Fiberglass as a building insulation has a much shorter history of use than asbestos. It was developed in the 1930s but was not used in quantity until the 50s, or in mass until the 70s when, with the oil embargo, people began to insulate everything in sight.

Fiberglass, like asbestos, is a mineral fiber, but the biologic mechanisms of asbestos, which are believed to inspire cancer, are generally not present in fiberglass. Fiberglass does break into small fibers that can be inhaled. Some researchers have indicated that inhalation of fiberglass fibers into lung tissue can cause stress to the immune system which, in turn, can relate to a higher incidence of cancer. Most researchers, however, dispute that fiberglass is truly a carcinogen.

One of the most reliable epidemiological studies was conducted by the University of Pittsburgh School of Public Health starting in 1974; it tracked 1,700 factory workers exposed to heavy levels of fiberglass. They detected a small, but what appears to be a statistically proven increase of lung disease. The increase was so small that it could be attributed to any number of variables, i.e. cigarette smoke, asbestos, etc.; nevertheless, it does show a possible correlation. Conversely, animal studies involving inhalation do not show related lung disease, even at extensive doses. There has been successful civil litigation, although a rather small settlement ($50,000), brought by a female office worker who had inhaled a substantial amount of fiberglass and appeared to have suffered health damage. The fiberglass industry commissioned extensive research, most of it in Switzerland, which indicated that fiberglass is not dangerous. Again, some researchers believe there may be a relationship between fiberglass and "building" disease, not necessarily cancer, while other researchers blatantly stated that there is a relationship between inhaling fiberglass and at least fibrosis (scarring of the lung tissue), and possibly cancer.

At this point, because of the confusion, we believe a proper procedure would be to install fiberglass in a manner unlikely to cause it to degrade and enter the general building atmosphere, i.e. it should be encased with drywall or at least polyethylene. Those installing or working around fiberglass should use appropriate face filters, and building inspections should make certain that fiberglass is not being introduced into the atmosphere through renovation or degradation.

OSHA has proposed a 1.0 fiber per cubic centimeter PEL for airborne levels of fiberglass to which workers may be exposed without personal protection. However, there is currently no requirement for personal protection for occupational exposure to fiberglass.

We believe it is unlikely that science will soon provide a clear answer regarding exposure and risk. The reason is, animal studies have limited value since most use rats, which have different breathing and natural filtering mechanisms than humans. Also, no epidemiological data, i.e. studies of people who are occupationally exposed, are likely to be gathered among working Americans who have not also been exposed to asbestos, which has a clear relationship to exposure and disease.

At this point, the best recommendations for people who govern buildings are:

• Inspect the building to make certain the air handling system is not introducing fiberglass fibers into the air.

• If people appear to be suffering from nasal irritation, sinus damage, allergies etc., it may be wise to run an air test and look for fiberglass, probably using TEM (Transmission Electron Microscopy). The cost is about $100 - $200 per sample. This should only be done if a problem is suspected.

• Make sure that workers wear proper filters when exposed to fiberglass fibers, and wear coveralls that are laundered separately so they do not take the fibers home with them.

• Begin a slow, disciplined, careful process of encasing fiberglass using drywall, polyethylene, or any mechanism that, from a commonsense perspective, isolates fibers from the air stream.

Although the relationship between cancer and fiberglass is not clear, once fiberglass products begin bearing a federal stamp declaring them to be a possible carcinogen, there will be enough public health concern to require controls and some management programming. Science, at this point, simply can not give us the legitimate power to contradict that concern, but we can say the following with confidence:

• If a high level of disease had been associated with small doses, we probably would have seen such a pattern emerging either in animals or people.

• Use responsible, cost-sensitive controls to keep airborne fiberglass out of lung tissue, particularly among those who are occupationally exposed.

In the future, there almost certainly will be public concern and consequent regulations regarding exposure to fiberglass.