We developed a series of articles concerning epidemiologic research on potential health effects of electric and magnetic fields. Our goal was to identify methodological issues that have arisen through past studies of cancer, reproduction, and neurobehavioral outcomes in order to suggest strategies to extend knowledge. Following an overview of relevant physics and engineering principles, cancer epidemiology of electric and magnetic fields is discussed separately with a focus on epidemiologic methods and cancer biology, respectively. Reproductive health studies, many of which focus on exposure from video display terminals are then summarized, followed by an evaluation of the limited literature on neurobehavioral outcomes, including suicide and depression. Methodological issues in exposure assessment are discussed, focusing on the challenges in residential exposure assessment and interpretation of wire configuration codes. An overview offers recommendations for priorities across these topic areas, emphasizing the importance of resolving the question of wire codes and childhood cancer. Collectively, these articles provide an array of observations and suggestions regarding the epidemiologic literature, recognizing the potential benefits to science and public policy

Savitz, David A.

English

PubMed

We developed a series of articles concerning epidemiologic research on potential health effects of electric and magnetic fields. Our goal was to identify methodological issues that have arisen through past studies of cancer, reproduction, and neurobehavioral outcomes in order to suggest strategies to extend knowledge. Following an overview of relevant physics and engineering principles, cancer epidemiology of electric and magnetic fields is discussed separately with a focus on epidemiologic methods and cancer biology, respectively. Reproductive health studies, many of which focus on exposure from video display terminals are then summarized, followed by an evaluation of the limited literature on neurobehavioral outcomes, including suicide and depression. Methodological issues in exposure assessment are discussed, focusing on the challenges in residential exposure assessment and interpretation of wire configuration codes. An overview offers recommendations for priorities across these topic areas, emphasizing the importance of resolving the question of wire codes and childhood cancer. Collectively, these articles provide an array of observations and suggestions regarding the epidemiologic literature, recognizing the potential benefits to science and public policy. 10 refs

Carolina Digital Repository

Health Effects Of Electric and Magnetic Fields:Overview Of Research RecommendationsDavid A. SavitzDepartment of Epidemiology, Campus Box #7400, School of Public Health, University of North Carolina, ChapelHill, NC 27599-7400We developed a series of articles concerning epidemiologic research on potential health effects of electric and magnetic fields. Our goal was toidentify methodological issues that have arisen through past studies of cancer, reproduction, and neurobehavioral outcomes in order to suggeststrategies to extend knowledge. Following an overview of relevant physics and engineering principles, cancer epidemiology of electric and magneticfields is discussed separately with a focus on epidemiologic methods and cancer biology, respectively. Reproductive health studies, many of whichfocus on exposure from video display terminals are then summarized, followed by an evaluation of the limited literature on neurobehavioral out-comes, including suicide and depression. Methodological issues in exposure assessment are discussed, focusing on the challenges in residentialexposure assessment and interpretation of wire configuration codes. An overview offers recommendations for priorities across these topic areas,emphasizing the importance of resolving the question of wire codes and childhood cancer. Collectively, these articles provide an array of observa-tions and suggestions regarding the epidemiologic literature, recognizing the potential benefits to science and public policy. - Environ HealthPerspect 101 (Suppl 4):71-72 (1993).Key Words: Epidemiology, electromagnetic fieldsIntroductionThe scientific literature on potential healtheffects of electric and magnetic fields hasevolved haphazardly, like many researchpursuits. The origins of the epidemiologicevidence can be traced to studies of neu-ropsychological symptoms in Soviet electri-cal workers in the 1960s (1,2), with animportant study of power lines and child-hood cancer published by Wertheimer andLeeper in 1979 (3). Through the 1980s,the pace and scope of epidemiologic researchaccelerated to the point that there are nowperhaps a dozen major ongoing epidemio-logic studies focused on cancer and asmaller number addressing reproductionand neuropsychological function.In an attempt to conceptualize andorganize better the evolving evidence, wehave developed a series of articles. Theintent was not to review comprehensivelythe past research or to draw specific condu-sions for decision-making purposes, butrather to focus on the frontiers of existingknowledge and make recommendations forhow to extend those frontiers. Somedegree of subjectivity is required to abstractthe important observations from the litera-ture and make recommendations aboutwhich of the many possible approaches ismost likely to advance our understanding.Individual authors undoubtedly have differ-ent priorities about what would constitutean exciting discovery, but we all share aninterest in the fundamental questions ofwhether exposures to power-frequencyelectric and magnetic fields affect humanhealth in clinically important ways.Overview of ArticlesTo orient readers miliar with the physicsand engineering aspects of electric and mag-netic fields, the articles begin with Kaune's"Introduction to Power-Frequency Electricand Magnetic Fields" (4). This defines thekey concepts, identifies principal sources ofelectric and magnetic fields and the levels ofexposure typically encountered, analyzes howthese fields affect humans, and describes thetechnology available for environmental mea-surements. The shielding of electric but notmagnetic fields by biological tissues is noted,with some discussion of the processes bywhich the weak fields of concern mightinduce biological effects.Two chapters are devoted specifically tothe study of cancer in relation to electric andmagnetic field exposure. In "EpidemiologicStudies of Electric and Magnetic Fields andCancer. Strategies for Extending Knowledge"(5), I focus on epidemiologic design andanalysis issues that are in need of examinationand improvement. The recommendation ismade for two specific efforts concerningresidential exposures and cancer: a compre-hensive evaluation of sources and patternsof individual magnetic field exposures toidentify exposure sources most worthy ofstudy and to clarify the role of "wire codes"(based on power lines outside the residence)Environmental Health Perspectives SupplementsVolume 101, Supplement 4, December 1993as an exposure source, and an examination ofthe sociology and geography of wire codes toevaluate confounding or selection bias or thepossibility that wire codes influence cancerthrough mechanisms other than magneticfields. Studies of occupational electric andmagnetic field exposure would benefit fromadditional surveys of exposure patterns indiverse industrial settings and from addi-tional empirical evidence on the patterns ofcancer risk in relation to those exposures.Stevens considers "Biologically BasedEpidemiological Studies of Electric Powerand Cancer" (6), in which he relates theindirect evidence from studies of DNAtranscription and translation, calcium bal-ance in cells, and pineal production of mela-tonin to modern concepts of cancer biology.The potential role of electric and magneticfields in the carcinogenic process is exam-ined in the context of a two-stage model forcarcinogenesis, consisting ofmutation ofDNAand cell growth. Integration of laboratoryevidence with this model of carcinogenesisleads to the following recommendations:a) given a number of points at which elec-tric and magnetic fields might operate,exposures over a broad time period shouldbe considered; b) effects on calcium balanceencourage studies of acute nonlymphocyticleukemia; c) influences on pineal functionsuggest studies of hormone-dependent can-cers (female breast, prostate) be conductedin conjunction with an evaluation of otherinfluences on pineal function; and d) alter-ation of calcium homeostasis might lead tooxidative stress, which encourages study of71This manuscrpt was prepared as part of the Environ-mental Epidemiology Planning Project of the HealthEffects Institute, September 1990- September 1992.D. A. SAVITZthe interactive role of radiation and otheragents that induce oxidative stress.Shaw and Croen's article on "HumanAdverse Reproductive Outcomes andElectromagnetic Field Exposure: Reviewof Epidemiologic Studies" (7) systemati-cally reviews the epidemiologic evidencefrom exposures in residences, in workplaces,and to specific electrical devices such as elec-tric blankets and video display terminals.Serious methodological deficiencies exist inmany of the studies, especially those exam-ining exposures other than video display ter-minals, so that research directions cannot bearticulated with a high degree of specificityand confidence. Nonetheless, recommenda-tions are made for: a) addressing the sug-gestion from laboratory studies of a possibleadverse effect on growth by studying selectedcongenital anomalies, intrauterine growthretardation, and chromosomally normalspontaneous abortions; b) consideration ofpaternal residential exposure in relation toreproductive outcomes; and c) applicationto reproductive health outcomes of theexposure assessment methods for residentialand occupational settings previously appliedto cancer, ideally incorporating diversesources of exposure."Neurobehavioral Effects of PowerFrequency Electromagnetic Fields" byPaneth (8) summarizes the evidence forpotential adverse effects on a number ofindices of neurological and psychologicalparameters. The unique challenges ofstudying behavior and cognition includethe problem of laboratory artifacts, the sub-tlety and transiency of many outcomes ofinterest, and the strong influence of socialfactors. The literature on neurobehavioraltesting of experimentally exposed subjects,assessments of occupationally exposedworkers, and the studies associating residen-tial exposure with suicide are reviewed.Laboratory evidence suggesting effects oncalcium efflux does not generate specificpredictions, whereas the potential role ofelectric and magnetic fields in pineal func-tion and circadian rhythms points directlytoward depression as a plausible outcome.Thus, the recommendation is made thatprospective studies of occupational expo-sure and depression be conducted, ratherthan pursuing additional studies of cogni-tion in occupationally exposed groups, forwhich the results have been largely negative,or studying depression in relation to resi-dential exposures, for which the social classinfluences would be difficult to remove.Kaune summarizes the key issues regardingascertainment of exposure in "AssessingHuman Exposure to Power-Frequency Electricand Magnetic Fields" (9). Occupational expo-sures have been inferred largely from job tides.Residential exposure sources are reviewed,with a focus on the rationale for wire codesand spot measurements as indicators oflong-term exposure. Recommendations aremade for: a) development of job-exposurematrices for occupational exposure assessmentbased on direct measurements of workers indifferent occupational groups; b) evaluation ofthe ability of wiring codes and spot measure-ments to predict long-term historical expo-sure; c) an examination of exposures that arepredicted by wire codes; d) an assessment ofthe contribution of residential and nonresi-dential exposures to total exposure; e) study oflong-term temporal variation in residentialexposure; and f ) consideration of alternateexposure metrics associated more dosely withwire code than is average magnetic field.Siemiatycki offers his perspective on"Problems and Priorities in EpidemiologicResearch on Human Health Effects Relatedto Wiring Code and Electric and MagneticFields" (10). He argues that the most press-ing need is to verify the finding that wirecodes are associated with childhood cancerbecause that possibility is the dominant basisfor public concern. This could be achievedby reexamining data from past studies as wellas by launching additional case-control stud-ies that are responsive to concerns about con-trol selection and incorporate measured fieldsand appliance exposures. Additional effortsare recommended for: a) reexamination ofcompleted studies of wire codes and child-hood cancer, b) new studies to examine thereported association between wire codes andchildhood cancer, c) methodological researchto evaluate the relation of wire codes to mea-sured fields and indicators of historical expo-sure, d) occupational studies of cancer, e)documentation of exposure patterns in work-ers outside the electric utility industry, f) ani-mal carcinogenicity studies, g) a broad surveyof residential exposure and ecological studiesof cancer; h) study of neurobehavioral effects,i) reproductive health studies focusing onresidential wire codes primarily and othersources secondarily, and j) studies of adultcancer in relation to nonoccupational expo-sure, with items a tofof high priority and gto j of lower priority. Current impedimentsto the conduct of environmental epidemiol-ogy are noted, with the suggestion thatlarge-scale monitoring systems are needed.In all chapters, the authors were encour-aged to express their own take on the litera-ture and avoid the noncommittal tone ofmany previous committee recommenda-tions. Neither the individual artides nor thesummary represents a consensus but, rather,the product of individual work and criticalresponses to the ideas at several steps alongthe way. As a result, these chapters offerperspectives with which the reader may welldisagree, but because the underlying assump-tions that lead to the recommendations areprovided, the debate itself should be a pro-ductive one. There was a consensus amongWorking Group members, however, aboutthe basic premise that the research area isimportant (in part, because the public hasdecided that it is) and that well-designedand carefully conducted epidemiologicresearch will be beneficial to scientists andthose concerned with the formulation ofpublic policy on this issue. eREFERENCES1. Asanova TP, Rakov Al. The state of health of persons working inthe electric field of outdoor 400 and 500 kV switchyards. Gig TrProf Zabol 10:50-52 (1966).2. Danilin VA, Voronin AK, Modorskii VS. The state of health ofpersonnel working in high-voltage electric fields. Gig Tr ProfZabol 13:51-52 (1969).3. Wertheimer N, Leeper E. Electrical wiring configurations andchildhood cancer. Am J Epidemiol 109:274-284 (1979).4. Kaune WT. Introduction to power-frequency electric and magneticfields. Environ Health Perspect lOl(Suppl 4):73-81 (1993).5. Savitz DA. Epidemiologic studies of electric and magnetic fieldsand cancer: strategies for extending knowledge. Environ HealthPerspect 101 (Supp[ 4):83-91 (1993).6. Stevens R Biologically based epidemiological studies of electric powerand cancer. Environ Health Perspect O1(Suppl 4):93-100 (1993).7. Shaw GM, Croen L. Human adverse reproductive outcomes andelectromagnetic field exposures: review of epidemiologic studies.Environ Health Perspect IO1(Suppl 4):107-119 (1993).8. Paneth N. Neurobehavorial effects of power-frequency electromagneticfields. Environ Health Perspect 101(Suppl 4):101-106 (1993).9. Kaune WT. Assessing human exposure to power-frequency electricand magnetic fields. Environ Heth Perspect 1O1(Suppl 4):121-133(1993).10. Siemiatycki J. Problems and priorities in epidemiologic research onhuman health effects related to wiring code and electric and magneticfields. Environ Health Perspect 01 (Suppl.4):135-141 (1993).72 Environmental Health Perspectives SupplementsVolume 101, Supplement 4, December 1993

Health effects of electric and magnetic fields: overview of research recommendations

Assessing human exposure to power-frequency electric and magnetic fields.

Biologically basedepidemiological studies ofelectric power andcancer. Environ Health Perspect O1(Suppl 4):93-100

Electrical wiring configurations and childhood cancer.

Epidemiologic studies of electric and magnetic fields and cancer: strategies for extending knowledge. Environ Health Perspect

Human adverse reproductive outcomes and electromagnetic field exposures: review ofepidemiologic studies. Environ Health Perspect IO1(Suppl 4):107-119

Introduction to power-frequency electric and magnetic fields.

Neurobehavorial effects ofpower-frequencyelectromagnetic fields.

Problems and priorities in epidemiologic research on human health effects related to wiring code and electric and magnetic fields.

The state of health of personnel working in high-voltage electric fields. Gig Tr Prof Zabol

The state ofhealth ofpersons working in the electric field ofoutdoor 400 and 500 kV switchyards. Gig Tr ProfZabol

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1519698

Health effects of electric and magnetic fields: overview of research recommendations

Abstract

Similar works

Full text

Available Versions

Carolina Digital Repository