2. PHYSICS AND POWERLINE HEALTH HAZARDS
Physics does not predict or preclude that powerline EMFs affect human health.
Historically, Herman Schwan was the first physicist who sought to explain powerline EMF bioeffects on the basis of the laws of physics. His analysis led to the conclusion that powerline EMFs do not affect human health., and his work still constitutes the most lucid explanation of the application of the physical thought-style to the issue of powerline-EMF health risks. It is the cornerstone and the substance of every subsequent opinion in which the physical thought-style was employed to rationalize the same conclusion.
Schwan assumed a model for the interaction between EMFs and biological tissue, and then applied the basic physical laws that govern electricity (Maxwell's equations) to assess whether any biological effects would be predicted or expected. The assumption of the linear model specified how Maxwell's equations should be used to make predictions.
Schwan reasoned that if powerline EMFs caused biological effects, then two things had to occur. First, the powerline fields needed to penetrate into the exposed subject and reach the place in the body where the presence of the fields could be detected. For Schwan, these possible locations were the body fluids (interstitial fluid and blood), and the membranes of nerve cells. Second - this is where the assumption of a linear model entered explicitly - the magnitude of the fields that penetrated into the body had to satisfy a numerical significance criterion, defined by the ratio of the strength of the EMFs produced by the powerline at the putative locus of interaction to the strength of the EMFs that were already present in the fluids or membranes. Schwan pegged this relationship at 1/100 to 1/10, and used it as a threshold for deciding whether or not the powerline EMF could cause a bioeffect. Below the threshold, the powerline EMF was regarded as insignificant.
The basic idea in Schwan's approach was that any possible cause-effect relationships would be explained on the basis of electrical forces. Prior to the penetration of powerline EMFs to the putative interaction locus, there were already fields naturally present that were exerting forces on ions and other electrical charges present at that location in the body. The motion of these ions and charges, as reflected in their chemical activity, was completely determined by the presence of the forces. A change in activity caused by powerline EMFs could occur only if the powerline EMF forces were 1-10% of the pre-existing forces.
To apply the model, Schwan calculated the strength of the powerline fields that would actually penetrate into the exposed subject. Because calculations based on biological reality are impossible, Schwan made simplifying assumptions regarding the shape and electrical properties of human tissue. He usually assumed that humans had a spherical or cylindrical shape, and were composed of only one tissue having the electrical properties of salt solution. The results showed that very small fields were expected inside the human model. Next, Schwan estimated the strength of the fields already present in the body and argued that they were very large, at least in the immediate vicinity of electrical charges. He concluded that powerline EMFs would not affect human health because it was essentially impossible for something very small to affect something very large.
To drive home this point, Schwan made a third assumption: he assumed that there were only two physical processes that could be affected by powerline EMFs that penetrated the body. One possibility was that the orderly pattern of electrical activity that occurs in excitable tissues such as the heart or nerves could be interfered with by the EMFs induced by powerlines. The second possibility was that, in principle, the powerline EMF fields that penetrated the body could affect the motion of ions and charges, resulting in the generation of heat. The utility of this third assumption was that it permitted Schwan to inject into his analysis two cases where the linear model of EMF-tissue interaction did apply, and could be used successfully to explain the data. The successful application of the linear model to explain two types of data was cited as evidence to support a claim of universality for the model.
Schwan's key assumption was that of the linear interaction model. Using it, Schwan calculated the magnitude of powerline EMFs that would be unsafe, and it turned out to be impossibly high. Any attempt to create an unsafe powerline EMF would result in the breakdown of the air surrounding the powerline, thereby preventing achievement of the air field necessary to produce an internal field that would be a health risk.
Schwan had two good reasons for assuming a linear model. First, it is the simplest way of modeling nature's response to physical stimuli. Although biological organisms are hugely complex and appear to carry out their activities in complicated ways, most practicing scientists subscribe to the metaphysical principle that nature follows the simplest efficacious pathway, and hence that models of nature should be as simple as possible. This notion, first explicitly identified with Occam, a 14th-century logician, requires that the simplest sufficient model be adopted and regarded as the best representation of reality, if it fits the data.
Second, early in the 1950s, when Schwan first considered EMF health hazards, the data was consistent with the linear model. Microwaves, the form of EMFs initially studied by Schwan, were known as early as the end of World War II to be capable of cooking tissue and interfering with heart rhythms, and no other physiological effects were then identified.
Unfortunately, the success of the linear model in explaining these two effects encouraged Schwan to abuse it. He ceased regarding the linear model as simply a tool, and advanced it as something akin to a law of physics. For Schwan and those who adopted his arguments, the fact that the EMF biological data could not be explained with reference to a linear model was evidence that the data was defective, rather than evidence that the model was inapplicable. When new data appeared, Schwan ignored it or attacked it without mercy.
Schwan's analysis of EMF health risks was reasonable in the 1950s, but demonstrably incomplete in the 1970s. In the 1990s, when used to conclude that powerline EMFs are safe, it is unreasonable because the number of studies whose results do not fit the linear model is vast, and their number is increasing exponentially. It is now the task of physicists to revise their assumptions and propose new models for use in understanding the interaction of electromagnetic fields and biological tissue, and such attempts are being made. In the meantime, in order to resolve the question whether powerline EMFs affect human health, it will be necessary to evaluate the biological literature to assess what scientific and public-health conclusions follow from that literature.
At the present stage of development of physical theory, the model that successfully (or best) explains EMF-induced bioeffects is unknown. I would like to make it clear, however, that some effects could someday be satisfactorily explained by an appropriate physical model. I will do this by showing that a nonlinear model of interaction is compatible with the laws of physics.
We have seen that the essence of a linear model is the proportionality between cause and effect. How do nonlinear models avoid such an enforced proportionality, and the inexorable conclusion to which it leads in the context of EMF bioeffects? How is it possible to retain Maxwell's equations and yet reach different conclusions simply by changing the model?
Consider the patterns exhibited by a set of 6 identical lava lamps (Figure 1). Although the lamps were identical in size, shape, weight, and chemical composition, after they were turned on for a few minutes, the pattern of the lava was different in different lamps. No matter how many times the experiment was repeated, no matter what efforts were expended to insure that there were absolutely no differences in the conditions that could affect the lava pattern, it was always the case that the lamps differed from one another and differed from how they appeared in all previous replicates of the experiment.
This example shows that unavoidably small differences in initial conditions can cause gross differences in the behavior of, for all practical purposes, identical physical systems. Put another way, the lava lamps could detect uncontrollably small differences between one another in ambient conditions and, in response, exhibit different behaviors. It was always possible to write an equation that described a particular observed pattern. It was never possible to write an equation that predicted a pattern that would be observed.
The laws of physics, in particular the laws of mechanics and thermodynamics, govern the motion of the lava, just as Maxwell's equations govern any possible effects of powerline EMFs on exposed subjects. But a linear model cannot be employed in conjunction with the laws of physics to explain the motion of the lava, and it would be absurd to argue that, as a consequence, the appearance of differences in the flow between different lamps is an illusion or artifact. The fact is, the lava flow differs in different lamps despite all attempts to assure identical behavior. If there is an intention to describe the flow, an appropriate nonlinear interaction model must be used. The seminal property of the required model is precisely that there is no proportionality between the input and the output of the system.
If a simple physical system such as a lava lamp can exhibit complex behavior and sensitivity to initial conditions, then it should be obvious that living systems, which are vastly more complex, may similarly be capable of detecting small changes in environmental conditions.
The example of the lava lamp shows that, even though the linear interaction model does not explain EMF-induced bioeffects, a nonlinear model could rationalize the existence of such effects in the sense that one could understand how their occurrence would be consistent with the general laws of physics.
Physicists have not determined what nonlinear model could be used to explain EMF-induced bioeffects or predict the time scale associated with their occurrence. But this is a practical limitation on the physics thought-style, not a theoretical limitation; it is possible, in principle, that the particular nonlinear interaction models may be discovered for some types of EMF-induced bioeffects.
The analysis presented here does not prove that EMF bioeffects are nonlinear. It shows only that such effects could exist and be compatible with the laws of physics and the hypothetical-deductive method of physics. Thus, with regard to these laws of physics, powerline EMFs could be a health risk. Physics simply can't say.
There is nothing novel in the conclusion that the laws of physics are powerless to predict or preclude some phenomena. The structure of normal joint cartilage is the result of a balance between synthesis and destruction of extracellular matrix proteins. If disruption occurs in regulation of the proteases that regulate the process, the result is osteoarthritis. The laws of physics neither predict nor explain how this process occurs, and it does not appear there is any reasonable likelihood that they will do so soon. Ultraviolet light, radon gas, tobacco smoke, and asbestos each can cause cancer but, again, the laws of physics neither predict nor explain the relationships. Following a fracture, the local cellular cytokine environment is altered, resulting in cellular proliferation and the formation of osteoblasts that synthesize new bone. Neither the appearance of the osteoblasts nor their disappearance following injury repair are predicted or explained by the laws of physics. These and myriad other examples plainly show that the laws of physics don't explain everything. Indeed, it might be the case that they explain almost nothing about complex systems such as biological organisms. The inability to predict or preclude powerline EMF bioeffects in the physics thought-style is a direct consequence of the complexity of biological organisms, in particular, their nonlinearity.
The ability to predict the future and to neglect small differences is usually confined to the context of closed linear systems. That is, systems that can be modeled linearly as if they do not exchange energy with their surroundings. In these instances, the laws of physics can explain and predict. The operation of automobiles, space ships, atomic bombs, and powerlines are all achievements of 20th century physics. But earthquakes, volcano eruptions, the weather, the activity in lava lamps, and the behavior of living things can not be predicted because these systems exchange energy with their environment and are governed by nonlinear empirical laws. These systems do not violate the laws of physics as would, for example, a perpetual motion machine, or a spaceship that could travel faster than the speed of light. It is simply that we do not know how to apply the laws of physics to them.
Theoretical Limit of the Physics Thought-Style
Some effort is presently being devoted to identifying the particular nonlinear model applicable to powerline EMFs, and the day may come when it is possible to satisfactorily explain or even predict some EMF-induced bioeffects. Even if that occurs, however, it will still be impossible to resolve certain kinds of crucially important questions concerning the health hazards of powerline EMFs within the physics thought-style.
Physics deals with empirical mathematical laws in the context of particular conditions of observation. The empirical law for a particular case is an amalgam of one or more of the laws of physics and one or more auxiliary hypotheses and models that are necessary to tailor the basic laws to the particular case. The empirical law is then said to "explain" the observations. The observations affect prediction in two ways. First, they help to define the particular auxiliary hypotheses that are needed. Second, they establish the starting point and general frame of reference of the applicable empirical law (that is, the initial conditions and the boundary conditions).
This normal process of physics is geared toward prediction because the ability to predict is what gives evidence of the ability to explain. But the method of physics is often useless with regard to attempts to explain what has already occurred. For example, it cannot be used to explain a specific observation recorded from a particular individual. In other words, if X is a stimulus, Y is a response, and Z is a particular subject, propositions of the form X caused Y in Z are meaningless within the physics thought-style because postdiction is impossible unless all conditions are known, and it is generally the case that the conditions that existed in the past are not known.
This analysis showed that whether or not powerline EMFs affect human health cannot be ascertained within the physics thought-style. This fact does not imply that powerline EMFs are not a health hazard. Rather, it indicates only that the question cannot be answered if one chooses to think solely as a physicist thinks.
Although the hazards question remains open within the physics thought-style, there is another way to establish scientific facts - the biological thought-style. It is possible, therefore, that the question could be answered affirmatively within that thought-style.
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