ASBESTOS WORKING GROUP; CHLOROMETHYL ETHER WORKING GROUP; EUROPEAN ACTION AGAINST TOBACCO COMM; IARC; LIAONING HEALTH INVESTIGATION BUREAU; NANJING HEALTH + ANTIEPIDEMIC STATION; NATL ARSENIC WORKERS LUNG CANCER WORKING; NATL COOPERATIVE OCCUPATIONAL TUMOR WORK; NCI, NATL CANCER INST; WHO, WORLD HEALTH ORG; WUHAN MEDICAL COLLEGE