Whitwell, F., Newhouse, Muriel, L., and Bennett, Diane R. (1974).British Journal of Industrial Medicine,31, 298-303. A study of histological cell types of lung cancer in workers suffering from asbestosis in the United Kingdom. The present study concerns the predominant cell type of lung cancer in workers with certified asbestosis who died of carcinoma of the lung in the United Kingdom between 1962 and 1972. Clinical data, necropsy reports, histological sections, and in some cases paraffin blocks were obtained from the nine pneumoconiosis panels in the country and from hospitals where the patients had been treated. Histological analysis was confined to the 88 male and nine female cases in which adequate postmortem tissue had been obtained. The number of female cases was considered to be too small to be of value as a separate series. Among the males, adenocarcinoma was the commonest type of lung cancer found in 34%. Information about the smoking habits of 69 of the 88 men was obtained; all had smoked at some time. There was little difference between the smoking habits of any group whatever the cell type of carcinoma. The difficulty in finding a comparable series of non-asbestos-exposed individuals is pointed out. It is the usual practice to hold a necropsy on any patient when asbestosis has been certified wherever the place of death. This series therefore has a wider basis of selection than any hospital-based series. Cigarette smoking can exert a carcinogenic effect on different parts of the bronchial tree, producing squamous or oat-celled tumours proximally and adenocarcinoma distally. Asbestos dust lying in distal parts of the lung may exert a co-carcinogenic probably a multiplicative effect with tobacco smoke, producing adenocarcinoma of the distal part of the respiratory tract.