Magnetobiology is the study of biological effects of mainly weak static and low-frequency magnetic fields, which do not cause heating of tissues. Magnetobiological effects have unique features that obviously distinguish them from thermal effects; often they are observed for alternating magnetic fields just in separate frequency and amplitude intervals. Also, they are dependent of simultaneously present static magnetic or electric fields and their polarization. Magnetobiology is a subset of

bioelectromagnetics Bioelectromagnetics, also known as bioelectromagnetism, is the study of the interaction between electromagnetic fields and biological entities. Areas of study include electromagnetic fields produced by living cells, tissues or organisms, the ...

Bioelectromagnetism Bioelectromagnetics, also known as bioelectromagnetism, is the study of the interaction between electromagnetic fields and biological entities. Areas of study include electromagnetic fields produced by living cells, tissues or organisms, the ...

and

biomagnetism Biomagnetism is the phenomenon of magnetic fields ''produced'' by living organisms; it is a subset of bioelectromagnetism. In contrast, organisms' use of magnetism in navigation is magnetoception and the study of the magnetic fields' ''effects'' ...

are the study of the production of electromagnetic and magnetic fields by biological organisms. The sensing of magnetic fields by organisms is known as

magnetoreception Magnetoreception is a sense which allows an organism to detect the Earth's magnetic field. Animals with this sense include some arthropods, molluscs, and vertebrates (fish, amphibians, reptiles, birds, and mammals). The sense is mainly used ...

. Biological effects of weak low frequency magnetic fields, less than about 0.1 millitesla (or 1

Gauss Johann Carl Friedrich Gauss (; ; ; 30 April 177723 February 1855) was a German mathematician, astronomer, Geodesy, geodesist, and physicist, who contributed to many fields in mathematics and science. He was director of the Göttingen Observat ...

) and 100 Hz correspondingly, constitutes a physics problem. The effects look paradoxical, for the energy quantum of these electromagnetic fields is by many orders of value less than the energy scale of an elementary chemical act. On the other hand, the field intensity is not enough to cause any appreciable heating of biological tissues or irritate nerves by the induced electric currents.

Effects

An example of a magnetobiological effect is the magnetic navigation by migrant animals by means of

. Many animal orders, such as certain birds, marine turtles, reptiles, amphibians and salmonoid fishes are able to detect small variations of the

geomagnetic field Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magne ...

and its magnetic inclination to find their seasonal habitats. They are said to use an "inclination compass". Certain crustaceans, spiny lobsters, bony fish, insects and mammals have been found to use a "polarity compass", whereas in snails and cartilageous fish the type of compass is as yet unknown. Little is known about other vertebrates and arthropods. Their perception can be on the order of tens of nanoteslas. Magnetic intensity as a component of the navigational ‘map’ of pigeons had been discussed since the late nineteenth century. One of the earliest publications to prove that birds use magnetic information was a 1972 study on the compass of European robins by Wolfgang Wiltschko. A 2014 double blinded study showed that European robins exposed to low level electromagnetic noise between about 20 kHz and 20 MHz, could not orient themselves with their magnetic compass. When they entered aluminium-screened huts, which attenuated electromagnetic noise in the frequency range from 50 kHz to 5 MHz by approximately two orders of magnitude, their orientation reappeared. For human health effects see

electromagnetic radiation and health Electromagnetic radiation can be classified into two types: ionizing radiation and non-ionizing radiation, based on the capability of a single photon with more than 10 electronvolt, eV energy to ionize atoms or break chemical bonds. Extr ...

Magnetoreception

Several neurobiological models on the primary process which mediates the magnetic input have been proposed: #

radical pair mechanism CIDNP (chemically induced dynamic nuclear polarization), often pronounced like "kidnip", is a nuclear magnetic resonance (NMR) technique that is used to study chemical reactions that involve radicals. It detects the non-Boltzmann (non-thermal) nuc ...

: direction-specific interactions of radical pairs with the ambient magnetic field. # processes involving permanently magnetic (iron-bearing) material like

magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula . It is one of the iron oxide, oxides of iron, and is ferrimagnetism, ferrimagnetic; it is attracted to a magnet and can be magnetization, magnetized to become a ...

in tissues # Magnetically induced changes in physical/chemical properties of liquid

water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

. In the radical pair mechanism photopigments absorb a photon, which elevates it to the

singlet state In quantum mechanics, a singlet state usually refers to a system in which all electrons are paired. The term 'singlet' originally meant a linked set of particles whose net angular momentum is zero, that is, whose overall spin quantum number s=0. A ...

. They form singlet radical pairs with antiparallel spin, which, by singlet–triplet interconversion, may turn into triplet pairs with parallel spin. Because the magnetic field alters the transition between spin state the amount of triplets depends on how the photopigment is aligned within the magnetic field.

Cryptochrome Cryptochromes (from the Greek κρυπτός χρώμα, "hidden colour") are a class of flavoproteins found in plants and animals that are sensitive to blue light. They are involved in the circadian rhythms and the sensing of magnetic fiel ...

s, a class of photopigments known from plants and animals appear to be the receptor molecules. The induction model would only apply to marine animals because as a surrounding medium with high conductivity only salt water is feasible. Evidence for this model has been lacking. The magnetite model arose with the discovery of chains of single domain magnetite in certain bacteria in the 1970s. Histological evidence in a large number of species belonging to all major phyla. Honey bees have magnetic material in the front part of the abdomen while in vertebrates mostly in the

ethmoid The ethmoid bone (; from ) is an unpaired bone in the skull that separates the nasal cavity from the brain. It is located at the roof of the nose, between the two orbit (anatomy), orbits. The cubical (cube-shaped) bone is lightweight due to a sp ...

region of the head. Experiments prove that the input from magnetite-based receptors in birds and fish is sent over the ophthalmic branch of the

trigeminal nerve In neuroanatomy, the trigeminal nerve (literal translation, lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for Sense, sensation in the face and motor functions ...

to the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...

Safety standards

Practical significance of magnetobiology is conditioned by the growing level of the background electromagnetic exposure of people. Some electromagnetic fields at chronic exposures may pose a threat to human health.

World Health Organization The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...

considers enhanced level of electromagnetic exposure at working places as a stress factor. Present electromagnetic safety standards, worked out by many national and international institutions, differ by tens and hundreds of times for certain EMF ranges; this situation reflects the lack of research in the area of magnetobiology and electromagnetobiology. Today, most of the standards take into account biological effects just from heating by electromagnetic fields, and peripheral nerve stimulation from induced currents.

Medical approach

Practitioners of

magnet therapy Magnetic therapy is a pseudoscientific alternative medicine practice involving the weak static magnetic field produced by a permanent magnet which is placed on the body. It is similar to the alternative medicine practice of electromagnetic the ...

attempt to treat pain or other medical conditions by relatively weak electromagnetic fields. These methods have not yet received clinical evidence in accordance with accepted standards of

evidence-based medicine Evidence-based medicine (EBM) is "the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients. It means integrating individual clinical expertise with the best available exte ...

. Most institutions recognize the practice as a

pseudoscientific Pseudoscience consists of statements, beliefs, or practices that claim to be both scientific and factual but are incompatible with the scientific method. Pseudoscience is often characterized by contradictory, exaggerated or unfalsifiable cl ...

one.

Effects

Magnetoreception

Safety standards

Medical approach

See also

References

Further reading

Scientific journals