Dr. Enterline's review [1991] of changing attitudes and opinions on the relationship between asbestos and cancer in the 1934-1965 period points to various factors that may have retarded U.S. recognition of the existence of the relationship in that era. It is particularly surprising that a British finding of lung or pleural cancer at autopsy in 13.2% of 235 asbestotics [Merewether, 19491, combined with earlier German experience, did not have more impact on U.S. thinking. These observations obviously received considerable exposure in the United States, including a 1949 editorial in JAMA, drawing attention to the numbers of workers employed in the asbestos industry, and the need for increased attention to the "probable occupational hazard" of lung cancer. The report of Doll from England in 1955, and the casecontrol study of Breslow from 11 hospitals in California in the same year strongly reinforced the evidence of a significant association between asbestos and lung cancer; yet, pockets of scepticism apparently persisted, at least for a few more years.
Enterline notes some of the influences, operating pre-1965, that may have sustained doubts about the significance of the asbestos-lung cancer linkage, and clearly some of these factors may have been influential, e.g., lack of experimental evidence, rejection or lack of knowledge of science conducted outside the United States, and the reluctance of individual writers to change their minds. However, Hueper, who was Chief of the Environmental Cancer Section of the U.S. National Cancer Institute, drew attention in 1965 to another consideration of potentially great importance. This concerned the absence of published reports from the giant U.S. and Canadian asbestos industries on the incidence, morbidity, and mortality rates of asbestosis and lung cancer. Later data relating to these industries leave little doubt that there must have been an awful lot of asbestos-related disease around some industries and occupations. Hueper also notes that a plan to have an epidemiological survey of Canadian mines and mills under the aegis of the National Cancer Institute of Canada was not adhered to, and that this study was carried out as an industrydominated venture which "yielded highly controversial negative results. '' Other