Probabilistic risk assessment cumulative exposure

ASSESSMENT OF RISKS TO HUMANS EXPOSED TO PESTICIDES 2 The Four Steps in Risk Assessment 2 Hazard Identification 2 Dose-Response Assessment 3 Margin of Safety Approach 3 Quantitative Risk Assessment 3 Exposure Assessment 4 Risk Characterization 4 RISK MANAGEMENT 5 ADVANCES IN DATA INTERPRETATION 5 Probabilistic Approaches 5 Recognition of the Tier Approach 5 Aggregate Exposure 6 Cumulative Exposure 6 Impact of New Scientific Advances 7 Post-Registration Monitoring 7 HARMONIZATION OF REGULATORY APPROACHES SUMMARY 9... 

Probabilistic risk assessment methods are described herein for determining a popnlation s distribution of the dose from exposure and the combination of that exposnre characterization with appropriate toxicological information to form aggregate and cumulative risk assessments. An individual s dose from exposure is characterized as a set of chemical- and route-specific dose profiles over time. Toxic equivalence factors (TEFs) that reflect the toxic endpoint and exposure duration of concern are used to scale chemical- and route-specific doses to toxic equivalent doses (TEDs). The latter are combined in a temporally consistent manner to form a profile over time of the Total TED. For each individual, a Total MOE is calculated by dividing a toxicologically relevant benchmark dose (e.g. an EDio) by the individual s Total TED. The distribution of the Total MOE in a popnlation provides important information for risk management decisions. 

This chapter describes and illustrates probabilistic approaches to aggregate and cumulative assessments of exposure, dose and risk. Aggregate assessments account for multiple sources (e.g. food, water, residence and occupation) and multiple routes (ingestion, dermal and inhalation) of exposure for a single pesticide. Cumulative assessments combine exposures for chemicals that share a... 

This chapter illustrates probabilistic approaches to residential and occupational exposnre assessment and their incorporation into aggregate and cumulative assessments of exposure, dose and risk. 

Figure 7.1 also depicts changes via behaviors, such as occupation, ambient exposure, and predisposition, such as genetic. Logically, it is correct regardless of the shape of the dose-response model. At low dose or at environmental (ambient) exposures, cancer risk assessment models used in regulatory law are either linear or linearized that is, each is a cumulative distribution function of lifetime cancer risk and thus is a monotonic function. Hormetic cancer dose-response models are also probabilistic however, they are nonmonotonic (they are relations). The EPA summarizes the reasons for using statistical and probabilistic methods in risk assessment as follows (EPA 2005) ... 

The methodology in the case study for chronic exposure, as well as several advances in probabilistic assessment methodology for acute exposure (e.g., a person s exposure on a single day), are being incorporated into the Cumulative and Aggregate Risk Evaluation System (CARES) begun in 2000 and being further developed with the International Life Sciences Institute (ILSI) in 2004. 

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