Document jBwMRe7XzNERyg3MZQqZ2v5eZ

^ fcture m 284 27 March 1980 str* U s v-S-ft - :r:: r -.in pr;o** cxPi ' * ^ "iTc--* jffrM,s*--. --1TT1 iW^ri JIIuI 'IvI*IW%jj Toi ^Distorting the epidemic! GT y* C? linx?.e H00^ for a more ^W - 297 . ' I : ^ - -m g of cancer: overview '**... =* ' ' JyVtS ft** . *4>- jjThe poiulcs of cancer are becoming increasingly polarised with ^;environ:ncRtalists taking one extreme view and industrialists the . T other. Richard Peio argues that a more dispassionate and disinterested approach is required for a realistic assessment both oi the risks from environmental carcinogens and of the t^fprr1 eventative- regulations needed Thexe exist, botr, in the general the consumers of their products, their environment and :.i certain occupations, immediate response has usually been to : :v,cTiical or physical agents which increase delay acceptance of the findings, to :m likelihood of human cancer. Our minimise their relevance to current : po!i::;a! response to this would, in an ideal practice, and in general to delay or obstruct frv*of:<i c ?cffisi*r.t knowledge was any hygienic measures which will cost ' iMiiat't.. .nta'.r'. o.i the direct and indirect money. Even when human danger has been ivVtjsts v* -/aridu* possible measures of unequivocally demonstrated, industrial jtVroc::,-.; s.ic jn now many cancers each . consortia may actively lobby for controls ST^jurV r.^isurf would prevent. In the real so weak that (as with the new UK animate* of the direct financial government regulations limiting inhaled ' nr the control of particular agents can asbestos to 1 fibre/ml from 1981) they ^ differ by one or two orders of leave no reasonable safety margin. Large V">4situde, the indirect costs may be amounts of money are available to mount ; crossly exaggerated, or some major press or TV publicity campaigns about the v... indirect costs may be completely homely apple-pie virtues of`asbestos, * overlooked. Worst of all, we have in journals financed by the tobacco industry t: ftnerai no remotely reliable estimates of run populist articles which misrepresent *'. the numbers of cancers which particular research results to lay readers,- and some legiiletive controls would prevent. US television journalists are explicitly told *Consequently, there is wide scope for always to ce or all refer- 'ce - the jK pressure groups to have considerable dangers of smoking. iter-:licence on public policy, Even the scientific literature is not j- r Historically, the most powerful pressure immune from distortion by financial 41- paups in US society have been the large interests. The decades-long argument that jjs financial interests, which have almost "threshold'' dose levels of carcinogens ij!' tlways put financial advantage before must exist below which the general kj. taiTia health. Over the past few years the population is absolutely safe has not been major tobacco companies have launched entirely motivated by the scientific - f missive sales drives in the Third World, plausibility of the hypothesis'. With ' ..Thiel; if successful will kill millions of increasing understanding of the derivation `people. (About one in four regular of tumours from single ceils acted on by -s-'ette smokers is killed prematurely by mutagenic carcinogens, industry is slowly .smoking.) In the US, where cigarettes abandoning "threshold" arguments in vi ..tsaie well over 100,000 deaths every year favour of arguments1,2 (where the -jl. frc-a lung cancer or chronic obstructive biological fallacies1,4 arc somewhat better *wi: disease, the tobacco industry refuses concealed by the mathematics) that ' : w accept in public that cigarettes cause thousandfold reductions in dose can 1 (t.her disease, let alone to collaborate in ' conveniently be "statistically guaranteed" '.i- wrinus public information, and no epithet to produce a million-fold or some other suitably describe the collective efforts enormous reduction in risk. < .oftheir advertisers. Even if the scientists who propound suejx ',fi otbcr industry kills people on models are disinterested, industrial ' line the scale that the tobacco endorsement of them is not. Much does, but where other industries excellent toxicology may be done by ba found to cause cancer (or dust- industry, and many industrial scientists ^T '-'duted lung disease) in their workers or in and managers may be directly and honestly - ; $^~r'i Pt:o is a reader in cancer studies at the ' 'ii yM'r!iiy of Oxford. This article developed , * v'*!'* " review of Samuel Epstein's book. The riarct r.f Cancer concerned with the prevention of hazards. But so many examples of financially* motivated bias exist that the motives and wnrlr csf tnHtufrtal gnH consultants are inevitably distrusted. : Over the past quarter century, the '' "environmentalist" camp in North American society has pressed for (and achieved) stricter control of particular carcinogens in the work-place, the general environment, and the diet. Usually, their : efforts have been directly resisted by the relevant financial interests. Inevitably, in view of the scantiness of reliable quantitative knowledge about the cancer -- risks to man of nearly all carcinogens, the argument has polarised. In the politics of cancer, each side takes a very extreme position. Industry usually argues for the irrelevance to man of animal or in vitro cancer tests, or minimisies the quantitative hazards and exaggerates the costs of control. The environmentalists usually exaggerate the likely hazards and are largely indifferent to the costs of control. `The most powerful pressure groups in the US have been the large financial interests which have almost always put financial advantage before human health' The vacuum of reliable scientific know ledge is such that each side can find scientists who will maintain in courts, in public hearings or in the scientific literature whatever is politically conven' it, and it is important to recognise that scientists on both sides of this debate now have career, interests at stake in it. A particularly good example of the biased writings of politically active environmentalists is Samuel Epstein's The Politics of Cancer (Sierra Club Books, 1978, revised in Anchor Press, 1979). Epstein outlines, for university-educated but not necessarily science-educated readers, his view of our present state of knowledge about prevention of death from cancer. He concludes that the cure rates for the major cancers have not been improving much over recent years, but that we do know enough now about the causes of cancer for the testing and regulation of environmental contaminants to prevent the majority of US cancer deaths, and that the main obstacles to our doing so are political rather than scientific. He therefore reviews the scientific and BFG06481 298 i -iure VoL 284 27 March Wo dozen or so disputed consumer products or occupational hazards, providing much fascinating political detail,' and then describes at length the internal politics of the various agencies which research, regulate and litigate in Washington. have refuted it (see table). This appears to- `Scientists on both sides of be a deliberate attempt to deceive the reader. It is not a casual slip in a 600-page the environmentalist : book, as Epstein devotes twenty pages and debate now have career ' two full-page tables to saccharin. His entire table 6.4, entitled ` 'Tumours other than the interests at stake' Epstein's book has been written to inflame political passions against environmental carcinogens, and parts of it bladder in rodents fed saccharin", appears to be so subject to artefacts ofselection that it provides no evidence that saccharin does - vriTzmerely be acting as a vehicle forfat-soluble " t-Y* pesticides and industrial chemicals,~whidi 1 I '"'are well worth reading. However, the cause any rodent tumours other than in the predictably emerge as his villains yet again. political punch is often achieved at the rat bladder. However, his suggestion is implausible: . mm.it ) expense of scientific accuracy and balance. Saccharin is not an isolated example of countries with high levels ofcontamination ) Despite this, the book has already gained bias; indeed, I found that in many places do not stand out from the general 'V..-. wide and apparently uncritical acceptance where he discussed data with which I was cancer/fat relationship, colorectal and "-even among scientists. For that reason, it is familiar inaccuracies were present, almost breast cancer were common long before the - worth considering some of the always in the direction of accentuating the widespread use of pesticides, and in misrepresentations of scientific evidence need for battle with the devils of industry. experimental animals high-fat or Iow-fat which it contains, and some of the more general defects in the environmentalist perspective on cancer. First, a few details. Epstein's book is Turning to more important matters, diets can greatly enhance or reduce die risk Epstein asserts that any benefits from the - of cancer". Something more interesting is :. "less dangerous" cigarettes which the waiting to be discovered in our diet than tobacco industry has developed will be simple contamination by carcinogens. very useful as a source of reference to original papers, but it is not in itself a reliable secondary reference because the material printed it tn pftry rtutnrfiirt Sometimes thil Hictnrtwwi i<; due to the efrects~orEpstein's vigorous campaigning style on his scientific judgement and is, nerhaos. forgivable: at other times it outweighed by people increasing their consumption to get more nicotine, and he is therefore in many places particularly scathing about (or even downright opposed to) research into changed cigarette composition. This is a distorted perspective on one of the more promising immediate means of preventing fatal The fat-associated and smoking-derived cancers collectively account for more than half of all cancer deaths, and people concerned with cancer politics should ttyto understand them considerably more accurately than Epstein appears to. One can list many other instances where Epstein's content or style are misleading or EaJSsSt r.icfSr. appears to oe deuoerate, wmch cannot so easilybe forgiven. ^ Tot example, consider the (by now generally agreed) finding that incor poration of about 5T by weight of saccharin into rat diets gives a few rats bladder cancer, but has no generally accepted effects on any other type of cancer. By human standards, ST repre sents a vast saccharin intake (and so, of course, the industrial "Calorie Control Council" have tried to shrug off these findings). To refute the common reaction that "anything given in large enough doses will cause cancer in animals", Epstein's chief argument is to report that 0.01 To saccharin has also been shown to be carcinogenic. In support of this extra ordinary claim, he presents in tabular form the control and 0.01 To data for selected cancers from certain multi-group feeding experiments, leaving out the observations from those same experiments which would cancers, a quarter of which in America are currently due to smoking. Smokers of "less dangerous" cigarettes have already been found in various epidemiological studies to have disease rates which are materially lower than smokers of other cigarettes*-7; at autopsy they have far fewer "pre-malignant" histological changes in their bronchi' and, perhaps due to the changes in cigarette composition 10 or 20 years ago male lung cancer death rates in early middle age are now decreasing in North America, in Britain and in Finland. After lung, the next commonest fatal cancers in the US are those of the breast and the large intestine, for which the most striking epidemiological finding to date is a 90To correlation between fat consumption in different countries and their breast or colon cancer rates (see figure; similar correlations exist for colon cancer10). Epstein suggests that dietary fat may unbalanced. For example: The discussion of alcoholism and cancer is entirely erroneous because of failure to standardise properly for age. One of Epstein's chapters ends: tJK.wt -'a oiJ-'.irV. "Eisenhower warned against the growing national threat of the military-industrial complex. The medical-industrial complex now appears to be as serious a threat". There is idealisation of the value of long term animal tests with concomitant denigration of the value of the Ames test and other short-term tests. This is one of Epstein's most inexplicable errors of scientific judgement, unless he wants fviSvsccancer tests to be difficult and expense for industry. He is irritatingly puritanical, sneering at "the plastic age which symbolises how the value of our lifestyle has been degraded". He seeks by stylistic tricks to attribute to oral contraceptives some of the established hazards of hormone replacement therapy and of diethylstilboestrol. Table: Data from OTA report1 on the tumour sites selected for presentation in Epstein's book to substantiate the claim that 0.01 Ts saccharin is carcinogenic. Croups selectively omitted in Epstein's book are marked with an asterisk. These omissions substantially alter the implications of the original data. He claims that cancer costs the US economy over S23 billion per year. (In fact, cancer must be prevented for humane, ao< for economic reasons; without cancct, Saccharin dose (Te in rat diet; these doses have no material effect on longevity) , - Male or female ' lymphosarcomas (FOA, 1948) - Female breast (FDA, 1973) . ` '. ^ Male breast (FDA, 1973) 0(control) 0.01 0.1 '. 0.5 S 0/20' (0%) ' - 8/14 (57%) : 3/16(31%)* 2/15 (13%)* ... 1/18 (6%)* 10/17 (59%) 6/26 (23%) 14/30(47%) 13/34 (38%)- 12/30(40%)* 12/27 (44%)* 6/29 (21 <7,) 14/23(56%) .. . . 9/27(33%)* 8/27(30%)* 7/23 (28%)* Omitted in Epstein's book. In addition to these 20, since some other sweeteners were being tested concurrently, 34 other control animals were studied in the same experiment, and the 1977 OTA review of these data, considering all the control animals to be equivalent, cited 9/34 control lymphosarcomas. (0/10 saccharin controls of each sex were studied, not 0 '70 as Epstein indvert y indicated.) there would be three or four million more retired North Americans to support, costing over S23 billion per year). And so on. He seems so certain about everything--how can anybody be justified in being so certain aBgGrWmarvy-detaili? Sometimes-! know he's wrongT^uTBlore often (especiaUvln~th'e~ffiany~Btacerwhcre inconcluslvescientifrcresults-ar e presented as estabfishccTTact) TknoWthat-rwbodT knows for"iure. Lewis Thomasonce wrote, in another contexu^Tfic sceptics g medicine have a hafd.UmSjbnt. It is mudT more difficult ,n hfl i-fm'/ini-?*ft--hnul ' ignorance concerning disease mechanisms 002<0*M/0/>3Z9*-0:SO!.00 U-r-ibld .than ii is lo make claims for full c od additives. Indeed, one of the most "comprehension, especially when the. ii. .guing animal findings is the effect in 'comprehension leads, logically or not, to many studies of gross aspects of diet on `Pre it day cancer rates and trends are probably ; some sort of action. When it comes to 'serious illness, the public tends, understandably, to be more sceptical about : the sceptics, more willing to believe the true believers." "f Epstein (like many others) is cancer; for example, mice randomised between 5g of food once daily and ad lib consumption averaging 6g/day of the same food, had respectively S% and **% spontaneous mammary turnout ', ana the role of dietary fat" has already been not dominated by v iWSHtMs occupational carcinogens ` l"" i'r'i S'! j. or environmental pollutants' M. jstrlt: unjustifiably definite about three major discussed. issues. He seems certain that even after the Thirdly, Epstein seems certain that at both of whom still seem more ready to effects of cigarettes have been allowed for, least a quarter of all cancer deaths are defend than to repudiate it. Americans live in an era of rapidly attributable to occupational exposure to Entitled "Estimates of the fraction of increasing cancer rates. But trends in carcinogens. There is as vet no good cancer in the US related to occupational ' recorded cancer death rates I And. perfiaos evidence for hazards of anything like this ' factors", i.t shows how a rouo of tnnrg so. recorded ineirienre rates') over the magnitude, and there is clear evident that reasonable men can collectively generate u past quarter century are biased upwards , many of his particular claims, are air unreasonable report. The group exaggerated-. For example, he says that multiplied theTfnuluon Workers exposed asbestos has led to approximately 50,000 in any way in 19724 to any of asbestos, As, ( improvements in medical care and cancer . deaths per year in the US from cancer and Ni, Cr, benzene or petrochemicals by the .-^counting. These improvements have related disease (referencing a paper by very large risk factors (e.g. fivefold lung |`The NCI-NIEHS report Selikoff11 which actually neither makes nor ` cancer excesses) typical of much more implies any such claim). This is sheer extensively exposed industrial populations, [/shows Iiow a group of [ reasonable men can [ collectively generate ah [[unreasonable report' nonsense; of 50,000 asbestos deaths, several thousand should be certified as being due to pleural mesothelioma, yet only several hundred per year are thus certified. Likewise, Epstein cites with approval finally multiplying again by "4-5" to allow for the additional cancers that will be caused by these six agents among workers exposed to them at times other than 19724. (In casual disregard of dosimetry, this whole process is very like predicting (indeed, he describes it as being of 100.000 occupational lung cancer deaths, a v affected all sectors of US society, but most "epochal significance") Health, per year among non-smokers due to their V * 'j jjjparticularly old people and previously poor ^([people, especially blacks. Epstein, along j-n-with most other US commentators, does Education and Welfare Secretary Califano's absurd 1978 estimate, in a speech to labour union leaders, that as stsexposure to other people's cigarette smoke at work, "since 207a of heavy smokers get lung cancer"). j^jnot allow for these biases even to the - many as half of the 8-11 million workers These assumptions "predict" over -.1--, Svf- ``.limited extent of restricting his attention to who have been exposed to asbestos could 200.000 extra respiratory tract cancers per -trends in age-specific mortality rates develop serious diseases such as cancer or year in the near future due to the above six vfimong middle-aged whites, where they asbestosis. In his second edition, Epstein agents alone (and are the sole source of the hmight be expected to be least prominent. draws extensively on Califano's source, a currently widespread prediction of !: Among middle-aged whites during the curious but extremely influential document "20-38%" of cancers being due to Ifpast quarter century, cancer cure rates have which has been circulating privately for the occupation). But, in reality, fewer than >^aot materially improved, but some US past year at more. This unpublished 90.000 males/year get respiratory tract s cancer mortality trends seem to be typescript, with no listed authors, was cancer in the US (and most of these are due ^"genuinely down (stomach, cervix) while prepared by a working group of nine well- to cigarettes and not to occupation at all), ii'iome seem to be genuinely up (pancreas, known scientists including Arthur Upton and moreover the US male rates in the first tvbelanoma, and certain lymphomas). I can and David Rail, the National Cancer 25 years of working life are currently ^'discern no net pattern other than that due Institute and National Institute of decreasing! A prediction of 100-200,000 the massive effects of smoking on lung Environmental Health Sciences directors. extras due to the above six agents is clearly ft cancer, although no extension to 1978 yet iVexists of the excellent 1950-67 trend Flgnrc: data plotting for 39 countries age-venus total dietary fat (animal or standardised breast I'j analyses in NCI monograph 33. In Britain, cancer death rate vegetable). ' . . - r' thc same is true11.as long as we examine i-: mortality in middle age. (Interestingly, f" although Epstein emphasises that bladder i. cancer death rates among whites in the | industrial north-castem US are high, this ri nay not be chiefly due to any current industrial hazard, for they have been decreasing both relatively and absolutely tr. for a quarter of a century11.) * Epstein also seems certain that the 25 C. e. 20- 15 Female ocn *Nw ZEAkAAO ' .OELarcA5'*''!!^ - ' BEl&UM -Australia SaEOEN , .. i rraur NORWAY FRANCE* . CZECH ^-..majority of human cancer is caused by PORtuCZ*. >\inGARv ^'/chemical and physical agents in the > `environment and could be prevented by 10 K3JGKONG BOWNO --'.their testing and regulation. There is no venezuElaV* #%&van!a Af^ '. sound scientific basis for this certainty. [`. Since the cancers (lung, breast, large 1 intestine) which are commonest in the US f are rare in certain other countries, and vice | versa, they probably really are preventable, "U 5J Pue^DC0 eMExCO J4PflN**raiwAN THAMI.ANO CEWON EL SA^viCCR --toil (see figure) not necessarily by zu 40 60 SO too IZO 140 160 160 ?' emulation of any environmental pollutants Total dietary fat intake (|/day) u/1 J2-o:joi.go Cl9IOMaeaiUaaioufmalaLid T? r'Lr4 r*' Tirr^uft irrMiy^ii-rrthiv JtAJ i--afrni Mature Yol. 284 2 7 Marc. i/K.:ji, ?very unrealistic. ---- - .ath rates12 should be more widely more than the equivalent amount of'. -_* '**'f. T?.e unreality, of the whole method is known. dietary saccharin would have done11)1. 2 * 14 15 * 17 * 19 20 futfher highlighted by the fact that the My criticisms of Epstein's science, Also, any chemical which causes prolifer '/assumptions `predict" 7,300x4.5 nickel- however, must be viewed in the light of the ation or necrosis in any organ that is rjfc-j- v-oxide induced occupational lung cancers/ continued resistance of many industries to subject to spontaneous cancers is likely to ' year. Since nickel refining causes a lot of reasonable controls. One has only to read modify the onset rate of tumours in that /.nasal as well as lung cancer, we would some of his descriptions of industrial organ, and since the aim of most animal /presumably then also soon "expect" behaviour to see where his passion comes experiments is to study a dose which is - /something like 13,000 nasal cancer death from, and a suitably sceptical reader could nearly, but not quite, sufficient to cause . certificates per year among nickel workers. derive much important information from significant weight loss or mortality within. Nickel has already been widely used for the dozen or so detailed case-histories of three months, it is not surprising that so decades, so many thousands of these particular carcinogens that make up the many chemicals at such doses can cause //should presumably already be evident. In bulk of this book. But, although I cannot. cancer in animals. ' . ^ reality, each year in the US population prove it, I suspect that environmentalist at However, it maybe that where adversary there are only 300-odd male and 200-odd a whole (including Epstein and those US politics operate one needs views at both *j female nasal cancer death certificates. The an3'~B'fitish~*fra3e'*miTons whrch have extremes in order to get a balanced out-'!?jv..-wij: .v majority of these are not ex-nickel workers already^moJelfecTtheir public-statements come. And there is a possibility that over- `J and no marked trends are evident. This closely"6n~Sis book) would bc_bcttcr emphasis on the avoidance of scientific Jjy? ' V demonstrates the unsoundness of the NCI--* error would emasculate the environmental- 'iNIEHS methodology.` v`; ~ - Unfortunately, such exaggerated `The politics of cancer is i estimates are so much what many people dominated on both sides i want to believe ot modern society that they ? hdveTrow/achievedTlIfeonhwrown, and. by exaggeration' Y?: 1st passions and merely lead to my rather inactive conservatism. (After all, no '.ffijjSfe scruples about scientific certainty of safer/ /SSwf? usually precede the widespread introduc-...,^^ . tion of new chemicals, so should the although'~THey~'afe~utTKrFnviThout imposition of prudent restrictions require. / foifhclatio~n*~tKcy _are _q.up_t.c.dJyidely, respected and couldJherefore^p.ress more absolute proof?) S /repeatedly andj;eputa^.bjjtiyaJhcJay effectively ^fdr^'ghTro.ls~.in..p'articular Environmentalists with biased judge- '-la ? aiRTTcienfific^press. In Geneva the instances j/their overview of cancer was ments and a quasireligious certainty of JrSfernational Labour Organisation more baTanced^~the7lollo.wihg,ways': right will fight more battles than any" ' ^' /f reportedly endorsed them, as did the Toxic if they'acceptetfthat present-day cancer reasonable sceptic .would do, and even if .^Substances Strategy Committee in their rates and trends are probably not their victories confer 10 or 100 times less i-&[ ^recent draft report to the US president14, _ dominated by occupational carcinogens or., benefit on humanity than they imagine, tST 0and they have been used in OSHA to environmental pollutants (especially since they will in the long run probably do more ^ emphasise the need for stricter laws. Most they could still warn that future rates might good than harm -- unless they materially frecently, the UK trade union the perhaps be so <*'wninated unless present- reduce food production, distort research Association of Scientific, Technical a. day expc -esac regulated20)*; 9 * priorities, ordirectattentionawayfromthe , Managerial Staffs (ASTMS) released a policy if their chief concern was with the smoking problem in the process. Epstein f document which appears to have been V strongly influenced by Epstein's book, and which is notable for its prominent but identification and control of the few major determinants of human cancer (or, in an industrial context, the few raajorihdustrial justly quotes, from the 1st century AD, the Plutarch chronicles: "He who in time of faction takes neither side shall be disen- erroneous assertion, derived solely from carcinogens) rather than the large frachised". So, I feel, should both environ the foregoing unpublished US typescript,' multitude ofsins which Epstein denounces; mentalists and industrialists who suppress . that 20-40% of current UK cancer deaths if they discussed the costs and benefits of or deliberately misinterpret data, but they are caused by occupational carcinogens. research into the control of toxie probably won't be. For the moment, the 5 Epstein now claims that these substances in the context of other possible `politics of cancer* is dominated on both ^exaggerated estimates seriously ways of improving longevity (bad diet and sides byexaggeration. -fuC ^underestimate the impact of industrial tobacco in rich countries, malnutrition and -/ carcinogens. There is obviously a valid infective and parasitic diseases elsewhere); . political need to exaggerate the importance if they took the costs of imposing of the preventive measures we can already- restrictions on society more seriously. Tor most toxic chemicals we now have both qualitative and quantitative uncertainty about the health benefits :,of restriction'. implement, but in the long run we do also still need to discover the main preventable - causes of cancer other than smoking. Bearing both these needs in mind, there are limits beyond which it is not even politically ; wise to distort the science of cancer, and . some of today's exaggerations may well transgress those limits. Reliable reviews of the known and suspected causes1'2'"3-14* of human cancer and of trends in British Epstein's general assertion is that the total direct and indirect costs of failing to regulate usually exceed the real costs of the testing and regulation, but 1 suspect that this is a slogan to avoid political embarrassment rather than a carefully researched conclusion; if they accepted that for most toxic chemicals we have-both qualitative and vast quantitative uncertainty about the health benefits of restriction. Particularly, even if the sort of grossly biased interpretation which Epstein applied to the animal saccharin data is avoided, the results of animal experiments simply are not an uncomplicated key to human hazard identification. First, moderate alteration of gross aspects of the diet of animals greatly modifies their spontaneous tumour onset rates11 (so, for example, increasing the sugar content of rat diets may increase their cancer rates 1. Confidd. J.$,WncrtW.e9](l9Tn. 2. Mantd.N.u45cfe&e4amua,Mj^C*ftrvrff<ftMrrk& IJ79U9*5). 3. Crump. KJ5. rf ConorflaeorrA34. yi (I9T<K 4. Guoa, W.A. <t*l Canctr Ratsrchn, H75(197T). ). Office of Technology Auessment of lit* US Coopsn (19TJV. Cancer Toting Tch#tofot7 and Seerhah*. (. Hammond, E.C- rt of itt Qafuv ofHuman Conor. Coil t f Spring Harbor NY < 1977). NIH 76-1221 (1976). I. Auerbach. O. et of N.E*fU.StdL J00.3*1 (1979). ' 9. CaroU. K.K. Canctr Raoaroh 44.JJ7a (1973). 1 ;#ftj`.ui 1 UL Armstrong, g.K. and DoU, R. InLj.Canor 15,41?(197JL II. Jo*e D.G. Nutrition o*4 Canerr l(J>. 5* (1979). (Mo) other paper* in all the 1979 iuucs of this journal are of ire* general interest e.g. l(3)-35, *7 and 27. See also part 2 4 November .197) Conof fiutmth devoted &oily u muuuoo and cancer). 12. DoU. ft. Proc.ftOy.Soc.Lo*d(B) 205, 47 (1979). 12. Blot. WJ. and Fraumcni, J.F. J.Ncrt.Cwcorfnsi. *1. lOll (1971). 14. Rot. FJ.C. and Tucker. MJ. Simpfr Medio (I* Contras Series) Jl I. 171 (1974). 15. Seiikoff, 1.2. in "Origins of Human Cancer", CoUSpnO Harbor NY (1977), 14. Norman. A. Nont* 290. (22 (1979). 17. Doll. R. Notv* 245, 299 (1977). It. Dott. R. Nutrition end CeneeMtJ), 35 (1979). 19. (ARC working group Conor Raoonh *9.1 09*0). .1 20. Dam, D.L. and Magee, B.H. Soonco&O,1324(1979). 'sfoo VO aO tin . CQ; US * ' 0029<0134/90/1320^03501.00 C1990Macmillan journal*Ld