Environmental Health Criteria 214

HUMAN EXPOSURE ASSESSMENT
Conceptually, as shown in Fig. 8, estimating and prioritizing
health risks are seemingly straightforward. Risk is a combination of
effects estimates, where "highest" priorities can be thought of as
those that entail both "high" toxicity for the agent of interest
(adverse effects are likely to occur in humans at relatively low
exposures or doses), and "high" exposures for the population,
subpopulation or individuals of interest (exposures or doses are above
a health-based standard). Conversely, "lowest" priority risks involve
"low" toxicity and "low" exposures. "Medium" priority risks are those
for which either toxicity or exposure is "low" while the other is
"high" (Sexton, 1993). The Windsor Air Quality Study, for example,
showed that incinerator emissions contributed little to total human
exposure for VOCs. Despite the fact that the pollutants were of high
toxicity, incinerator emissions were considered to be of relatively
low risk to the population. In contrast, studies show that second-hand
smoke has both high toxicity and high human exposures, and should
therefore be identified as a high priority risk.
http://www.inchem.org/documents/ehc/ehc/ehc214.htm
Page 38 of 284
6/1/2007