Even though 40 years have passed since their exposure to asbestos, workers’ risk of developing mesothelioma continues to rise, new research shows.
Individuals exposed to asbestos four decades ago are nearly three times more likely to develop the disease than those exposed five years ago, a risk that surpasses even that seen in patients exposed 30 years ago.
The study, “Mesothelioma continues to increase even 40 years after exposure – Evidence from long-term epidemiological observation,” was published in the journal Lung Cancer.
Asbestos is the primary cause of pleural mesothelioma, and due to a long latency period it tends to develop decades after exposure. Despite a ban on all forms of asbestos in the European Union, asbestos-induced diseases have not decreased in prevalence in most European countries.
Researchers at the Nofer Institute of Occupational Medicine in Poland conducted a study to analyze the relationship between the time since last exposure and the subsequent risk of developing mesothelioma in a population of workers who had been exposed to asbestos at some point in time.
To conduct this study, researchers used data gathered from 2000 to 2014 of 131 patients with pleural mesothelioma and 655 people matched by gender and age (the control group) who were enrolled in the Amiantus Programme, which conducted examinations for employees who had been exposed to asbestos in Polish asbestos processing plants.
Analyses conducted in the study showed that the risk of developing pleural mesothelioma continues to increase even if workers’ last exposure to asbestos was 40 years ago. In fact, researchers discovered that when compared to workers who had been exposed to asbestos five years ago, patients exposed 40 years ago had a 2.68-fold higher risk of developing mesothelioma.
Additionally, researchers also looked at determining the type of asbestos which caused the highest risk of developing mesothelioma. They showed that exposure to crocidolite — often referred to as blue asbestos — was highly associated with a significantly higher mesothelioma risk.
In fact, the risk was five times greater when workers were exposed to crocidolite along with other types of asbestos compared to those who were exposed to chrysotile — also called white asbestos, the most common form of asbestos — alone, with no other types of asbestos.
The researchers noted that like the results seen in other studies, they found that the risk of mesothelioma is related to the amount of exposure. Therefore, the greater the amount of exposure, the higher the risk of developing the cancer. In fact, individuals with the greatest amount of exposure were at a 50 percent increased risk of developing mesothelioma compared to unexposed patients.
This was also true for the duration of exposure. Patients exposed for 40 years to asbestos were 2.79 times more likely to develop mesothelioma than those exposed for only one year, even after adjusting for birth year, gender, time since the last exposure, and amount of exposure.
The authors conclude by noting that even after 40 years since their exposure to asbestos ended, workers’ risk of developing mesothelioma continues to increase. Therefore, it is important to follow up with workers who have been exposed to asbestos even though decades have passed since they worked around the carcinogen.