Is Fiberglass Dangerous?

By: John Fuller  | 
Hidden Home Dangers Image Gallery A worker sprays fiberglass over a spa mold at Sundance Spas. Is insulation like fiberglass dangerous? See more pictures of hidden home dangers.
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Is fiberglass dangerous? Picture this, you're rummaging around your friend's newly renovated attic and notice what looks like a rolled-up blanket in the far corner. You give it a kick, and the blanket unfurls onto the floor. It's pink, and the light weight materials look a little like cotton candy. You run your hand over it to see what it feels like, but you soon realize that was a mistake. Before you know it, your hand is red and itchy -- you've just come in contact with fiberglass insulation.

Insulating our homes is one of the most important parts of house construction, and insulation has a big effect on the costs of energy. Heat naturally flows from a warm space to a cool space, and our homes suffer from this transfer. In the winter, warm air from the inside will move to the outside and make us cold. In the summer, hot air moves from the outside to the inside and makes it uncomfortably warm.


We have heating and air conditioning systems to fix these problems, but the more opportunities warm air has to flow out of or into the house, the harder those systems have to work. As those systems work harder, we use more energy and pay much higher utility bills. A properly insulated home will save money on energy costs by resisting the flow of heat and making your heating and air conditioning work less.

Fiberglass insulation, a man-made mineral fiber con­structed from a variety of materials, such as sand and recycled glass fibers, is the most popular form of insulation in the United States -- more than 90 percent of homes in America are lined with the pink stuff [source: Spencer and Gulick]. But while many see the benefits of insulating our houses with fiberglass, some are worried fiberglass can cause various health problems -- it's capable of causing immediate skin irritation.

But while some research suggests that inhaling fiberglass particles could cause cancer, but in 2001, the International Agency for Research on Cancer removed glass, rock and slag wool fibers -- common elements of fiberglass insulation -- from its list of substances possibly carcinogenic to humans [sources: NTP, IARC].

Why might fiberglass be dangerous to us? To learn more, read the next page.


Fiberglass and Asbestos

A worker pulls fiberglass straight as it is manufactured at a factory in Chengdu, Sichuan Province, China.
China Photos/Getty Images

If you've ever come in contact with it, you already know what fiberglass exposure can do to your skin. The tiny fibers of glass from insulation wool can irritate your skin and eyes. If you experience too much contact with fiberglass, it can cause what's called irritant contact dermatitis, or inflammation of the skin. Breathing in airborne fiberglass fibers can also increase the difficulty of breathing. Is that the extent of the trouble fiberglass can cause, or are there more serious health effects?

Builders began to install fiberglass insulation in the United States just as another insulating material -- asbestos -- was phased out of use. Asbestos, unlike fiberglass, is a naturally occurring silicate material found in rocks. Its known use goes back to the ancient Greeks, who admired it for its heat resistance.


Indeed, asbestos isn't just resistant to heat. It also doesn't evaporate in the air, dissolve in water or react with most chemicals. All of these properties made it particularly attractive for home construction, and asbestos was the main insulation material used for building insulation for the late 19th century and much of the 20th century.

But as early as the 1930s, the health hazards of asbestos became clear. When asbestos fibers are released into the air, they split into microscopic pieces. Once breathed in, asbestos fibers will be inhaled deep into the lungs, where they stay for long periods of time.

During that time, the fibers irritate lung tissue and any other part of the body they may travel to, disrupting cell division by interfering with chromosome distribution and changing important genetic material. This increases the chances of developing illnesses such as asbestosis, mesothelioma and other cancers, although symptoms of any such disease typically won't show up for 10 to 40 years.

Asbestos is classified as a known human carcinogen by state, federal and international agencies, and new uses of the material were banned in 1989 by the Environmental Protection Agency. Still, we frequently see asbestos-related problems, from the evacuation of poorly constructed school buildings to debris created from Hurricane Katrina in New Orleans in 2005.

While asbestos is a natural material and fiberglass is man-made, the two materials are often compared because they're both fibrous. This quality made fiberglass a good substitute once the health effects of asbestos became apparent. It also has the heat-resistant qualities that made asbestos so desirable for insulation.

Rolls of natural cotton and recycled cotton prepared for use as an alternative to fiberglass insulation.
James Keyser/Time Life Pictures/Getty Images

It also has some worried that the fibers from fiberglass are just as dangerous as asbestos -- it's sometimes referred to negatively as "man-made asbestos" or the asbestos of the 20th century. But while early research on rats in the 1970s stated that "fibrous glass of small diameter is a potent carcinogen," more modern research isn’t as sweeping in its findings [source: Montague].

The American Conference of Governmental Industrial Hygienists, on the other hand, claims fiberglass is "Not Classifiable as a Human Carcinogen," meaning there isn't even data to say whether or not it causes cancer in people [source: Yeshiva University].

The U.S. National Toxicology Program issued its 13th Report on Carcinogens in fall of 2014, and while its entry on Certain Glass Wool Fibers (Inhalable) states that they are “reasonably anticipated to be human carcinogens,” it also goes on to say that there is so much variation in production that full assessments must be made on a case-by-case basis [source: NTP].

Exposure to fiberglass is generally considered safe, especially when properly installed. Still, those that plan to handle it are encouraged to avoid skin contact by wearing protective gear like gloves and safety goggles. Once it's installed, fiberglass rests safely between plastic reinforcement panels, sheetrock and plaster -- only when it's removed will fibers become airborne.

In the meantime, people are still suggesting alternative ways to insulate homes -- everything including cork, corn cobs, cotton, newspapers and brick are other ways to keep the heat from escaping houses.

To learn more about house construction and related information, see the next page.


Dangerous insulation FAQs

Why was vermiculite insulation banned?
Vermiculite insulation was banned once it was discovered that it contained a high percentage of asbestos fibers that were proven to cause several deadly diseases. The United States decided to ban the sale of this insulation in 1978.
How dangerous is vermiculite insulation?
When vermiculite is circulated in air, it could cause small, needle-like asbestos fibers to lodge into the lung and cause severe damage. Asbestos is not dangerous if it doesn’t become airborne.
Can asbestos kill you?
Asbestos doesn’t kill directly humans but it can lead to the development of asbestos-related diseases such as lung cancer and diffuse pleural thickening. In many cases, the mere exposure to asbestos fibers can prompt an allergic reaction and asthma episodes.
What are the characteristics of fiberglass?
Fiberglass has all the makings of a good insulative material. It is naturally incombustible because it is a mineral material, which means it does not support flames. Fiberglass is a good insulator of electricity even at low thickness.
Is it safe to buy a house with vermiculite insulation?
If possible, try not to buy a house with vermiculite insulation. If you plan to buy a house with vermiculite insulation, make sure to not use storage. Do not attempt to clean up asbestos fibers yourself and only ask certified professionals to do any remodeling work.

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More Great Links


  • "A consumer's guide to energy efficiency and renewable energy." U.S. Department of Energy. Sept. 12, 2005.
  • "Asbestos fact sheet." Office of Environmental Health Hazard Assessment. 2003.
  • Barbalace, Roberta. "Asbestos, its chemical and physical properties." Oct. 2004.
  • “Certain Glass Wool Fibers (Inhalable)” Report on Carcinogens, Thirteenth Edition. National Toxicology Program, Department of Health and Human Services. Oct, 2, 2014.
  • "Fiberglass." Yeshiva University.
  • "Insulation fact sheet." Department of Energy. Jan. 15, 2008.
  • Montague, Peter. "Fiberglass: a carcinogen that's everywhere -- the asbestos of the 21st century." Environmental Research Foundation. June 1, 1995.
  • Spencer, Susan and Amy Gulik. "Security blanket: fiberglass' potential dangers can be avoided with insulating alternatives." E: The Environmental Magazine. May-June 1997.