Pesticide estimating exposure

Exposures of Children. Data need to be developed to properly assess the exposure of infants who eat processed baby foods containing residues of pesticides such as endosulfan. Several studies have estimated exposure based on endosulfan concentration found in foods typically eaten by infants however, no studies that directly studied infant exposure could be located. Attention should also be given to infant formulas and to the tap water used to prepare infant formulas from condensed or powdered forms. More data are also required to properly assess endosulfan exposure to children who live, play, or attend school near farmlands that are treated with endosulfan. Maps that catalog endosulfan use on crops and present average application rates would better allow an assessment of the potential for children in farming communities to be exposed. The possibility that farming parents work clothes and shoes may carry endosulfan residues into the home also should be studied. In addition, home use of endosulfan, which may result in exposure of children, needs to be investigated. 

Hardy, A.R. (1990). Estimating exposure The identification of species at risk and routes of exposure. In L. Somerville and C.H. Walker (Eds.) Pesticide Effects on Terrestrial Wildlife, 81-98, London Taylor Francis. 

Studies may be designed for estimating exposures to a wide array of wildlife, including birds, mammals and amphibians. Many regulatory requirements involve birds, and less emphasis is currently placed on other species. As regulatory requirements evolve, ecological risk assessments will be required for more species. This may require alternative approaches for food item analysis to allow estimates of pesticide ingestion. 

Based on the patch method to assess worker or re-entry exposure, researchers have developed a database, which may be used to estimate exposure. Each patch from an individual in a study can be entered into the database separately, the residue data from patches from various body areas can be summed to yield a whole-body exposure number, and the data may be sorted as to worker tasks, equipment used, protective clothing worn, formulation types and other parameters. This is the basis for the currently used Pesticide Handlers Data Base (PHED), which was developed through a joint effort in the 1980s of CropLife America [formerly known as American Crop Protection Association (ACPA) and National Agricultural Chemicals Association (NACA)], the Environmental Protection Agency (ERA) and Health Canada. " The PHED is discussed in detail in another article in this book. 

A report entitled Chemical Trespass was issued in May 2004 by the Pesticide Action Network (Schafer et al., 2006). It contained detailed analysis of 2000/01 National Health and Nutrition Examination Survey (NHANES) OP urinary metabolite data and used published methods to estimate exposure levels to parent compounds from creatinine corrected urinary metabolite levels. They focused on chlorpyrifos and its metabolite 3,4,6-trichloro-2-pyridinol (TCP), and found that chlorpyrifos exposures for children ages 6-11 and 12-19 exceeded EPA s chronic population-adjusted dose (cPAD) by surprisingly wide margins. Geometric mean TCP levels were 3 to 4.6 times higher than the EPA-estimated safe dose, as shown in Fig. 14.2. The more heavily exposed children received daily doses more than ten times the safe level. 

This document deals only with estimating exposure to direct additives and chemical contaminants. The procedures used to estimate exposure to chemical contaminants in food (including naturally occurring toxicants, such as mycotoxins) are essentially the same as those used for direct additives. Thus, contaminants will be considered in the discussion of direct additive exposure estimation. The procedures discussed herein are equally applicable to color additives, GRAS substances, prior-sanctioned ingredients, and pesticide residues. 

To illustrate the application of 2nd-order Monte Carlo analysis, we estimated exposure of Carolina wrens to a hypothetical pesticide in cotton fields in the southwest United States. For this case study, the pesticide is assumed to be persistent, and the goal is to estimate chronic exposure (i.e., total daily intake) at the local field scale. The input data are representative of the kinds of data available during reregistration but, for this case study, are entirely hypothetical. 

Inputs for a 2nd-order Monte Carlo analysis to estimate exposure of Carolina wrens to a hypothetical pesticide (random variables are included in the inner loop of the Monte Carlo analysis, while random variables with uncertainty are included in both the inner and outer loops of the Monte Carlo analysis)... 

Using a model that was developed to estimate exposure to pesticides when spraying plants indoors to describe an outdoor situation will not correctly capture the different dispersion conditions outdoors. 

Use of increasingly complex exposure algorithms has led to development of predictive models to estimate exposure. Key models in the field of pesticide exposure assessment are surveyed in Chapters 5 and 6 of this text. With the... 

A tiered approach is used for pesticide exposure assessment at the surface water level. Depending on the results of the initial risk assessment, more extensive testing relative to the environmental exposure or hazard may be required to define the full environmental risk. The data are generated from such increasingly comprehensive series of studies (higher tiered studies). At each tier a comparison has to take place between the estimated exposure and... 

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