NERL Research Abstract EPA's National Exposure Research Laboratory GPRA Goal 8 - Sound Science Significant Research Findings Development of a Consolidated Human Activity Database (CHAD) Purpose Recent exposure monitoring studies have demonstrated the importance of activity pattern data in explaining and predicting variation in human exposures to environmental pollutants. These studies also have demonstrated that time-activity pattern data developed from general population studies often have little scientific value in understanding the activity patterns and exposures of children. Factors such as age, mobility, dermal-oral transfer, daily activities, residential and commercial locations, and transportation options influence the magnitude, frequency, duration, and intensity of pollutant exposure. The Consolidated Human Activity Database (CHAD) responds to these concerns by assembling data from ten existing human activity databases and making them easily accessible to the public via EPA's internet web page. This provides consistent, comprehensive, and quality-assured activity data for exposure and risk assessors in an easy-to-use format. About one-fourth of these data focus on children and young adults (less than eighteen years old). Research Approach The study's primary objectives were to develop a common set of activity and location codes so that the separate formats used by the original ten databases could be easily accessed by exposure analysts. There are 140 activity codes and 114 location codes used in CHAD, in a hierarchal structure so that as much detail in the original surveys could be maintained as possible. A common format for handling time was also established, so that all the individual activity data starts and ends at midnight. This facilitates computer modeling, because code "translations" no longer have to be used to bring together the data. A unique feature of CHAD is that a distribution of physiologically-based estimates of personal energy expenditure (called a MET) is provided for every activity coded in the database. Since inhalation, water consumption, and food ingestion can be related ------- to the MET indicator, CHAD facilitates multi-route exposure/uptake dose modeling. CHAD includes data from EPA-funded activity surveys, including the 1992-1998 National Human Activity Pattern Survey (NHAPS), and the Denver and Washington DC surveys undertaken in the mid-1980s. CHAD also includes data from a Cincinnati survey funded by the Electric Power Research Institute; a survey of activities in Valdez, Alaska funded by Alyeska- a consortium of petroleum companies; an activity survey in Los Angeles undertaken by the American Petroleum Institute; and the two large studies of Californian's activities conducted by the State's Air Resources Board in the early 1990s. Major Findings and Significance Over 17,000 person-days of data are included in the database. About one quarter of these data focus on children (over 4,500 days of children's activities). CHAD provides a synoptic basis for undertaking multi-route, multi-media exposure and dose assessments. The data can be accessed by age, gender, location of the country, housing characteristics, and/or socioeconomic factors. The significant portion of these data which focus on children's activities represent a valuable contribution to understanding children's time-activity patterns, exposure, and risk, and to developing multi-route exposure and dose models. Research Publications CHAD is easily accessible on EPA's internet system at the following address: http://www.epa.gov/chadnetl/index.html. The study design, protocols, and project technical reports for CHAD were developed, reviewed, and published in accordance with ORD's scientific peer review procedures. Contact Person: Thomas McCurdy U. S. Environmental Protection Agency; MD-56 Research Triangle Park, NC 27711 (919)541-0782 mccurdv ,thomas@epamail. epa. gov ------- |