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 e ...

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 e ...

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'' on ...

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, though not humans). The se ...

. Biological effects of weak low frequency magnetic fields, less than about 0.1

millitesla The tesla (symbol: T) is the unit of magnetic flux density (also called magnetic B-field strength) in the International System of Units (SI). One tesla is equal to one weber per square metre. The unit was announced during the General Conferenc ...

(or 1

Gauss Johann Carl Friedrich Gauss (; german: Gauß ; la, Carolus Fridericus Gauss; 30 April 177723 February 1855) was a German mathematician and physicist who made significant contributions to many fields in mathematics and science. Sometimes refer ...

) 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 magnetic fi ...

and its

magnetic inclination Magnetic dip, dip angle, or magnetic inclination is the angle made with the horizontal by the Earth's magnetic field lines. This angle varies at different points on the Earth's surface. Positive values of inclination indicate that the magnetic fi ...

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 The European robin (''Erithacus rubecula''), known simply as the robin or robin redbreast in Great Britain & Ireland, is a small insectivorous passerine bird that belongs to the chat subfamily of the Old World flycatcher family. About in le ...

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 eV energy to ionize atoms or break chemical bonds. Extreme ultraviole ...

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 Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. With the ...

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

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

. 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 fields i ...

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 grc, ἡθμός, hēthmós, sieve) 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 orbits. The cubical bone is lightweight due to a ...

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 ( lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and chewin ...

to the

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

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 specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of h ...

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, the 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 t ...

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. 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 claim ...

one.

Effects

Magnetoreception

Safety standards

Medical approach

See also

References

Further reading

Scientific journals