Gloves and loose-fitting, long-sleeved, and long-legged clothing are recommended to prevent irritation whenever workers are using fiberglass. A head cover is also recommended, especially when working with material overhead. (Photo courtesy of Owens Corning.)
Steel price increases and shortages are not expected to abate any time soon (The News, April 26, 2004). Higher steel prices have spurred increased interest in fiberglass duct materials, and manufacturers and other industry groups state it is important to understand the safety issues surrounding "man-made vitreous fibers" (fiberglass).

The most serious question raised is whether glass fibers could cause cancer through inhalation, either during the manufacturing process or while working with the material. Members of the North American Insulation Manufacturers Association (NAIMA) argue this question has been answered through extensive research, and cite experts who assert you have to physically plant a lot of glass fibers into a lab rat's chest cavity to cause cancerous cell growth. Fiberglass particles that are inhaled normally are broken down safely like household dust, studies show.

The problem is getting the government to officially reclassify this material as noncancerous. Until that happens, manufacturers and others worry litigation-weary engineers and architects may shy away from specifying it.

Moving Slowly

Paul Newton calls the slowness of the federal Department of Health and Human Services "your tax dollars at work."

Newton is the manager of advertising and promotions at CertainTeed Corp., Valley Forge, Pa. He and other members of the manufacturing community have been waiting for the reclassification of fiberglass as a noncarcinogen.

In the 1980s, both asbestos and fiberglass were examined for carcinogenic effects. According to Newton, fibers from both materials have been closely examined for carcinogicity.

In 1994, Health and Human Service's National Toxicology Program (NTP, Research Triangle Park, N.C.) listed fiberglass as being "reasonably anticipated to be a human carcinogen" based on animal test data.

Early research of fiberglass that led to its classification as a carcinogen did not use real-world exposure paths, Newton said. "In the original studies that lead to the classification, researchers opened up lab animals and implanted fibers in chest cavities," he said.

In 1999, OSHA and NAIMA, voluntarily agreed on ways to control workplace exposure to avoid irritation. As a result, OSHA agreed not to regulate exposure to fiberglass insulation.

In 2000, the National Academy of Sciences (NAS) reported that among fiberglass manufacturing workers, "glass fibers do not appear to increase the risk of respiratory system cancer."

In 2001, the International Agency for Research on Cancer (IARC) revised its previous classification of glass wool being a possible carcinogen, pointing out that newer man-made fibers have been developed specifically to replace asbestos and other "bio-persistent" products used in home building. (The slow breakdown of those older materials equated to their higher carcinogenic risks, the agency said.)

"Some of these newer materials have now been tested for carcinogenicity and most are found to be noncarcinogenic, or to cause tumours in experimental animals only under very restricted conditions of exposure," stated IARC.

Fiberglass "is currently considered not classifiable as a human carcinogen," stated the American Lung Association (ALA). "Studies done in the past 15 years since the previous report was released do not provide enough evidence to link this material to any [lung] cancer [or mesothelioma] risk."

Mind you, the stuff still itches. People who work with it need to protect their eyes, cover their skin, and wash their work clothes separately from the rest of the family's laundry. They need to change clothes as soon after work as they can.

"Although IARC is located in Europe, the reclassification has not resulted in any changes in the EU because it had already been treated as such under the EU's classification scheme," said Jim Worden, director of corporate communications, environment health and safety, Owens Corning, Toledo, Ohio.

"In the United States, the next step is for the NTP to review the science that IARC considered and decide whether to change its classification, which is currently ‘reasonably anticipated to be carcinogenic,'" Worden said. "Although that process has already begun, we do not anticipate that it will be completed until 2006. The same research would likely be reviewed at some later date by the state of California" for Proposition 65, the Safe Drinking Water and Toxic Enforcement Act of 1986.

In general, "fiberglass went from possible carcinogen to nonclassifiable, which is a step in the right direction," Worden said. He also pointed out that permissible exposure limits to fiberglass particles have not changed. They remain 1 respirable fiber per cubic centimeter of air.

Sidebar: Handling Fiberglass Without The Itch

According to the North American Insulation Manufacturers Association (NAIMA), "Fiberglass is now the most thoroughly evaluated insulation material in the market. Scientific evidence demonstrates that fiberglass is safe to manufacture, install, and use when recommended work practices are followed. Following these work practices will help to reduce irritation." These include:

  • Setting a voluntary workplace permissible exposure limit (PEL) of 1 respirable fiber per cubic centimeter of air.

  • Requiring that workers wear respiratory protection when workplace exposures exceed this PEL and for certain designated tasks.

  • Monitoring workplace airborne fiber levels and providing a centralized exposure monitoring database.

  • Providing information and training for workers who handle glass wool products.

    NAIMA also recommends following these safe work practices for handling synthetic vitreous fiber (SVF or fiberglass) products.

    Minimize Dust Generation

  • Keep the material in its packaging as long as practical.

  • Tools that generate the least amount of dust should be used. If power tools are to be used, they should be equipped with appropriate dust collection systems as necessary.

  • Keep work areas clean and free of scrap SVF material.

  • Do not use compressed air for cleanup unless there is no other effective method. If compressed air must be used, proper procedures and control measures must be implemented. Other workers in the immediate area must be removed or similarly protected.

  • Where repair or maintenance of equipment that is either insulated with SVF or covered with settled SVF dust is necessary, clean the equipment first with HEPA vacuum or equivalent (where possible) or wipe the surface clean with a wet rag to remove excess dust and loose fibers. If compressed air must be used, proper procedures and control measures must be implemented. Other workers in the immediate area must be removed or similarly protected.

    Maintain Adequate Ventilation

  • Unless other proper procedures and control measures have been implemented, dust collection systems should be used in manufacturing and fabrication settings where appropriate and feasible.

  • Exhausted air containing SVFs should be filtered prior to recirculation into interior workspaces.

  • If ventilation systems are used to capture SVFs, they should be regularly checked and maintained.

    Dress Appropriately

  • Loose-fitting, long-sleeved, and long-legged clothing is recommended to prevent irritation. A head cover is also recommended, especially when working with material overhead. Gloves are also recommended. Skin irritation cannot occur if there is no contact with the skin. Do not tape sleeves or pants at wrists or ankles.

  • Remove SVF dust from work clothes before leaving work to reduce potential for skin irritation.

  • To minimize upper respiratory tract irritation, measures should be taken to control the exposure. Such measures will be dictated by the work environment and many include appropriate respiratory protective equipment. (See OSHA's Respiratory Protection Standard.)

  • When appropriate, eye protection should be worn whenever SVF products are being handled.

  • Personal protective equipment should be properly fitted and worn when required.

    Removing Fibers

  • If fibers accumulate on the skin, do not rub or scratch. Never remove fibers from the skin by blowing with compressed air.

  • If fibers are seen penetrating the skin, they may be removed by applying and then removing adhesive tape so that the fibers adhere to the tape and are pulled out of the skin.

  • SVF may be deposited in the eye. If this should happen, do not rub the eyes. Flush them with water or eyewash solution (if available). Consult a physician if the irritation persists.

    For more information, contact NAIMA, 44 Canal Center Plaza, Ste. 310, Alexandria, VA 22314; 703-684-0084;

    Sidebar: Safe Duct Removal

    "These recommended practices are applicable for workers removing synthetic vitreous fiber (SVF) products during significant repair or demolition activity," stated the North American Insulation Manufacturers Association (NAIMA). "Additional precautions may be required if workers are also exposed to other products or substances. In such circumstances, more stringent recommendations may apply."

    Recommended practices include:

  • Workers should wear a NIOSH-certified dust respirator (certified N95 or greater) when removing SVF products. (See OSHA's Respiratory Protection Standard.)

  • Practice good housekeeping procedures.

  • Where appropriate, dust-collection systems may reduce the exposure to dust. If a dust collection system is used, follow the recommended work practices for ventilation.

  • Follow recommended work practices for selecting work clothing and appropriate personal protective equipment to be used.

  • Use a light water mist on the SVF to minimize airborne dust during product removal and disposal.

    For additional information, contact NAIMA, 44 Canal Center Plaza, Ste. 310, Alexandria, VA 22314; 703-684-0084; 703-684-0427 (fax);

    Publication date: 10/25/2004