Asbestos cement pipes (ACPs) containing 15 to 20% chrysotile or crocidolite have been used for underground conduits. Even today 16.2% of all conduits in Japan are ACPs, though the production of ACPs was suspended in 1985. When such a conduit is accidentally damaged the workers belonging to the Waterworks Bureau of a local government cut off the damaged conduit using a high-speed disk cutter and replace it with a new conduit. This operation develops a cloud of dust and the workers involved run the risk of asbestos exposure. It was the aim of the present study to estimate asbestos exposure levels among these workers. First, in the experiment, we established the typical working conditions and requested an experienced worker to cut an ACP using a highspeed disc cutter in a hole dug in the ground as he routinely does. The experiment was repeated three times. During a bout of each experiment, dust was sampled at several points both inside and outside the hole. Second, a self-administered questionnaire survey was conducted to obtain information from the workers regarding their working conditions in cutting ACPs. The subjects of the survey were 1, 048 men belonging to conduit repair sections of the Waterworks Bureau of 119 local governments. The results obtained can be summarized as follows.
1) Each bout of cutting ACPs requnired about five minutes. The concentration of asbestos fibers longer than 5 μm with 3:1 aspect ratio ranged from 48 to 170 fibers/ml (92 fibers/ml on an average) inside and 1.7 to 15 fibers/ml outside the hole. The concentration inside the hole exceeded the ceiling limit (10 fibers/ml) recommended for asbestos by the Japanese Association of Industrial Health. A concentration of 92 fibers/ml is equivalent to 0.96 fibers/ml as 8-h time-weighted average.
2) The number of subjects with experience of cutting ACPs was 849 (81.0%). The average length of service in conduit repair section was 14.2 yr. Based on the information obtained from each subject regarding the average working days per yr for each decade from 1946, the cumulative days to date expended in cutting ACPs was estimated to average 235 d, that is, 17 d per yr. Only 18.1% of the subjects used a protective respiratory device.
3) On the assumption that these workers worked 17 d per yr in cutting ACPs for 14 yr and were exposed to 1 fiber/ml of asbestos per d, the life-time excess mortality rate of lung cancer would be 30 per 100, 000 and that of mesothelioma 30 per 100, 000 by OSHA's model, and that of lung cancer would be 15 and that of mesothelioma 28 by Hughes' model.
These results suggested that workers belonging to the Waterworks Bureau have a possibility of being exposed to relatively high levels of asbestos when cutting ACPs and have a risk of developing asbestos-related diseases.

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In order to examine the differences in which blue- and white-collar workers perceive their own health status, a survey using self-administered questionnaire was conducted. The subjects were 1, 428 male workers in a tire manufacturing factory, consisting of 1, 185 blue-collar workers and 243 white-collar workers. Most of the blue-collar workers were engaged in shift work consisting of three shifts/d. The questionnaire included 32 items concerning health habits, life and job satisfaction, mental stress, and type A behavior. The following findings were obtained. Good daily health habits were related to age. Older workers had better health habits than the younger ones both in white- and blue-collar workers. The white-collar workers were more satisfied with their life and jobs, and also showed type A behaviors at a higher rate. As for fatigue and dissatisfaction associated with shift work, the workers' complaints increased in the order of day shift, evening shift and midnight shift. The older workers had fewer complaints than the younger ones. These results suggested that health management and education will be more effective if the working conditions and the background of each worker are taken into consideration.

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