A new study finds that low-dose occupational radiation exposure is unlikely to cause mesothelioma by itself. Instead, the study confirms what scientists have suspected for at least 60 years: The primary cause of mesothelioma is almost always asbestos.
The goal of the study was to see if radiation exposure by itself raises the risk for mesothelioma. Researchers analyzed three groups of people exposed to radiation on the job.
After reviewing more than 50 years worth of records, the team found that some workers were more likely than others to get malignant mesothelioma. But these were not the workers with the most radiation exposure.
Radiation, Asbestos, and Mesothelioma
A team of epidemiologists, cancer specialists, and radiation experts ran the new study. It included more than 250,000 workers routinely monitored for radiation exposure at work.
One group of workers were industrial radiographers who worked at shipyards. The second group was made up of nuclear power plant workers.
The third group included industrial radiographers who had never worked at a shipyard or a nuclear power plant. This is an important distinction because asbestos is common in shipyards and nuclear power plants.
Researchers analyzed the rate of worker deaths from mesothelioma or asbestosis between 1969 and 2011. They compared the rates to the general population and to workers’ radiation exposure levels. The average length of follow-up for an individual was 25 years.
Radiation Exposure Does Not Raise Risk
It turns out that radiation exposure level does not impact mesothelioma risk nearly as much as where the exposure happened.
The mean cumulative radiation dose among the workers was 28.6 mGy. Almost 20 percent of workers had died by 2011. More than 400 of those deaths were from malignant mesothelioma. Most of the mesothelioma deaths occurred after 1999.
Even though all of the workers had higher-than-normal radiation exposure, the shipyard and power plant workers had the highest mesothelioma rates.
“Likewise, deaths from asbestosis were also increased for shipyard and NPP workers, but not among workers who never worked at a shipyard or NPP,” states the report.
The researchers conclude that radiation exposure was “not associated with a statistically meaningful dose-response trend for mesothelioma”.
The radiation-exposed workers who died of mesothelioma or asbestosis likely got it because of asbestos in the shipyard or power plant and not from the radiation.
More than 2,500 people still died of mesothelioma each year in the US. Nearly all of those deaths can be traced to asbestos exposure. Although asbestos is heavily regulated, it is not banned in the US.
Mumma, MT, “Mesothelioma Mortality Within Two Radiation Monitored Occupational Cohorts”, July 10, 2019, International Journal of Radiation Biology, Epub ahead of print, https://www.tandfonline.com/doi/abs/10.1080/09553002.2019.1642540?journalCode=irab20