One of several factors used in deriving a reference dose from experimental data. UFs are intended to account for: the uncertainty in extrapolating from animal data to humans, i.e., interspecies uncertainty factor; the variation in sensitivity among the members of the human population, i.e., intraspecies variability factor; the uncertainty in extrapolating from effects observed in a short term study to potential effects from a longer exposure, i.e., subchronic-to-chronic uncertainty factor; the uncertainty associated with using a study in which health effects were found at all doses tested, i.e., LOAEL-to-NOAEL uncertainty factor; and the uncertainty associated with deficiencies in available data, i.e., database uncertainty factor. Uncertainty and variability factors are typically values of three or ten and are multiplied together. The Department has not developed a HRL if factors total over 3000.
Synonymous with Safety Factor
One of several, generally 10-fold factors, used in deriving the reference concentration from experimental data. Uncertainty factors are intended to account for: 1) the variation in sensitivity among the members of the human population; 2) the uncertainty in extrapolating animal data to humans; 3) the uncertainty of extrapolating from data obtained in a study that is less than lifetime exposure to lifetime exposure, i.e., extrapolating from subchronic to chronic exposure; 4) the uncertainty in extrapolating from an lowest-observed-adverse-effect-level (LOAEL) rather than from a no-observed-adverse-effect-level (NOAEL); and 5) the uncertainty of extrapolating from animal data when the database is incomplete.
Derived to determine a margin of safety consistent with adequate precautionary approaches and good public health practices.
When scientists don't have enough information to decide if an exposure will cause harm to people, they use "uncertainty factors" and formulas in place of the information that is not known. The factors and formulas can help determine the amount of a chemical that is not likely to cause harm to people.
See Safety Factor.
A number (equal to or greater than one) used to divide the NOAEL or LOAEL value derived from measurements in animals or small groups of humans, in order to estimate a NOAEL value for the whole human population.
One of several factors used in calculating the reference dose from experimental data. UFs are intended to account for (1) the variation in sensitivity among humans; (2) the uncertainty in extrapolating animal data to humans; (3) the uncertainty in extrapolating data obtained in a study that covers less than the full life of the exposed animal or human; and (4) the uncertainty in using LOAEL data rather than NOAEL data.