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' s.-' RFEKNC PEES CONSULT IN I2B2U2Y A. 1 A. ARCHIVES OF ygiene EDITORIAL BOARD . PHILIP DRINKER. Qiiti Editor U Shateacit Stmt. Boston U CHRISTOPHER LESGO, Cnekrtt. CallC. OSCAR A. SANDER. MU' ROBSCT O'CONNOR. Bostoo H. a. SCHRENX. PlttsaorsJb 5RANE PRDfd, Clatiasatf CHARLES F. SHOOK. Toledo ~ HERBERT E. STOKINGtH. Oaelnsaa JUNE 1954 VOLUME 9 DUMBER PoMiiM MontMr Or AMERICAN MEDICAL .ASSOCIATION 3S NORTH DEARBORN STREET CHICAGO IQ. 1LUNOI3 Eatcrad as Second CIiss Mssar Jas. 4. 1910. at tbs PmtidSra at Di als. Undsr tbs Aa at Morcfc 1. 1179. Aaauoi Suoacripuoa. IS.00 4 TABLE OF CONTENTS FIRST PAGE ms iJSi ^ & &g3s&z* S$ . S.'Tt +*' . ` tt'/a.' . *>T*. __ - - ';> 5*i3atr~; rvw 5 .& asa^se. r*f| SS b.t ft sen } 83$|p 5** 3sSsti/&* Sftfiis&se- - ssi4*-i;~Sr % $*&*?$*; <?* Ca5r='" ,c.*y r .- "Vs ^aC8-"^V'^Mr* * ViT "Se *SS?r5T- >. p rP*wf ^ftr. - - ;Sp* lW-C>*4 &'<U s. A. M. A. , Archives of Industrial Hygiene and Occnpational Medicine VOLUMZ 9 JUNE 19S4 CopmicsT, 19K rr ms AsniGut Miwgil AutKUTion Editorials EXPERIMENTAL LUNG CANCER GREAT caution must be exercised in assigning a causative relation between inhaled materials and lung cancer in human beings. In considering the cause of lung cancer and in experimental studies of lung oncer, one naturally examines critically those materials which get into the lungs and which may have a local effect on lung tissue. Thus, various industrial dusts and fumes, tobacco smoke, and exhaust gases from heavy automotive traffic have been suggested as possible factors in lung oncer. These materials lave been tested chiefly on the skin of mice. However, the mere demonstration of materials in the air which are"known be carcinogenic to nouse skin is not proof that they can ouse human lung cancer. Experimental caranagenesis has aught that different species react differently to the same material (i. e^ the mouse skin is very receptive to methyichoianthrene but the rat and guinea pig skins are very insensitive) and different tissues of the same species have widely varying sensitivity to the same material (i. e_ the rat skin is unresponsive to car cinogens but the rat subcutaneous tissues are so reactive that they respond with sarcoma production even to glucose). Human epidemiological data give the only really sound way of associating human cancer with an environmental exposure. In the collection of such dao, a sufficiently large sample must be obtained to permit satisrial analysis and valid conclusions. Even so, causal relationships must be further validated by continuing epidemiological methods, supplemented by animal experimenation. It is neither valid to conclude :har animal experimenation provides definitive answers to the human cancer problem nor valid to conclude that it offers nothing to an undemanding'of the human cancer problem. Intelligent use of daa obtained with animals should be coupled with intelli gent application of the information learned from human epidemiological data, is order to understand the further research effort needed and the pracrial control methods indicated. Skin caronogenesis in the mouse has been used, and effectively, as a guide to the control of potential occupational skin cardnogens in mao. The whole held of experi mental skin carcinogenesis arose out of the epideniologiol studies of occupational skin cancers in numans, begun some 35 to 50 years ago, .-and y today a complete undersanding of the mechanism of human skin arrinogenesis has by no means best realized. For instance, the relative imponance of carcinogens and co-carcinogens in skin caronogenesis is still being intensively investigated. The mechanism of lung carcinogenesis in the mouse has not yet been worked out. let alone this mechanism in the human. We are today in about the same stage of understanding lung carcinogenesis as we were in skin carcinogenesis in 1900, prior 449 jlsgaggs'.',. INDUSTRIAL HYGIENE AND OCCUPATIONAL MEDICINE to the ardfidal production of skin tumors in experimental animals. A study of occupational lung oncers suggests that a completely different set of mechanisms may be at work. Thus, chromium and nickel under some conditions, asbestos, and an as yet unidentified factor in isopropyl alcohol manufacture are today most suspect as human pulmonary carcinogens. The only experimental lung cancers produced by inhalation have been in response to beryllium and radioactive metals. It therefore seems highly dangerous to draw conclusions about human lung cancer from experimental evidence hased on the presence of mouse skin carcinogens. Rather would it be wiser to display temperance in the interpretation of present day data until we have developed a much greater fund of knowledge concerning the mechanisms of lung carcinogenesis. Ro>ox r Psan Duxsaa (Courtesy of the Sarirday Revira and of the artist, Robert Kraus.)