This episode's headline: The Urge to Tamper; Dangerous Cargo; Empty Gondolas; Importing Doctors. The guests include In New York: Dr. ARTHUR HULL HAYES, Jr., Former Commissioner, FDA; In Los Angeles: Dr. BRUCE DANTO, Psychiatrist; In Washington: FRED MILLAR, Environmental Policy Institute; CYNTHIA DOUGLASS, Transportation Department; REPORTS FROM NEWSHOUR CORRESPONDENTS: SHELLIE KARABELL, in Italy; FRED SAM LAZARO (KCTA), in North and South Dakota. Byline: In New York: ROBERT MacNEIL, Executive Editor; In Washington: JIM LEHRER, Associate Editor; JUDY WOODRUFF, Correspondent