The threat from asbestos exposure in the ship recycling industry goes far beyond the realm of mesothelioma, raising the incidence rates for a wide variety of cancers, according to a recent study examining the health history of workers in Taiwan.
Although the relationship to mesothelioma is well documented, the latest study also found an alarming rise in the incidence of esophageal, liver, tracheal, bile duct and lung cancers for those exposed to asbestos on scrapped ships.
Shipyards are dangerous places, and the shipbuilding industry is known as a high-risk occupation because of the heavy reliance on asbestos products in the past.
And while the use of asbestos in newer ships is significantly lower, because less toxic materials replaced it, working with older ships remains particularly dangerous if precautions are not taken consistently.
This study was one of the few that involved only “shipbreaking,” which is the dismantling of old ships for salvage or scrap. It also examined cancers beyond mesothelioma, a cancer caused almost exclusively by inhalation or ingestion of asbestos.
The study, published in the on-line medical journal PLOS One, was linked to the Taiwan Cancer Registry and involved 4,227 workers from the 1985 Kaohsiung Shipbreaking Workers Union who belonged to the Labor Insurance Program.
They were followed until 2008. There were 940 deaths and 436 cancer cases reported. Their numbers were compared to a control group of 22,135 who worked elsewhere.
Researchers from the National Health Research Institute and three universities in Taiwan participated in the study.
Asbestos Leads to Many Cancers
“Shipbreaking workers had a significant percentage difference of cancer in comparison with matched-cohort,” the authors concluded. “Overall, cancer also was seen in a dose-dependent relationship with asbestos exposure.”
The study revealed that shipbreakers had a 9.9 percent chance of a cancer diagnosis, compared to 6.7 percent for those in the control group. They also were diagnosed at a younger age, 54.5 years old, compared with 57 years for the control group.
The high rates of cancer incidence beyond mesothelioma were startling. Shipbreakers were 2.31 times more likely to be diagnosed with esophageal cancer, 1.6 times more likely with liver and bile duct cancer and 3.08 times more likely to get cancer of the lung, trachea or bronchus.
Previous studies from Finland and Norway included a 26 percent higher risk of lung cancer for shipyard workers.
Taiwan Is Home to the Shipbreaking Industry
Taiwan played a particularly relevant role in the study because the small Pacific island is home to the largest shipbreaking operation in the world.
The authors estimated that 65 percent of all ships worldwide are crushed and recycled in Taiwan. It accounted for 67 million tons of recycled ship scrap during one 10-year period.
Older ships often included asbestos materials from bow to stern.
As many as 300 different parts containing asbestos were commonly used on Navy ships built in the 20th century. Asbestos was used to insulate boilers and pipes and virtually everything on a military ship. It would resist heat, fire and corrosion.
The authors of the study called for “persistent monitoring,” of those in the shipbreaking industry, hoping it will detect any cancers in the earliest stages when they can be treated more effectively.