Calculating exposure requires information about several exposure variables. Some of these variables can be derived from the human exposure survey; however, many may not be easily available. Health Canada (2004) provides a table of standard exposure values that can be used in the absence of information collected at the site, but they may not be representative of the area being surveyed because they reflect Canadian conditions/characteristics. Risk assessors are encouraged, as much as possible, to use values that are reflective of their country (i.e., average body weight, average lifetime etc.).
The Health Canada standard exposure values can be viewed online here (pdf file).
Other sources of Standard Exposure Parameters include: Richardson (1997) and U.S. EPA Exposure Factors Manual (U.S. EPA, 1997).