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confounders, prior cigarette use remained the most significant predictor of risk of adenocarcinoma among males and females. Analysis restricted to nonsmoking females revealed a risk of adenocarcinoma of 1.68 (95% confidence interval (CI) = 0.39-2.97) for passive smoke exposure of four or more hours per day. Neither sex showed sig- nificantly elevated risk for oc- cupationsl exposures, although males bordered on significance (OR = 2.23, 95% CI = 0.97-5.12). The results sug- gest the need to develop cell type- specific etiologic hypotheses.

Diet and Lung Cancer. A Review of the Epidemiologic Evidence in Humans. Colditz, G.A., Stampfer, M.J., Willett, W.C. Channing Laboratory, Boston, MA 02215, U.S.A. Arch. Intern. Med. 147: 157-160, 1987.

We reviewed the human epidemiologic studies of the possible protective ef- fect against lung cancer of various dietary constituents, including preformed vitamin A, carotene, vitamine E, selenium, and vitamin C. Beta carotene has strong potential as a protective agent, though constituents of green and yellow vegetables other than carotene may account for the reduced cancer incidence observed in many studies. Selenium also deserves attention as a potential chemopreven-

tive nutrient, though data are limited. Data on vitamin E are sparse and inconclusive, and there is little evidence that vitamin C provides protection against human lung cancer. It is likely that cessation of cigarette smoking would have a far greater influence on reducing lung can- cer incidence than any known dietary modification.

The Changing Pattern of Bronchial Carcinoma. Belcher, J.R. The London Chest Hospital, London, U.K. Br. J. Dis. Chest 81: 87-95, 1987.

The figures for the incidence of bronchial carcinoma have been monitored in various age groups and in both sexes since 1975 when a previous paper on the subject was published. These figures are available up to 1983. The total in- cidence of bronchial carcinoma in men started to fall after 1974, while in women it is still rising. The incidence amongst men up to the age of 59 started to fall after 1960; in women, this oc- curred 20 years later, and it has fal- len in the 60-64 age group since 1982. The incidence is still rising in older women, but is falling in all groups of mean up to the age of 80. Thus the trend seen amongst the men in 1975 seems to be being repeated amongst the women. The fall in the incidence of

bronchial cancer has occurred amongst the group of women who have smoked more than any of their predecessors. Some possible reasons for this surprising finding are discussed.

Measurements of Passice Smoking and Es- timates of Lung Cancer Risk Among Non- Smoking Chinese Females. Koo, L.C., Ho, J.H.-C., Saw, D., Ho, C. Department of Community Medicine, University of Hong Kong, Hong Kong. Int. J. Cancer 39: 162-169, 1987.

Lifetime exposures to environmental tobacco smoke from the home or workplace for 88 'never-smoked' female lung cancer patients and 137 'never- smoked' district controls were es- timated in Hong Kong to assess the pos- sible causal relationship of passive smoking to lung cancer risk. Relative risks based on the husband's smoking habits, or lifetime estimates of total years, total hours, mean hours/day, or total cigarettes/day smoked by each household smoker did not show dose- response results. Similarly, when such categories as mean hours/day, or ear- lier age of initial exposure, were com- bined with years of exposure, there were no apparent increases in relative tisk. However, when the data were segregated by histological type and location of the primary tumor, it was seen that Deripheral tumors in the middle or lower lobes, or, less strongly, squamous or small-cell tumors in the middle or lower lobes, had in- creasing relative risks that might in- dicate some association with passive smoking exposure.

Mortality from Lung Cancer and Respiratory Disease Among Pottery Workers Exposed to Silica and Talc. Thomas, T.L., Stewart, P.A. Occupa- tional Studies Seciton, Environmental Epidemiology Branch, National Cancer Institute, Bethesda, MD 20892, U.S.A. Am. J. Epidemiol. 125: 35-43, 1987.

A cohort mortality study of white men employed for at least one year be- tween 1939 and 1966 at three plants of a single United States company was con- ducted to evaluate the risk of lung cancer and nonmalignant respiratory disease among workers exposed to silica dust and nonfibrous (nonasbestiform) talc in the manufacture of ceramic plumbing fixtures. Follow-up of 2,055 men through January i, 1981, indicated a substantial excess of nonmalignant respiratory disease among those with high levels of exposure to silica dust (standardized mortality ratio = 2.26). The risk of nonmalignant respiratory disease rose with the number of years exposed, was not further enhanced by talc exposure, and appeared to be ap- preciably lower among those exposed in