However, there are a number of other factors that can affect the amount of carbon present in a sample and how that information is interpreted by archaeologists.Thus a great deal of care is taken in securing and processing samples and multiple samples are often required if we want to be confident about assigning a date to a site, feature, or artifact (read more about the radiocarbon dating technique at: For example, rootlet intrusion, soil type (e.g., limestone carbonates), and handling of the specimens in the field or lab (e.g., accidental introduction of tobacco ash, hair, or fibers) can all potentially affect the age of a sample.
Radiocarbon dating rests heavily on this assumption such that other sources of carbon 14 had, at first, not been considered nor accounted for.
Nowadays, radiocarbon scientists had to perform calibration not only to convert their radiocarbon year results into calendar year but also to take into account the various factors that have major effects on the global levels of carbon 14, one of which is nuclear weapons testing.
There are two human activities recognized to have irreparably changed the global radiocarbon levels—the burning of fossil fuel and nuclear weapons testing.
The introduction of "old" or "artificial" carbon into the atmosphere (i.e., the "Suess Effect" and "Atom Bomb Effect", respectively) can influence the ages of dates making them appear older or younger than they actually are.
This is a major concern for bone dates where pretreatment procedures must be employed to isolate protein or a specific amino acid such as hydroxyproline (known to occur almost exclusively in bone collagen) to ensure accurate age assessments of bone specimens.
Radiocarbon dating is especially good for determining the age of sites occupied within the last 26,000 years or so (but has the potential for sites over 50,000), can be used on carbon-based materials (organic or inorganic), and can be accurate to within ±30-50 years.