This episode's headline: News Summary; Mercy Killing; Foster Homes Wanted; Union Carbide: Sizing Up Safety. The guests include In Los Angeles: DEREK HUMPHRY, Hemlock Society; In Seattle: KELLY HANCOCK, Assistant State Attorney; In Huntington, West Virginia: PERRY BRYANT, Director, Citizens Action Group; RUSSELL WEHRLE, National Institute of Chemical Studies. Byline: In New York: ROBERT MacNEIL, Executive Editor; In Washington: JUDY WOODRUFF, Correspondent