By Edward P. Richards, 16 IEEE Engineering In Medicine And Biology Magazine, (Sept.-Oct. 1997) #5 p. 176-178.
A large number of persons in the United States and Europe believe that EMF causes human illness. These illnesses include childhood leukemia, other cancers, high blood pressures, the aggravation of other diseases, and electrical sensitivity syndrome. Given our field, this is probably of some concern to the readers of this journal. EMF has become a legal issue as people seek compensation for alleged injuries and try to have power lines relocated away from their homes. This column discusses the problem of making good legal decisions about complex scientific problems such as EMF.
Since the discovery of electricity, people have believed that electrical fields must have some influence on the body. In the late 19th and early 20th centuries the US was flooded with quack medical devices purporting to cure various ailments by exposed people to electric and magnetic fields. Many of these devices posed the risk of old-fashioned electrocution, especially those that combined power from the electric mains with saline solutions and body cavities.
Since the FDA was given the power to regulate medical devices, it has greatly limited quack electrical and magnetic healing devices. During the same period, the public has started to search for environmental causes for illness. As one public health professor explained: 200 hundred years ago people believed that diseases were caused by miasmas from swamps and other unhealthy vapors; 100 years ago they started worrying about germs; and now they have come full circle and are worrying about miasmas again.
EMF fits the bill because it is mysterious. Most individuals, including a lot of health care providers, do not understand EMF. They do know that ionizing radiation from radioactive substances is bad, so it is clear that invisible rays can be dangerous. Since scientists have the unfortunate habit of referring to electromagnetic radiation, the general public hears radiation and starts worrying. A great example of the power of words in this area is the renaming of nuclear magnetic resonance (NMR) imaging to magnetic resonance imaging (MRI) for fear that nuclear would frighten patients. (Of course, now they are frightened of magnetic fields, so a new name should not be long in coming.)
The starting point for the current EMF controversy was an epidemiological study done in Denver about 20 years ago. The researchers looked at childhood acute lymphoblastic leukemia (ALL), a disease with a 30% mortality, and a difficult course of treatment for those who survive. While it is known to be caused by a ionizing radiation, this only accounts for a small number of cases. The rest are distributed apparently at random. The incidence of the disease has increased by about 20% over the past two decades, also for no know reason.
The research began because there were puzzling clusters of disease. While such clusters are to be expected mathematically - it would be unlikely that the cases would be perfectly evenly distributed - it makes sense to investigate them because clustering can also be due to a common causal agent. The epidemiologists took a list of children diagnosed with leukemia, and identified a control group who were demographically similar to the affected children. The researchers then compared the proximity of high voltage power lines to the houses of the leukemia victims and the control group. They did not measure electrical or magnetic fields, but estimated them by the distance of the power line to the home, and number and types of power lines.
They found that the risk for childhood leukemia was more than double for the children living near power lines. The study had substantial methodological flaws: 1) many of the children had lived in different houses during the period when the disease developed; 2) because electrical fields fall off quickly with distance, electrical appliances and home wiring make a bigger contribution to local electrical and magnetic fields; and 3) since the disease is fairly rare, and Denver was small, the number of cases was too limited to have much statistical validity for such a low risk ratio. (A doubling of risk in small and inhomogeneous sample is not really much of an increase.) While scientists discussed the methodological flaws, the popular press reported that power lines cause cancer.
More studies were done in the subsequent years. They found either no risk or a risk that was lower than that found in the Denver study. The public's view did not track the science: One recent survey found that half of the American pubic knows that there is a controversy over the health effects of EMF, and of this group, 49% believe that the EMF causes cancer.
People fear the unknown. This is part of human culture and characterizes all known civilizations. Once it was eclipses and comets, now it is invisible things in the environment. In the past, such fears were expressed in terms of demons and curses, and malign forces of nature and the gods. Now, we medicalize our problems, so the fears are expressed in terms of illness. We exacerbate this focus on external causation with our emphasis on healthy living and risk avoidance. While it is important to wear your seat belt and to not smoke cigarettes, the personal responsibility theory of health gets carried to extremes. This is most true with children. The implicit message we send pregnant women is that everyone can have a perfect baby but, if you screw-up once, your child could be born with birth defects or have problems later in childhood. The end result has been lots of litigation against obstetricians for unpreventable birth defects or injuries. The parents must prove it was the physician's fault to in order to believe that it was not their own fault.
Cancer engenders the same reaction. Since some cancer is clearly preventable, it is assumed that most cancer must be preventable if we only knew what caused it. Electrical power is a logical culprit: the modern increase in cancer seems to parallel increased use of electrical power. This is especially true for childhood cancers. While epidemiologists know that cancer is a major source of childhood mortality, most people do not think of cancer as a child's disease. This drives them to want to see it as caused by something, preferably something that can be changed so no more children will get cancer.
The result is fear, and fear leads to litigation. The parents of children born with birth defects sue pharmaceutical manufacturers claiming that drugs the mother took during pregnancy caused the defects, irrespective of whether there is scientific evidence to back their claim. The Daubert case, which sets the current United States Supreme Court standard for the admission of scientific evidence in the courtroom, was a lawsuit against the manufacturer of Bendectin, an anti-nausea for pregnant women. Women with breast implants sue because they believe the implants cause a multitude of diseases. While they have won some substantial jury awards, and almost got a $4 billion settlement, there is no evidence that silicone causes their diseases.
The problem in the courtroom is that epidemiological studies only show the probability of a particular event, not its absolute causation. The strongest scientific evidence comes when there is a biological theory of causation for the epidemiologically observed data. Bendectin is the best studied example. In the case of Bendectin, it is well known that some drugs are teratogens, i.e., they cause birth defects when given to pregnant women while the fetus is differentiating. It is also known that teratogenesis is not predictable in all cases through animal models. Thus, it is plausible that Bendectin could cause birth injuries. The conventional view of the epidemiological studies show no increased risk for birth defects among the children of women who took Bendectin during pregnancy. However, they do not rule out the risk of birth defects, they only say that the risk of birth defects is too low to measure to an acceptable level of confidence, which is usually taken to be P = .05. The bigger the study, the better the predication, but there are practical limits on such studies: As soon as there is a perception that the drug is dangerous, it has to be removed from the market, and you cannot do any prospective studies because no Institutional Review Board would approve a study to find out if a drug is a potential teratogen.
The problem is that in the courtroom few judges understand statistics, and no one with a good statistics background will be allowed on a jury in a case that involves statistics. The plaintiff is an identified child with birth defects that arose through no fault of the parents. Although the background rate of serious birth defects is at least 3%, which is nearly 150,000 cases a year, most jurors see them as extremely rare. Juries start with the premise that something external must have caused the defect. The plaintiff's attorney's strategy is to focus on the uncertainty in the epidemiology. They put on experts to show that drugs can cause teratogenesis. They have their experts discuss the very real problem that epidemiologic studies cannot rule out some low level of risk. The key at this point is to magnify the uncertainty of the study.
One popular way to do this is to attack the confidence levels that scientists demand for statistical certainty. The plaintiff's expert will explain that the choice of a confidence level is arbitrary, that scientists choose .05, or .01 because they are more interested in the elegance of their own studies than in protecting the public health and safety. The expert will then explain how, if you change the confidence level to .2 or .3, there is clearly a much greater chance that Bendectin causes birth defects. This has been an especially powerful argument in breast cancer cases where there is always the underlying hint that male scientists are conspiring to hide the real risks of breast implants. The jury is left with a seemingly simple choice: since the choice of confidence levels is arbitrary, they can choose to use the plaintiff's expert's level and then they can compensate the injured, innocent plaintiff. They do not have to reject the science presented by the defendants - they need only interpret it differently. This is important because most jurors want to do a good job and the defense experts are generally much more credible than the plaintiff's experts.
So far, no one has come up with a plausible mechanism for low energy EMF to cause cancer. This weakened the plaintiff's arguments compensation in individual injury cases. There have been only a few cases for compensation by individuals who claim to have been injured by EMF, and the plaintiffs have not won any of these. So far the courts have not been willing to let in plaintiff's experts who claim they can link individual exposure to power lines to cancer. (As one commentator has pointed out, this has not been an area that has attracted serious plaintiff's litigation. One win by a plaintiff could change this overnight.)
The real conflict has been over the fear that EMF causes cancer. The studies of EMF cannot rule out the risk that it causes disease. Some have found a linkage, however small, and there are scientists who say that the they do not believe that there is sufficient evidence to rule out a link. While the newest study, which measured electrical fields and avoided many of other methodological flaws of previous studies, found no linkage between ALL and EMF, this does not address all the other cancers that might be caused by EMF.
Fear of the unknown, especially fear of other's fear of the unknown, makes for hard personal and policy decisionmaking. The biggest impact of this fear has been on the price of houses near major power lines. You do not have to believe in the link between EMF and cancer to be worried that a house near power lines might be less valuable on resale because many potential buyers do believe that EMF causes cancer. A prudent buyer would consider both the current fears and the potential future fears at the time of resale. This prudent buyer would also have to consider that public fears are not well-correlated with scientific evidence. Thus, one might be convinced that as better studies are done they will determine that whatever risk there is must be vanishingly small. At the same time, it is clear that no foreseeable study will eliminate the possibility of risk. Each time a new study is published, the more sensational press tends to emphasize the caveats more than the results. For example, when the National Research Counsel published its review of the literature, the journalists and advocates who want to believe that EMF is harmful only focused on the conclusion that more research was necessary, ignoring the central conclusion of the report that there appears to be no connection between EMF and human illness.
We also know that fears of environmental contamination have had devastating effects on house prices in other circumstances. Ironically, another example comes from Denver: The Rocky Flats nuclear processing facility is located near a large track of residential housing. Investigators found that the plant could not account for a lot of plutonium, and that some of it probably went up the stack. This lowered housing prices in the surrounding neighborhoods, and even raised the issue of whether potential buyers would have to be warned about the risk of plutonium contamination. Thus our prudent buyer (perhaps a reader of this magazine), who well is versed in EMF and health, and convinced that EMF poses no health risk, could very well refuse to buy a house near power lines because of the fear that other buyers would avoid house because of their irrational fears of EMF.
A number of home owners have sued their local power company to try to recover the lost value of their homes. The legal theory is called inverse or reverse condemnation. In a normal condemnation, say for a right of way for power lines, the power company condemns the land and pays the owner its fair market value. In an inverse condemnation, the land owner still owns the land, but the power company destroys the value of the land. While these cases have been successful in situations with obvious physical damage or interference with the land, the courts have been less willing to find inverse condemnation in EMF cases because of the potential impact on both communities and on the utility companies.
There are millions of homes and schools near power lines. Most judges are aware that if they award damages to a home owner because EMF has reduced the value of the home, the press and the general public will see this as endorsing the idea that EMF causes human illness. Tens of millions of people will be terrified, and housing prices will crash for their homes. Many people will find they cannot sell their house or, if they can, that they have lost their life savings by the loss in equity. The amount of dollars is too high to just charge it against the utility companies because the resulting increases in power costs would cripple local economies.
In many states the court have said that the courts are not the right forum to resolve issues such as inverse condemnation by EMF. They have held that decisions about EMF should be made by public utility commissions, the state agencies that regulate power companies in the state. Public utility commissions have experts on their staff who understand EMF and are able to make objective judgments about its health effects. At the same time, public utility commissions are political entities, especially in states that elect the head of the commission or its commissioners. This subjects them to pressure to do something about EMF, even if scientifically the agency is not convinced that EMF causes any harm.
A public utility commission has three choices: 1) study and wait; 2) prudent avoidance; or 3) aggressive action. Scientifically, study and wait is probably the most defensible course, but politically it can be a difficult course to maintain. While most states are still in the study and wait posture, they are under increasing pressure to do more about the "problem."
Prudent avoidance is the most politically appealing course. Power companies are required to site new power lines away from existing homes and schools, as long as it can be done at reasonable expense. In other cases, they require power lines to be buried: partly because earth provides some shielding, and partly because out of sight is out of mind. Aggressive action, which only a few states do, includes monitoring of EMF at residential sites, using low EMF designs for all power lines, locating new lines away from homes and schools without regard to extra costs, and, in some cases, relocating existing lines.
Prudent avoidance and aggressive action both have the pitfall of seeming to endorse fears that EMF causes human illness. This creates ever greater demands for action and, in the long run, probably hurts property values in the areas where lines are located. More problematically, it creates a regulatory precedent for acting on poor or none existent scientific evidence.
So far, the courts and most state public utility regulatory commissions have acted reasonably when dealing with EMF. They have recognized that the potential risk is very small, if there is any risk at all, and that the potential harm from regulation is very high. This is a precarious balance, however, and it could easily be upset by either trial judges allowing EMF cases to be litigated or a state public utility commission to give in to public pressure and declare EMF a threat to health. Scientists and others who understand these problems should speak out and try to shape public opinion to diminish the suffering that comes from irrational fears and the social dislocations that follow bad policy choices.
1. Edward W. Champion. Power Lines, Cancer, and Risk, New England Journal of Medicine 337:44-46 (July 3, 1997).
2. Martha S. Linet, et al. Residential Exposure to Magnetic Fields and Acute Lymphoblastic Leukemia in Children, New England Journal of Medicine 337:1-7 (July 3, 1997).
3. National Research Council. Possible Health Effects of Exposure to Residential Electrical and Magnetic Fields. Washington DC, National Academy Press, 1997.
4. James H. Stilwell. Walking The High Wire: Practical Possibilities For Regulatory Responses To The Electromagnetic Field Quandary, 15 Review of Litigation 15:141-168 (Winter 1996).
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