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Cumulative risks - Source-to-Dose Models
A key to understanding the risk posed by exposures to toxic chemicals is the accurate estimation of the route/pathway and concentration of the chemical that comes into contact with the individual (exposure), the activities that result in individual exposures, estimates of how much of the chemical is absorbed into the body (absorbed dose), and the amount of the chemical that is delivered to the targeted body organ (i.e., the target tissue dose). Rarely is dose known or measured, and typically exposure is only inferred from the knowledge of selected microenvironmental concentrations (ambient, indoor, or personal) or information about source concentrations. Risk assessments are aided greatly by the ability to link source emissions to doses through understanding potential exposures and their key determinants. NERL's source-to-dose modeling research is designed to answer the question "What is the best way to update and link existing exposure and dose models and their supporting data bases to address cumulative risk?" Through this research program, risk assessors are being provided fully evaluated models they can use to predict distributions of exposures for assessing cumulative risk. The research program builds upon source-to-dose modeling efforts originated with a one chemical focus, and progresses to modification, validation, application and documentation of their appropriate use in assessing aggregate exposures and cumulative risk assessments.