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Modeling ETS Exposure and Dose Using PDA E-Diaries

Institution: San Diego State University Research Foundation
Investigator(s): Marilyn Johnson-Kozlow, Ph.D.
Award Cycle: 2006 (Cycle 15) Grant #: 15KT-0175 Award: $245,214
Subject Area: Epidemiology
Award Type: New Investigator Awards

Initial Award Abstract
The 2006 TRDRP call for proposals has prioritized the need for measurement models of exposure to environmental tobacco smoke (ETS) in non-laboratory settings. The purpose of the proposed investigation is to improve the measurement of ETS exposure and ETS dose using handheld computer devices (personal digital assistants, or PDAs). The study also catalogs various household factors which may lead to nicotine contamination in the home. Such factors may affect measures of ETS dose, and this is also investigated.

Large scale studies of exposure to ETS typically rely on retrospective self-reports of exposure due to their convenience and cost effectiveness. For example, exposure may be measured as the number of cigarettes to which a person is exposed over a 7-day period. An objective measure of ETS exposure that is commonly used is cotinine from saliva, urine, or blood. However, the correlation between self-reports and cotinine is not perfect. Differences between cotinine and self-report values may be due in part to the inaccuracy of self-reports or a mismatch between what they measure.

While self-reports measure exposure, cotinine may more accurately be said to measure ETS dose. While ETS exposure is the contact of ETS with a surface of the human body such as the surface of the lungs, dose is the amount of contaminant that crosses a boundary of the body, such as cotinine found in saliva. ETS exposure may best be objectively measured by personal air monitoring. Unlike ETS exposure (i.e., #cigs exposed), dose is affected by a number of factors, including metabolism and ETS contamination in the home. Because nicotine is easily absorbed by household surfaces, it can be off-gassed into the home atmosphere, thus affecting the ETS dose.

One promising way of improving the correspondence between reported and biological exposure measures is the use of personal digital assistants (PDAs). PDAs may improve the accuracy of self-reported ETS exposure by decreasing the time between exposure and recall and by assessing where exposure occurs on a real-time basis.

The proposed study investigates the relationship between a 7-day retrospective self-report, a PDA-based measure, salivary cotinine, and personal air monitor data. Models of ETS exposure and ETS dose will be based on ETS concentration, duration of exposure, and intake (or respiratory) rate. Environmental factors in the home, such as ventilation, volume of the home, and carpeting, which may affect ETS dose, will be cataloged. The addition of environmental factors to dose and exposure models will be determined.

To control for differences in metabolism, the study utilizes a sample of women aged 18-39. Forty-two nonsmoking women who live with one or more smokers will be recruited into the study. They will keep a daily e-diary by using a personal digital assistant (PDA) on which is stored ETS exposure- and dose-related questions. On Day 1 participants begin wearing a personal air monitor and using the PDA; PDA-based and monitor data are collected for 7 days. On Days 4 and 7 participants collect two salivary samples. On Day 7 a study interviewer meets with the participant to collect the samples, the PDA, and air monitor, and conducts an environmental audit of the home and the 7-day retrospective recall interview.

Models of ETS exposure and dose will be developed. These will aid investigators in determining the important factors to assess with self-report measures. The kinds of household contamination factors that are important to consider in models of ETS dose will also be determined. In the future, tobacco control researchers will have better knowledge about what self-report measures should be included in order to accurately measure ETS exposure and dose. Improving measures of ETS exposure and dose allows researchers to do a better job of evaluating interventions to decrease exposure to ETS, determining the health risks associated with ETS exposure, and obtain more accurate estimates of the relationship between ETS exposure and various chronic diseases, such as cancer and heart disease.