As discussed in Chap. 7, debates have been intensifying since the mid-1980s as to the safety of using fiberglass insulation. The concern has been that the fibers that comprise fiberglass may replicate the affects of the fibers found in another silicon dioxide material, asbestos. The structure and size of these glass fibers vary. The smaller fibers, which cannot be seen by the naked eye, can enter the lungs, whereas larger, visible fiberglass particles can be irritating to the skin, eyes, nose, and throat. According to a recent
Figure 8.10 Polypropylene-faced fiber glass roll. (CertainTeed)
report, the larger size of fiberglass fibers is a critical physical property difference from asbestos. “Since large-diameter fibers fall out of suspension in the air faster than small-diameter fibers, work with SVFs is less likely to generate high concentrations of airborne fibers than work with asbestos.”4
Fiberglass is listed by the International Agency for Research on Cancer (IARC) as a possible carcinogen and by the National Toxicology Program (NTP) as “reasonably anticipated to be a carcinogen.”1 Although occupational and residential exposures to fiberglass fibers are low when compared with past asbestos exposures, all fiberglass insulation is required to have a cancer warning label as mandated by the Occupational Safety and Health Administration’s (OSHA) hazard communication standard.1 Full hazard disclosure is also found in the product’s Manufacturer’s Safety Data Sheet (MSDS).
The Consumer Product Safety Commission (CPSC) also has found (1992) that “fibrous glass is carcinogenic in animals only when surgically implanted into the lung or abdomen. In tests where animals were exposed by inhalation, the expected route of human exposure, the animals did not develop tumors. Therefore, the animal implantation studies do not establish a hazard to humans.”5
A common complaint about fiberglass has been the use of formaldehyde in its manufacturing process, and the danger the chemical may present to humans. Conventional fiberglass insulation is made with 5 to 7 percent phenol formaldehyde resin.6 Industry officials report that formaldehyde is found in the final product in only trace amounts. After being sprayed on as part of the manufacturing process, it goes through an oven curing process where the majority of the formaldehyde is cured and the excess collected by precipitators to ensure that harmful amounts are not released into the atmosphere.1
The greatest concern with fiberglass, however, is not necessarily aimed at the home occupants surrounded by the insulation but at the installers of the insulation. Workers in fiberglass manufacturing plants, as well as people working with or using materials that contain fiberglass, may develop a skin irritation. This mechanical irritation is a physical reaction of the skin to the ends of fibers that have rubbed against or become embedded in the skin’s outer layer. Any skin irritation caused by fiberglass is temporary. Washing the exposed skin gently with warm water and mild soap can relieve it. The vast majority of workers and consumers, however, can control skin irritation by following recommended work practices when handling the material. Fiberglass is also the catalyst for eye irritation if deposited in the eye by the user’s fingers or through fibers in the air. If this should happen, the eyes should not be rubbed but rinsed thoroughly with warm water, and a doctor consulted if irritation persists.7
Fiberglass released into the air during its manufacture or handling also may create temporary upper respiratory tract irritation. Like skin irritation, upper respiratory tract irritation is a mechanical reaction to the fibers. It is not an allergic reaction, and the irritation generally does not persist. Such exposures to high concentrations of airborne fiberglass may result in temporary coughing or wheezing. These effects will subside after the worker is removed from exposure.7
In response to these health concerns, several manufacturers have developed new products that attempt to reduce the amount of airborne glass fibers. Generically called encapsulated batts, these blanket products seal the fiberglass in a polyethylene covering that minimizes contact and also serves as a vapor barrier. Reportedly easier to install, there is no itching, and the price is only about 5 to 30 percent higher than traditional batts depending on the manufacturer.
One product is produced by fusing together two different types of glass, which gives the fiber a curving or twisted configuration and eliminates the need for binders to hold the fibers together. The fibers are more resilient, stronger, and less prone to breakage, so fewer fiber particles will get into the air or into the installer’s skin. Since the fiber is twisted, a binder (typically formaldehyde) is not required to hold batts together.6
Another formaldehyde-free fiberglass insulation product uses an acrylic binder to hold the fibers together. Unlike the phenol – formaldehyde resin used in conventional fiberglass, it does not offgas formaldehyde during either manufacture or use. The acrylic binder is a thermosetting resin. Although heat is used to cure the binder, as with phenol-formaldehyde, this binder releases very few volatiles.8
As will be discussed later in this chapter, proper clothing and handling and the use of approved respiratory protection can effectively control exposure to airborne fibers and therefore reduce the likelihood of skin or upper respiratory tract irritation.