E D Acheson

A job-exposure matrix for use in population based studies in England and Wales

The job-exposure matrix described has been developed for use in population based studies of occupational morbidity and mortality in England and Wales. The job axis of the matrix is based on the Registrar Generals 1966 classification of occupations and 1968 classification of industries, and comprises 669 job categories. The exposure axis is made up of 49 chemical, physical, and biological agents, most of which are known or suspected causes of occupational disease. In the body of the matrix associations between jobs and exposures are graded to four levels. The matrix has been applied to data from a case-control study of lung cancer in which occupational histories were elicited by means of a postal questionnaire. Estimates of exposure to five known or suspected carcinogens (asbestos, chromates, cutting oils, formaldehyde, and inhaled polycyclic aromatic hydrocarbons were compared with those obtained by detailed review of individual occupational histories. When the matrix was used exposures were attributed to jobs more frequently than on the basis of individual histories. Lung cancer was significantly more common among subjects classed by the matrix as having potential exposure to chromates, but neither method of assigning exposures produced statistically significant associations with asbestos or polycyclic aromatic hydrocarbons. Possible explanations for the failure to show a clear effect of these known carcinogens are discussed. The greater accuracy of exposures inferred directly from individual histories was reflected in steeper dose response curves for asbestos, chromates, and polycyclic aromatic hydrocarbons. The improvement over results obtained with the matrix, however, was not great. For occupational data of the type examined in this study, direct exposure estimates offer little advantage over those provided at lower cost by a matrix.

A survey of cancer and occupation in young and middle aged men. I Cancers of the respiratory tract

In a search for clues to previously industrial carcinogens the occupational and smoking histories of young and middle aged men with different types of cancer were compared. The study population comprised men aged 18-54 and resident in the counties of Cleveland, Humberside, and Cheshire (including the Wirral). From hospital and cancer registration records 2942 members of the study population in whom cancers were diagnosed during the period 1975-80 were identified retrospectively. The occupational and smoking histories of these patients were sought by a postal questionnaire addressed either to the patients themselves or, if they had died, to their next of kin. The overall response rate to the questionnaire was 52.1%. Additionally, limited occupational information was obtained for 89% of cases from their hospital notes. Analysis of these data suggests that no serious bias arose as a consequence of the incomplete response to the questionnaire. This paper concentrates on the results for cancers of the respiratory tract and mesothelioma. Mesothelioma was found to cluster in laggers, electricians, and shipyard workers, and nasal carcinoma in woodworkers. Carcinomas of the larynx and of the bronchus were examined by formal statistical techniques, each being compared with a control group made up of all other cancers combined. Several interesting occupational and industrial associations were shown, in particular, an excess of bronchial carcinoma in the leather industry (RR = 2.6, CI 1.2-6.0), in building labourers (RR = 1.7, CI 1.0-2.9) and other construction workers (RR = 1.8, CI 1.0-3.0), in bakers and pastry cooks (RR = 3.6, CI 1.3-10.4). and in cooks (RR = 2.5, CI 1.2-5.1). In addition, a small cluster of lung tumours was observed in men who had worked as dental mechanics.

Occupation and five cancers: a case-control study using death certificates.

A case-control approach has been used to examine mortality from five cancers--oesophagus, pancreas, cutaneous melanoma, kidney, and brain--among young and middle aged men resident in three English counties. The areas studied were chosen because they include major centres of chemical manufacture. By combining data from 20 years it was possible to look at local industries with greater statistical power than is possible using routine national statistics. Each case was matched with up to four controls of similar age who died in the same year from other causes. The occupations and industries recorded on death certificates were coded to standard classifications and risk estimates derived for each job category. Where positive associations were found the records of the cases concerned were examined in greater detail to see whether the risk was limited to specific combinations of occupation and industry. The most interesting findings to emerge were risks of brain cancer associated with the production of meat and fish products (relative risk (RR) = 9.7, 95% confidence interval (CI) 2.6-36.8) and with mineral oil refining (RR = 2.9, CI 1.2-7.0), and a cluster of four deaths from melanoma among refinery workers (RR = 16.0, CI CI 1.8-143.2). A job-exposure matrix was applied to the data but gave no strong indications of further disease associations. Local analyses of occupational mortality such as this can usefully supplement national statistics.

DO PHENOXY HERBICIDES CAUSE CANCER IN MAN

Two Swedish case-control studies have shown an increased risk of soft-tissue sarcomas in men exposed to phenoxy herbicides and chlorophenols during their application. A high incidence of soft-tissue sarcomas has also been observed among workers employed in the manufacture of these products in the U.S.A. Other studies have failed to demonstrate this association. A third case-control study in Sweden suggests that phenoxy acids and chlorophenols may also predispose to Hodgkins disease and non-Hodgkins lymphoma, but as yet there is little support for this theory from other sources. Further research is urgently needed to confirm or refute these associations, to define the extent of the risk (if any), and to identify the carcinogen(s).

Accuracy of occupational histories obtained from wives.

The study was conducted at two Southampton hospitals during evening visiting periods. Female patients under the age of 55 who were being visited by their husbands and who were well enough to take part were asked to complete a self administered questionnaire giving their husbands lifetime occupational history. Simultaneously, one of us interviewed the husband and requested the same information. To ensure that the histories from husbands and wives were independent, the interviews and questionnaires were completed in separate rooms as

Analysis of trends in cancer mortality in England and Wales during 1951-80 separating changes associated with period of birth and period of death.

Cancer mortality rates in England and Wales were analysed so to describe simultaneously changes affecting successive generations--that is, associated with period of birth--as well as changes associated with the period of which the deaths took place. When mortality from all cancers was considered the analysis implied that, contrary to a widely held view, the rate of death from cancer had been declining in each sex in successive generations. For men the decline had occurred in generations born since 1900, whereas for women the peak came in the 1925 birth group. On the other hand, there had been little decline in the rates associated with period of death. Five examples of cancers of specific organs for which the trends contrasted are shown.

A survey of cancer and occupation in young and middle aged men. II. Non-respiratory cancers.

In a search for clues to previously unrecognised industrial carcinogens the occupational and smoking histories of young and middle aged men with different types of cancer have been compared. The study population comprised men aged 18-54 and resident in the counties of Cleveland, Humberside, and Cheshire (including the Wirral). Within this population 2942 patients in whom cancers were first diagnosed during the period 1975-80 were identified retrospectively from hospital and cancer registration records. Lifetime occupational and smoking histories were then sought from these subjects (or if they had died by proxy from their next of kin), using a postal questionnaire. The overall response rate was 52.1%. Analysis of limited occupational data obtained from the hospital notes of 89% of the patients suggests that no serious bias arose from the incomplete response to the questionnaire. The present paper describes the findings for non-respiratory cancers. Some tumours did not occur with sufficient frequency to warrant formal statistical analysis. Nevertheless, examination of the histories of patients with these cancers showed several interesting occupational clusters. In particular, five out of 29 patients with acute myeloid leukaemia had worked in electrical trades. The more common cancers were studied by statistical techniques. A large number of possible occupational associations were examined, and some will probably have achieved conventional levels of statistical significance by chance. The results should therefore be interpreted with caution, taking into account evidence from other studies and the biological plausibility of suggested hazards. Among the more interesting findings were an excess of bladder cancer in lorry drivers (RR=1.6, CI 1.0-2.4) and in men employed in the manufacture of vegetable and animal oils and fats (RR = 4.8, CI 1.8-12.9).

Mortality of tanners.

The mortality of 833 male tannery workers known to have been employed in the industry in 1939 and who were followed up to the end of 1982 was studied. A total of 573 men had been employed in making leather tanned by vegetable extracts for soles and heels, and 260 men had used chrome tanning to make leather for the upper parts of shoes. No significant excesses of deaths were found for any of the common sites of cancer in either group of workers. One death from nasal cancer (0.21 expected) was reported among the men who worked with sole and heel leather.

MESOTHELIOMA IN A FACTORY USING AMOSITE AND CHRYSOTILE ASBESTOS

Abstract 5 deaths have been certified as due to mesothelioma (4 pleural and 1 peritoneal) in men who worked at a London factory where insulation board has been manufactured since 1946 from a mixture of amosite and chrysotile asbestos. It seems reasonable to relate 4 of these cases to work at the factory. Amosite has been the fibre predominantly in use and seems likely to be the cause of the tumours.

Variations in cancer mortality among local authority areas in England and Wales: relations with environmental factors and search for causes.

Geographical variations in specific causes of mortality among the 1366 local authority areas of England and Wales as defined at 1971 were studied by examining extracts from death certificates held on computer tape. Five items of information on each death--year of death, age at death, sex, local authority area of residence, and the underlying cause of death, during the 11 years 1968-78--permitted a more detailed investigation than had been possible before. Analysis of some early results of the study--including maps of mortality for pleural mesothelioma, nasal cancer and bladder cancer--suggested that, despite the known limitations of death certification, systematic study of the mortality of small areas may give clues to aetiological factors in the environment. Analyses relating mortality to the distribution of environmental factors and examining disease profiles of each area may also provide clues. These will be followed up by other methods of study, such as case-control techniques.