Workers who are exposed to asbestos early in their career are at higher risk of developing pleural mesothelioma (PM) than those who were exposed later in their career, or at a constant level over their entire working life, according to results of a new study.
These findings may be used to help plan PM surveillance programs for workers who are exposed to asbestos.
The study, “Dose-time-response association between occupational asbestos exposure and pleural mesothelioma,” was published in the journal BMJ Occupational & Environmental Medicine.
MPM is one of the rarer forms of cancer, but patients are sometimes resistant to treatment. Consequently, prognosis can be very poor. Previous studies have shown that early exposure to asbestos in certain work activities increases the risk of PM, suggesting that the timing of exposure may play a role in disease onset.
However, no studies have compared the work history of PM patients and their exposure to asbestos during work. The aim of this study was to compare the risk of MPM associated with different profiles of asbestos exposure during work activities.
To do so, researchers analyzed the medical record data of 1,196 male patients from 1987 to 2006, and 2,369 age-matched control individuals.
“We found that an increase [in asbestos exposure] occurring more than 40 years before diagnosis, or at 15–20 years old, had the strongest impact on the risk of PM,” the researchers wrote. “As a result, subjects who accumulated asbestos fibres in early career were at higher risk than those who accumulated them at the end of their career or at a constant level over the entire career.”
Researchers also found that the doses of asbestos exposure within the 10 years preceding diagnosis likely do not contribute to cancer onset, but they may play a role in later stages of disease development.
“Our study should encourage epidemiologists to consider such modelling of asbestos exposure in studies on PM, as well in other contexts,” they wrote. “Our results may also help deciders in planning epidemiological surveillance programs of workers occupationally exposed to asbestos.”
Asbestos fibers can be inhaled or swollen and no level of exposure to asbestos is considered safe. Because the body is unable to properly expel the fibers, they accumulate in the lungs or other organs, causing scarring and inflammation. Workers from almost every trade can be exposed to asbestos, including drywall tapers, electricians, firefighters, auto mechanics, shipyards, power plants, metal works, schools, chemical plants, oil refineries, and many others.