Defining the relationship between individuals’ aggregate and maximum source-specific exposures
Citation:
Price, P. Defining the relationship between individuals’ aggregate and maximum source-specific exposures. 2017 ISES Annual Meeting, RTP, Noth Carolina, October 15 - 19, 2017.
Impact/Purpose:
The talk will present a novel method for evaluating source-specific and aggregate exposures that can support the management of risks from aggregate exposures.
Description:
The concepts of aggregate and source-specific exposures play an important role in chemical risk management. The concepts of aggregate and source-specific exposures play an important role in chemical risk management. Aggregate exposure to a chemical refers to combined exposures from all sources and source-specific exposure refers to exposures from a specific source of a chemical. Both types of exposures can occur by multiple routes and exposure pathways and both can be determined on a population and individual level. The issue for aggregate and source-specific exposures is that while an individual’s source-specific exposures may all be acceptable, an individual’s aggregate exposure may not. Examples of regulatory issues that reflect this relationship include the “relative source contribution” used in setting ambient water quality standards, the regulation of sources under the Toxic Substances Control Act within a framework of aggregate exposure, and the assessment of impacts for life-cycle impact assessments. This talk presents a method (Maximum Aggregate Ratio or MAR) for evaluating the relationship between the two metrics. MAR is defined as the ratio of an individual’s aggregate dose to the maximum source-specific dose received by the individual. The MAR can be viewed as a parallel concept to the Maximum Cumulative Ratio (MCR)1,2,3,4 used in mixture risk assessments. The MAR can be used to explore the relationship between interindividual variation in source-specific doses and interindividual variation in aggregate exposures and the impacts of controlling smaller sources on aggregate exposures. A case study of the use of MAR to assess aggregate exposures to chemicals present in different types of consumer products is provided.
