The 28 represent more than half the 48 people recognised with asbestos injuries in the entire prefecture. It is feared that there could be more asbestos victims among those who worked at the bases. A former worker said Japanese workers were not provided adequate protective gear or informed of the dangers of asbestos.
Of the 28 workers, 19 were officially recognised in the period through fiscal 2012 as having suffered work-related asbestos hazards. Fourteen suffered lung cancer, with nine of them already dead, two suffered mesothelioma, and three suffered asbestosis, with all of the three already dead.
There were nine other people certified as asbestos victims in accordance with a relief act for people ineligible for workers' compensation because of the statute of limitation. In some cases, asbestos-related diseases do not surface until after several decades. Eight suffered lung cancer and one suffered asbestosis, and all of them are already dead, according to the data.
Workers' compensation certification standards for asbestos were established in 1978 and the relief act came into force in 2006.
Those who were officially recognized as asbestos victims were involved in works such as demolition of buildings containing asbestos, spraying of asbestos, waste disposal and collection, and repair and manufacturing of machines.
Asbestos is easily dispersed and those who have inhaled the material can develop diseases such as lung cancer, mesothelioma, and asbestosis, a type of lung disease.
Apparent lax handling of asbestos has drawn attention in Okinawa. Asbestos was found in former US military sites returned to Japan, and Japanese workers renovated military bases without being notified of the existence of asbestos.
Eizo Yonaha, a former worker who represents the Okinawa chapter of the All Japan Garrison Forces Labour Union, said Japanese workers were forced to work with asbestos with almost no protective equipment such as masks until the early 1990s.
"There was also a time when supervising U.S. military personnel never tried to enter the worksite. I believe they knew about the danger. The recognised cases are probably the tip of the iceberg. The central and prefectural governments need to step up efforts to identify more victims," Mr Yonaha said.