13:30 - 15:30, No.2 Conference Room
Workshop E
Epidemiology and Public Health
Chairs: Gunnar Hillerdal and Kohki Inai
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Hitoshi Kubota1, SJian Sun2, Naomi Hisanaga1, Ippei Mori1 and Eiji Shibata3
1National Institute of Industrial Health, Japan
2Institute for Health Economics, Canada
3Aichi Medical University
ABSTRACT
We have been engaged in a cohort study on the mortality of members of a construction workers' health insurance society to evaluate the influence of exposure to hazardous factors such as asbestos on the health status of construction workers.In the study, we observed significantly elevated standardized mortality ratio of cancers of trachea, bronchus and lung among ironworkers (2.88, 95%CI: 1.44-5.15) compared with Japanese male population. In addition, according to the chest X-ray investigation in the society, the prevalence of pleural thickening among ironworkers (9.3%) was higher than the whole workers (2.1%).
In order to elucidate the background of the above-mentioned findings, we carried out a questionnaire survey by mailing. The subjects of the survey were ironworkers and two relevant jobs, welders and reinforcing-bar placers. The questionnaire consisted of questions on previous experiences in 18 types of jobs with possible exposure to hazardous substances such as asbestos, subjective respiratory symptoms, and smoking history.
Of a total of 1,021 workers, 452 (44.3%) responded, and complete answers were obtained from 398 comprised of 202 ironworkers, 142 welders and 54 reinforcing-bar placers. Some of the ironworkers had welding jobs as well as iron work. Among 202 ironworkers, rates of experience in asbestos-related jobs such as building demolition, handling asbestos-slate board, installation/removal of heat-insulation materials, working in asbestos-sprayed buildings and handling calcium silicate board in the past were significantly higher than other groups. The combined percentages of current smokers and ex-smokers in three jobs ranged from 70 to 87%.
Taking into account of the high frequency of asbestos exposure and welding job in ironworkers shown in the present questionnaire survey, and no significantly excess death by cancers of trachea, bronchus and lung in welders demonstrated in our cohort study, we suspect that elevated mortality caused by lung cancer in ironworkers has association with their asbestos-related jobs.