Biological transmutation

A biological transmutation is defined as a nuclear transmutation occurring in living organisms.

Observation
By definition, chemical reactions rearrange the bindings of atoms, but do not change the number of protons or neutrons in the nucleus of atoms. Defining the kind of an atom as the number of neutrons and the number of protons in its nucleus, the evolution over time of the number of atoms of a given kind in a system where only chemical reactions occurs will therefore be the difference between the number of atoms of that kind entering and exiting the system. Some scientists claim to have observed biochemical systems where this relation does not hold: the systems were inexplicably gaining or losing atoms of some kinds, indicating non-chemical reactions and possibly transmutation. Phenomena reported include:
 * Anomalous increase in calcium and decrease in magnesium, during the synthesis of egg shells
 * Anomalous excretion of magnesium

Orthodox view and responses from proponents
The phenomenon is rejected by mainstream science on the following grounds: The precise energies involved are codified in the curve of binding energy. The current consensus is that biological systems get their energy from biochemical reactions; the low energies involved in chemical reactions makes nuclear transmutations difficult to explain in the frame of current theories
 * Nuclear reactions such as transmutations require, according to current models, relatively large amounts of energy per particle.
 * The biological system would have to have a means of controlling the high energies produced by nuclear reactions, which would otherwise damage the biological system by breaking many chemical bonds.

Proponents respond that evidence shows that transmutations do occur, and that the lack of a theoretical model adequately explaining the mechanisms involved (that is, without a source for, or the emission of, deadly amounts of energy) does not render that evidence invalid.

Proponents involved in the controversy
The most prominent defender of the existence of biological transmutations is the French scientist Corentin Louis Kervran, who investigated discrepancies between the dietary or environmental intake of elements such as calcium, potassium or magnesium by various organisms and the quantities they hold or excrete. For instance he investigated the source of calcium chickens use for their eggshells, and concluded that they probably convert it from dietary potassium.

The "Prof. Dr. L.W.J. Holleman Stichting" foundation also supports research in this field.

Links to cold fusion
Interest has been revived with the controversy on cold fusion. In 2003, Russian researchers claimed to have converted nuclear waste into non-radioactive elements using microbiological cultures.