Exposure to pesticides is an important cause of public concern and may be implicated in a range of health effects.  Exposure pathways and transfer mechanisms are complex, and are not discussed in detail here, but can be found elsewhere (see references below).  Important routeways include ingestion via food and water, as well as dermal contact while handling pesticides and inhalation of pesticide sprays. 

Ingestion of food items is reported to be the predominant exposure route for pesticides (Margni et al., 2002; Juraske et al., 2007; 2009).  The exposure assessment of food products may be very complex due to both the variety of food items to which human beings might be exposed and the spatial distribution of food production.  Exposure assessment is usually based on administrative units, and takes account of pesticide imports via food transfers into each spatial unit (through both national and international trade) as an extension of the (natural) environmental fate of the pesticides.  A number of models have been developed that can be used for this purpose, including dynamiCROP. 

Exposure assessment typically starts by estimating concentrations in the harvested fraction.  This is determined by quantifying the pesticide residue found in harvest expressed as a fraction of the pesticide amount initially applied, hF [kg/kg].

where m_{residue}(t) [kg/m²] denotes the residue found in harvested wheat parts at harvest time, m_{applied} [kg/m²] is the total applied pesticide mass and m_{background} [kg/m²] refers to the background mass in the system, e.g. from previous applications.

The total amount of the harvested crop which is finally eaten provides the basis for estimating the intake fraction, iF [kg/kg] as defined according to Bennett et al. (2002) and Huijbregts et al. (2005).  However, with respect to the final consumption of food items, an additional aspect needs to be taken into account - namely, the effects of processing of food.  Food processing may lead to a significant reduction of pesticide residues and plays an important role for agricultural field crops (Kaushik et al., 2009).  Assuming that 100 percent of the harvested crops are taken in via ingestion, thus, leads to the following equation:

where iF_{population}(t) is the total population intake fraction based on the time of harvest, P_n [n capita] denotes the total population, hF(t) the harvest fraction at harvest time and the constant pf [-] refers to the applied food processing factor.