A descriptive epidemiological study on pleural plaque cases identified from the worker's periodical health examinations in Kitakyushu, Japan.

Thirty-six pleural plaque (PP) cases, were identified from the worker's periodical health examination and were described in terms of its association with occupational exposure to asbestos and radiographic findings. Based on thorough interviews about job histories, 23 (64%) of the cases were classified to have had "definite" and an additional 5 (14%) with "possible" asbestos-exposed job histories. Asbestos-exposed job histories were represented mostly by plumbing and pipe fitting, insulating, and boiler and pipe insulating. The latency period between initial age of asbestos exposure and age at time of initial plaque detection was 31.1 +/- 10.3 yr. Calcified plaques were most prevalent in the diaphragm and the most frequent combination of multi-site PPs was found in the diaphragm and lung fields. All cases were either current or ex-smokers. The findings suggest that subjects with a history of asbestos exposure can be identified through the detection of PPs in chest X-ray films obtained in the worker's periodical health examinations.