In the midst of so much political noise, the correct decision of the Federal Supreme Court made in 2016, overturning the decision of the São Paulo court that forced Eletropaulo to reduce the intensity of the electromagnetic fields created by high voltage power transmission lines, went almost unnoticed. . The action was initiated by the association of residents of some neighborhoods in São Paulo, which alleged a supposed relationship between the incidence of cancer and the proximity of transmission lines.
The STF recognized, by six votes to four, that scientific studies do not prove that human exposure to electromagnetic fields is related to a higher incidence of cancer. Therefore, the parameters recommended by the WHO (World Health Organization), followed by Brazilian legislation (83,3 microteslas), were valid. Reducing these parameters would imply unnecessary costs, which would certainly lead to an inconsequential increase in already exorbitant tariffs, risking the democratization of access to electricity in the country. Furthermore, a different decision would have led to a situation of fear without any scientific proof, as hundreds of experiments in several countries deny any consistent evidence about a relationship between non-ionizing electromagnetic fields and cancer.
To understand the controversy a little more, it is important to remember a little physics. Moving electrical charges (currents) generate magnetic fields. Similarly, varying magnetic fields generate electric currents in conductors. High voltage cables are surrounded by magnetic and electric fields. The intensity of the electric field depends on the voltage, while the intensity of the magnetic field depends on the current. Both fields attenuate strongly with distance.
There is a consensus that electric fields do not pose any risk to health, as, as the skin itself is an excellent conductor of electricity, it acts as a shield, preventing the penetration of electric fields into the body. Magnetic fields penetrate almost all materials without hindrance. Transmission lines are designed to transport energy with as little electrical current as possible, which also minimizes associated magnetic fields.
We have always been exposed to magnetic fields, in particular, the natural magnetic field of the Earth itself. Furthermore, it is estimated that per capita electricity consumption in the industrialized world has increased more than twenty-fold in the last 50 years, and thus our exposure to electromagnetic fields generated by high voltage cables, household appliances, radio waves and TV, and other devices (such as Wi-Fi antennas, cell phones, for example) have also increased significantly.
Despite this, the magnetic fields to which we are subjected daily are on the order of hundreds of times smaller than the Earth's field, with just one difference: electrical energy is supplied in the form of alternating current, which reverses its direction approximately sixty times. per second (60 Hz). Faraday's famous Law (1831) predicts that an alternating magnetic field interacts with our bodies differently than Earth's relatively constant field. In fact, very weak electrical currents are induced in our body.
The question that arises is whether these tiny currents could affect our health through a possible reduction in the body's defenses, for example. Although there is no plausible mechanism to think that this was possible, several studies have been carried out over the years to answer this and other questions. In some animal experiments, for example, rats lived healthy for several generations in magnetic fields up to one millitesla, thousands of times stronger than the fields from power lines. The vast majority of epidemiological studies have also found no relationship between transmission lines and cancer incidence. The few exceptions have been questioned and verified.
In fact, a 1996 National Research Council (USA) report already concluded: “Based on a thorough evaluation of published studies relating the effects of electric and magnetic fields generated by high voltage lines on cells, tissues and organisms (including humans), The committee's conclusion is that the current body of evidence does not show that exposure to these fields poses a danger to human health.
Specifically, there is no conclusive and consistent evidence showing that exposures to residential magnetic and electrical fields produce cancer, adverse neurobehavioral effects, or reproductive or developmental effects.” It is impossible to definitively demonstrate that there is not some correlation and/or mechanism that the current state of science does not allow us to identify, but the existing results are very strong in indicating that high voltage lines are not responsible for increases in the incidence of cancer.
As in other cases involving public health and various groups with specific interests (real estate market, lawyers, electrical companies, scientists, politicians, among others), the issue takes on gigantic and multimillion-dollar proportions.
This time the STF got it right, but barely. Just like the recent case of the “Cancer Pill”, this episode illustrates the lack of spaces for discussion and the search for consensus on issues involving science, risk perception, potential costs and consequences for society.
Marcelo Knobel is a professor of Physics and dean of Unicamp
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