NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.

Support for this project was provided by the U.S. Department of Energy under Contract No. DE-FC01-99EW59049, the U.S. Department of Defense under Purchase Order No. DASW01-00-P-3588, the U.S. Army and the U.S. Air Force under Purchase Order No. DAAD05-00-P-7387, the Strategic Environmental Research and Development Program under Contract No. DACA72-99-P-0210, the National Institute of Environmental Health Sciences under Purchase Order No. 273-MH-918344, the Agency for Toxic Substances and Disease Registry under Contract No. 200-2000-00629, the U.S. Environmental Protection Agency under Grant No. X-82966601, and the Gas Research Institute under Grant No. 8339.

Library of Congress Control Number: 2002117001