Mixing and exchanges happen between the atmosphere and the biosphere until such time that equilibrium is established.
Radiocarbon dating rests heavily on this assumption such that other sources of carbon 14 had, at first, not been considered nor accounted for.
Dating Subject to Error But scientists have long recognized that carbon dating is subject to error because of a variety of factors, including contamination by outside sources of carbon.
Therefore they have sought ways to calibrate and correct the carbon dating method.
In principle, any material of plant or animal origin, including textiles, wood, bones and leather, can be dated by its content of carbon 14, a radioactive form of carbon in the environment that is incorporated by all living things.