrate ljuie property which etui lie regarded as ferrcd In `Something more than inertness." en asbes- | These authors advance the theory that, lorted iu p s0nic n,ore cxieriinctual evidence tif. * Present wined 1>y Sorpc *\ ancer in ctos carcinogenesis, by asbestos or a de position product of it enn he obtained, tos might lie considered as a "en-ettr- n" which only induces a further dclopment of a prcueoptastic condition ancer (ought about by something independent of fis have " as^>C9t0!>> *uch ns 311 endngeiinus factor, 'iueper * Thus (he literature. while lending tn up- mrtcrl up ' ort *hcsis d^t asliestusis is in some ' between r *7 rebited. to the development of lung been ac- A0, is by no means unanimous. Abo il writers " ether, it is perhaps more confusing than Ulcer" of ' lightening. A careful review shows that ted cue- be majority of the re|*orts are clinical and eases of <* epidemiological. They lack nvunr ele- of about es estab- ;ts necessary for the application of lidcmiological lechuiques to their content, most of the authors do not make claim thors ac- having done so. What has happened is without rted that succeeding authors have drawn condu- and generalised beyond the of ig cancer works which they quote. Xowherr. for vhich be pie, have we fouml references to a illeb and otion of asbestos workers, allbough fiat the al authors who have quoted the ob- ith lung d incidence of lung cancer in autopsies l evalua rrsont who oho had asbestusis imply ted 126 his incidence applies to asbestos work- Iisbestosis generally. We have likewise been e to find any study which actually lated the incidence of luitg cancer g a population of persons who had losis, and not just those who came to isy. With the exception of a paper oil,* none of those reviewed gave any 'on exposure and dust coiirculnlu-ms. _, W1 even Dulls |Kqicr merely mentions ' there -f fhttuB--Trmn "sclieiluliil" arras. by wbirli is meant, "those ateas where processes are carrietl on which were scheduled under the Asbestos Industry Regulations of 1931 as being dusty." There is, furtlicmuirc, a complete kick of delinilioii of terms as used in (he pub lished literature. hor extuutde, the term ".isbestosis," as used, may refer to citauges observable only by microscopic examination of the hmg- (issue, or i( may mean a radiologically detectable coiHlitiou. Most of the published rvjiorts obviously included women aiming their cases, but some of them do not give the number or profiurlion of women involved in the study. There is also a lack of uniformity as to what tyie of exposure most studies have lealt with. Of 99 cases enumerated by llucpcr1* in 1955. only III aiqiear to have originated in the I'nilcd States, and 7 iu Canada. Some of the earlier reports ap parently included asbestos miners, but it can be assumed, since 82 of the 99 eases had originated in England, and' since no asbestos mining operations arc carried on in that country, that ninst of the reported cases have involved workers in the textile nr fabricating industries. Such factors as smoking habits, family history of cancer, length of time in the industry, and age of the individual case arealso notably absent iu the majority of these reports. With this understanding of the limita tions of the existing literature with respect to epidemiological generalization, it may be of value to consider in somewhat more de tail some representative earlier publications, a few of which were referred to briefly above. One of the most detailed studies and une which deserves the must serious considera tion is that reported by DollM in 1955. This study reviews causes of death among asbestos workers based on coroners' rec ords. It also attempts to estimate the risk hy studying records of men who worked for al least 2d years in exposed situations. 635 I "71UJJUS>I rvojntti^.varu*-.- f I' fi'