1. Time Use Research for Exposure and Risk Assessment
Rosemary Zaleski, ExxonMobil Biomedical Sciences, Inc., and
Virpi Tenhola, KTL National Public Health Institute, Finland
International Association for Time Use Reseach
Brussels, Belgium, September 2003

2. Introduction Ultimate Goal: Ensuring protection of public health
Risk = function of (hazard, exposure)
Exposure data critical to estimate risk
Develop most realistic, complete estimates of exposure as possible
Time Use Information is critical to developing exposure estimates

3. Time Use Information and Exposure Assessment
Media Concentration X Intake Rate X Contact Time
e.g., Inhalation Exposure (mg/day) =
Pollutant in air (mg/m3) X Breathing Rate (m3/hr) X Time (hrs/day)
Occupational scenario: requires time at work in task area
Indoor residential scenario: requires time indoors at home
age-specific exposures require age-specific time indoors
multi-chamber residence models require room-specific movement patterns

4. Example of Exposure Model Input Data

5. Examples of Time Use Parameters Relevant for Exposure Assessment
Hours indoors/outdoors
Time in specific environments (home, work, school, driving)
Time in specific microenvironments (kitchen, bedroom, garage)
Time in specific tasks (gardening, recreation, bathing)
Time using or in presence of certain products (paints, adhesives, cigarettes)
Residence time, employment tenure

6. Ideal Level of Information for Time Use Parameters for Exposure Assessment
Distributions
by age
by gender
by time of year
by region or population
by activity level
by other significant factors
significant factors may differ across time parameters
ex. Day of week, employment status, education status
Sequentially (preserve potential correlations)

7. Why Does Time Use Information Matter?
A few of the many applications of time use information in exposure and risk assessment include:
Occupational exposure and safety assessment
Consumer product safety assessment
Children’s exposure assessment
Ambient air pollutant risk assessment
Environmental emissions exposure and risk assessment

8. Examples of Time Use Data in Exposure Assessment
US National Human Activity Pattern Survey:
distributional data by environments (e.g., work) and activities (e.g., bathing)
Summary data in USEPA Exposure Factors Handbook:
US Consolidated Human Activity Database:
includes activity level estimates for each task

9. Examples of Time Use Data in Exposure Assessment (cont’d)
ECETOC European Exposure Factors Sourcebook, with Focus on UK Data:
OECD: years with employer for multiple countries
Gershuny 1995: estimated weekly work hours for multiple countries

10. Multinational Time Use Data: Relevance for Exposure Estimates
Differences: weekly work hours & employer tenure

11. Summary So Far
Time use data for exposure assessment is nowadays mostly from the U.S.
For other countries, data are still (largely) missing
Always looking for most current, representative data
Possible ways to leverage social science and exposure science studies:
EPA/ ACC RfA announcement:
ExpoFacts:

12. ExpoFacts

13. Do you have data for ExpoFacts? Do you want to use the ExpoFacts?
The database will be free to use
The database will be available on the Internet
Users can search and combine data tables to best suit their needs
The database will be published in 2004
Do you have data for ExpoFacts?
Do you want to use the ExpoFacts?

14. Conclusions Ultimate Goal: Ensuring protection of public health
Risk = fn (hazard, exposure)
Exposure data critical to estimate risk
Develop most realistic, complete estimates of exposure as possible
Time Use Information
Critical to developing exposure estimates
Utilize all sources of relevant data
Interdisciplinary studies - a good use of time!