March 3 (UPI) -- Researchers at the Centers for Disease Control and Prevention report in a new study that cases of malignant mesothelioma are on the rise, and they don't understand why.
Malignant mesothelioma is caused by exposure to asbestos, a substance comprised of six naturally occurring minerals, that was commonly used before the 1980s in manufacturing, home insulation, cigarette filters, vehicle brakes and other commercial products.
Asbestos is now considered a dangerous chemical because when the substance is handled or damaged, airborne fibers can get into the lungs causing lung disease, respiratory problems and a rare form of cancer in the lungs, chest, abdomen and heart known as mesothelioma.
The Environmental Protection Agency banned the use of most asbestos-related products in the United States beginning in the 1970s due to the health risks associated with it.
The new report from the CDC found cases of malignant mesothelioma have increased from 2,479 in 1999 to 2,597 in 2015. Overall, between 1999 and 2015, there were 16,914 deaths from mesothelioma in people between age 75 and 84, as well as 682 deaths in people between age 25 and 44.
Scientists are baffled at why people born after asbestos was banned in manufacturing -- there has been a series of bans enacted since 1973 -- are still getting asbestos-related mesothelioma.
"Although deaths among persons aged less than 35 years are of concern, we do not have information to understand potential causes," Dr. Jacek Mazurek, lead author of the CDC study, told CNN.
Researchers believe the asbestos exposure in younger people may be a result of existing asbestos in older buildings and products made before the ban, but further studies will need to be conducted to determine if that is true.