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 board responsible for the report were chosen for their special competences and with regard for appropriate balance.
This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine.
Support for this project was provided by the U.S. Environmental Protection Agency under Agreement No. 68C00082/C.
Library of Congress Catalog Card No. 95-68895
International Standard Book Number 0-309-05286-6
Additional copies of this report are available from:
National Academy Press
2101 Constitution Avenue, N.W. Box 285 Washington, D.C. 20055 800-624-6242 202-334-3313 (in the Washington Metropolitan Area)
B-550
Copyright 1995 by the National Academy of Sciences. All rights reserved.
Cover by John Eberhard, Pittsburgh, PA.