US EPA

83583 

Journal Article 

Modeling the dose profile in human exposure assessments: Ozone as an example 

Mccurdy, T 

1997 

1 

Revista de Toxicologia
ISSN: 0212-7113
EISSN: 1697-0748 

1 

3-23 

A case has been made here to incorporate potential dose measures in an airborne substances exposure model. Dose received is highly dependent upon breathing rate, VE or EVR, which in turn is directly associated with human activities-an inherent part of an exposure assessment. A case has also been made for evaluating the entire dose profile of the populations being assessed. Measures commonly used in exposure assessments (for example, time-weighted averages and cumulative exposure ["Sigma" c times t]) usually do not adequately relate to dose received and certainly do not reflect the dose rate received, both of which are found to be important in many health studies of air pollutants. Ozone effects were used as an example of an air pollutant where c times t does not perform well in explaining adverse health effects due to an exposure to the pollutant. A few possible dose metrics that can be derived from a dose profile were highlighted. These metrics act as a surrogate for the true potential dose that crosses the oral/nasal interface. Specific dose metrics used in the O3 NAAQS review were provided. As more emphasis is placed upon biokinetic modeling in the setting of environmental health standards, the need for a full description of the dose profile will increase. Many of the tools needed to develop such a profile now exist, and better data become available daily. The stage is set for true probabilistic risk assessment. Improvements in human exposure assessment are leading the way toward that end.