13:30 - 15:30, No.2 Conference Room
Workshop E
Epidemiology and Public Health
Chairs: Gunnar Hillerdal and Kohki Inai
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Hiroshi Udo
Department of Human Science, Hiroshima Bunkyo Women's University, Japan
ABSTRACT
Labor in the iron industry often involves high-heat processing using hot metals and molten steels, as well as the frequent use of asbestos as a heat resistant or insulation material. Given that no studies have ever been performed on asbestos problems in iron foundries, I present a case study on an iron foundry company that started tackling with asbestos at an early stage.
At an iron foundry, use of asbestos is found in the following:
(i) Blast furnaces/ steel converters/ rolling
(ii) Hot blast stoves
(iii) Molding boards for steel making/ casting
(iv) Boilers at power plants
(v) Brake lining for cranes
The iron foundry company cited here started to tackle with asbestos when dust emission caused by the high-pressure air cleaning of asbestos for steel making/casting molding boards emerged as a problem, and use of rock wool as an alternative material started in 1977. In the 1978 revision of the company-wide work environment control manual, the company set forth stricter environmental control criteria for asbestos, setting the asbestos concentration limit at 0.2 fibers/cm3.
Yokosuka Kyosai Hospital's 1982 report on asbestos lung cancer among shipbuilding workers gave rise to even stricter asbestos controls. In 1983, the company compiled an asbestos handling manual, which prohibited use of asbestos for new facilities. In the same year, the company replaced asbestos with glass fiber in drop curtains of blast furnaces for duct collection. In 1988, the company conduced internal fact-finding surveys and started sampling research. In 1990, it was found in the analytical results that 161 (85.2%) out of 189 samples had been asbestos. In the same year, the company started to use non-asbestos alternatives for crane brake linings (an asbestos content of 40% to 50%). Also in the same year, the old naval shipyard reported malignant mesothelioma among workers of private shipbuilding companies. The company requested its relevant departments to remove all asbestos from existing facilities by May 1992. In the same year, all employees were examined for pleural thickening using chest XP. Of 2,689 employees, 16, 11 and 21 were diagnosed as IIIa, IIIb and IV, respectively (48 in total: 1.79%) . Follow-up surveys are currently underway.
To date, none of those employees have been found to develop asbestos tumor. Removal of asbestos is nearly complete, although it is still found in some existing facilities or part of brake linings for which no alternative materials are available. The company is now making efforts to remove all asbestos. Today, industry-wide efforts are needed to tackle with asbestos to prevent asbestos related health problems in the iron industry.