Document rxRojp6388KgJOaq8r8E6jk7a

o ] I .-:f Industrial P3sgaaoa Hotea on the roport by Dr* Doll and Dr* Knox 27th July, 1954. . Prom a first rending of the report, It would aeon that In some Important respects the conclusions roachcd are not supported by adequato evifionce* and these notos aro Intended to draw attention to cortnin points which appear to show that tho roport should be the subject of critical examination and that the conclusions reached In the report ought not to be accepted, at any rate at present* . The report (when drawing conclusions) fails to distin guish betveon asbestos workers generally on the one hand, and the relatively few asbestos workers who have actually contracted aabostosis on the other* This is the main reason why it would seem that the conclusions reached are unsound* In any event, ( all references to "asbestos workers'* should be to "asbestos textile workers"* ------ 1. In the first paragraph of the report on page 1, the first sentences read as follows 1- "Fifty-nine cases of lung cancer have been rocorded 3,n persons with asbostosls (Hueper, 1953) since. Lynch and Smith (1935) reportod the first case* In view of the infrequency of asbestosls, this large number of cases suggests - but does not prove -.that lung cancer is-an occupational hazard of asbostos workers." ' ' The existence of fifty-nine cases of lung cancer in persons with asbestosls can only suggest that an individual who contracts asbestosls may lator suffer from cancer as well* Is there in fact any evidence that the number of cancer coses in the asbestos industry as--is significant? Thero is nothing "in thev^eportTto suggest that that is so, and in fact the report Itself appears to contain ovidence to the contrary* Did Hueper, Lynch and Smith find any. and if so how many, cases of cancer amongst asbestos workers vno had not got asbestosls? In the case of T.B^A.Co., Tablo.l* attached to tho roport shows that during a period of ninetoen years there were only thjrg.? deaths from cancer (not.accompanied by asbestosls) amongst'the'whole of T.B.XiCo's employees* It can hardly therefore be correct"to"" suggest that lung cancer is an occupational hazard for asbestos workers. Tho ovidence in the report only shows that a man who ' is suffering from asbestosls may also contract lung cancor* 2* In the second paragraph of tho report on Page 1, the following statement appears*- J o "The majority of workers (citod by Hueper. 1953) consider that a causal relationship betvoon asbestosis and lung cancor is either provod or is highly probablo .......... etc*" It will be noted that in the case of this atatoraont the relationship mentioned is between lung cancer on the one hand and asbestosis on the other; thoro is no suggestion that there is a relationship betweon cancor and asbestos workers generally* 3* The statements containod in the paragraphs headed "Autopsy data" at the bottom of page 1 and tho top of pago 2 of the report are of considerable interest* particularly as they show tho substantial advanco made in reducing the asbestosis risk since 1931* In particular tho statements containod in the last two sontencos as set out below require to be carefully notedi- "All tho subjects in whom the two diseases wore found together had boon employed for at least 9 years under the old conditions and although 11 of the 15 men and women died under 30 years from their first exposure, the association of the two conditions has not yet been found in any person takon into employment during the last 31 years (1923 - 1953)* It is, therefore, possible that tho reason more cases were not found in the socond period, is that roduced exposure to dust has alroady begun to lessen the incidence of asbestosis." ' Tho statement that the two diseases have not yet been found in any person token into employment during the last 31 years (from 1923 to 1953) is particularly interesting; this is concrote evidonca and appears to be completely, inconsistent with the con clusions drawn in the last paragraph of the report on page 5* Moreover, the final sentenco as sot out above, which states that the reason that moro cancer cases were not found in the socond half of the poriod is that reduced exposure to dust had alrondy bogun to lesson the incidence of asbestosis* supports the point made in these notos that the cancor risk usually arises only in the case of thoso few employoos who have contracted asbostosls* 4. ,, ',/ <" / (1 /' /**" /t ' /v - /'I ' Under the heading "Results" the third paragraph on page 4 of the report concludes that the asbestos workers who had worked for 20 or more years in the "Scheduled areas" suffered a notably highor risk from lung cancor than the rest of the population, and tho following paragraph says that the si2e of the risk appears to have been of tho order of 10 times that experienced by other men. It would seen however that the roport is still drawing conclusions solely from tho relatively.few casos of men who have contracted asbostosis^ and therefore the failure to distinguish ibVtween asbestos" workers'as a whole and asbestos workers who have contracted asbostosis would seem to vitiate the conclusions reachod. j3 it not a fact that in the case of employoos who have contracted asbestosis and lung cancer it is normally the cancor which occurs after the contraction of asbostosis? Have we heard of any cases whero asbostosis supervenod eftor the contraction of cancor? 1 9 '1 -3 - 5* Tho last three sentences of the final paragraph undor tho handing "Rosults" on page 4 ore of considerable lntorost. They* ore as follovsi- .... "It Is beliovod that tho groat roductlon In the oxtont of the oxposure to asbestos dust vhleh has boon brought about In the Industry since tho oarly thirties has lod to a consldorablo fall In tho Incidence of asbostosls and vlll rosult In Its eventual suppression. Whether tho specific Industrial risk of lung cancer has, In fact, been eliminated can only bo shown by future experience* Tho `number of men at risk who have been exposed only to tho now conditions Is at prosent too small for any certain conclusions to bo drawn from their experience*" . As to the first sentence, we know that the Incidence of asbostosls has very substantially decreased and we are con fidently expecting that that disease will oventually disappear ontiroly. As to the second sentence set out above, Is there any evidence In tho report or elsowhero that there Is a "specific Industrial risk of lung cancer" among asbestos workers? Does not the true position appear (from the evidence in the report) to be that there Is a risk (of which we have been aware for some time) that occasionally In a case of asbostosls'(a slowly developing disease) supervening cancer may occur?' ' As to the third sentence set out abovo, it seems curious for tho report to state that the number of mon at risk who hove been exposed only to the now conditions Is at prosent too small for any cortain conclusions to be drawn* Tho position appears to be that (as mentioned In the report) among the whole of the employees of T.B.A.Co. first employod since 1923 (31 years ago) not a slnglo case of cancer supervening on asbostosls has occurred; tho period is lengthy and the number of mon must be substantial, and T.B.A.Co's records will show how many hundrods (if not ' thousands) of employees aro concerned* If the report roalises that valid conclusions can not always be drawn from a small number of oxamplos,.is It not Incon sistent for the report to draw such wide conclusions as it doos from a comparatively small number of asbostosls cases whose experience ' forms tho basis of the report? It applies its conclusions to the industry generally although such conclusions are based only on 1? cases (all first employod, on the old conditions, bofore 1931) arising during a period of nearly 20 years whore an employee suffered both from asbostosls and lung cancer and throe cases whore employees suffored from lungRancor only* 6* Tho final paragraph under the heading "Summary" on page 5 of the report states that from the data it can bo con cluded that lung cancer was a specific industrial hazard of asbestos workers and that the risk among mon employed for 20 or more yeors may have been of tho order of 10 times that experienced by the general population* Is thst conclusion soundly based, or is the only sound conclusion which can be reached from the evidence in the report to tho effect that lung cancer may be contracted by an asbestos worker who has already contracted asbestosis? t