The determination of uncertainty factors involves expert judgment and scientific consensus. Typically, a default value of 10 is used for interspecies extrapolation (from animals to humans) and another factor of 10 for intraspecies variability (differences within human populations). Additional factors may be applied to account for data quality, exposure duration, and specific population sensitivities. These factors are then multiplied to derive a composite uncertainty factor applied to the NOAEL (No Observed Adverse Effect Level) or other relevant benchmarks.
