1. Department of Chemical Engineering, University of Tulsa, 600 S. College Avenue, Tulsa, Oklahoma 74104, R. W. Holland Engineering, P.O. Box 472336, Tulsa, Oklahoma 74147, and Department of Environmental and Community Medicine University of Medicine & Dentistry of New Jersey-Robert Wood Johnson Medical School, 170 Frelinghuysen Road, Piscataway, New Jersey 08854