The dangers of asbestos: What the public should know

Marilyn Howarth and Ian Blair of the Perelman School of Medicine discuss the hazards of asbestos, how it harms the body, the crisis in the school district, and why there is no safe level of asbestos.

Workers wear protective masks, goggles, gloves, and clothing with removing asbestos.
Workers wear protective masks, goggles, gloves, and clothing while removing asbestos from a structure.

The School District of Philadelphia has an ongoing asbestos crisis that, as of Feb. 12, has closed seven schools this academic year for varying intervals of time. Hundreds of reports of damaged asbestos in city schools have been filed in the district’s system, which the administration has yet to resolve.

Asbestos, a material mined in the ground, is one of six fibrous silicate metals. Useful because it is chemically non-corrodible and fire- and heat-resistant, it has been used in roof shingles, ceiling and floor tiles, brake linings and pads, and as insulation on pipes. Although no longer excavated in the United States, it can be imported and is still utilized in the manufacture of brake pads.  

Ambler, Pennsylvania, about 14 miles outside of Philadelphia, was formerly home to the biggest asbestos manufacturing facility in the world. Giant piles of asbestos were stationed all around the city, the so-called “white mountains of Ambler.” The Environmental Protection Agency (EPA) has remediated these sites by covering them with clean soil and plants designed to keep people from coming in contact with the asbestos and prevent the asbestos from contaminating the air.

Aerial view from the 1930s of the former Keasbey and Mattison manufacturing facilities and waste disposal areas. Keasbey and Mattison was a large producer of asbestos. (Image: Environmental Protection Agency)

As asbestos deteriorates, it can release hazardous small fibers into the air. When inhaled, these fibers can cause lung cancer, asbestosis, or scarring of the lung tissue, mesothelioma, a deadly cancer of the lining of the lungs, and other asbestos-related diseases, which can take decades to manifest. 

Homes, schools, and buildings built before 1980—the majority of structures in Philadelphia—have a higher risk of containing asbestos, usually covering pipes or in roofing tiles. 

Each year, approximately 50,000 people in the United States die from asbestos-related diseases, and more than 100,000 people perish worldwide.

Penn Today spoke with Ian A. Blair, a scientist at the Perelman School of Medicine who has worked on community-based concerns about hazardous asbestos waste in Ambler, and Marilyn Howarth, an occupational and environmental medicine physician at Penn Medicine and a technical adviser on the Philadelphia Healthy Schools Initiative, about the dangers of asbestos, how it harms the body, the crisis in the school district, and why there is no safe level of asbestos. 

What is it about asbestos that makes it so dangerous?

Howarth: When asbestos fibers are released into the air, we can easily inhale them, and our bodies, unfortunately, are unable to degrade them. Just like chemicals don’t degrade asbestos when it’s in use for oven mitts or car brakes, the chemical defenses of our immune system can’t degrade them either. 

Blair: Most of the asbestos from Ambler is called chrysotile. It’s been used more than any other type of asbestos. Because of the asbestos products manufactured in Ambler, it’s what’s found in most U.S. buildings. According to some people, chrysotile is less dangerous than the other forms of asbestos, but if you actually really look at the data, it seems just as dangerous to me. I think they’re all really dangerous. Crocidolite is thought to be the most dangerous.

An aerial view of the former asbestos manufacturing site in Ambler, Pennsylvania.
An aerial view from the 1930s of the former Keasbey and Mattison manufacturing facilities and waste disposal areas in Ambler, Pennsylvania. The company made a large number of asbestos products. (Image: Environmental Protection Agency)

When you say ‘degrade,’ do you mean our immune system trying to remove the asbestos fibers from our body?

Howarth: Yes, the immune system tries to break them up. Our immune system recognizes that the asbestos fibers are foreign, that they don’t belong there, so they attack. An immune cell will engulf fibers and use enzymes to try to break them down, only it doesn’t work, so it just keeps trying, and trying, and trying. Then ultimately that cell dies and those enzymes spill out, and they injure the cells around them. The enzymes are useful inside cells but harmful outside cells in contact with other cells. This process causes inflammation. When it happens over, and over, and over again, that’s how conditions like asbestosis occur.

So, the asbestos fibers just remain in your body?

Howarth: Yes, they do. They don’t go anywhere. They remain there and continue to cause trouble.

How are people usually exposed to asbestos?

Blair: Apart from brake pads, there is very little manufacturing of asbestos in the United States. Most of the exposures now come from natural asbestos or potential exposures from sources such as the piles of asbestos material that was left in Ambler. There is environmental exposure that you’ve been hearing about in schools. Most of the Philadelphia schools have asbestos-insulated pipes. What happens is as the insulation ages, it becomes very friable and tends to break up, and you see deposits of asbestos fibers on floors and surfaces of rooms. I think some people’s attitude is, ‘Well, they’re not in the air, so you can’t breathe them in, so it’s not dangerous.’ But of course, who knows how much these fibers are disturbed when many children, teachers, and staff move through buildings all day. Its easy to imagine how a dust pile might be disturbed. 

Howarth: We all breathe in some asbestos most days. If you live in a city, there are asbestos fibers in the air that we breathe from brake pads and from the demolition of buildings that contain asbestos materials. Traditionally, the people who have been most heavily exposed to asbestos have been people who’ve worked in and around insulated pipes, so plumbers, for example, and people who worked on ships. There was a lot of asbestos used in our naval ships as a fire retardant. People who worked in maintenance or the engine room on ships were certainly at high risk. These days, car mechanics are still at risk. There can be significant exposure of people when asbestos is not removed properly. If someone has asbestos in their home—for example, in the basement covering pipes—and they aren’t aware that the material is asbestos, if it’s damaged and they decide to remove it, they themselves can get a large asbestos exposure, and that could put them at risk for mesothelioma in the future. In addition, if you have a contractor who doesn’t remove it safely, they too can contaminate your home with asbestos. If the dust in your home has been contaminated by someone not renovating properly, you can create for yourself an opportunity to be exposed each day for a long time.

A car mechanic works on a brake pad.
Asbestos is used in the manufacturing of brake pads.

Could a person look at something such as a dust pile and tell with the naked eye that it is asbestos? 

Blair: No. People would need to have an environmental company take a sample and send it to an accredited lab. At our center at Penn, we have very sophisticated ways of evaluating fibers, not only whether they are asbestos, but what kind they are. In fact, we have one of the most sophisticated atomic-resolution transmission electron microscopes for looking at the fibers. It’s a very high-end instrument that can tell you the composition of the fiber, as well as the size. That’s one thing about the schools, there hasn’t really been a rigorous, detailed, structural characterization of the asbestos that’s there.

So, someone would have to hire a professional in order to determine if there is asbestos in their home?

Howarth: Yes. Homes that were built before 1980 in general do have a higher risk of having asbestos. However, to actually be sure, you’d need to have a professional perform the evaluation. It’s not the sort of thing people should do on their own. And if they find that they do have asbestos, there are contractors who have asbestos certification. That list is available on the Pennsylvania Department of Labor & Industry website

Would wearing one of those white masks over the mouth and nose protect someone from asbestos?

Howarth: No. The casual paper dust masks keep out large molecules. Asbestos fibers are fairly small particles that can easily get through that type of mask or go in around the sides, so it really wouldn’t protect you.

Asbestos used to insulate a pipe. (Image: Maine Department of Environmental Protection)

How much asbestos does someone have to breathe in for it to become dangerous? What are the safe and dangerous levels?

Blair: There is no safe level of asbestos. Typically, the safe level is the lowest level that can be detected. There are standards that the EPA lays out, but the agencies who publish data on these things, such as the International Agency for Research on Cancer, have determined that there’s no safe level of asbestos in the air.

Howarth: We don’t know the exact number of asbestos fibers that can lead to cancer. We do know that you usually have to have an occupational-type exposure where you have higher concentrations over a longer period of time in order to develop asbestosis. Generally, just a couple of weeks of asbestos exposure wouldn’t cause asbestosis and the low-level exposure in schools would not cause asbestosis. But with mesothelioma, we have examples of people developing mesothelioma with having a summer job. Consider this example: You have a summer job for eight weeks in your teens in a place where there was a daily occupational exposure to asbestos in the air, and then for the rest of your career, you work in an office. Twenty-five to 30 years after that summer job, you may develop mesothelioma. Although we can’t predict who will get cancer, it seems that even brief exposure can cause cancer. So, we can’t say that there is any amount of asbestos exposure that is safe.

How many asbestos fibers does it take to cause mesothelioma? Could exposure to to two or three fibers cause cancer?

Howarth: We don’t know how many it would take, but there’s no reason to think that a small number of fibers couldn’t cause cancer. That is why the safest approach is to try to minimize exposure in all circumstances.

Blair: A lot of advocacy groups are trying to get asbestos banned, particularly those who have had loved ones who have died of asbestos-related diseases. It’s such a horrific disease, particularly mesothelioma. If you see pictures of people in disease, it’s just heartbreaking.

In these so-called white mountains of Ambler, people used to sled down them and treat them as if it was snow, and many of those people have developed mesothelioma in later life. 

Is it correct that asbestos is fine unless it is damaged?

Blair: That’s the current theory. The idea is that unless it’s in the air, it’s safe. Now whether that’s true or not, we don’t know. We currently believe that if it’s in the water supply, there’s really no concern. What we’re more worried about in Ambler is if it gets washed away into the streams, and then when the water evaporates, it’s left on the side on the streams and can end up in the atmosphere. It could actually move even though the sites have been remediated. That’s one of the major concerns of the community.

Howarth: We believe the danger from asbestos occurs only when the fibers are available to enter the lungs. That is why the hundreds of locations of damaged asbestos materials in schools are so troubling. Each area of damage releases fibers into the air. If not immediately breathed in by a passing student or teacher, they settle to the ground with the potential to be stirred up into the air repeatedly unless removed through cleaning.

Professionals in protective suits remove asbestos cement corrugated roofing.

If someone is exposed to asbestos, would he or she exhibit any symptoms?

Howarth: No. There’s no expectation that there would be any acute symptoms, especially in the low-level exposures in schools and homes. There’s only the potential for increased risk for cancer down the line. We should not take increased cancer rates lightly because Philadelphia has among the highest cancer rates of large cities, and it is likely due to a combination of factors. Asbestos exposure is surely one of those factors.

Are there any treatments for asbestos-related diseases?

Blair: For mesothelioma, some immunotherapy-based approaches seem to be having some success, however, the prognosis is grim. Most people don’t know they have mesothelioma until they go to the doctor with pain in their lungs, and then they typically die within a year of being diagnosed. The survival rate is often four or five months from diagnosis.

I’m sure many parents whose children attend schools with an asbestos problem are concerned about the health of their children. What would you say to parents? Should they be concerned?

Blair: The reality is there’s no safe level for asbestos. You can’t get away from that. The other problem is you can’t predict who’s going to get mesothelioma. Not everyone exposed to asbestos gets mesothelioma, obviously. It’s a big concern. We have no idea how much of the asbestos that’s lying on surfaces and the floor ends up in the atmosphere and is breathed in through the lungs. It seems to me that this is a very serious issue. Although there is risk to everyone, it might be an even bigger risk for teachers who are going to be exposed for the whole of their working lives. The children are there for a finite time. I certainly wouldn’t like my children to be going to a school where there was damaged asbestos. But a lot of people don’t have any choice.

Asbestos with a penny for scale. (Image: National Institute for Occupational Safety and Health)

Are the children who attend schools with an asbestos problem in any danger?

Howarth: Children are probably in a variable amount of danger. In some schools, it’s been found that there are very large areas, or many areas, where the asbestos materials have been disrupted, like the covering on pipe. In these schools, fibers accumulate on the floor, desks, and bookcases. It’s my understanding that regular wet mopping and wet dusting does not occur in school. Without being removed by cleaning, the asbestos fibers have the opportunity to remain in classrooms and also be spread around. As more and more asbestos fibers accumulate on floors, desks, and bookcases, the risk to people in schools increases. Since we don’t know how much exposure any individual student or teacher will have, I think it is important to identify strategies that would make it safe for everyone all the time, such as cleaning. Enhanced surveillance—the regular observation of all areas where asbestos material exists in schools to make sure that it is intact—is important. Of course, most important is the rapid remediation of damaged asbestos materials.

You mentioned enhanced surveillance; what do you think the solution is to the school district’s asbestos problem?

Howarth: It’s very clear that the school district can’t remove all the asbestos from all the schools in a rapid time frame. That’s not practical. But what is practical is to decrease the opportunity for children to breathe in asbestos that is present in schools. And the way to do that is to have nightly wet dusting of surfaces and wet mopping of floors in every school that has asbestos. That sounds like a very low-tech process and strategy—and it is. Wet dusting and wet mopping has been shown in studies to reduce the amount of asbestos fibers in the air. In addition, regular cleaning would tend to decrease the dust in the schools. It would actually have the additional benefit of decreasing exposure to other allergens, too. We have a high rate of asthma in Philadelphia among children. Regular cleaning of the schools may decrease the other allergens in schools in such a way that it may allow for children to be healthier in schools.

Is this something that the school district is doing?

Howarth: No. It’s my understanding that the school district employs cleaners in the schools only until about 8 o’clock at night. There has been reluctance to keep the schools open and heated or cooled all night until the following morning. I believe that was a cost-cutting maneuver. Therefore, schools are only cleaned from when the school day ends until 8 p.m. Unless you had an army of cleaners, you wouldn’t be able to adequately clean schools in a few hours each day. Until schools can be adequately cleaned on a daily basis, which is the norm in many area school districts, the establishment of several large teams of cleaners who rotated through schools to do the systematic, thorough wet mopping and dusting on a weekly basis would reduce the risk.

Ian A. Blair is the A.N. Richards Professor of Pharmacology at the Perelman School of Medicine, an investigator at the Abramson Cancer Center, and director of the Penn Superfund Research and Training Program, which focuses on developing biomarkers for personalization of asbestos risk, methods for remediating asbestos, studies on asbestos transport, the development of chemoprevention strategies to prevent asbestos-related diseases, and their potential use to improve human health in the community.

Marilyn Howarth is Adjunct Associate Professor of Emergency Medicine and Systems Pharmacology and Translational Therapeutics at the Perelman School of Medicine and director of the Community Engagement Core at the Center of Excellence in Environmental Toxicology at Penn Medicine, where she engages health professionals, regulators, legislators, communities, and researchers around environmental health science to improve environmental health. She is also a senior fellow at the Center for Public Health Initiatives.