Probabilistic exposure assessment

US-EPA. 2007b. Consolidated Human Activity Database, http //www.epa.gov/chadnetl/ van Drooge, H.L. and A.G. van Haelst. 2001. Probabilistic Exposure Assessment is Essential for Assessing Risks - Summary of Discussions. Ann. Occup. Hyg. 45 S159-S162. 

OFFICE OF PESTICIDE PROGRAMS (1998). Guidance for Submission of Probabilistic Exposure Assessments to the Office of Pesticides Programs Health Effects Division. US Environmental Protection Agency. 

The additional data provided from the probabilistic exposure assessment also require greater interpretation. Under provisions of FQPA, the EPA is not allowed to grant tolerances for pesticides unless the aggregate and cumulative... 

To address these questions, an exposure assessment should begin with a definition of the assessment objective (section 2.2.1). From this follows the need to define and evaluate the conceptual exposure model (section 2.2.2). The goal of the conceptual model is to establish exposure links via exposure pathways to exposure routes and relative magnitude of uptake or intake by different exposure routes. These questions are discussed in more detail in section 5.4 with respect to interpretation of the results of a probabilistic exposure assessment. 

Two important considerations in probabilistic exposure assessment are whether to quantify uncertainty and whether to separate it from variability within the analysis and output ... 

Mekel O, coord. (2003) [Evaluation of standards and models for probabilistic exposure assessment. Interim report.] Bielefeld, Universitat Bielefeld (Forschungs- und Entwicklungsprojekt http //www.math.uni-... 

There is a transition away from nsing a deterministic approach in which high end or upper bound point estimates and defanlt valnes are nsed towards nsing a probabilistic approach in distribntional models which incorporate complex data sets to build realistic estimates of exposure. While probabilistic dietary exposure assessments can now be carried out routinely for many pesticides, available occupational and residential exposure data sets are typically insufficiently robust. Work on developing newer exposure databases (e.g. ARTF, ORETF, AHETF and EUROPOEM II) and distributional use pattern data would facilitate this transition. The topic of probabilistic exposure assessment is covered in Chapter 8. 

TIERED APPROACHES TO EXPOSURE ASSESSMENT 144 Deterministic (Point-Estimate) Exposure Assessments 145 Probabilistic Exposure Assessments 145 REPORT WRITING 145 Protocol/User s Guide 146 General Description of Exposure Model 146 Detailed Description of Model Inputs and Outputs 146 Exposure Model Validation 146 Quality Assurance Practices 147 Archiving 147... 

In 2000 in The Netherlands, a workshop was held on innovative elements in the exposure assessment for pesticide operators. This also covered the use of probabilistic exposure assessment (van Hemmen and van der Jagt, 2001). 

Approaches for aggregating exposure for simple scenarios have been proposed in the literature (Shurdut et al., 1998 Zartarian et al., 2000). The USEPA s National Exposure Research Laboratory has developed the Stochastic Human Exposure and Dose Simulation (SHEDS) model for pesticides, which can be characterized as a first-generation aggregation model and the developers conclude that to refine and evaluate the model for use as a regulatory decision-making tool for residential scenarios, more robust data sets are needed for human activity patterns, surface residues for the most relevant snrface types, and cohort-specific exposure factors (Zartarian et al, 2000). The SHEDS framework was used by the USEPA to conduct a probabilistic exposure assessment for the specific exposure scenario of children contacting chromated copper arsenate (CCA)-treated playsets and decks (Zartarian et al, 2003). 

Mitchell, M. and C. Campbell (2001). Probabilistic Exposure Assessment of Operator and Residential Exposure A Canadian Regulatory Perspective, Ann. Occup. Hyg., 45, S43-S47. 

Taylor AC (1993) Using objective and subjective information to develop distributions for probabilistic exposure assessment. Journal of Exposure Analysis and Environmental Epidemiology 3 285-298. 

Finley, B. L., and Paustenbach, D. J. (1994). The benefits of probabilistic exposure assessment Three case studies involving contaminated air, water, and soil. Risk Anal 14, 53-73. 

M. Trapp, G. Tintrup, R. Kubiak, Investigation of Methods and Geo-Databases for a Refined Probabilistic Exposure Assessment on a National Scale, Poster Presentation at SETAC Europe 16th Annual Meeting, 8.-11.5.2006,... 

Investigation of new methods and geo-databases for a refined GIS-based probabilistic exposure assessment (R. Kubiak, RLP AgroScience, Germany)... 

Canada submitted a probabilistic exposure assessment based on occurrence data for ochratoxin A in cereals and other food commodities and on food consumption data from the USA. Detailed individual data on occurrence were not submitted, but ochratoxin A was detected in 436 samples out of 1668 analytical results. 

For the assessment of dietary exposure, the authors used the full distribution of the contamination for all commodities combined with the frequencies and amounts consumed and estimated an average dietary exposure below 5 ng/kg bw and high percentiles of exposure below 15 ng/kg bw. Because of the methodological choice of a probabilistic exposure assessment, cut-off points on the right of the distribution curve to simulate enforced MLs have an impact on dietary exposure when the cut-off points are located in the tail (e.g. at the level of 5 pg/kg). On the contrary, a cut-off point at a level above most of the observed values of contamination (e.g. 20 pg/kg) is ineffective. 

N. Warren and R. Cotton, The development of a web-enabled framework for probabilistic exposure assessments. Research Report 763, Healthy and Safety Laboratory, Health and Safety Executive, Buxton, Derbyshire, United Kingdom, 2010. 

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