cancer clusters: findings vs. feelings

AMERICAN COUNCIL ON SCIENCE AND HEALTH1995 Broadway, 2nd Floor, New York, NY 10023-5860

Tel. (212) 362-7044 • Fax (212) 362-4919URL: http://www.acsh.org • E-mail: [email protected]

Cancer Clusters:Findings Vs. Feelings

Prepared for the American Council on Science and Healthby David Robinson

American Council on Science and Health

Project CoordinatorAshlee Dunston

Art DirectorYelena Ponirovskaya

PresidentElizabeth M. Whelan, Sc.D., M.P.H.

March 2002

THE AMERICAN COUNCIL ON SCIENCE AND HEALTH (ACSH)APPRECIATES THE CONTRIBUTIONS OF THE REVIEWERSNAMED BELOW.

ACSH accepts unrestricted grants on the condition that it is solely responsible for theconduct of its research and the dissemination of its work to the public. The organizationdoes not perform proprietary research, nor does it accept support from individual corpo-rations for specific research projects. All contributions to ACSH—a publicly fundedorganization under Section 501(c)(3) of the Internal Revenue Code—are tax deductible.

Individual copies of this report are available at a cost of $5.00. Reduced prices for 10 ormore copies are available upon request.

Copyright © by American Council on Science and Health, Inc.This book may not be reproduced in whole or in part, by mimeograph or any othermeans, without permission.

Michael Bracken, Ph.D., M.P.H.Yale University School of Medicine

Sir Richard Doll, M.D., D.Sc., D.M.University of Oxford

George Ehrlich, M.D.University of Pennsylvania School ofMedicine

Sander Greenland, Dr. P.H., M.S., M.A.UCLA School of Public Health

Clark Heath, M.D.American Cancer Society

William Jarvis, Ph.D.Loma Linda University Schools ofMedicine and Public Health

Alan Kristal, Dr.P.H.Fred Hutchinson Cancer ResearchCenter

Steven Rosen, M.D.Northwestern University MedicalSchool

Gilbert Ross, M.D.Medical Director, ACSH

Wallace Sampson, M.D.Stanford University School ofMedicine

David Schottenfeld, M.D., M.SC.University of Michigan School ofPublic Health

Michael Simon, M.D., M.P.H.Barbara Ann Kamanos CancerInstitute, Wayne State University

Mark Utell, M.D., University ofRochester Medical Center

Elizabeth Whelan, Sc.D., M.P.H.President, ACSH

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Table of ContentsExecutive Summary Introduction What Is A Cancer Cluster? How Common Are Cancer Clusters? Why Are Investigations of Potential Environmental CancerClusters So Often Inconclusive?

The Bull’s-eye Problem Public Pressure Problems with Data Collection Chance Geography as Symptom Proving a Negative—Never Say “Never”

A Case in Point—Long Island and Breast Cancer Conclusion A Checklist: ACSH Recommends References

Executive Summary

The issue of cancer clusters, which has been in the spotlightrecently, is plagued by a wide disparity between public perceptionsand scientific findings. Movies like Erin Brockovich and A CivilAction have led the public to think that industrial pollution in theenvironment is causing local “cancer clusters” where cancer casesare more prevalent due to cancer-causing chemicals.

There are many scientifically documented instances in whichchemical exposure has caused cancer in humans, but these havegenerally not been purely environmental. Contamination in thewater supply or air causing residents of a neighborhood to developcancer, although popularly thought to be a common occurrence, hasrarely been documented through scientific investigation. Instead,the clusters that scientists have been able to attribute successfully toa particular cause have been occupational—such as workers in afactory developing a particular type of cancer as a result of expo-sure to one of the chemicals they handle every day—or have beenlinked to a particular medicine, or to behaviors such as smoking orsunbathing. The evidence for environmental contamination causingcancer, however, is sparse. There is some indication that chemicalsdissolved in drinking water may elevate the risk of gastrointestinaland bladder/urinary tract cancers, and that living next to a smelteror other “point source” of air pollution may elevate risk of lung can-cer. The many efforts that have been made to demonstrate linksbetween other types of cancer and environmental contaminationhave not conclusively identified such links.

Science does not support the popular image of traces of chemicalcontamination elevating the cancer risk of everyone who lives in aneighborhood regardless of where they work, what sort of lives theylead, and what hereditary influences may predispose them to cancer.The absence of conclusive scientific evidence in this area may bepartially explained by the myriad challenges that bedevil cancercluster investigations—challenges that are explored in this report.

This report discusses the potential cancer clusters in Toms River,New Jersey and Long Island, New York, because they contain manyelements typical of cancer cluster investigations and have receivedconsiderable media attention.

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Cancer Clusters: Findings and Feelings

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Introduction

The fear that industrial pollution, present in trace amounts in theenvironment around us, may be causing “cancer clusters”—localareas where cancer is more prevalent as a result of cancer-causingpollutants—has received a great deal of attention recently. Filmssuch as Erin Brockovich and A Civil Action have helped bring clus-ters to the forefront, and community concern over possible clustershas led to congressional mandates, federal investigations, and anincrease in public sensitivity to the issue. In this report, ACSH pro-vides a concise introduction to the issue, to help journalists, publicofficials, and members of the public understand both the scienceand the beliefs that drive the discussion.

What Is a Cancer Cluster?

Cancer clusters are a frequent topic of media attention, and havecome to have two different meanings, one for the public and onefor scientists. While the public typically thinks of cancer clusters interms of cancer caused by industrial pollution, scientists tend to seethe issue differently. Robert N. Hoover, M.D., Sc.D., Director of theEpidemiology and Biostatistics Program in the Division of CancerEpidemiology of the National Cancer Institute (NCI) defines a can-cer cluster as a geographic area, time period, or group of peoplewith a greater than expected number of cases of cancer.1Epidemiologists—scientists who study the causes and distributionof human diseases—expect cancer rates to vary slightly from yearto year and use statistical tests to determine whether or not a givenrate is different enough from the average to qualify as unexpected.2Proving that a cluster exists entails a rigorous statistical analysis, inwhich the number of cases observed in some area over a specifiedinterval of time is compared to the expected number of cases forthat time period and area.

Scientists can use clustering as a way to learn about associationsbetween cancer and any external agent, not only pollutants. Forexample, much of the scientific literature on clusters involves theevaluation of hypotheses that attribute the spread of cancer to infec-tious agents. The U.S. Centers for Disease Control and Preventionhas conducted cancer cluster investigations for over 20 years.

G. Caldwell, of the Arizona Department of Health Services, review-ing this body of work, explained that “the original plan was toinvestigate such clusters to determine if they were a phenomenonindicative of cancer transmissibility.”3 Likewise, the 1982 edition ofSchottenfeld and Fraumeni’s authoritative textbook CancerEpidemiology and Prevention begins its chapter on clustering byexplaining that it is “especially directed towards examining morelocalized variations in the incidence of cancers in space and timethat might suggest that the cancers are induced by infectiousagents.” 4

The realization that smoking elevates the risk of lung cancer isdescribed in much of the early (pre-1970) scientific literature as ananalysis of clustering—nations and areas with more residents whosmoke evince higher rates of lung cancer. Such instances demon-strate that the term “cluster” can be used on a very large scale, torefer to an elevated incidence of cancer in the entire population ofone nation as compared to that of another, or to similarly largegroups. It is more commonly used, however, to describe elevatedrates in more localized areas, such as a single town or neighbor-hood.

The public and the media, on the other hand, often use the term“cancer cluster” in a more general way. When members of a com-munity believe that the number of cancer cases in their communityis abnormally high, they will often seek an explanation for the “can-cer cluster.” The media may then report on efforts to explain thecluster, before a statistical analysis has verified that the rates of can-cer in the community are actually elevated. Thus, the term “cancercluster” is often used by the public and the media to refer to theperception of an elevated number of cancer cases, and by epidemi-ologists to refer to confirmation of this perception. The communityperception may reflect an elevated rate of cancer, or it may not.

How Common Are Cancer Clusters?

Scientists and researchers have verified a number of cancer clus-ters. Diethylstilbestrol (DES), a drug used during the 1940s and1950s to prevent premature labor in pregnant women, is the causeof one such cluster. Because a prestigious group of Boston physi-cians advocated the use of DES, many of the women who used it

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lived in the Boston area. Fifteen to 20 years after these women hadused DES, doctors noticed a miniature “epidemic” of vaginal can-cers among their daughters. The specific form of cancer observed—adenocarcinoma—is so rare that the hospital where eight of thedaughters were treated within the space of a few years had neverencountered any cases of it before. Physician concern over the can-cer led to an investigation that linked the vaginal cancers to DES.5Most observers might not call this a “cluster” because it does notinvolve supposedly carcinogenic conditions in the environmentwhere people live, but it is considered one by epidemiologists sincea large number of rare cancers in one area (Boston) prompted thestudy.

Other cancer clusters have been found in occupational settings.One example concerns the material polyvinyl chloride (PVC), morecommonly known as vinyl. PVC is one of the most widely usedsynthetic compounds in the world. It is an important material forconstruction and siding, a common insulator of electrical and otherwiring, and a common material for making shower curtains. At fac-tories around the world, workers were exposed to very high concen-trations of one of the ingredients used to make PVC, a volatilechemical known as vinyl chloride monomer (VCM). VCM is notused directly by the public, but it is a key part of the PVC manufac-turing process. The workers who handled VCM, it was observed,had elevated prevalence of a rare liver cancer, hepatic angiosarco-ma. Rigorous investigations eventually proved that VCM elevatedthe risk of hepatic angiosarcoma in these factory workers.6

The public expresses concern over many possible clusters eachyear. In most cases, the perceived increase in the prevalence of can-cer that has generated alarm is not in fact an increase in prevalenceat all. According to public health officials, 85 percent or more ofthe possible clusters reported to them by concerned communitymembers are in fact not statistically significant elevations of cancerrates.7,8 Many of these supposed clusters include whatever types ofcancer have been diagnosed in the area. This ignores the reality thatdifferent cancers are really different diseases.

As noted, cancer clusters have been reliably linked through con-trolled studies with specific medicines, like DES, and with occupa-tional exposures to chemicals like VCM. Scientific findings do not,however, match up with public perceptions about localized eleva-tions in prevalence of many different cancers as a result of industri-

al pollutants in the environment. To quote from the most recent edi-tion of Cancer Epidemiology and Prevention, “Overall, there are asufficient number of point source studies to conclude that excesslung cancer risk was very likely caused by large, relatively uncon-trolled sources of community air pollution, particularly arsenic-emitting smelters…. However, the risks for community exposureare likely to be quite small, between 1.5 and 2.0 [times the normalrate] and will require substantial study populations and carefulassessment of other known lung cancer risk factors.”9 Thus, ambientair pollution in non-occupational settings may be linked to lung can-cer—not to the wide range of other cancers for which it is oftenblamed. At present, lung cancer is the only cancer that has been sci-entifically tied to ambient air pollution.

As to pollution in drinking water, the evidence is similarly lack-ing compared with public fears. There is a complex mixture of traceelements present in drinking water, usually at levels of 10 or fewerparts per billion. Cancer Epidemiology and Prevention reviews sev-eral suggested cancer links—including possible carcinogenic effectsof arsenic and organochloride compounds with bladder, GI tract,and other cancers. It does not identify any chemicals about whichthe body of evidence is large or consistent enough to support theconclusion that they increase cancer risk in the amounts that arepresent in U.S. drinking water.10

Some clustering should be expected as the result of chancealone.11 Wherever this chance clustering occurs, it is reasonable toexpect that people will want to know why it has happened—andequally reasonable to expect that no cause will be found.

Why Are Investigations of Potential EnvironmentalCancer Clusters So Often Inconclusive?

The “Bull’s-eye” Problem

A variety of factors often work together to create the appearanceof a cluster where nothing abnormal is occurring. Looking for clus-ters is analogous to drawing a bull's-eye after you have thrown dartsat the wall at random. In this situation, there is possibly a place inwhich a bull's eye can be drawn that will leave multiple darts in

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close proximity to some common center. According to theAmerican Cancer Society, cancer will be diagnosed in an estimated1,268,000 Americans in 2001.12 Finding clusters in cancer data isthus something like looking for patterns in the location of over amillion darts thrown at a dartboard the size of the United States.

The definition of what geographic area is to be investigated in acancer cluster study is often problematic. If the hypothesis that can-cer rates in a certain area may be elevated provides the initial impe-tus for the study, the natural temptation is to study only the areathat includes the cases that inspired the study. This problem iscalled “pre-selection bias” because it involves researchers pre-selecting the geographic area of a study based on what they alreadyknow an investigation of certain areas would reveal. In much thesame way as gerrymandering—to include certain voters in an elec-toral district—can shape the outcome of elections, pre-selectionbias—to include certain patients in the geographic area of a study—can shape the outcome of cancer cluster investigations.

The problem of “drawing the bull’s-eye” applies not only tospace, but also to time. A study of two clusters in one Ontario townnoted that “…the tendency is to include all years in which caseswere reported [in the date range chosen for analysis], thereby maxi-mizing, and magnifying, any effect which may be present.”13

A third way in which the bull’s-eye problem can skew results isin the selection of which cancer to include as part of a possiblecluster. In the case of possible pediatric cancer clustering in TomsRiver, New Jersey, investigators began by looking at every categoryof childhood cancer and included in their investigation those cate-gories of cancer whose rates were significantly elevated in TomsRiver.14 The threshold of significant elevation that was used meantthat for every twenty cancer categories examined, one would quali-fy as significantly elevated.

These sorts of expansions are problematic because the greaterthe number of possible cancers, areas, and time periods that areevaluated as potential clusters, the greater the chance that randomlydistributed cases will appear as a cluster. In addition, the links thathave been proven between exposure to carcinogenic chemicals andelevated incidence of cancer have entailed elevated rates ofextremely specific cancers: DES, in high doses, elevates risk ofvaginal adenocarcinoma, exposure to VCM elevates risk of hepaticangiosarcoma. One thing these documented instances of elevated

prevalence have in common is that the chemical agent consistentlyelevates risk of a specific cancer, not of all cancers equally.

Often in these debates, however, a burgeoning set of effects isputatively linked to a single cause. This is aptly illustrated throughone of the most widely publicized cancer cluster cases in recentyears, the Erin Brockovich case. Dramatized in a major film withJulia Roberts portraying Ms. Brockovich, an overworked paralegal,the case dealt with the release of chromium-6 into the Hinkley,California water supply by Pacific Gas and Electric. The suitblamed the chemical for dozens of symptoms, from nosebleeds tobreast cancer, miscarriages, Hodgkin’s disease, and spinal deteriora-tion.15 Workers who inhale large amounts of chromium-6 over longperiods have been shown to be at elevated risk of developing lungand sinus cancers. But chromium-6 has never been shown to berelated to any other human cancer, or to be carcinogenic to anydegree when dissolved in drinking water.16

Public Pressure

Sometimes, public pressure can impel public health officials toundertake an investigation they do not believe is warranted.Investigations undertaken after experts have concluded that nothingout of the ordinary is occurring are unlikely to produce noteworthyresults.

Community members who raise concerns about possible clusterswill frequently explain themselves in terms of a “common sense”feeling that something is wrong. Often, they are not inclined to waitpatiently for an in-depth, methodical investigation by public healthauthorities.

An investigation into childhood cancer in Toms River, NewJersey, provides insight into the pressures that can work against bal-anced scientific inquiry. Toms River is the location of two“Superfund” sites, places the Environmental Protection Agency(EPA) has designated as a high priority for clean-up due to the pres-ence of hazardous waste.

A nurse in a Philadelphia pediatric oncology ward noticed thatmany of her patients were from the Toms River area, and speculatedthat an environmental cause might be elevating the pediatric cancerrates in Toms River. When parents brought their concerns to theattention of state authorities, in 1996, the state evaluated the cancer

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rates and found no cause for alarm. A spokeswoman from the NewJersey Department of Health explained that the state, based onexisting data about cancer rates, did not think a comprehensivecluster investigation would be economical or useful, because thenumbers of childhood cancers were “not statistically meaningful.”17

Nonetheless, the state moved to address community concernwith a series of investigations into possible sources of cancer risk,including the Superfund sites. The parents brought a sense ofurgency to the discussion. “This is a terrible disease, and these kidssuffer…. These kids don’t have time to wait. I have two other chil-dren, and I’m scared to death,” said one mother of a childhood can-cer victim.18

“In my heart and in my mind, I have no question. Now, it's up tothe scientists to use logic and common sense to get at the truth,”said Linda Gillick, chairwoman of a citizen's committee organizedto address the issue and the mother of another cancer victim.19

Where parents were certain, scientists were not. The data oncancer rates that was available when community members firstraised concerns did not show more cancer than scientists mighthave expected to be found in a random distribution in Toms River.Residents prevailed on their congressional representatives to askfederal officials for an investigation that state health officials saidwould be futile.20 Ultimately, the study was undertaken as a jointeffort between state officials and the federal Agency for ToxicSubstances and Disease Registry.21

As part of her group’s effort, Linda Gillick traveled toWashington, D.C. to defend a special line-item allotment of $1 mil-lion for the Toms River study in one of Congress’s annual appropri-ations bills.22 Ultimately, Congress passed the item.

Concerned citizens thus had a doubly decisive impact on theissue. After convincing Congressional representatives to circumventstate cancer experts and launch a federal investigation, the citizenactivists intervened again to increase the funding for the study overthe amount allotted it in the normal budget process. At both junc-tures, public concern and fear overrode the decisions of administra-tors charged with setting public health priorities based on scientificfindings.

The study, which took more than five years to complete, con-cluded that “no single risk factor evaluated appears to be solelyresponsible for the overall elevation of childhood cancer incidence

in Dover Township.”23 The study found that most of the childhoodcancer cases in the area have no explanation; the only supportableenvironmental link was that between prenatal exposure to contami-nated drinking water and pediatric leukemia in girls.

Dr. Eddy Bresnitz, a New Jersey state epidemiologist, explainedthat even the narrow relationship found in the study might be afluke. “Due to the relatively low number of study subjects and otherfactors, chance cannot be excluded as a possible explanation for thefindings.”24

“You can't have a child with leukemia living two houses downfrom a child with a tumor, drinking the same water and breathingthe same air, and tell me they didn't get cancer from exposure,”Linda Gillick told the New York Times. “That's my common sensespeaking.”25

Problems with Data Collection

Scientific studies linking elevated cancer risk to environmentalcauses have generally involved years-long latency periods betweenexposure to carcinogenic factors and development of cancer. TheDES cases did not become obvious until more than 10 years after itsuse, and exposure to VCM in vinyl plants takes years to cause can-cer. Even smoking and sun exposure, the two most widely docu-mented avoidable cancer risk factors, can take half a lifetime tomake their effect apparent. The latency problem surfaces in twoways in community-inspired cancer cluster investigations.

First, some of the people who were exposed to the environmentalchemical under investigation may have moved away from the areabefore the investigation began. If they subsequently develop cancerin their new homes, their absence diminishes the perceptibility ofthe cluster. If they remain healthy, their absence from the area effec-tively increases the apparent magnitude of the cluster.

Second, it is possible that some of the cancer cases that occurwithin the investigated area may not be attributable to the localenvironment. If some of the people who are diagnosed with cancermoved into the area shortly before being diagnosed, steps must betaken to assure that their cancer cases are not attributed to localcauses.

The most significant problem plaguing data about possible can-cer cases is that cancer is typically not a reportable disease. The

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government keeps extensive, complete records of the incidence ofmany infectious diseases—such as tuberculosis and venereal dis-ease—in order to track and counter potential outbreaks. For cancer,however, no such record exists. Recently, several states have begunstatewide cancer registries. These are helpful to some degree, butthey lack historical data, are plagued by physician compliance prob-lems, and may not be able to keep accurate account of diagnosesmade out of state. This last issue is particularly problematic, sincemany definitive cancer diagnoses are made at major medical cen-ters for patients who come from out of state in search of top expert-ise.26

In the absence of reporting requirements, the NCI runs a pro-gram called SEER (Surveillance, Epidemiology, and End Results),which documents cancer prevalence in a sample of the U.S. popula-tion to determine the baseline levels of various cancers. The pro-gram uses information from hospitals, pathology laboratories,physicians, and death certificates to determine who has cancer, sup-plemented by population surveys. The SEER program has been inoperation since 1973 and has quality control procedures in placethat maximize the accuracy and completeness of its results. In addi-tion, many states provide additional support for the maintenance ofcancer registry information beyond that provided by SEER.

These programs are helpful, but long-term historic informationabout cancer incidence is only available for some parts of the coun-try. The population surveyed by SEER —a subset of the total USpopulation—is designed to be a representative sample of the nation-al population. If the local area in which a cancer cluster investiga-tion is conducted differs demographically from the national popula-tion, the expected cancer levels established by SEER may not applyto the area being studied.

The data collection problem is significant because the only wayto determine whether or not the cancer rate in a community isabnormally high is to compare it to an expected rate. Expected ratesdetermined with reference to populations different from the oneunder study in the area of a potential cluster may not provide a reli-able guide as to how much cancer should be expected in the areaunder study.

Chance

As discussed above, the nature of random distributions is suchthat some amount of clustering may be expected to occur simply bychance. It is conventional among scientists to regard an elevatedcancer rate as “statistically significant” if chance alone would pro-duce as much or more elevation less than 5% of the time. This iscommonly written in the scientific literature as “p<0.05”, where p isthe probability of seeing such an elevation if only chance is at work.With this criterion, if one examines the cancer rates in 100 neigh-borhoods, and cancer cases are occurring randomly, one shouldexpect to find about five neighborhoods with statistically significantelevations.

Any unusual amount of cancer will tend to provoke concern,regardless of whether it stems from chance or a more concretecause. As a result, the finding that there is a substantial elevation incancer rates suggests that further investigation into possible causesmay be warranted, but does not in itself establish that any particularcause is at work.

Geography as Symptom

When a group of people who live in geographic proximity to oneanother exhibit an elevated rate of cancer, the rate may reflect char-acteristics other than geography that those in the affected area share.Characteristics like similar diets and exercise patterns may tend tobe geographically “clustered” because low-income people who eatdisproportionately more fatty foods live near one-another, becausehealth-conscious suburbanites live in the same neighborhood, orbecause rates of smoking tend to differ from one community to thenext. In any of these cases, a geographic cluster might be proved toexist even if there were no chemical carcinogen in the environment.

Proving a negative—Never Say “Never”

No matter how many possible environmental cancer causes arecontemplated, it will always remain possible that some heretoforeignored chemical in the environment is elevating cancer rates. Thus,investigations of possible environmental causes for cancer can be

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extended almost indefinitely, as more and more possible carcino-gens are examined.

For all these reasons—the many ways in which a “bull’s-eye”can be drawn, problems of latency, the lack of reportability of can-cer, the similar behaviors and backgrounds of people who live nearone another, and the vagaries of chance—investigations into pro-posed environmental cancer clusters are unlikely to confirm envi-ronmental hazards as a source of human cancer.

A CASE IN POINT—LONG ISLAND AND BREASTCANCER

One example of how science can be overtaken by public concerncan be found in the ongoing investigation of breast cancer rates onLong Island. Several advocacy organizations have sprung up tourge public health authorities to take action regarding a perceivedbreast cancer “epidemic.” The oldest of these groups is 1 in 9: TheLong Island Breast Cancer Action Coalition. Operational since1990, 1 in 9 (along with the similar groups that have since beencreated) serves as a highly effective force in the public debate. 1 in9’s website explains: “We have organized and participated in tripsto Albany and Washington to educate our legislators about the needfor action that will help prevent the breast cancer epidemic.” 27

1 in 9 has tenaciously supported the idea that industrial pollutionis elevating the rates of breast cancer on Long Island. Geri Barish,the group’s president, wrote an instructive editorial in response toclaims that her group was doing more to stoke fears than to supportscience:

As activists, we are motivated by an absolute andunflinching commitment to examine every possible sce-nario for the unacceptably high levels of cancer in ourmidst. While we recognize that many factors, includinggenetics, diet, and poor health practices contribute to therates of the disease, we believe that industrial chemicals,such as pesticides and other environmental contaminants,may also play a role.28

One breast cancer victim, voicing concerns typical of thoserecorded by news media, seems convinced that pesticide use onneighboring lawns caused her cancer. Noting that her neighborswant “their lawns green and bug-free,” she feels the fact that threewomen on her block have died from cancer is “not a coincidence. Itcan’t be.”29 Concerns like these highlight the quandary in whichpublic health officials find themselves—they cannot, no matter howmuch they investigate, prove that the elevated rate is a coincidence,even if that is the real explanation, because it is not possible toprove a negative.

Ms. Barish and her colleagues do not appear to consider it a pos-sibility that, when known breast cancer risk factors such as Jewishethnicity, bearing a first child later than usual in life, socioeconomicstatus, early age at menarche, and late age at menopause are consid-ered, the rates of cancer on Long Island might be no higher thanshould be expected. Geography might be symptom rather thancause, because people who live on Long Island tend to share othercharacteristics beyond area of residence. Any cancer, anywhere,deserves the attention of medical professionals. The question iswhether the number of breast cancer cases on Long Island suggeststhat Long Island should get more attention than other localities,breast cancer more attention than other diseases, or the environmentmore attention than other potential risks. The answers to these ques-tions might be no—a possibility that 1 in 9 does not consider.

1 in 9’s legislative activism, combined with that of other LongIsland breast cancer groups, succeeded on June 10, 1993, when theU.S. Congress passed a bill mandating an investigation into possibleenvironmental causes for breast cancer on Long Island by the NCI.The bill, which was supported by then-New York Senator AlfonseD’Amato, explicitly required the NCI to examine five possible envi-ronmental risk factors—“contaminated drinking water, sources ofindoor and ambient air pollution, electromagnetic fields, pesticidesand other toxic chemicals, and hazardous and municipal waste.”30

Thus, the power of public pressure was responsible for getting aninvestigation launched. This intervention by activist groups is oftencounterproductive because it has the effect of circumventing thenormal mechanisms that guide scientific inquiry. By creating a nar-rowly tailored federal mandate to investigate putative environmentalcauses of breast cancer, advocates and legislators have taken over atask for which scientists are the most qualified—deciding how lim-

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ited research and public health dollars ought to be spent.The Long Island breast cancer issue also provides a demonstra-

tion of the “bull’s-eye” problem. An article in Newsday entitled“Waiting for Science Can Cost Lives” celebrated the day when “thedetermined and creative women of Long Island went door-to-doorand began plotting cases of breast cancer in the area.”31 As dis-cussed above, the increased scrutiny to which the area under studyis subject may create an inaccurate impression of an elevated can-cer rate.

The mandated investigation, called the Long Island BreastCancer Study Project (LIBCSP), is ongoing. The findings releasedthus far, available to the public at the Project’s website,32 do notseem to bear out the fears of community activists.

One of the questions at the core of this debate is whether or notbreast cancer rates on Long Island are elevated at all, and if theyare, whether or not this elevation can be explained in terms of non-environmental risk factors like those outlined above. The LIBCSPhas just released a comprehensive Geographic Information Systemdesigned to help researchers investigate the situation. Meanwhile,using already available tools, a group of researchers at the NCIcompleted a study, “Breast Cancer Clusters in the Northeast UnitedStates: A Geographic Analysis.”33 Taking pains to avoid the bull’s-eye problem discussed above, the researchers used a computermodeling system to scan the study area for significant clustering.They found that “there is a statistically significant and geographi-cally broad cluster of breast cancer deaths in the New York City-Philadelphia, Pennsylvania, metropolitan area” and noted that with-in this large cluster are four smaller clusters, each significant in itsown right—Philadelphia with suburbs, central New Jersey, north-eastern New Jersey, and Long Island. The researchers explain: “Theelevated breast cancer mortality on Long Island may be viewed lessas a unique local phenomenon and more as part of a more generalsituation involving large parts of the New York City-Philadelphiametropolitan area.” This study thus confirms that rates on LongIsland are elevated, but does not do so in a way that lends supportto theories about localized pollution causing cancer, since it exam-ines such a broad area. Whether the use of pesticides in a neighbor-hood, or proximity to power lines or to a factory (or any similar sit-uation) is responsible for the elevated rates cannot be determinedfrom a study that considers such large aggregates of people. It isworth noting, however, that the cluster identified by the study

extends well beyond Long Island. The area of the cluster does notshare proximity to any single source of industrial pollution. Manyactivists have pointed to the Long Island aquifer, which is thesource of drinking water for all Long Island residents, as a potentialrisk because of seepage of chemicals into the aquifer from theground. The identified cluster, however, includes many sources ofdrinking water other than the Long Island aquifer, suggesting thatwater contamination is likely not the reason for the increased risk.

Looking at these data, the researchers conclude that the highbreast cancer risk is likely due to one of the factors that they werenot able to incorporate in their study. “The several known andhypothesized risk factors for which we could not adjust that mayexplain the detected cluster are most notably age at first birth, age atmenarche, age at menopause, breastfeeding, genetic mutations, andenvironmental factors,” they wrote. They group “known andhypothesized” risk factors together, but it is important to differenti-ate between the two—environmental factors are a “hypothesized”source of risk. For example, the author of a paper entitled“Epidemiology of breast cancer: an environmental disease?”explains that the goal of the paper is to consider “potentially contro-versial conditions which could in the future be recognized as newrisk factors.”34

An in-depth study of the two most frequently blamed chemicals,the pesticide DDT and a now-banned industrial insulator calledPCBs, investigated Long Island women and concluded thatincreased risk of breast cancer does not appear to be associated withpast exposure to these compounds.35 Further, the study’s authorsfound that “breast cancer risk among Long Island residents was notelevated compared with residents of the adjacent New York Cityborough of Queens.”36 Some smaller-scale studies completed in theearly 1990s had indicated that PCBs might be a cancer risk, butthese results were not confirmed by this LIBCSP study.

The investigation mandated by the 1993 law funded five separatelarge U.S. studies of women located mainly in the northeasternU.S., to evaluate the association of blood and serum levels of DDE(a chemical produced as DDT breaks down in the environment) andPCBs with breast cancer risk. In a review of these five studies pub-lished in the Journal of the NCI, researchers conclude that “com-bined evidence does not support an association of breast cancer riskwith plasma/serum concentrations of PCBs or DDE. Exposure tothese compounds, as measured in adult women, is unlikely to

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explain the high rates of breast cancer experienced in the north-eastern United States.”37

Another area which the LIBCSP is investigating in response tothe congressional mandate is the possibility of carcinogenic effectsfrom electromagnetic fields. A research group at the StateUniversity of New York at Stony Brook conducted a review ofoccupational studies evaluating correlation between women’s work-place exposure to electromagnetic fields and the incidence of breastcancer. They report that eleven such studies have been conducted.Six of the studies found no association between cancer and work-place exposure, three of the studies found an association for thewhole group studied, and two of the studies revealed associationsonly in subgroups of the population under study.38 These studiesshow a fairly typical distribution of positives and negatives that arefound when there is no association. When an association representsa causative relation, studies are much more consistently positive.

The LIBCSP’s largest, definitive report has yet to be published.Based on the findings released thus far, however, it seems that thepolitical impulse to tie breast cancer on Long Island to industrialpollution is not being validated by science.

Conclusion

Based on the data available today, there is no firm evidence thattraces of industrial pollution diffused in the environment are caus-ing cancer clusters. This could change as the issue receives continu-ing scientific scrutiny. For now, however, there is a substantial gapbetween scientific findings on this issue and public perceptions.Science continues to indicate that the primary sources of cancer riskare obesity, diet, exercise, smoking, alcohol, sun exposure, occupa-tional chemical exposure, genetic familial cancer syndromes andsusceptibility risk factors such as infectious agents—and not envi-ronmental chemical exposure. Beyond these, chance (random caseclustering) is a major predictor of perceived cancer clustering.Citizens, journalists, and public officials share in the responsibilityfor accurate and fact-based discussion.

A Checklist: ACSH Recommends

For members of the community:

• Be skeptical. “Common sense” does not trump science in thisrealm.

• Know your sources: Activists and experts often disagree when itcomes to cancer clusters.

• Remember the bull’s-eye effect: Check for bias in the way sta-tistics are organized or calculated.

For journalists:

• Help consumers differentiate among suspected clusters in whichincidence is actually not increased, clusters in which incidenceis increased, and clusters for which a cause other than chancehas been identified or is at least strongly suspected on good sci-entific grounds.

• Put community concern in context—use information like thatcontained in this report to ensure that the science of cancer clus-ters gets covered along with the human side of the issue.

• Clearly distinguish between helpful actions that people can taketo reduce cancer risk—frequent checks for early detection, ahealthy diet and exercise, and in some cases chemoprevention—from steps like filtering the water that are not proven ways ofreducing cancer risk.

For politicians:

• Focus on measures that are both popular and proven—likemammograms and chemoprevention when appropriate forbreast cancer, and frank but well-informed discussion of con-firmed lifestyle risks for all cancers.

• Explain the facts about environmental clusters—we may havenothing to fear but fear itself.

• Maximize the efficacy of cancer research and epidemiologydollars by allowing public health officials and scientists todirect and manage the details of research efforts.

21


22

References

1. Testimony of Robert Hoover, M.D., Sc.D., Dir. Epidemiologyand Biostatistics Program, NCI, to the Senate CancerCoalition, U.S. Senate, June 5, 2001.

2. Typically, the statistical threshold p<0.05 is used.3. Caldwell, G.G., Twenty-two years of cancer clusters investiga-

tions at the Centers for Disease Control, Am J Epidemiol1990;132:S43-S47.

4. Schottenfeld D. and Fraumeni J. F. Cancer Epidemiology andPrevention, W. B. Saunders and Company, 1982.

5. p. 305 in Cancer Epidemiology and Prevention.6. Lewis, R., Vinyl Chloride and Polyvinyl Chloride, Occup Med

1999 Oct-Dec;14(4):719-42.7. Bender. A.P., et al., Appropriate public health responses to

clusters: the art of being responsibly responsive, Am JEpidemiol 1990;1322:S48-S52.

8. Testimony of David W. Fleming, M.D. Deputy Director forScience and Public Health, Centers for Disease Control andPrevention, and Deputy Administrator, Agency for ToxicSubstance and Disease Registry, Department of Health andHuman Services, Before the Senate Cancer Coalition, U.S.Senate, June 5, 2001.

9. Schottenfeld D. and Fraumeni J. F. Cancer Epidemiology andPrevention 2nd Edition, Oxford University Press, 1996Schottenfeld and Fraumeni, 2nd ed., p. 414.

10. Schottenfeld and Fraumeni, 2nd ed. ch. 20—“WaterPollution”.

11. Fleming testimony (ibid.).12. Cancer Facts & Figures 2001, American Cancer Society.

13. Kreiger, N. and D. Reynolds, An investigation of two apparentcancer clusters in one community, Revue Canadienne Du SantéPublique, 83:2:116-119.

14. Carol Gorga Williams. “Probers cast wider net for childhoodcancer victims.” Asbury Park Press, 4/19/96.

15. Fumento, Michael. “’Erin Brockovich’ Exposed.” The WallStreet Journal, March 28, 2000.

16. Ibid.17. “TRACKING DOWN A CAUSE; Lawmakers pledge fund to

better assess child cancer cluster.” Asbury Park Press. 3/19/96.18. Terry Dube of Lakehurst, NJ as quoted in “Cancer-fearing

families rally; authorities advice patience.” Asbury Park Press,3/16/96.

19. “State says Toms River water supply is OK now, but studiescontinue.” AP Newswire. 11/16/99.

20. TRACKING DOWN A CAUSE, ibid.21. Ibid.22. Press Release, Congressman Jim Saxton. June 23, 2000.

<http://www.house.gov/saxton/pr62300.htm>.23. Case-control Study of Childhood Cancers in Dover Township

(Ocean County), New Jersey. < http://www.state.nj.us/health/eoh/hhazweb/dovertwp.htm>.

24. “Little Reassurance for Toms River Residents About Causes ofCancers” Iver Peterson, New York Times, December 19, 2001.

25. “Toms River Still Asking A Question: 'Why Us?'” IverPeterson, New York Times, December 21, 2001.

26. Testimony of Randall L. Todd, DrPH, State Epidemiologist,Nevada State Health Division, before the Senate Committee onEnvironment and Public Works, June 11, 2001.

27. <http://www.1in9.org/mile.htm>.

23


24

28. “LI Topic / Should we trust the government to see if our landis safe?” Geri Barish. Newsday. Feb. 7, 1999.

29. “Long Island cancer rate prompts debate, congressional hear-ing.” AP Newswire. June 10, 2001.

30. Public law 103-43, June 10, 1993, from http://epi.grants.can-cer.gov/LIBCSP/PublicLaw.html.

31. Davis, Devra Lee et. al. “Waiting for Science can Cost Lives.”Newsday. December 31, 2000.

32. http://epi.grants.cancer.gov/LIBCSP/.33. Kulldorff M. et al., Breast Cancer Clusters in the Northeast

United States: A Geographic Analysis, Am J Epidemiol1997;146:161-170.

34. Sasco A.J., Epidemiology of breast cancer: an environmentaldisease?, APMIS 2001 May;109(5):321-329.

35. Stellman, S.D., et al., Breast cancer risk in relation to adiposeconcentrations of organochloride pesticides and polychlorinat-ed biphenyls in Long Island, New York, Cancer EpidemiolBiomarkers Prev 2000 Nov;9(11):1241-9.

36. ibid.37. Laden F., et al., 1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene

and Polychlorinated Biphenyls and Breast Cancer: CombinedAnalysis of Five U.S. Studies, J National Cancer Inst2001;93:768-76.

38. Caplan L.S., et al., Breast cancer and electromagnetic fields—a review. Ann Epidemiol. 2000 Jan;10(1):31-44.

Elizabeth M. Whelan, Sc.D., M.P.H.President

A C S H B O A R D O F D I R E C T O R S

Fredric M. Steinberg, M.D. Chairman of the Board, ACSHHertfordshire, England

Terry L. Anderson, Ph.D., M.S. Political Economy Research Center

Elissa P. Benedek, M.D. University of Michigan

Norman E. Borlaug, Ph.D. Texas A&M University

Michael B. Bracken, Ph.D., M.P.H. Yale University School of Medicine

Christine M. Bruhn, Ph.D. University of California

Taiwo K. Danmola, C.P.A.Arthur Andersen llp

Thomas R. DeGregori, Ph.D.University of Houston

Henry I. Miller, M.D.Hoover Institution

A. Alan Moghissi, Ph.D. Institute for Regulatory Science

John H. Moore, Ph.D., M.B.A. Grove City College

Albert G. Nickel Lyons lavey Nickel swift, inc.

Kenneth M. Prager, M.D.Columbia College of Physicians andSurgeons

Fredrick J. Stare, Ph.D., M.D.Harvard School of Public Health

Stephen S. Sternberg, M.D. Memorial Sloan-Kettering Cancer Center

Mark C. Taylor, M.D.Physicians for a Smoke-Free Canada

Lorraine Thelian Ketchum Public Relations

Kimberly M. Thompson, Sc.D. Harvard School of Public Health

Elizabeth M. Whelan, Sc.D., M.P.H. American Council on Science and Health

Robert J. White, M.D., Ph.D. Case Western Reserve University

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James E. Enstrom, Ph.D.,M.P.H.University of California, Los AngelesStephen K. Epstein, M.D.,M.P.P., FACEPBeth Israel Deaconess Medical CenterMyron E. Essex, D.V.M., Ph.D.Harvard School of Public HealthTerry D. Etherton, Ph.D.Pennsylvania State UniversityWilliam Evans, Ph.D.Georgia State UniversityDaniel F. Farkas, Ph.D., M.S., P.E.Oregon State UniversityRichard S. Fawcett, Ph.D.Huxley, IAJohn B. Fenger, M.D.Phoenix, AZOwen R. Fennema, Ph.D.University of Wisconsin, MadisonFrederick L. Ferris, III, M.D.National Eye InstituteDavid N. Ferro, Ph.D.University of MassachusettsMadelon L. Finkel, Ph.D.Cornell University Medical CollegeJack C. Fisher, M.D.University of California, San DiegoKenneth D. Fisher, Ph.D.Washington, DCLeonard T. Flynn, Ph.D., M.B.A.Morganville, NJWilliam H. Foege, M.D., M.P.H.Emory UniversityRalph W. Fogleman, D.V.M.Upper Black Eddy, PAChristopher H. Foreman, Jr., Ph.D.University of MarylandE. M. Foster, Ph.D.University of Wisconsin, MadisonF. J. Francis, Ph.D.University of MassachusettsGlenn W. Froning, Ph.D.University of Nebraska, LincolnVincent A. Fulginiti, M.D.University of Colorado Arthur Furst, Ph.D., Sc.D.University of San FranciscoRobert S. Gable, Ed.D., Ph.D., J.D.Claremont Graduate UniversityShayne C. Gad, Ph.D., D.A.B.T., A.T.S.Gad Consulting Services

William G. Gaines, Jr., M.D., M.P.H.Scott & White ClinicCharles O. Gallina, Ph.D.Professional Nuclear AssociatesRaymond Gambino, M.D. Quest Diagnostics IncorporatedRandy R. Gaugler, Ph.D.Rutgers UniversityLaNelle E. Geddes, Ph.D., R.N.Purdue UniversityJ. Bernard L. Gee, M.D.Yale University School of MedicineK. H. Ginzel, M.D.University of Arkansas for Medical SciencesWilliam Paul Glezen, M.D.Baylor College of MedicineJay A. Gold, M.D., J.D., M.P.H.Medical College of WisconsinRoger E. Gold, Ph.D.Texas A&M UniversityReneé M. Goodrich, Ph.D.University of FloridaFrederick K. Goodwin, M.D.The George Washington University Medical CenterTimothy N. Gorski, M.D., F.A.C.O.G.Arlington, TXRonald E. Gots, M.D., Ph.D.International Center for Toxicology and MedicineMichael Gough, Ph.D.Bethedsa, MDHenry G. Grabowski, Ph.D.Duke UniversityJames Ian Gray, Ph.D.Michigan State UniversityWilliam W. Greaves, M.D., M.S.P.H.Medical College of WisconsinKenneth Green, D.Env.Reason Public Policy InstituteLaura C. Green, Ph.D., D.A.B.T.Cambridge Environmental, Inc.Saul Green, Ph.D.Zol ConsultantsRichard A. Greenberg, Ph.D.Hinsdale, ILSander Greenland, Dr.P.H., M.A.UCLA School of Public HealthGordon W. Gribble, Ph.D.Dartmouth CollegeWilliam Grierson, Ph.D.University of FloridaLester Grinspoon, M.D.Harvard Medical School

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F. Peter Guengerich, Ph.D.Vanderbilt University School of MedicineCaryl J. Guth, M.D.Hillsborough, CAPhilip S. Guzelian, M.D.University of ColoradoAlfred E. Harper, Ph.D.University of Wisconsin, MadisonClare M. Hasler, Ph.D.University of Illinois at Urbana-ChampaignRobert D. Havener, M.P.A.Sacramento, CAVirgil W. Hays, Ph.D.University of KentuckyCheryl G. Healton, Dr.PH.Columbia University, School of Public HealthClark W. Heath, Jr., M.D.American Cancer SocietyDwight B. Heath, Ph.D.Brown UniversityRobert Heimer, Ph.D.Yale School of Public HealthZane R. Helsel, Ph.D.Rutgers University, Cook CollegeDonald A. Henderson, M.D., M.P.H.Johns Hopkins UniversityJames D. Herbert, Ph.D.MCP Hahnemann UniversityVictor Herbert, M.D., J.D., M.A.C.P.Bronx Veterans Affairs Medical CenterGene M. Heyman, Ph.D.McLean Hospital/Harvard Medical SchoolRichard M. Hoar, Ph.D.Williamstown, MARobert M. Hollingworth, Ph.D.Michigan State UniversityEdward S. Horton, M.D.Joslin Diabetes CenterJoseph H. Hotchkiss, Ph.D.Cornell UniversitySteve E. Hrudey, Ph.D.University of AlbertaSusanne L. Huttner, Ph.D.University of California, BerkeleyRobert H. Imrie, D.V.M.Seattle, WALucien R. Jacobs, M.D.University of California, Los AngelesAlejandro R. Jadad, M.D., D.Phil., F.R.C.P.C.University of Toronto, CanadaRudolph J. Jaeger, Ph.D.Environmental Medicine, Inc.William T. Jarvis, Ph.D.Loma Linda UniversityDaland R. Juberg, Ph.D.International Center for Toxicology and MedicineMichael Kamrin, Ph.D.Michigan State UniversityJohn B. Kaneene,Ph.D., M.P.H., D.V.M.Michigan State UniversityPhilip G. Keeney, Ph.D.Pennsylvania State UniversityJohn G. Keller, Ph.D. Olney, MDKathryn E. Kelly, Dr.P.H.Delta ToxicologyGeorge R. Kerr, M.D.University of Texas, Houston George A. Keyworth II, Ph.D.Progress and Freedom FoundationMichael Kirsch, M.D.Highland Heights, OHJohn C. Kirschman, Ph.D.Emmaus, PARonald E. Kleinman, M.D.Massachusetts General Hospital

David M. Klurfeld, Ph.D.Wayne State UniversityKathryn M. Kolasa, Ph.D., R.D.East Carolina UniversityAlan R. Kristal, Dr.P.H.Fred Hutchinson Cancer Research CenterDavid Kritchevsky, Ph.D.The Wistar Institute Mitzi R. Krockover, M.D.Humana, Inc.Manfred Kroger, Ph.D.Pennsylvania State UniversityLaurence J. Kulp, Ph.D.University of WashingtonLeonard T. Kurland, M.D., Dr.P.H.Mayo ClinicSandford F. Kuvin, M.D.University of MiamiCarolyn J. Lackey, Ph.D., R.D.North Carolina State UniversityJ. Clayburn LaForce, Ph.D.University of California, Los AngelesJames C. Lamb, IV, Ph.D., J.D.Blasland, Bouck & LeeLawrence E. Lamb, M.D.San Antonio, TXLillian Langseth, Dr.P.H.Lyda Associates, Inc.Brian A. Larkins, Ph.D.University of ArizonaLarry Laudan, Ph.D.National Autonomous University of MexicoTom B. Leamon, Ph.D.Liberty Mutual Insurance CompanyJay H. Lehr, Ph.D.Environmental Education Enterprises, Inc.Brian C. Lentle, M.D., FRCPC, DMRDUniversity of British ColumbiaFloy Lilley, J.D.University of Texas, AustinPaul J. Lioy, Ph.D.UMDNJ-Robert Wood Johnson Medical SchoolWilliam M. London, Ed.D., M.P.H.Fort Lee, NJFrank C. Lu, M.D., BCFEMiami, FLWilliam M. Lunch, Ph.D.Oregon State UniversityDaryl Lund, Ph.D.University of WisconsinGeorge D. Lundberg, M.D.MedscapeHoward D. Maccabee, Ph.D., M.D.Radiation Oncology CenterJanet E. Macheledt, M.D., M.S., M.P.H.Houston, TXRoger P. Maickel, Ph.D. Purdue UniversityHenry G. Manne, J.S.D.George Mason University Law SchoolKarl Maramorosch, Ph.D.Rutgers University, Cook CollegeJudith A. Marlett, Ph.D., R.D.University of Wisconsin, MadisonJames R. Marshall, Ph.D.Arizona Cancer CenterMargaret N. Maxey, Ph.D.University of Texas at AustinMary H. McGrath, M.D., M.P.H.Loyola University Medical CenterAlan G. McHughen, D.Phil.University of SaskatchewanJames D. McKean, D.V.M., J.D.Iowa State University

John J. McKetta, Ph.D.University of Texas at AustinDonald J. McNamara, Ph.D.Egg Nutrition CenterPatrick J. Michaels, Ph.D.University of VirginiaThomas H. Milby, M.D., M.P.H.Walnut Creek, CAJoseph M. Miller, M.D., M.P.H.University of New HampshireWilliam J. Miller, Ph.D.University of GeorgiaDade W. Moeller, Ph.D.Harvard UniversityGrace P. Monaco, J.D.Medical Care Management Corp.Brian E. Mondell, M.D.Baltimore Headache InstituteEric W. Mood, LL.D., M.P.H.Yale University School of MedicineJohn W. Morgan, Dr.P.H.California Cancer RegistryW. K. C. Morgan, M.D.University of Western OntarioStephen J. Moss, D.D.S., M.S.Health Education Enterprises, Inc.Ian C. Munro, F.A.T.S., Ph.D., FRCPathCantox Health Sciences InternationalKevin B. MurphyMerrill Lynch, Pierce, Fenner & SmithHarris M. Nagler, M.D.Beth Israel Medical CenterDaniel J. Ncayiyana, M.D.University of Cape TownPhilip E. Nelson, Ph.D.Purdue UniversityMalden C. Nesheim, Ph.D.Cornell UniversityJoyce A. Nettleton, D.Sc., R.D.Elmhurst, ILJohn S. Neuberger, Dr.P.H.University of Kansas School of MedicineGordon W. Newell, Ph.D.,M . S . , F . - A . T . S .Palo Alto, CASteven P. Novella, M.D.Yale University School of MedicineJames L. Oblinger, Ph.D.North Carolina State UniversityJohn Patrick O’Grady, M.D.Tufts University School of MedicineJames E. Oldfield, Ph.D.Oregon State UniversityStanley T. Omaye, Ph.D., F.-A.T.S., F.ACN, C.N.S.University of Nevada, RenoOsterholm, Michael T., Ph.D., M.P.H.ican, Inc.M. Alice Ottoboni, Ph.D.Sparks, NVMichael W. Pariza, Ph.D.University of Wisconsin, MadisonStuart Patton, Ph.D.University of California, San DiegoTimothy Dukes Phillips, Ph.D.Texas A&M UniversityMary Frances Picciano, Ph.D.Pennsylvania State UniversityDavid R. Pike, Ph.D.University of Illinois, Urbana-ChampaignThomas T. Poleman, Ph.D.Cornell UniversityCharles Polk, Ph.D.University of Rhode IslandCharles Poole, M.P.H., Sc.DUniversity of North Carolina School of Public HealthGary P. Posner, M.D.Tampa, FL

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Myron Solberg, Ph.D.Rutgers State University of New JerseyRoy F. Spalding, Ph.D.University of Nebraska, LincolnLeonard T. Sperry, M.D., Ph.D.Barry UniversityRobert A. Squire, D.V.M., Ph.D.Baltimore, MDRonald T. Stanko, M.D.University of Pittsburgh Medical CenterJames H. Steele, D.V.M., M.P.H.University of Texas, HoustonRobert D. Steele, Ph.D.Pennsylvania State UniversityJudith S. Stern, Sc.D., R.D.University of California, DavisC. Joseph Stetler, Esq.Potomac, MDMartha Barnes Stone, Ph.D.Colorado State UniversityMichael M. Sveda, Ph.D.Gaithersburg, MDGlenn Swogger, Jr., M.D.Topeka, KSSita R. Tatini, Ph.D. University of MinnesotaSteve L. Taylor, Ph.D.University of Nebraska, LincolnDimitrios Trichopoulos, M.D.Harvard School of Public HealthMurray M. Tuckerman, Ph.D.Winchendon, MARobert P. Upchurch, Ph.D.University of ArizonaMark J. Utell, M.D.University of Rochester Medical CenterShashi B. Verma, Ph.D.University of Nebraska, LincolnWillard J. Visek, M.D., Ph.D.University of Illinois College ofMedicineDonald M. Watkin, M.D., M.P.H., F.A.C.P.George Washington UniversityMiles Weinberger, M.D.University of Iowa Hospitals and ClinicsJanet S. Weiss, M.D.University of California at San-FranciscoSteven D. Wexner, M.D.Cleveland Clinic FloridaJoel Elliot White, M.D., F.A.C.R.John Muir Comprehensive Cancer CenterCarol Whitlock, Ph.D., R.D.Rochester Institute of TechnologyChristopher F. Wilkinson, Ph.D.Burke, VAMark L. Willenbring, M.D.Veterans Affairs Medical CenterCarl K. Winter, Ph.D.University of California, DavisLloyd D. Witter, Ph.D.University of Illinois, Urbana-ChampaignJames J. Worman, Ph.D.Rochester Institute of TechnologyRussell S. Worrall, O.D.University of California, BerkeleyPanayiotis M. Zavos, Ph.D., Ed.S.University of Kentucky Steven H. Zeisel, M.D., Ph.D.The University of North CarolinaEkhard E. Ziegler, M.D.University of Iowa

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The opinions expressed in ACSH publications do not necessarily represent the views of all ACSH Directors and Advisors.ACSH Directors and Advisors serve without compensation.

cancer clusters: findings vs. feelings

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