The U.S. banned asbestos, but its health impact will still be felt for decades

A new rule announced by the Environmental Protection Agency this week puts an end to the use of asbestos, a known carcinogen, in the United States. But researchers caution that we’ll likely still be dealing with the mineral’s public health harms for decades.

The recently announced ban covers all forms of asbestos, including chrysotile asbestos, the only form still in use in the U.S., where it can be found in brake linings and is used to manufacture caustic soda (drain pipe cleaner) and chlorine bleach. The use of asbestos has continued for decades despite evidence that the mineral can cause several types of cancers, including mesothelioma, leading to thousands of deaths in the U.S. each year. Its use had already been banned in 55 countries, including all European Union member states. But a 1989 asbestos ban in the U.S. was all but reversed in 1991 by a court ruling, leaving in place regulations that varied by state.

The comprehensive EPA ban “is a very important and welcome step. I think it’s going to have a bigger impact on human health in the future,” said Ian Blair, a professor of pharmacology at the University of Pennsylvania who researches biomarkers of asbestos exposure.

Still, it will likely take decades to see the effects of the ban. That’s in large part due to the long latency period of mesothelioma; people exposed to asbestos today may not develop disease until up to 40 years later.

Researchers don’t completely understand how asbestos causes cancer. The most common theory is that asbestos fibers accumulate in the lungs, causing constant irritation and oxidative stress that eventually lead to mesothelioma or other types of cancer.“You’re exposed, and then many, many years later you get mesothelioma, and the problem is that it is very difficult to recapitulate that in a laboratory setting,” said Blair.

Quantifying deaths and illness directly linked to asbestos exposure isn’t easy, though an EPA press release announcing the ban stated that the mineral is linked to 40,000 deaths a year. “There are many estimates of deaths from asbestos exposure, from an alarming number to not very many. But I suspect that there’s a very large number of people who suffer from lung disease because of exposure to asbestos,” said Blair.

Since it is the fibers that pose danger, some uses of asbestos are more hazardous than others. Brake linings, for instance, a common application of asbestos because of its fireproof qualities, could be especially dangerous because the continuous friction is likely to release stray fibers.

“I think it’s a good start, but to see the effects of this [ban] will take a very, very long time,” said Emanuela Taioli, director of the Institute for Translational Epidemiology at Icahn School of Medicine at Mount Sinai, who was an external reviewer of 2020 EPA documents that informed the recent rule.

Asbestos was so ubiquitous in the past that exposure remains possible in many everyday situations. It was a staple of construction in the 1970s, and fires, accidents, and uncontrolled demolitions of older buildings could release asbestos fibers. The mineral was also used to line air conditioner filters on 1990s airplanes that are still in use today.

The ban doesn’t guarantee an end to imports of products containing asbestos. “Even in Europe, there are still ways to bring in asbestos without breaking the laws… because of the way things are transported and produced,” Taioli said. Products can be made in China, for instance, where asbestos is legal, and then imported via a country where it’s not, thereby bypassing import regulations.

She adds that patients who have or will develop mesothelioma due to asbestos exposure still don’t have great treatment options. “In treatment, [there’s been] absolutely no improvement,” said Taioli. “Immunotherapy isn’t working.”

Mesothelioma has a five-year survival rate of 12%, in part because it is typically diagnosed at a late stage, and most patients’ life expectancy is between four and 18 months post-diagnosis. About 3,000 new cases are diagnosed every year in the U.S.

There are some glimmers of hope, however, such as the discovery of blood-based biomarkers and genetic variants linked to increased susceptibility to mesothelioma, tools that could lead to early detection, and, potentially, a better prognosis.

Taioli is hopeful the EPA’s announcement won’t be its last on this issue. She points out that there needs to be more research into other elongated fibers with potentially harmful health effects, as well as studies of naturally occurring asbestos, which is found in certain rocks. “The wheels started moving,” she said of the ban, “and they will roll over the years.”