Pesticides dietary exposures

Melnyk LJ, Berry MR, Sheldon LS. 1997. Dietary exposure from pesticide application on farms in the agricultural health pilot study. J Expo Anal Environ Epidemiol 7 61-80. 

Brock JW, Melynk LJ, Caudill SP, et al. 1998. Serum levels of several organochlorine pesticides in farmers correspond with dietary exposure and local use history. Toxicol Ind Health 14(l/2) 275-289. 

One common objective of an LSMBS is to refine the estimates of actual exposure of consumers to ingredients or impurities in one or more products. For example, study results might be intended to determine a realistic human dietary exposure to pesticide residues in fresh fruits and vegetables. The advent of the Food Quality Protection Act of 1996 (FQPA) has produced an enhanced focus on the exposure of children to pesticides. A well-designed and implemented LSMBS would afford the opportunity to delineate better the exposure and risk to children and other population subgroups. The LSMBS would provide consumer-level data at or near the point of consumption, allowing the refined, relevant, and realistic assessments of dietary exposure. 

Pesticide residues consist of chemicals that might occur in a commodity as a result of application of a pesticide. Such chemicals typically correspond to compounds for which a regulatory agency has or will set a tolerance, i.e., a maximum residue limit, specific to the commodity. In either a field study or a market basket survey, residues to be determined will be those which result from application of the specific pesticide that the study is intended to support. A market basket survey, however, might be intended to support not just one but several different pesticides of the same or different chemical classes. In addition, a market basket survey might include pesticides not used in the USA but for which import tolerances exist. For example, some uses of the parathion family of pesticides on food products have been abandoned in the USA but remain in other countries that export the products to the USA. A market basket survey offers a means to evaluate actual dietary exposures to residues of such pesticides. In addition, tolerance expressions frequently include multiple compounds, all of which must typically be determined in residue field trials. The sponsor of the market basket survey must decide whether to analyze for all compounds in the applicable tolerance expression or to restrict the program to selected analytes, such as the active ingredient. 

Dietary exposure to pesticides from organic and conventional food production systems... 

In Tables 14.9 and 14.10, the last column reports the environmental impact points (EIPs) for typical applications of organic and conventional pesticides derived from the Pesticide Environmental Assessment System, or PEAS. This model produces relative rankings of risks based on defined use rates and use patterns (the formulation used to apply a pesticide, timing, target of the application, spray equipment used, etc). PEAS scores reflect an equal balancing of acute pesticide risks to farm workers, chronic risks via dietary exposure and exposures to birds, Daphnia and bees. 

Lu, C., Toepel, K., Irish, R., Fenske, R. A., Barr, D. B. and Bravo, R. (2006). Organic diets significantly lower children s dietary exposure to organophosphorus pesticides . Environ. Health Perspect., 114(2), 260-263. 

Measurement of dietary exposure to pesticides has historically relied upon deterministic methods that assign finite values to both the pesticide residue level and the food consumption estimates to yield a point estimate of exposure. The calculations are relatively simple, but consideration needs to be given to the accuracy of the assumptions concerning residue level and food consumption. 

TEFs were also used by the NRC Committee on Pesticides in the Diet of Infants and Children to estimate the aggregate risk to children from dietary exposure to a mixture of pesticides (NRC 1993). 

Ito et al. (1995) examined the combined dietary administration to rats of 19 organophosphate pesticides and 1 organochlorine pesticide, aU permitted for use in Japan, each at its ADI level. The dietary exposure at this level did not enhance the development of diethyl nitrosamine initiated pre-neoplastic lesions whereas at 100 times the ADI, the number and area of lesions were increased. The authors concluded that the study provided direct support for the present use of the safety factor approach in the quantitative hazard evaluation of pesticides. 

Similarly, uncertainty can also have substantial implications for assessment outcomes. For example, there is uncertainty about the importance of exposure of birds to pesticides via dermal absorption. This route of exposure is generally ignored in regulatory assessments, but there is evidence that it may be as important as dietary exposure, at least in some circumstances (Driver et al. 1991 Mineau 2002). This uncertainty, therefore, implies a potential 2-fold error in the assessment of exposure. 

TMRC is an acronym for Theoretical Maximal Residue Contribution, and is an estimate of chronic dietary exposure which could result from the consumption of the foods on which tolerances for a specific pesticide are established. 

These and other changes In the methodology used by the Agency in estimating dietary exposure to pesticides are currently under review. 

MACINTOSH D L, SPENGLER J D, OZKAYNAK H, TSAI L and RYAN B, Dietary exposures to selected metals and pesticides , Environmental Health Perspectives, 1996 104 202-9. 

The NZTDS thus provides a reliable snapshot of the overall quality and safety of the NZ food supply, and is a means (albeit not ideal) of checking the effectiveness of regulatory systems established to control pesticide residues in food. Total Diet Studies are also valuable in determining whether particular pesticide residues occur across the diet as a whole, or are restricted to certain food groups or even individual foods. The NZTDS provides readily understandable information on the dietary exposures of pesticide residues for the use of regulatory agencies, lawmakers and the public. 

EPA (2000), Choosing a Percentile of Acute Dietary Exposure as a Threshold of Regulatory Concern, EPA Office of Pesticide Programs, Washington DC. 

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