Magnetobiology

the branch of biophysics that studies the influence of artificial and natural external magnetic fields on living systems (cell, organism, population) and the generation of magnetic fields by living structures (heart, brain, nerves) and determines the magnetic properties of substances of biological origin.

The first information on the influence of artificial magnetic fields on the human body dates from antiquity. Aristotle (fourth century B.C.), Pliny the Elder (first century B.C.), the German physician Paracelsus (16th century A.D.), and the English naturalist W. Gilbert (17th century) all mentioned the therapeutic properties of magnets. In antiquity, these properties were often exaggerated in the claim that they could cure any disease and even restore youth. In the 19th century, European medical workers, including the French neuropathologist J. M. Charcot and the Russian clinician S. P. Botkin, noted the tranquilizing effect of magnetic fields on the nervous system. At the turn of the 20th century, the use of magnetic fields in physical therapy was sup-planted by a more powerful means—electrotherapy (diathermy, ultrahigh-frequency fields).

Intensive development of magnetobiology began in the 1960’s with the development of space biology. Most works on the subject have dealt with the effect of artificial magnetic fields of greater intensity than the geomagnetic field. The intensity of these fields has varied from fractions of an oersted to 140,000 oersteds, although it has been the biological effect of fields with an intensity of several hundred oersteds that has been studied most often. Such fields induce diverse effects in man, animals, plants, and microorganisms, as well as in isolated tissues, cells, and intracellular organelles. In mammals, all systems react to magnetic fields, but those that perform regulatory functions (the nervous, endocrine, and circulatory systems) are most reactive. Embryonic tissues and, in adult animals, the most intensively functioning organs are especially sensitive.

Magnetic fields have a mostly inhibitory effect on the nervous system—suppressing conditioned and unconditioned reflexes, altering the electroencephalogram in favor of slow rhythms, and reducing the frequency of electric discharges by some neurons. In this case, biochemical processes are altered in neuroglial cells. Studies by electron microscope have revealed disruptions in mitochondrial structure in nerve cells. Of the sections of the brain, the hypothalamus and cerebral cortex appear to be the most magnetosensitive. Isolated brain structures react more intensively to magnetic fields than does an intact brain, indicating the direct effect of magnetic fields on nerve tissue. The output by the pituitary of certain hormones (especially gonadotropic) is altered. Significant morphological changes have been observed in the gonads (especially male), adrenals, and thyroid. Changes in the circulatory system are manifested in vascular dilation and hemorrhaging. In the blood, an elevated leukocyte count, a change in the properties of the thrombocytes, and changes in the erythrocyte sedimentation rate are observed. The reactions of experimental animals to magnetic fields have usually been reversible.

In plants, strong magnetic fields (several thousand oersteds) suppress root growth, reduce the intensity of photosynthesis, and cause changes in oxidative processes. The character and rate of growth of microorganisms, the activity of their enzyme systems, the synthesis of ribonucleic acid, and sensitivity to elevated temperatures have also been altered by exposure to magnetic fields. Some of these effects are due to changes in the permeability of the biological membranes, the orientation of macromolecules, and the properties of the aqueous solutions present in the organism.

It is believed that the geomagnetic field, as well as changes in it, plays an important role in the orientation of animals in space and time. Along with other physical factors, it may have an orienting effect in the long-distance migrations of birds and fish and in the movements of insects, worms, mollusks, and other animals. Certain plants orient their root systems relative to the magnetic meridian. Fluctuations in the geomagnetic field induced by changes in solar activity affect many processes in the biosphere; these are studied by heliobiology. Prolonged artificial attenuation of the geomagnetic field by screening or compensation have shown an unfavorable effect on the vital activities of animals, plants, and microorganisms; this forces us to assume that the geomagnetic field has ecological significance.

The data of magnetobiology are important for therapeutic purposes and for the assessment of the effects on health of the magnetic fields used in various industries. Insofar as a magnetic field is penetrating and affects mostly the body’s regulatory systems, it can serve as a convenient tool for regulating certain biological processes. In order to carry out this task, it is necessary to elucidate the dependence of the biological effect on the intensity, gradient, frequency, and direction of the magnetic field and on the localization and length of exposure to it. Data on the antitumor, antiradiation, and antitemperature protective effects of a stationary magnetic field are of great interest. However, the lack of a generally accepted theory of the primary (physico-chemical) mechanism of the biological effect of magnetic fields, as well as the disconnected empirical character of the majority of studies, are slowing the development of magnetobiology. Three symposia in Moscow (The Biological Effect of Magnetic Fields and Static Electricity, 1963; The Reaction of Biological Systems to Weak Magnetic Fields, 1971; and Approaches to the Hygienic Assessment of Magnetic Fields, 1971), conferences in Tomsk (1964, 1965), and all-Union conferences on the study of the influence of magnetic fields on biological objects (Moscow, 1966, 1969) have been conducted to discuss results obtained and coordinate magnetobiological projects. International symposia on magnetobiology have been held in Chicago (1961, 1963, 1966).