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Human Exposure and Atmospheric Sciences

Consolidated Human Activity Database - CHAD

To understand how humans are exposed to chemicals, scientists need to have accurate information on what people do every day – where they spend their time, what they eat, and how long they sleep, for example. These activities determine the contexts, circumstances, and durations of our chemical exposures. Using these data, scientists can better understand the chemicals that pose threats to human health, and how best to limit or eliminate these risks.

EPA scientists have compiled detailed data on human behavior from 22 separate studies into EPA’s Consolidated Human Activity Database (CHAD). The database includes a total of more than 54,000 individual study days of detailed human behavior, with each day broken down into individual hours and activity types. The data also include demographic information, including age, sex, employment, and education level, which allows researchers to examine specific groups within the general population and how their unique behavior patterns influence their exposures to chemicals.

Results and Impact
Scientists at EPA, other government agencies, academia and private organizations routinely use CHAD data in human exposure and health studies and in models used for exposure and risk assessment. EPA’s program offices use CHAD to help develop strategies to protect human health, and scientists around the world have cited it in hundreds of peer-reviewed studies.

Public Availability
The CHAD data are freely available for download to the public from the links at the right. Both an older version of CHAD (CHAD-2000) containing detailed information on early studies, and the current maintained CHAD version (CHAD-Master) are available.

Technical Contact
Kristin Isaacs, Ph.D.

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