3.4 POPULATION HEALTH IMPACTS
Health impacts from exposure to carcinogenic chemicals
and radionuclides can be estimated for the entire exposed population. For
these pollutants, the population health impacts are assumed to be proportional
to the exposure level. This allows a population health impact to be evaluated
as the product of the lifetime risk to the average member of the population
times the number of people in the population. This calculation can be expressed
by the following equations for the two types of cancer risk considered:
(124)
where
RPfkki = total fatal cancer risk to the population exposed via pathway kk to pollutant i (fatal cancers)
Rfkki = fatal cancer lifetime risk to an average member of the population exposed via pathway kk to pollutant i (fatal cancer risk/lifetime)
PEkk = number of people exposed via exposure pathway kk (people).
(125)
where
RPtkki = total cancer incidence risk to the population exposed via pathway kk to pollutant i (cancers)
Rtkki = total cancer incidence lifetime risk to an average member of the population exposed via pathway kk to pollutant i (fatal cancer
risk/lifetime)
and PEkk is as previously defined.
There are no meaningful measures of health impact
to population from exposure to noncarcinogenic chemicals.