Slide 20 of 49
There is natural variability in the population (look around the room) and uncertainty in the estimates about the population. Something like body weight is a good example of a value that is needed in the calculations but is not constant in the population
EPA suggests that reasonable maximum exposure (RME) factors be used. These combine in the calculations to compound conservatism and are used to identify the upper bound exposure.
The most likely exposure (MLE) factors are typically appropriate where site-specific information supports values different than the RME