The authors of a 1978 NIOSH study on the effects of dioxin discussed portrayal of their results as a mixture of previous and inconsistent findings. The study included all 5172 chemical workers in the United States who had work records verifying assignment to the production of 2,4,5-trichlorophenoxyacetic-acid (93765) or its precursor 2,4,5- trichlorophenol (95954), both contaminated with 2,3,7,8- tetrachlorodibenzo-p-dioxin (1746016) (TCDD). A standard epidemiologic method was used but findings differed from those of other reports. A 15% overall excess of all cancers was found; this excess reached 46% in a subcohort having exposures over 1 year and latencies over 20 years. This group also exhibited a 42% excess of respiratory cancer and a nine fold excess of soft tissue sarcoma. Contributions of other occupational carcinogens or smoking were not ruled out; but, the authors conclude that their results indicate that TCDD is a carcinogen.