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CYNTHIA HILL FORD, et al.

Plaintiffs and Appellants,

- vs. -

PACIFIC GAS & ELECTRIC COMPANY, INC., and
DOES 1 through 100, inclusive,

Defendants and Respondents.

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Introductory Statement

Amici curiae Eleanor R. Adair, Robert K. Adair, Leo L. Beranek, Nicolaas Bloembergen, Patricia A. Buffler, Allan Cormack, Kenneth R. Foster, David Hafemeister, Leonard D. Hamilton, Robert L. Park, Robert V. Pound and Glenn T. Seaborg respectfully submit this amicus curiae brief in support of defendant-appellant Pacific Gas & Electric Company (hereafter "PG&E").

Interest of Amici

Amici are scientists who have studied the issue of the health effects of electromagnetic fields ["EMF"] and believe that the current concern that EMF causes disease, particularly cancer, is not supported by the weight of credible scientific evidence. Amici further believe that the very recent report of the National Research Council of the National Academy of Sciences, issued October 31, 1996, which finds that there is no evidence that extremely low frequency electromagnetic fields causes disease in humans correctly evaluates, assimilates and articulates the current state of scientific knowledge regarding the health effects of EMF. Amici are concerned that any decision which even implicitly can be seen as support for the concerns about EMF would lend credibility to beliefs which are essentially without scientific foundation and based on irrational or speculative fear of injury.

Eleanor R. Adair is Senior Scientist, Electromagnetic Radiation Effects, Armstrong Laboratory, Brooks Air Force Base. She is also a senior research scientist and lecturer at Yale University. She holds a Ph.D. in psychology with a minor in optical physics. Her current field of specialization is the study of the thermoregulatory effects on humans of exposure to electromagnetic fields. She is a Fellow of the IEEE. She has been a co-chairman of Subcommittee 4 of IEEE SCC28 (formerly ANSI C95.4) which promulgated ANSI/IEEE C95.1-1992 guidelines for human exposure to radio frequency fields, and a member of Subcommittee 3 of SCC28, which is charged with setting guidelines for exposure to electric and magnetic fields from 0 to 3 kHz (which includes powerline fields).

Robert K. Adair is Sterling Professor of Physics at Yale University and formerly the chairman of the Department of Physics at Yale University. He was previously Associate Director for High Energy and Nuclear Physics of the Brookhaven National Laboratory. He holds a Ph.D. in Physics. He is a member of the National Academy of Sciences.

Leo L. Beranek holds a doctorate in applied physics from Harvard University. He was a tenured professor of electrical engineering at the Massachusetts Institute of Technology, where he taught magnetic theory, circuit theory and acoustics. He was a co-founder of the engineering consulting firm Bolt Beranek and Newman. He recently served as president of the American Academy of Arts and Sciences.

Nicolaas Bloembergen is a Nobel Laureate in Physics. He is Professor Emeritus of Physics at Harvard University. Prof. Bloembergen was awarded the National Medal of Science in 1974.

Patricia A. Buffler is Dean of and Professor of Epidemiology at the School of Public Health of the University of California at Berkeley. Among many honors and activities in the field of epidemiology, she is currently the Principal Investigator, Molecular Epidemiology of Childhood Leukemia for the National Institutes of Environmental Health Sciences. Dr. Buffler has been Principal Investigator on numerous projects involving occupational cancer, the risks of exposure to electromagnetic forces and environmental risks. In 1991 and 1992 she served as a member of the Nonionizing Electric and Magnetic Field Subcommittee of the Environmental Protection Agency Science Advisory Board's Radiation Advisory Committee; the subcommittee was created to peer review the EPA's draft report "Evaluation of the Potential Carcinogenicity of Electromagnetic Fields," (EPA/600/6-90/005B). Between 1989 and 1992 she served as the chair of the Texas Public Utility Commission's Electro-magnetic Health Effects Committee which issued a report in March 1992 entitled "Texas PUC Electro-magnetic Health Effects Committee Report: Health Effects of Exposure to Powerline Frequency Electric and Magnetic Fields." Dr. Buffler is a Fellow of the American College of Epidemiology, and was President of that organization in 1991-1992. Dr. Buffler is one of the authors of L.I. Kheifets, A.A. Afifi, P.A. Buffler and Z.W. Zhang, "Occupational Electric and Magnetic Field Exposure and Brain Cancer: A Meta-Analysis", 37 J. Occupa. Env. Med. 1327 (1995). Dr. Buffler is a member of the Institute of Medicine of the National Academy of Sciences and a Fellow of the American Association for the Advancement of Science. She is or has been an editor of and a member of the editorial boards of numerous scientific journals, including Journal of Occupational Medicine, the Annals of Epidemiology and the International Journal of Exposure Analysis and Environmental Epidemiology. Dr. Buffler received her Ph.D. in Epidemiology from the University of California at Berkeley.

Allan Cormack is a Nobel Laureate in Medicine and University Professor Emeritus at Tufts University.

Kenneth R. Foster is Associate Professor in the Department of Bioengineering at the University of Pennsylvania. His research involves the study of the interactions between nonionizing electromagnetic fields and biological systems, health and safety issues related to electromagnetic fields, and biomedical applications of electromagnetic fields. Professor Foster has lectured on the health effects of EMF to medical school students and faculty, hospital staffs, graduate students in biophysics and electrical engineering, staffs of university science laboratories, the Institute of Electrical and Electronic Engineers, and science staffs of corporations. He has lectured on, or is the author or co-author of numerous scientific papers and articles in refereed journals on microwave biophysics, dielectric properties of human and animal tissue and chemical components of tissue, electrical and thermal properties of animal and human tissue, the biological effects of low-frequency electromagnetic fields. He co-author of Phantom Risk: Scientific Inferences and the Law (MIT Press, 1993) and Judging Science (MIT Press, to be published April 1997).

David Hafemeister is Professor of Physics at California Polytechnic State University.

Leonard D. Hamilton is Professor of Medicine at the State University of New York at Stony Brook and Adjunct Professor of Biometry and Epidemiology at the Medical University of South Carolina at Charleston. He was, until his retirement from that position, the Head of the Biomedical and Environmental Assessment Group at the Brookhaven National Laboratory, whose task is to assess the health and environmental effects of energy sources, including the effects of radiation. He received his doctorate in medicine from Oxford University and a Ph.D. in Experimental Pathology from Cambridge University.

Robert L. Park is Professor of Physics and former chairman of the Department of Physics at the University of Maryland.

Robert V. Pound is Mallinckrodt Professor of Physics (emeritus) at Harvard University, former Chairman of the Department of Physics and former Director of the Physics Laboratories at Harvard University. Professor Pound was awarded the National Medal of Science in 1990.

Glenn T. Seaborg is a Nobel Laureate in Chemistry, University Professor of Chemistry at the University of California, former Chancellor of the University of California at Berkeley, and former Chairman of the United States Atomic Energy Commission, .

FACTS

Amici understand that plaintiffs allege that the decedent, Mark William Callan, worked as an electrical and telecommunications lineman and engineer for 17 years prior to his death. Amici understand that the plaintiffs allege that his death from brain cancer was caused by Mr. Callan’s exposure to electromagnetic fields surrounding the power lines and PGE failed to warn the deceased of risks of working in close proximity to power lines and equipment which produced electromagnetic fields.

ARGUMENT

Amici understand that the gravamen of Plaintiffs' claim is that their decedent, Mark William Callan, developed cancer of the brain due to exposure to electromagnetic fields produced by high voltage electric power lines. Amici believe that this claim is not supported by scientific principles and research, and that the claim therefore has no substantive merit.

In the United States and Canada, the flow of current in electric powerlines reverses direction 60 times each second: the power is therefore said to have a frequency of 60 cycles per second, or 60 hertz (Hz). In turn, this oscillation causes the electric and magnetic fields arising from the powerlines to likewise reverse their direction 60 times each second; they are therefore said to be "60-hertz fields" or "power-frequency fields."

Sixty-hertz fields are also called extremely low frequency fields, for the following reason. Such fields are only one form of the energy known as electromagnetic radiation. That energy, which is both natural and man-made in origin, has a wide variety of effects on matter depending on its frequency: the higher the frequency, the shorter the wavelength and the greater the energy. The frequencies of different forms of electromagnetic energy extend over an enormous range, commonly represented as the "electromagnetic spectrum." At one end of the electromagnetic spectrum are X-rays and gamma rays, which have extremely high frequencies (10¹⁶ Hz to 10²⁵ Hz and above) and hence extremely high energy. Next on the electromagnetic spectrum is ultraviolet light, which has somewhat lower frequencies (10¹⁵ Hz to 10¹⁶ Hz) and hence somewhat lower energy. Below that is the familiar spectrum of visible light, followed in sequence by infrared waves, microwaves (1 billion Hz (1 x 10⁸) to 300 billion Hz), and television and radio waves (500,000 Hz to 1 billion Hz). Although each of these has progressively lower frequencies and energy, even the lowest (AM radio) has a frequency range of 500,000 Hz (500 kHz) to 1.6 million Hz (1600 kHz). Lowest of all on the electromagnetic spectrum are electric and magnetic fields such as those arising from the powerlines involved in this case. When their frequency of a mere 60 Hz is compared with the frequency of the other forms of electromagnetic energy, it is evident why they are called "extremely low frequency" fields.

An important consequence of the low frequency and resulting low energy of electric and magnetic fields is that they are non-ionizing. An atom or molecule is said to be ionized when one or more of its electrons is dislodged by an energetic outside force such as very high frequency radiation. Gamma rays, X-rays, and high frequency ultraviolet light are termed "ionizing radiation" because their energy is so great that they are capable of ionizing atoms or molecules of ordinary matter.

When that matter is human tissue, ionization can damage the DNA molecules of the cells, causing mutations and various forms of cancer. However, the energy carried in 60 Hz fields is much too small to break molecular or chemical bonds. Like visible light, infrared, microwaves, and television and radio waves, electric and magnetic fields are therefore termed non-ionizing radiation.

One form of non-ionizing radiation-microwaves-can nevertheless cause biological damage by a different process: microwaves are absorbed by the water present in tissue, and can induce currents strong enough to heat the tissue. But while 60 Hz fields can also set up currents in tissue, these currents are much weaker. The amount of heat they generate is trivial compared to the natural heat that comes from the cells of the body. There is no reason to believe that health effects can be caused by such minuscule amounts of heat.

It would be helpful to understand the basic components of the electric power "grid" or system. Power plant generators deliver electric power to the system at approximately 20 kV. "Step-up" transformers increase that voltage to higher levels for transmission purposes, because the higher the voltage, the less power lost in the wires. The power is then carried long distances over transmission lines at voltages that range between 50 kV and 765 kV. Transmission lines terminate at substations, where "step-down" transformers reduce the voltage for distribution purposes. The power is then carried shorter distances over various types of distribution lines, at various voltages below 50 kV, to the ultimate users. By the time the power is delivered to the commercial or residential user, its voltage has been reduced to 120 or 240 volts.

It is also important to stress that electric and magnetic fields arise not only from powerlines but also from the distribution and use of that power inside the home, office, or factory. One common source of such fields is the wall and ceiling wiring of the building itself, which delivers the electricity to the individual rooms in which it is used for lighting, heating, or operating appliances. Although the magnetic fields of modern wall and ceiling wiring are small, older wiring can make significant contributions to the average magnetic field in homes. Another source, often overlooked, is the "ground currents" that flow through the water pipes, gas lines, or steel framing typically used for grounding the wiring system of the building: the magnetic fields that they produce can contribute substantially to the overall magnetic field in homes or offices.

A third common source of electric and magnetic fields is electric equipment and appliances. In the factory, this means all machines and tools powered by electricity-in other words, virtually all industrial machinery in use today. In the office, this means fluorescent light fixtures and all such equipment as computers, video display terminals, printers, copiers, typewriters, and fax machines. In the home, this means television sets, videocassette recorders, compact disc players, radios, table lamps, vacuum cleaners, power tools, portable heaters, electric blankets, electric shavers, hair dryers, clothes washers and dryers, irons, electric ovens and ranges, refrigerators and freezers, as well as toasters, coffeemakers, food processors, and all other small kitchen appliances. The most intense magnetic fields in the home are found near appliances (particularly those with small motors or transformers such as hairdryers and fluorescent light fixtures). Although they are probably not the main source of the magnetic background because their fields decrease rapidly with distance and users generally spend only brief periods of time operating such appliances (with the exception of electric blankets and television sets), they are ubiquitous in the modern home or office.

In the typical home or office, fields of various strengths arise from the wall and ceiling wiring, the ground currents, and all electric machinery, equipment, and appliances. Keeping fields out of the home and office would mean keeping any electricity from coming into or being used in the home or office.

The present public concern that low intensity electromagnetic fields that are near electric power lines are hazardous originated primarily from a report of an epidemiological study that the incidence of childhood leukemia near Denver was greater among families who lived close to power lines than among those that lived further away. In addition, it appears that the only, or certainly the principal, evidence plaintiffs have introduced or sought to introduce to establish a link between electromagnetic fields and disease are epidemiological studies.

In this brief, therefore, we address the epidemiological evidence that low intensity electromagnetic fields from power lines can cause cancer. We conclude that the evidence does not justify the link between proximity to 60 hertz electric power sources and cancer, such as that claimed by plaintiffs.

Epidemiological data are often expressed in terms of a "Risk Ratio." The "Risk Ratio," found by the Denver study, that is the ratio of the number of leukemias seen in the population studied to the number one would expect if a similar population chosen at random were studied, is about 2.3, whereas it would be approximately 1 (unity) in the absence of an association. The authors of the Denver study postulated that leukemia incidence is "associated" with the presence of power lines, and by inference with magnetic fields of very low intensity -- 3 milliGauss (one milliGauss is one thousandth of a Gauss). This postulate was immediately linked to an earlier suggestion that electric and magnetic fields of low intensity can produce effects on cells -- particularly on the rate of calcium efflux from the brain tissue of chickens.

It is important to realize that if an epidemiological study were repeated under otherwise identical conditions at a different place and time, the result will not be identical. There will almost certainly be differences because of the limited number of people observed in each study. One can, however, imagine the repetition of the study a large number of times, and a distribution of Risk Ratios would be found. If the Risk Ratio were found to be greater than unity in 97.5% of the repeated studies, it is the usual practice in epidemiology to call it "statistically significant." The value of the Risk Ratio below which 2.5% of the repeated studies fall is called the "lower confidence limit," and the Risk Ratio above which 2.5% of the studies fall is called the "upper confidence limit." Since 95% of the studies fall within these limits, the upper limit is often called the "upper 95% confidence limit." But statistical variation due to population sampling is only one reason for the Risk Ratio being different from the "true" answer. There are other uncertainties which are hard to assess, and which, in epidemiological studies (unlike in experiments in the physical sciences), are not estimated and quoted.

The "residential" studies of proximity to power lines have led to other epidemiological studies and laboratory attempts to induce cancer in animals and studies in vitro, such as those of Bawin and Adey. The results of these laboratory studies are reported in over 1,000 references. However, they are far from conclusive, and they would not be considered significant indicators of any problem without the epidemiological studies.

The published epidemiological studies of electromagnetic fields are of three distinct types. The first type concerns the effects of power lines on nearby residents, the second type examines the effects of electric blankets on users, and the third type explores the effects of exposure to magnetic fields (among many other environmental polluting agents) on workers in various occupations.

It is a fundamental statistical principle that one should not ask a statistical question when one already knows the answer -- the so-called "Feynman Trap." Wertheimer and Leeper, the authors of the Denver study, did not ask whether leukemias were associated with the proximity to power lines until they had already noticed that some were. Their observation is thus inherently incapable of proving, statistically, that proximity to power lines causes cancer. Yet it is obvious that Wertheimer and Leeper generated two hypotheses by asking two questions: "Is proximity to power lines associated with increases in leukemia?" and "Is this association due to the magnetic fields at the houses in question?" Their study is what is called a "hypothesis generating study." We must turn to the work of other investigators to address the two questions generated by the Denver study.

Epidemiological studies by Savitz, et al. and London, et al. also found that there seems to be an association between childhood leukemia and proximity to power lines, albeit smaller than that suggested by Wertheimer and Leeper (the Risk Ratio is smaller in each of the subsequent studies). This might suggest that the hypothesis of Wertheimer and Leeper had been confirmed, but the experiments were not exact replications. The effects observed by Savitz, et al. were not apparent if the exposure classes were taken to be identical with Wertheimer and Leeper, but only showed up when a fourth (sub)class was added. Therefore, the statistical interpretation is not obvious, and the magnitude of the problem has not been assessed.

Moreover, before reaching a conclusion, one must look at all the data. Thirteen studies of childhood leukemia due to residential exposure were reviewed and compared by Washburn, et al. If one makes the assumption that the only uncertainty in each study was the statistical sampling error due to the limited number of leukemias observed and then weighted each study by the number of cases and averaged the results, one finds a statistically significant relationship between leukemia and some measure of proximity to power lines (Risk Ratio = 1.49 with 5% and 95% confidence limits of 1.11 and 2.00).

But one should look at the data further. If the magnetic fields really increased the incidence of leukemia, we would expect that the Risk Ratio would be higher when the fields themselves were measured than when only a "surrogate" for the fields, the proximity to power lines, is used. The opposite is the case. In only three studies were magnetic field measurements made contemporaneously at the houses in question. In these the Risk Ratio for proximity to power lines was 1.57 (and statistically significantly different from unity) but for actual field measurements was 1.30 (and not statistically significantly different from unity). This seems to many scientists to exonerate magnetic fields as the real cause of the leukemias found.

Various alternative explanations have been postulated for the claimed association. Jones, et al. showed that there is a selection bias: people who live near power lines move residences more frequently and hence are not comparable to those who do not live near power lines. This will produce a "selection bias." If the persons who moved their residence frequently respond to researchers' questions if they have leukemia, but do not usually respond if they do not have the disease, it would (erroneously) appear that the power lines cause leukemia. Proximity to power lines is not then a proper "surrogate" for whatever causes the disease. It has been noted that overhead power lines are usually found in older neighborhoods where straight roads lead to moderate traffic. Newer secluded neighborhoods often have no overhead powerlines.

It remains possible that the proximity to power lines is a better indicator of past electromagnetic fields than present (contemporaneous) measurements. A recent study from Sweden included in the review by Washburn, et al., was one of the studies that found no correlation between cancer and contemporaneously measured magnetic fields, but found a correlation with fields calculated from historically recorded electric currents in the wires. The historical calculation was made for the time when the leukemia was diagnosed. Although the Risk Ratio in this particular study is reasonably large (about 3), the number of leukemias observed was small and therefore the study is of marginal statistical significance. Moreover, it appears that the authors chose to examine the historically calculated fields after seeing the data. Since they did not ask the specific question in advance, the "Feynman Trap" may apply and the statistical validity is reduced by an unknown amount. There are other concerns with this study. There are two possible surrogates for the relevant past average of electromagnetic fields -- contemporaneous measured fields, and fields calculated from historical usage. Marshall has pointed out that if there is really a causal relationship one would expect a higher Risk Ratio if a combination of the two measures of exposure to electric transmission lines were used. Yet the Risk Ratios average to be less when a combination of the two measures, historically calculated fields and contemporaneously measured fields, is used.

In five of the studies searches were made for lymphomas (found not to be statistically significant) and in seven for nervous system tumors (statistically significant relationship found with proximity to power lines). After the Wertheimer and Leeper study, there was a search for situations where there is a larger magnetic field than produced by power lines, and also situations where there is a reliable comparison population.

One comparison is with electric blankets. The wires in almost all electric blankets were wound very simply, and produced a magnetic field 10 to 100 times that of neighboring power lines. This immediately suggests that one compare cancer incidence rates among those who regularly use electric blankets with the rates among those who do not. The first such study suggested a difference, but more careful studies found none. This is a very important conclusion, because the comparison is direct and the likely confounding effects are fewer than for the power line studies described earlier.

The ORAU report carefully analyzed a number of occupational studies. These are grouped under studies with different cancer end points. They include brain cancer in children, lung cancer, and leukemia. It is important to note that leukemia is at least four different diseases. The different types are:

If the effect of exposure to EMF is real, one expects the same distribution of cancers in all studies, and the same distribution of types of leukemia. Indeed, there should be the same type of leukemia in the residential studies also. This does not seem to be the case.

The studies of leukemias among people in occupations where there is exposure to electromagnetic fields involve situations which are more complex than the studies of exposure to electric blankets. Occupations expose people to many different pollutants, so that a small overall increase in cancer is not unlikely and would be hard to attribute to electromagnetic fields. Because these are case control studies there was no automatic search for all cancers. There are now 52 studies that looked for undifferentiated leukemia, several more than reviewed in the ORAU report. The additional studies do not change the picture. The average Risk Ratio (properly weighted for statistical accuracy) is small -- 1.12. It is significant if only statistical sampling errors are included. The non-statistical errors change this picture. The incidence of Acute Myelogenous Leukemia (AML) in 27 studies gives an average Risk Ratio of about 1.35, but in the studies where both total (undifferentiated) leukemia and AML were studied the risk of AML is greater than the risk of undifferentiated leukemia only half of the time. The slight average increase need not, however, be related to electromagnetic fields even if it can be properly attributed to occupation. AML can be caused, for example, by exposure to benzene, probably by exposure to other solvents and also by exposure to ionizing radiation.

A listing of the epidemiological data on brain tumors can be found in the paper by Loh²⁸. A review of the epidemiological data that might relate to occupational exposure to electric and magnetic fields and brain cancer is presented in Kheifets, et al. Both of these articles agree that a meta analaysis suggests a small statistically significant association. Further, it is noted that in the article by Kheifets, et al., the association observed is with occupational job titles presumed to be associated with exposures to electric and magnetic fields, and not with actual measurements of the fields themselves.

A summary of the results of the occupational studies also shows a small increase for CLL. (The Risk Ratio for an average of 14 studies is 1.26). One of the recent studies, from Sweden shows a small (statistically insignificant) trend of an increase of Risk Ratio with occupational exposure to magnetic fields.

But one must be cautious. While it might be true that the proximity to electromagnetic fields in the workplace is statistically associated with brain cancer incidence, that does not constitute proof that electromagnetic fields are responsible for the increase. One must distinguish between risks that are occupationally related and risks that are related specifically to electromagnetic fields.

In the discussion in the paragraphs above, epidemiological studies, weighted by their statistical accuracy, have been combined. This would a correct approach if there are no systematic errors, such as a selection bias or unknown "confounders" (alternative explanations). Epidemiologists, in contrast to physical scientists, quote only the statistical errors, and merely attempt to describe the other errors in the test, but do not quantify them. But it must not be assumed that they do not exist. In the much simpler field of measurement of physical constants, scientists endeavor to estimate these systematic errors and they routinely quote their estimates. Nonetheless, many authors have demonstrated that physical scientists routinely underestimate the errors and that the confidence limits are much wider than usually stated. Presumably the practitioners of the difficult field of epidemiology are no better at reducing unknown errors than are their colleagues in the physical sciences. This suggests that a small effect, which would just be considered significant if only statistical sampling errors are included, should be considered insignificant if other systematic and unsuspected errors are included.

The American Physical Society in the Spring of 1995 issued a formal statement declaring that "The scientific literature and the reports of reviews by other panels show no consistent, significant link between cancer and power line fields.... While it is impossible to prove that no deleterious health effects occur from exposure to any environmental factor, it is necessary to demonstrate a consistent, significant, and causal relationship before one can conclude that such effects do occur. From this standpoint, the conjectures relating cancer to power line fields have not been scientifically substantiated." (Council of Am. Physical Society, Power Line Fields and Public Health (April 1995).) The American Medical Association (AMA) likewise adopted a policy statement declaring that the association "will continue to monitor developments and issues relating to the effects of electric and magnetic fields, even though no scientifically documented health risk has been associated with the usually occurring levels of electromagnetic fields; (AMA Policy Compendium (1995) Policy No. 60.938, emphasis supplied).

The most recent study, by the Committee on the Possible Effects of Electromagnetic Fields on Biologic Systems of the National Research Council of the National Academy of Sciences, prepared pursuant to a request of the United States Congress made in 1991 and issued October 31, 1996, after extensive effort, is a comprehensive examination and evaluation of approximately 500 published studies relating to the effects of power-frequency electric and magnetic fields on cells, tissues and organisms (human and non-human). The National Research Council study concluded that:

National Research Council of the National Academy of Sciences, "Possible Health Effects of Exposure to Residential Electric and Magnetic Fields" at 1 (1996)(hereafter the "NRC Study") (emphasis supplied). The NRC Study continued, "In the aggregate, epidemiologic evidence does not support possible associations of magnetic fields with adult cancers, pregnancy outcome, neurobehavioral disorders, and childhood cancers other than leukemia." (Id. at 3)(emphasis supplied).

B. The Epidemiological Principles

Since it is the epidemiological evidence that is at the root of the recent concerns, it seems worthwhile reviewing that evidence in light of scientific principles that are used to evaluate whether a statistical association that is found should be considered to be causal.

Sir Austin Bradford Hill in his Presidential Address to the Section of Occupational Medicine of the Royal Society of Medicine (U.K.) suggested such a list of "attributes" of the association to be considered:

The "strength" of the association was most convincing in Percival Pott's original observation a century and more ago that almost all chimney sweeps developed scrotum cancer. (i.e. the Risk Ratio is very large). Little other evidence seemed necessary. But even for cigarette smoking, where the Risk Ratio is over 10, it was many decades before scientists were convinced of the causal connection.

Although the "ecological" studies started by Wertheimer and Leeper showed a Risk Ratio of about 2.28, the statistical significance was marginal. As noted above, Washburn, et al. find a Risk Ratio of 1.57 for some sort of association with the presence of power lines which is statistically significant. We emphasize the difference between the standard practice in epidemiology and the standard practice in the physical sciences. Physical scientists routinely discuss non-statistical and systematic errors in great detail, and usually attempt a quantitative description of them. Epidemiologists sometimes discuss the non-statistical errors in the text, but do not make a quantitative estimation or include the qualifying phrases in the abstract of an article. Great caution is necessary in any interpretation of these numbers, especially when the effect is small. We note that the reduction in Risk Ratio from 2.28 to 1.57 is a two fold reduction in predicted excess cancers since the excess cancers are proportional to (Risk Ratio -1). This is the type of reduction we would observe because of the fact that some of the cases were known before the study started (the "Feynman Trap").

Although a few of the occupational studies listed in the ORAU report, and others that have appeared since, have high Risk Ratios which, by themselves, seem statistically significant, the average is much closer to unity.

If the average found in either the ecological studies or the occupational studies were found in a single study, the Risk Ratio of 1.57 would not normally be considered large enough to be deemed evidence for a causal relationship. Of situations where the measured Risk Ratio is less than 2, only two have been accepted as evidence of harm, and these are special situations. The effects of tobacco smoke on the families of smokers (with an average 19% increase or a Risk Ratio of about 1.19) have been accepted by the Environmental Protection Agency, and by many physicians and scientists: this is because tobacco smoke is known to be hazardous to the smoker who has a large dose. Likewise it is generally accepted that there is an effect of X-rays during pregnancy on the probability of childhood leukemia, even though the Risk Ratio averaged over studies is less than two, because at high level exposure radiation does clearly cause cancer. But there is no intensity or situation where electromagnetic fields are known to cause cancer, so one cannot argue that the existence of an effect in a higher intensity field reduces the standard of proof of causation for lower intensity fields. A recent article in Science discusses problems of accepting epidemiological studies with a small risk ratio.

Hill's Attribute 2 asks whether "the same result has been repeatedly observed by different persons, in different places, circumstances and times." The record is mixed. The initial observation that excess childhood leukemias are observed near power lines has been repeated a few times, and there seems to be a consistent relationship with proximity to power lines, but not with the measured magnetic field itself. The Swedish residential study is consistent with earlier studies in that no association was found with fields measured contemporaneously, but since no one else calculated fields from wire codes and historical usage, the statistically significant result here cannot be properly said to be completely consistent with earlier data.

Consistency is also related to the next Attribute, specificity. As noted earlier it is not enough for successive studies to find that cancer is elevated in the presence of electromagnetic fields. The Feychting and Ahlbom study suggested that magnetic fields cause an increase in Acute Lymphocytic Leukemia (ALL) but not in Chronic Lymphocytic Leukemia (CLL), whereas the study by Floderus, et al. showed the opposite -- an increase in CLL, but not in ALL. The residential studies show no increases in leukemia in adults, and only effects in children are claimed. The most recent study of electric company workers by Savitz and Loomis shows no increase in any leukemia. For brain cancer Savitz and Loomis found that the Standard Mortality Ratio (SMR) was less than unity (showing fewer cancers than normal), for the group as a whole, but there was a marginally significant trend with estimated dose. This phenomenon has been found in no other study. There is no set of observations consistently found in all studies.

Attribute 3 emphasizes that "if the association is limited to specific workers and to particular sites and types of disease, and there is no association between the (postulated cause) and other modes of dying, then clearly there is a strong argument in favor of causation." This Attribute must be interpreted with full understanding of the generality of the exposure mechanisms. Unlike chemical carcinogens, which give the dose at well defined parts of the body, electromagnetic fields might well affect all parts of it. In this respect, and this respect only, the problem might be similar to external gamma radiation, which affects all parts of the body. This Attribute might, at first sight, be considered not to apply at all. However, if electromagnetic fields produce several types of cancer in one group of people, they should produce the same types of cancer in similar proportions in all other groups similarly exposed.

Attribute 4 demands that the adverse outcome occur after the postulated cause by whatever delay (latent period) has been seen in other studies, or is reasonable from biological principles. In other words, "Which is the cart and which the horse?" In the existing epidemiological studies, the cancer incidence has not been associated with a contemporaneously measured electromagnetic field, in spite of searches for an association, nor has it been possible to associate incidence with a field measured at an earlier time, because of an inability to get data. Instead, the association is with a field assumed, or calculated, from configurations of high tension transmission and local distribution wires.

A very important anchor for epidemiologists is Attribute 5 on Hill's list -- the existence of a biological gradient or dose response relationship. In the usual models, "more is worse" and "less is better," and the adverse effect is at least proportional to the exposure if it does not rise faster than proportionality suggests. There is no accepted medical effect of a pollutant where the effect does not increase as the dose increases, at least initially. The effect of magnetic fields on cells is expected, on general symmetry principles, to vary as the square of the field (B²) at low fields. This dependence arises because the magnetic field comes from the motion of electric charges rather than from the charges themselves, and it is not sensible to envisage that cancer incidence changes sign (from plus to minus) as the magnetic field changes sign. When one considers alternating fields, the principle is even more general. Electric power lines produce magnetic fields of 3 milliGauss or less in nearby houses. A study of Norwegian railroad workers (who work on an electric railroad with regular exposure to approximately 30 milliGauss fields and peaks of 300 milliGauss) showed no brain tumors, even though the exposure was probably greater than that of utility workers of reference discussed in Savitz and Loomis. In the past, electric blankets gave still larger fields (300 milliGauss) (before they were made with twisted pair wire), but epidemiological studies of people who used older-type blankets have not shown a very large effect, even though the general argument suggests that the effect should be 10,000 times greater than the effect on persons exposed to 3 milliGauss fields. The initial epidemiological study on the effects of electric blanket use showed a small effect, but a later study with improved methodology found no effect at all. Moreover still larger fields are known in laboratories, and no ill effects are known.

Since effects are claimed with 60Hz fields of a few milliGauss, the question at once occurs, "What is the effect at a few kiloGauss (ten thousand Gauss, or one million times larger than household exposure)?" We might no longer expect the effects to vary as B² (where B represents the value of the magnetic field). For any postulated effect on people, a similar saturation might be expected at similar fields. But below 30 Gauss we might still expect that the phenomenon varies as B² and any effect at 3 milliGauss would be one hundred million times smaller than that at 30 Gauss. Many scientists and other test "guinea pigs," including some of the amici, have deliberately or inadvertently exposed themselves to magnetic fields of tens of kiloGauss without obvious adverse effect. Ten seconds of work in such a field would be equivalent, on the basis above, to a lifetime of exposure to 3 milliGauss fields. The only observed effects were a tasting of the fillings in the teeth and flashes of light in the retina as the head moved in the field.

Although there are a few theoretical models that suggest that effects of specific environmental pollutants first increase with dose and then decrease as dose increases further, these have so far only been postulated to occur in situations where there is unequivocal evidence of cancer at high doses. The most important conclusion that can be drawn from the mass of data is that there is no exposure level where electromagnetic fields have been demonstrated to cause cancer. There seems, therefore, no reason to make electromagnetic fields a logical exception to the usual rule that "more is worse."

Attribute 6 demands that the claimed effect be biologically plausible. Hill emphasized that we cannot always demand this because "what is biologically plausible depends upon the biological knowledge of the day." But one can interpret this broadly, and Hill does this under "Coherence". A mechanism must be postulated that is not at variance with other knowledge. Before cancer was widely known, an attribution of cancer to a particular cause such as a dose of a chemical could have been considered implausible. However, such an attribution was not considered impossible. There existed (and still exist) models of chemical carcinogenesis which, although unproven and not easily provable, are nonetheless plausible. That is not the situation with electromagnetic fields. At the present time, no mechanism has been successfully postulated by which 3 milliGauss magnetic fields could cause any cancer. Because of the absence of any such model, the claims of cancer from magnetic fields fail Hill's Attribute 6.

Attribute 7 requires coherence of the data. This Attribute is related to the general plausibility mentioned in the previous paragraph. The idea that the association of lung cancer with cigarette smoking is coherent both with the increase in cigarette use, and the increase in lung cancer that followed it by a couple of decades is plausible. It is also coherent with the sex difference in both these variables.

Hill also mentions, under this heading, coherence with laboratory experiments on animals and in vitro. Many experiments on the effects of electromagnetic fields have been quoted as evidence that low intensity magnetic fields cause effects in biological systems. It has been suggested that the experiments on calcium efflux from chicken brains substantiate the epidemiological results. There are two problems with such a statement. Firstly the results of these efflux experiments have not been closely similar when they have been repeated, so that the ordinary scientific concept of repeatability, which can and should be applied to laboratory experiments and which is closely connected with factor (3) on the United States Supreme Court's list of criteria in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993), on remand 43 F.3d 1311 (9th Cir. 1995), is not satisfied.

Other claims have been made which looked, at first sight, highly attractive for an independent replication. For example, Blackmun, et al. reported an experiment that purported to show that weak 45 Hz magnetic fields inhibit the growth of neurites from PC-12 cells treated with a growth stimulation factor. The inhibition was assessed by a "yes/no" judgment whose statistical precision is similar to that of tossing a coin. Adair correctly pointed out that the precision of the reported points is too good and could not possibly have been correctly derived from the stated measurements without adjustment. The arguments of some proponents of an effect that the attempted repetitions have not been properly done are here irrelevant because the burden of proof is on the proposer that electromagnetic fields cause cancer. Secondly, even if such laboratory tests are found to produce results contrary to existing scientific understanding, and show that there is a measurable biological effect, they say nothing about cancer. The measurable effect might be benign, or even good.

Attribute 8 demands that the results be consistent with experiment. Hill here considers the possible experiment of taking preventive action by cessation of exposure. "Does it in fact prevent?" No one has dared to propose cessation of exposure to electromagnetic fields, because society needs (or wants) the enormous benefits that the technology brings. The opposite of cessation has, of course, occurred. The considerable increase in electricity use in the past century does not seem to have been accompanied by major increases in the incidence of the types of cancers discussed.

Hill's Attribute 9 would suggest that an effect could be accepted if it is analogous to another situation where the proof is more substantial. Are there other situations in which people detect external influences below the calculated limits of sensitivity? The physiological literature describes over 50 sensory modalities for living organisms in each of which man can detect at very close to the limit but not below it. For example in the retina of the eye, cells are sensitive to an individual quantum of light -- the limit of sensitivity. Bialek makes three points as he concludes his review of these systems:

Bialek's discussion shows that analogy not only fails to suggest that an effect might exist, but instead suggests that it is improbable. The burden of proof on anyone who claims otherwise is heavy.

It would be inappropriate for a court to allow the introduction of "scientific" evidence that satisfies few of Hill's principles, without extensive evidence also being proffered on the principles themselves and the logic behind them.

Of course opinions can differ on whether these principles are met, but there is a growing scientific consensus that the epidemiological studies do not show an association between 60 Hertz EMF and cancer. We refer to reviews by committees composed of distinguished and competent persons and set up by responsible public bodies and professional associations. We list some reviews below:

None of the groups listed has concluded that there is an effect of electromagnetic fields against which we must guard.

Moreover, the California Supreme Court, in San Diego Gas & Electric v. Superior Court (Covalt), 13 Cal. 4th 893, 920 P.2d 669, 55 Cal. Rptr. 724 (Sup.Ct. Cal. 1996) surveyed the scientific literature, and concluded, as do these amici and the consensus of the scientific community, that the present state of scientific knowledge does not support a finding of causation between EMF and disease in humans. We submit that the decision in Covalt is dispositive as to the lack of sufficient scientific evidence upon which to predicate a finding of liability.

CONCLUSION

While the scientific literature on the biological effects of electromagnetic forces is extensive, and some recognized scientists suggest that exposure to electromagnetic fields may cause leukemias, brain cancers or other diseases, most scientists in the field conclude that no serious danger to health due to exposure to normal intensities of low frequency electromagnetic fields has been established. The ORAU Report surveyed more than 1,000 articles published from 1977 to 1992, and found

The Committee on the Possible Effects of Electromagnetic Fields on Biologic Systems of the National Research Council of the National Academy of Sciences, in its comprehensive examination and evaluation of the leading published studies relating to the effects of power-frequency electric and magnetic fields on cells, tissues and organisms concluded that:

The physics and cellular biology combined strongly indicate that it is not scientifically reasonable to believe that 60Hz magnetic fields increase the incidence of cancer. There are no reasonable proposed mechanisms by which 60 Hz fields from power lines can interact with human tissue to cause cancer which do not violate well established laws of electromagnetism and thermodynamics. While it is conceivable that reliable biomedical experiments or epidemiological studies could show that 60 Hz fields are a cancer risk, the voluminous biomedical and epidemiological literature that now exists does not indicate any such risk. In some circumstances, scientists recommend that more research is necessary. But at some point there comes a time, and many of the amici believe that time is at hand, to say that there is enough research to enable us to conclude that there is no risk that low frequency power lines cause cancer.

Amici submit that this Court should affirm the decision of the Superior Court.

Dated: New York, New York
February 5, 1997

Respectfully submitted,

______________________________________

MARTIN S. KAUFMAN

ATLANTIC LEGAL FOUNDATION
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