Uncertainty Factor (UF)

Uncertainty Factor (UF):An uncertainty factor (UF) is a number used to account for uncertainty in the data used to assess risk. UFs are used in both toxicology and epidemiology. In toxicology, UFs are used to extrapolate from animal data to humans; in epidemiology, UFs are used to extrapolate from small studies to the general population. UFs are usually multiplied by a dose or exposure level to estimate an acceptable level of risk.