Intake fraction: exposure to pesticides in food

The text on this page is taken from an equivalent page of the IEHIAS-project.

This example illustrates the use of the intake fraction (iF) method for evaluating the exposure via ingestion after direct application of pesticides. The example was implemented in the dynamiCROP model.

Explanation of the method

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

m<supb>background</sub> [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

the constant pf [-] refers to the applied food processing factor.

References

• Bennett, D.H., Margni, M.D., McKone, T.E. and Jolliet, O. 2002 Intake fraction for multimedia pollutants: a tool for life cycle analysis and comparative risk assessment. Risk Analysis 22, 905-918.
• Huijbregts, M.A.J., Geelen, L.M.J., Hertwich, E.G., McKone, T.E. and Meent, D.v.d. 2005 Human intake fraction of toxic pollutants: a model comparison between CalTOX and USES-LCA. Lawrence Berkeley National Laboratory, pp. 34.
• Juraske, R., Antón, A., Castells, F. and Huijbregts, M.A.J. 2007 Human intake fractions of pesticides via greenhouse tomato consumption: comparing model estimates with measurements for Captan. Chemosphere 67, 1102-1107.
• Juraske, R., Castells, F., Vijay, A., Muñoz, P. and Antón, A. 2009 Uptake and persistence of pesticides in plants: Measurements and model estimates for imidacloprid after foliar and soil application. Journal of Hazardous Materials 165, 683-689.
• Kaushik, G., Satya, S. and Naik, S.N. 2009 Food processing a tool to pesticide residue dissipation - a review. Food Research International 42, 26-40.
• Margni, M.D., Rossier, D., Crettaz, P. and Jolliet, O. 2002 Life cycle impact assessment of pesticides on human health and ecosystems. Agriculture, Ecosystems and Environment 93, 379-392.
• Pennington, D.W., Margni, M.D., Ammann, C. and Jolliet, O. 2005. Multimedia fate and human intake modeling: spatial versus nonspatial insights for chemical emissions in Western Europe. Environmental Science and Technology 39, 1119-1128.
• Pennington, D.W., Margni, M., Payet, J. and Jolliet, O. 2006. Risk and regulatory hazard-based toxicological effect indicators in life-cycle assessment. Human and Ecological Risk Assessment 12, 450-475.