Document rxx2gvEE5eqZB83DLKjnn1zq0

FILE NAME State of the Art Literature SAL DATE 1949 Jan DOC SAL048 DOCUMENT DESCRIPTION Journal Article - Cancer and Environment +t4w/24/83 ANUARY 1949 57 SCIENTIFIC AMERICAN 1949 VOL 180. NO 1 CANCER AND ENVIRONMENT . Scientific and technological progress have exposed man to new physical and chemical agents Some are believed associated with the rise of cancer as a cause of death by Groff Conklin ( THE industrial era in its full expan sion is barely two generations old yet during that short period literally thousands of entirely new chemical and ical constituents have been added to uman environment Few of these con- kituents have been exhaustively analyzed for their range toxic effects on man They are now being studied however as possible contributors to the rise of cancer The growth in the relative importance of cancer as a cause of death is one of been considered comparatively harmless It has been established that certain agents to which people are exposed in industrial nccupations cause cancer if the y eee @ oe ? Saran - Alpha roys Beta rays Gamma rays Ultraviolet rays rays the outstanding medical facts of the past 30 years The disease has moved from righth to second place in the U. S. since 1900 and today only heart ailments sur---- it The reasons customarily given for this improved diagnosis and the azing of the population not entirely explain it They provide no satisfactory answer to the fact that approximately seven and a half per cent of the known cancer deaths in 1941 occurred in age groups under 40. There is evidence more* that the disease is not an inevitable consequence of bodily degeneration due to age although the changes of senescence umier certain conditions may be con- tributing factors It seems certain that thee is a net increase in true cancer deutus if only because fewer people die from other diseases than in the past An explanation of this increase and of the causes of the disease is therefore | being sought our environment so much Pee nae complex than it was in 1900. The investigation is focused on carcinogenic agents as the substances that produce eureee are called and on the general question question at the extent to which the in- ' se ^fin camer may be caused by agents t he environment environment them have hitherto ' Asbestos - : Chromates Nickel carbamyl Beryllium Anthracene ail Aromatic amines Benzol * Carbon black Creosote Mineral oils Paraffin oil . Polycyclic hydrocarbons ; Shole oil Soot Tor and Pitch Aniline Azo dyes Estrogens Schistosoma hematobium hematobium Viruses Clonorchis sinensis -_ ao ee CARCINOGENS known to be pres ent in human environment environment are classic lied Less certain agents are in italies exposure to them is sufficiently intense and prolonged As an exampie over 15 per cent of the miners in the Schneeberg uranium mines of Germany die of lung cancer more than 50 per cent af those in the Joachimsthal uranium mines across the border in Czechoslovakia dim of the same cause In the 18th century it was learned that among chimney sweeps exposed to intense concentrations of sunt deaths from cancer were between three and four times as high as those the general population It is known also that certain common substances in concen- trated doses can produce cancer for example usouth cancers are uncommonis frequent in a tribe in India which smokes eigars with the lighted end in the mouth This causes them to suffer frequent burns and to receive a concentrated dosage of tobacco tars Although these are special cases of intense exposure they naturally suggest speculation as * whether the average human being's relatively mild but long- continued exposure to new substances in a contaminated atmosphere in processed foods in cosmeties and in other elements of our environment may be a contributory cause of cancer We have as vet no cons clusive evidence for or against illis possi- bility We have mis how many of the accurate estimate of artificial substanc common to nur industrial civilization may be carcinogenic under special circum staners nor how many seemingly harmid- + substances interacting with others that appear to be eqprally miocious duce carcinogenic results There an al COLESIN many may pre theories about cancer's eiusest chronie inter jcritations m11 the body changes in cell a q SINUS Nickel carbonyl Wee ee 1 ea em oe q MOUTH Betel nut and tobacco chewing ee 4 THYROID Jodine deficiency ~. 4 BRONCHI Nickel carbonyl Radioactive substances - : 4 LUNGS Asbestos Mo Chromates 7. Nickel carbonyl Radioactive substances a q UVER Distory deficiency 4 BLADDER Aromatic amines Schistosoma hematabium eae OS 4 URETER Aromatic 4SCROTUM Soot tar and < ; e7 metabolism tissue degeneration viruses sub on Most of these theories how ever describe mechanisms rather than first causes Indeed with two or turee ex- ceptions all of them seem to require the presence of a triggering agent Possibly the most fruitful current theory is the one that attributes cancer to mula- tions in body cells causing mutations it has been demonstrated by experi ments may be produced by ultraviolet radiation rays radioactive substances and a number of chemicals While more than 99 per cent of all cancers are still of unknown origin nearly all of those for which a proved cause has been found arise as the result of external agents These seem to mutate the cells into a state which is or can become cancerous The methods by which these external agents act upon the body vary considerably depending on the substance involved Some carcinogens may cause cancer directly Examples of these are tar the mineral oils and certain dye intermedi- ates known as aromatic amines Tars gen- erally affect the skin Mineral oils may cause cancer of the lungs through inhala- tion The aromatie amines strangely con- centrate on the bladder no matter what their route of attack Whether they enter the body through the respiratory system the mouth or the skin they gravitate to the genitourinary system and there build up a concentration that eventually causes cancer Other agents seem to cause cancer by altering organs so that the organ itself produces a carcinogen resulting in a cancer The mechanism of this transformation is little understood It is known that some radiations and certain metallic compounds including the chromates the arsenicals nickel carbonyl and possibly asbestos cause cancer in this relatively roundabout way . } | SKIN Radioactive substances gek J Soot tar and oils BONE BONE MARROW Radioactive substances es e we os ab o ey ORIGINAL SITES of malignant growths due to carcinogens in the en vironment are scattered among almost all the organs of the body Some agents such as the aromatic amine dye intermediates regularly affect the sathe organs even though they may use any one of many routes for attack RADIO ACTIVE materials are less spi cialized in their effects they can produce a wide variety of cancers They may cause skin cancer by direct attack on the skin and lung cancer in people who inhale radioactive dust When expos sure is intensive and prolonged as in the case of the women who worked in the radi- un watch and clock dial industry some 25 years ago they produce bone cancer And a slight but very prolonged exposure exposure to penetrating radiation can result in leukemia a cancer of the blood cells The latter kind of cancer is often foumi among radiologists whose whole professional lives have been spent in theoretically safe and protected dealings with rays or radioactive materials Most subtle of all carcinogens are those believed to cause general metabolic disturbances that produce cancers in roundabout way Thus the liver may produce carcinogens that can cause or some udher tissue to turn malignant Among the agents thought to have this effect are the  4a se - 3ds r~ ~ and 3ds and certain eblorinated aliphatic hydrovartions But the mechanism ins v^lverk is so obscure that the carcinogenjeity of these sulestaners has not been com- Vetely priced One aspect of such indirect causation however is susceptible of proof Among Some Negra tribes working in the gold mines of Africa an excessive incidence of cancer of the bladder has been traced to deficiencies in the workers diet It was found that most of the Negroes had lived lor years on deficient diet of pap and sour milk Only recently South Afri- can research workers have succeeded in producing cancer of the liver in rats fed just this diet IN view of the relative novelty of the con- cept of environmental cancer and of the small amount of organized research in this field it is not surprising that most of the known carcinogenic agents have been found in industry Here workers suffer exposures many times more concentrated than the average citizen en- metaleslie differences were completely understood luman beings might be endowed with resistance to certain types of cancer by modifying the individual's metabolic processes Such ideas are still beyond the realm of practical application in man In experimental animals however cancer susceptibility or resistance to certain external carcinogens such as several of the azu dves may be created at will by the omission or addition of certain vitamins in the diet Without animal experimentation scientifte proof of the carcinogenicity of various substances and radiations would be nearly impossible On the other hand laboratory experiments alone cannot prove definitely that such agents are dangerous to man Other methods must be used and the principal instruments so far available have been statistical studies and medical rec- ords In large unselected population groups variations in the incidence of one kind of cancer are usually not sufficiently marked to be significant That is why environmens men who are employed in these plants Obviously Obviously such investigations present difficult problems and demand a high order of judgment has often been said that statisties can be useil to prove both sides of a question Environmental carcinogenesis is no exception An example in American experience is a study which was made some time ago of the incidence of lung cancer among 10,000 workers in an industry suspected of pros ducing a carcinogenic agent It was known from studies in other countries that lung cancers were exceptionally frequent in this industry and there was no evidence that American manufzeturing methods differed in any major respect from those abroad Yet this study reported no lung caneers at all In any group of 40.000 adult males several cases of lung cancer are bound to occur merely in the basis of the incidence of the malignancy in the population as a whole The results at the study surely suggest a lack of thorough- ness in the collection and evaluation of data counters in industrial environment Fully 90 per cent of the known careinugenic agents are industrial and a similar proportion of cancers of known cause arises from carcinogens of industrial im- portance These known agents are listed in the chart in page H. The difficulties in the scale study of carcinogenic agents are formidable The mislern environment is su ramified that efforts to evaluate it in terms of long range carcinogenicity may appear nearly Impeless Nevertheless the techniques al ready developed in the study of cempa tional carcinogens may be of some value in analyzing the environment as a whole even though more refined methods may have to be developed if such a program is to be successful The two principal methods now used to uncover the more obvious occupational cancer hazards are animal experimentation and statistical analysis Cancers have bern produced in experimental animals by most of the known physical and chemical carcinogens Hundreds of other substances have been and are being tested Some that have been shown to be carcinogenie in animals have not as yet been proved dangerous man or else they do not form a part of his normal environment Among these substances are urethan ergot sele- sium and diethylene glycol One aspect of the work on animals that is important in consid^ringhuman cancer is the phenomenon known as species specificity Many carcinogens that cause cancer in some anim^lspecies have thus far proved harmless to others For exam ple certain tars when correctly applied produce skin cancer in mice rats rabbits and dogs but not in monkeys Rats and mice get skin cancer from ultraviolet rays but rabbits do not The probability is that specialized metabolism is at the bottom of this species specificity for cancer If such tal carcinogens are usually difficult to detect Up to half a century ago indeed evis dence of specific extrinsic causations of cancer was discovernil largely by clinical observation Physicians practicing in urban or manufacturing areas began to notice a remarkably high incidence of cer- tain types of cancer among workers in individual trades Sitch was the case in the diagnosis of cancer of the scrotum ^fin chimney sweeps Discoveries by direct ab servation continue to be made as in the case of radium and ray cancers that in's curred with alarming frequency among people working with these agents in the not distant past BUT observation has its limitations Un- less very careful medical records are kept or unless workers remain in a earcinogenie job for many years the fact that the job is carcinogenic may escape notice Characteristic of environmental cancers is the long period between the beginning of exposure to the carcinogen and the actual appearance of a tumor A worker who leaves a dangerous job before the cancer appears may later develop a malignant tumor without realizing its origin The process of tracing cancers to their source through medical records and health statisties has become a work of skilled de- duction When agiven community is found on careful examination of its illness and mortality statistics to have an nousual number of cases of cancer in certain sites the biometrician at once suspects the prese ence of an active environmental carcinis gen The chances today are very great that it will be traced one or more factories in the area since so few industrial cur- cinogens have been found Conversely if it is known that certain plants are priducing or using known carcinogens the statistician searches for evidence of au abnormal incidence of caneer Jamong CLEAR example of the intelligent ase of statistics as a tool in uncovering environmental carcinogens is the way in which cancers of the bladder were identi- lied as an occupational hazard in plants using the aromatic amine dye intermne diates mentioned earlier The following composite description based on a number of European and American investigations of this problem illustrates the method The people in a certain industrial region have a frequency of bladder cancer that is a slight fraction higher than nor- mal The variation is well within the range of random probability but the fact that several cases of this not too common ma- lignancy have been found in a single community leads to a further study of the region It is found that the incidence of bladder cancer jumps from .02 per cent in the province as a whole trs 21 per cent in the particular community under study an increase of 400 per cent On further investigation it is learned that among the workers in a particular dye plant in the town 5 per cent are suffering from or have died from bladder cancer- mearly a 5.000 per cent increase Follow ing this clue every operation the plant is studied and one particular job is frerend in which over 90 per cent of the workers have hladder cancer or have died from it Obviously the focal point of the disease has been established It is from just such relatively slight statistical anomalies that much of the original esidence of carcinogenesis in industry arises Of course as more carcinis gens become known and are added to thre list the statistical techniquesehange techniquesehange With the cooperation of the industries involvest mertical and public health experts go .. rectly into the plants and study the opera- tions and the workers Otten Juuwpver pubdie medical and death records offer the 13 unfy'reliable unfy'reliable source of information Many jadustries actually do not know of the ex- jstemer ul carcinogenic hazards in their pictories The study is so new that only Fants in which the incidence of specific cancers is notoriously high are aware of the problem A few industries du know of the existence of carcinogens in their plants and probably some of them have developed their own methods of coping with them The reluctance of industrial manage- ments to publicize the existence of a car- cinogenic hazard is understandable for it could easily become difficult for plants so labeled to recruit workers or even to sell their commodities To make factories eme ploying carcinogenic materials safe to work in furthermore sometimes requires extensive and costly alterations If one firm makes such alterations and others do not the competitive position of its product perted The incidence of lung cancer did not diminish ^fin faci soon afterward canvers began to appear among workers who had been exposed for less than six years a nich shorter period than had been previously observed What had happened was that at the time when the protective measures were adopted the factory had also begun to use a more finely ground materia to improve production The finer dust though present in a much lower concent tration than the original material pene- trated farther within the bronchi of the lungs Thus despite the installation of the latest in protective devices and procedures the cancer hazard was actually increased It is therefore that the control of occupational carcinogenesis even to a great extent of cancers stem- ming from more indefinite environmental closed that the community be protected by the prevention of the discharge of earcinogenic wastes that factories be li censed and inspecter that workers be provided with protective clothing equips ment and medical supervision including frequent and thorough ical examina tions The Environmental Cancer Section of the Institute which is a part of the U. Public Health Service is preparing an immediate comprehensive campaign of education and information the purpose of which is to being physicians to a realization of the existence of the problem Plans are also under way to make exhautive surveys of major industrial areas in the nation These studies are essential preliminaries to the institution of the controls that Dr. Hueper has suggested Many of the control recommendations admittedly are reaching in their impli is endangered Generally speaking however employ ers are no more responsible for the lack of information about industrial cancer than Percent of total possible sunlight * Skin cancers per 100,000 population are the many thousands of physicians win have cancer patients in industrial areas ur who actually are associated with factories It is an unquestionable fact that an appreciable number of occupational cancers -lip through the hands of doctors unidentified This is due in a great degree to a orp =X DALLAS 60-80 percent 140 errr general ignorance of the occupational as pects of cancer Physicians have never been adequately informed of the basic feet symptomatic and sociological factors in- volved in identifying occupational carcino ORLEANS NEW : 62-64 percent J / 129 genesis HE medical profession should be bet- ter educated about the need for exhaustive case histories which carry the individual's job record in detail back as far as 25 years about the urgency of check- ing medical suspicions of industrial cancer hazards against careful epidemiological studies of all the workers in a plant and about the paramount importance of impressing plant management with the seriuusness of the problem The standard protective and hygienic measures currently used in industry to combat industrial poisons and other health hazards are not always adequate for the control ol occupational cancer The following ease history is a compelling illus tration Some 30 years ago workers in one of the newer metal industries began to develop lung cancers At that time the cancers were found to remain fatent from to 15 years The incidence was unusu- ally high in certain operations where the carrinogenic substance was present in par- nieularly high concentration as an air- Murne dust An effort was made to safe- guard these operations date equip ment for removing dust and fumes was installed and a standard industrial hy- giene program was inaugurated including including including protective clothing But the outcome was exactly the opposite if what had been ex- ee: : , PITTSBURGH * * 50-57 percent 37 | DETROIT * 25-40 percent 24 CARCINOGEN IN NATURE is sunlight Such natural carcinogens however are few An abnormally high concentration of arsenic in drinking water has been shown to eatise cancer of the skin and internal organs Infees tions of certain parasites have also been found to lead to malignant growths growths agents if and when they are discovered is a public health problem of considerable magnitude This is made even more apparent by the scupe l a control program that has been proposed by Dr. Willielina C. Hueper head of the new Environmental Cancer Section of the National Cancer Institute Dr. Hueper one of the world's leading experts sin occupational cancer has studies the problem the U. S. and elsewhere for many years Several of the elements of his program have already been put into effect in European European countries The program proposes that carcinogenic agents be eliminated from industrial milj tary and civilian use as far as is possible and practical that manufacturing process- vs which must use such materials be en cations Years of work will be required to put them into practice with maximal eifretiveness This is particularly true of the recommendations for social controls On the technical side some of the elements can be instituted at once and without great expense management and labor can be persuaded to agree to them For example effective medical and sani- tary supervision supervision supervision of exposed exposed workers can be undertaken immediately This supervis sion should include ray examinations at Frequent intervals caretul etinical stuiv of suspicious lesions preparation of ex- haustive and netailid job analyses analyses and ease histories regular quarterly or semiannual physical examinations examinations of all works works ers who might possibly suffer exposure to ove . the carcinogenic agents a constant review of dangerous plant operations to enforce constant good housekeeping and to check the level of carcinogenic dusts fumes id mists Protective measures for the workmen themselves are also simple and relatively inexpensive although the enforcement of their use is sometimes made difficult by the discomfort they cause They include the ee ret regular wearing of respirators and sealed clothing whenever exposure to a carcin~--- rere genic hazard is likely daily showers for all persons working in or near the hazard- Pt ous operations use of separate lockers f^,r en street and work clothes and adoption of work techniques that will minimize the dangers of exposure Fa Other and more important technical measures are likely to involve heavy ex- penditures for management In some in- stances entire factories would have to be rebuilt Others would require costly control equipment such as elec tronic dust precipitators and extensive remodeling to enclose carcinogenic opera tions and keep the workers from any contact with dangerous agents Few plants could afford the necessary changes unless all other plants in the same industry were required to make the same improvements at the same time : N some instances such changes might possibly be undertaken as a result of ry industry agreement In others Megislative and administrative enforcement might be essential Such action would in- clude factory licensing and inspection by government improved compensation laws recognizing occupationally acquired can- cers as compensable and revision of the health codes to make occupational cancers ; notifiable just as are many other diseases These measures would require coordinated and carefully planned action on the part of management labor the medical profess sion state public health and labor departments and state and Federal legislatures A precedent for such a program has already been set by the successful control of communicable diseases through public health laws and through the organized : comperation in their enforcement of both private and public agencies How effective these controls would be in diminishing the hazards of still undiscovcred environmental carcinogens is a question that only time can answer Mean while the known causes of occupational cancers would be placed under technical and social restraint and patterns would be established for the future control of new carcinogens as they are found in our environment - ~ ee e ry POPULATION OF WHICH PLANT LOCATED <4 percent percent affected ed 8 ae welt WORKERS EMPLOYED IN vee ~ e : THE ENTIRE Oe} <8 whe eee WORKERS IN DEPARTMENT WHERE CARCINOGENIC ACTIVITY TAKES PLACE Nesoe +: 20-50 percent affected . ea) ee SS oP te. ; re TT WORKERS DIRECTLY INVOLVED The, go IN THE CARCINOGENIC ACTIVITY me 90-100 percent affected Grof Conklin is a science teriter and a former consultant with the Na tional Cancer Institute EXTREME CASE of environmental cancer is represented by record of aro- aromatic amine plant in Germany Of workers directly in contact with chemicalchemical 90 to 100 per cent developed cancer of the bladder Running from top to bottom is illustration of statistical analysis used to locate such hazards hazards 15