Simplified human exposure assessment of chemicals with the help of intake fraction?

Abstract: The concept of intake fraction (iF) relates the emitted amount of a particular chemical to the subsequent human intake of that substance. Intake fractions have been calculated for more than 300 substances, spanning a range of up to seven orders of magnitude. It has furthermore been suggested that intake fractions can be estimated based on a few properties of the chemical. In this study, the following two questions are discussed: Can this type of relationships be used for simplified human exposure assessment? Does high total production volume of a chemical imply high human exposure? In this report the available research on the concept of intake fraction is scrutinized, including the suggested methods to calculate intake fractions. It is concluded that variability and uncertainty in the intake fractions estimated so far is considerable, implying that the concept needs further development before it can be used for simplified exposure analysis in the regulatory context. It is furthermore concluded that there seem to be a positive correlation between the amount of a chemical emitted into the environment and the magnitude of human exposure to that particular substances. This does however not imply that a high total production volume of a chemical necessarily will result in high human exposure.