William J. Threlfall

Identification of occupational cancer risks in British Columbia. Part I: Methodology, descriptive results, and analysis of cancer risks, by cigarette smoking categories of 15,463 incident cancer cases.

To identify occupational cancer risk factors, lifetime occupational, smoking, and alcohol-consumption histories were collected by means of a self-administered questionnaire from 15,463 male cancer patients aged 20 years and over as ascertained from the British Columbia population-based cancer registry; all cases were histologically confirmed. The study methodology, descriptive results, and cancer risks from cigarette smoking are reported. Assessment of questionnaire validation and reliability showed very high correlations between all variables analysed. Non-response bias, assessed among 221 non-responders and 432 matched controls, revealed no statistically significant differences for smoking status, education, or for 11 usual (longest-held job) occupational groups, except for managerial occupations and for four pooled groups that represented 6.7% of all occupations. Except for pancreatic cancer, a significant relationship was found for all cancer sites known to be strongly associated with cigarette smoking.

Occupational mortality patterns among British Columbia farm workers.

To examine mortality risks for farm laborers proportional mortality ratios (PMRs) were calculated for 2,328 British Columbia farm workers who died at age 20 years or over during the period 1950 through 1978. Significantly fewer deaths than expected from degenerative heart disease (PMR = 91, p less than .01) and from all cancers combined (PMR = 78, p less than .001) were observed. Deaths from bronchitis and emphysema (PMR = 70, p less than .05) were also fewer than anticipated. Elevated risks of death were found for accidents (PMR = 129, p less than .001), for homicide (PMR = 242, p less than .01), and for pneumonia (PMR = 146, p less than .001).

Identification of occupational cancer risks in British Columbia. Part II: A population-based case-control study of 1516 Prostatic cancer cases.

We have, as part of a program aimed at detecting occupational risk factors in British Columbia, collected lifetime occupational histories from 15,643 incident cancer cases, of whom 1519 had a diagnosis of prostate cancer. Occupational risks for this cancer site are examined using this large data set, and the results are presented in this report.