Is insulation dangerous?

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Rummaging around in your friend's newly renovated attic, you 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 material looks 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.

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A worker sprays fiberglass over a spa mold at Sundance Spas. Is insulation like fiberglass dangerous?

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, 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: The Environmental Magazine]. 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, and some researchers fear inhaling fiberglass particles could cause cancer.

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

Fiberglass and Asbestos

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

If you've ever come in contact with fiberglass, you already know what it 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 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?

Fiberglass became popular in the United States 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 ability to withstand very high temperatures. 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 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 the lungs 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.

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. Research on fiberglass inhalation has come to various conclusions. A study in 1970 on rats stated that "fibrous glass of small diameter is a potent carcinogen" [source: Consumer Law]. 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].

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Rolls of natural cotton and recycled cotton prepared for use as an alternative to fiberglass insulation.

Even the American Lung Association says fiberglass is safe "when properly installed" [source: ALA]. Once it's installed, fiberglass rests safely between 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.

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Is insulation dangerous?