Deaths related to malignant mesothelioma are at a record high, according to a new report from the Centers for Disease Control and Prevention (CDC).
Mesothelioma was the underlying or contributing cause of death on more than 45,200 U.S. death certificates between 1999 and 2015, the most recent years for which complete data is available.
Annual deaths increased by 5 percent — from 2,479 to 2,597 — in that span.
The findings puzzled CDC researchers, who projected mesothelioma deaths to decline after 2005. Researchers now struggle to understand why mesothelioma continues to impact younger generations despite a significant decrease in the use of asbestos, the overwhelming cause of the cancer.
“The continuing occurrence of malignant mesothelioma deaths underscores the need for maintaining measures to prevent exposure to asbestos fibers and other causative [elongate mineral particles] and for ongoing surveillance to monitor temporal trends,” lead researcher Jacek Mazurek wrote in the report.
The most significant increase in mesothelioma deaths occurred in people 85 and older, while deaths decreased among other age groups.
People in the 75-84 age range still represent the majority of mesothelioma deaths (37.4 percent), despite a slight decline compared to the 1999 to 2005 numbers.
Age-adjusted death rates — calculated by applying age-specific death rates to the 2000 U.S. Census standard population age distribution — decreased 21.7 percent from 1999 to 2015.
The age-adjusted death rate decreased significantly among people 45-74.
Construction remains one of the riskiest industries for asbestos exposure. While asbestos is highly regulated in manufacturing today, the carcinogenic mineral is still prevalent in older infrastructure.
“Current occupational exposure occurs predominantly during maintenance and remediation of asbestos-containing buildings,” Mazurek wrote.
Buildings constructed before 1980 likely contain asbestos products, including insulation, roofing, tile flooring and drywall. Disturbing these materials during home repairs and renovations causes toxic asbestos fibers to become airborne, where they can remain for hours.
Inhaling or swallowing these fibers can lead to serious health conditions such as mesothelioma and lung cancer. Mesothelioma and other asbestos-related diseases typically carry a long latency period, meaning it can take decades after initial exposure for the diseases to develop.
“Continuing occurrence of malignant mesothelioma deaths in persons aged [less than] 55 years suggests ongoing inhalation exposure to asbestos fibers and possibly other causative [elongate mineral particles],” Mazurek wrote.
According to the report, the construction and shipbuilding industries account for 96 percent of workplace asbestos exposures.
Individual occupations with a high rate of mesothelioma deaths include pipefitters, plumbers, pipelayers, steamfitters and electricians.
“The problem with asbestos exposure is, there are really so many places where one can be exposed,” Dr. Hedy Kindler, professor of medicine at the University of Chicago and director of its mesothelioma program, told CNN. “This disease remains relevant and it remains a killer of people who, of no fault of their own other than doing their job, were exposed to something that was preventable.”
Pleural mesothelioma, which develops on the lining of the lungs, is still the most common type of asbestos-related cancer, accounting for nearly 64 percent of all mesothelioma deaths.
But deaths related to peritoneal mesothelioma — which forms on the protective tissue surrounding the abdomen — increased significantly in recent years. Peritoneal now accounts for roughly 35 percent of mesothelioma deaths, while pericardium (lining of the heart) makes up less than 1 percent.
Other notable findings from the report:
In the report, CDC researchers stressed the importance of following effective asbestos exposure prevention strategies for employers, noting guidelines from the Occupational Safety & Health Administration and CDC’s National Institute for Occupational Safety and Health are available to the public.
“Despite regulatory actions and decline in asbestos use, the annual number of malignant mesothelioma deaths remains substantial,” Mazurek wrote.