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| > | Safety Overview | > | Research Results |
Research on Fiber Glass and Rock and Slag Wool
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Synthetic Vitreous Fibers (SVFs) are some of the most tested products in the world. Research over the last 70 years clearly demonstrates the safety of these products. Below are links to some of the seminal studies and reviews of research available. NAIMA maintains copies of many of these studies. Click here to request copies.
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Fiber Biosolubility Research
Fiber glass and rock and slag wool manufacturers, through their trade association (NAIMA) have sponsored a series of studies on the biosolubility of fibers once they enter the body. The scientific community considers this biosolubility factor, which measures how long a fiber remains in the lung, an important gauge of the possibility that fibers may cause adverse health effects. The latest results of the NAIMA biosolubility research show a clear difference between asbestos and glass wool, with glass wool disappearing from the lung in about 30-50 days compared to thousands of days for asbestos.
University of Pittsburgh Study
In 1992, as part of an ongoing University of Pittsburgh mortality study of the health of workers at 11 fiber glass plants in the United States over the last 18 years, Dr. Gary Marsh, the study's principal researcher, concluded: "...Aside from the issue of uncontrolled confounding, our study provides no evidence to date that respiratory cancer mortality is related to fibrous glass exposure."
Georgetown University Medical School Study
Georgetown University Professor Leonard Chiazze reported in 1992 on a study of men employed at a large U.S. fiber glass plant. Dr. Chiazze concluded, "A case control study.. .demonstrated that a history of cigarette smoking and not exposure to respirable glass is the most important factor in lung cancer risk. ..."
Tulane University Study on Glass Fibers
Dr. Hans Weill, principal researcher of a Tulane University study of more than 1,250 current workers at five U.S. manufacturing plants, concluded in 1992 that "...[A]fter 10 years of these investigations, we have failed to demonstrate any adverse effect of [glass fiber] exposure on respiratory health. We have found workers in this industry to be generally healthy, without any detectable evidence of occupationally induced respiratory disease."
The Netherlands
In 1995, the Dutch government released a report in which an expert committee on occupational standards, assessing man-made vitreous fibers concluded: "Based on the currently available epidemiological data and animal studies, the committee concludes that occupational exposure to glass wool, rock wool or slag wool fibers does not pose a carcinogenic hazard."
United Kingdom
A 1994 report by the United Kingdom's Department of Health stated that rock, slag and glass wool should not be classified for carcinogenicity based on the criteria in the European Union's Dangerous Substances Act. The conclusion reflects the "full consideration of all relevant research" and was adopted by the UK's Departments of Health and Education and Employment; the Health and Safety Commission; and the Health and Safety Executive.
In 1994, U.S. Department of Health and Human Services (HHS) Secretary Donna Shalala included "glasswool (respirable size)" in HHS's Seventh Annual Report on Carcinogens (ARC). The HHS classification does not reflect any new scientific information about fiber glass. According to Shalala, "The listing of a substance in the Annual Report is descriptive in nature and represents an initial step in hazard identification, which is generally considered the first step in the analytical process known as risk assessment. It is necessary to conduct a risk assessment in order to estimate the potential for any substance to harm human health." She said, "the listing of a substance in the Annual Report, therefore, does not establish that any such substance presents a risk to persons in their daily lives."
International Labor Organization
The International Labor Organization (ILO) concluded in 1989 that "available [human and animal] data on disease incidence and mortality in populations exposed to respirable fiber concentrations in the manufacture and use of insulation wools (rock, slag and glass) indicate that with the adoption of appropriate control and preventive measures any risk associated with production and use of the insulation wools should be minimal."
The most recent update of an ongoing U.S. study evaluating the health of workers in manufacturing settings (Marsh 1996) summarized the 1946 through 1989 mortality experience of more than 3,400 workers at six rock and slag wool plants. No increased risk for mesothelioma, a type of lung cancer, was observed among the workers. Overall, the researchers reported that there was "no consistent evidence of an exposure-response relationship between rock/slag mortality .... And any of the many fiber indicators considered.
Tulane University Study on Rock and Slag Wool
The most comprehensive morbidity study (one that researches the causes and effects of diseases) of rock and slag wool workers was conducted by researchers at Tulane University who reported no increase in respiratory symptoms and no evidence linking respiratory symptoms to exposure to rock and slag wool fibers. A more recent update of this study again found no lung abnormalities that could be attributed to rock and slag wool fiber exposure. Evaluation of chest X-rays and lung function tests indicated a generally healthy population; any observed abnormalities were attributed to smoking habits. In summarizing the results of these studies, the researchers stated in 1992: "We have concluded that after 10 years of these investigations, we have failed to demonstrate an adverse effect of man-made vitreous fiber exposure on respiratory health. We have found workers in this industry to be generally healthy, without any detectable evidence of occupationally induced disease." Results from two European studies of rock wool workers are consistent with the Tulane study's findings.
USG Corporation
A case-control study drawn from a population of about 5,000 U.S. workers (Wong 1991) compared slag wool exposures among workers who had died of lung cancer to workers in the same plants who had died of other causes. The study found no association between lung cancer and exposure to fibers. Neither duration of exposure, nor cumulative exposure to mineral wool fibers was associated with lung cancer. The authors reported: "Consistently, no relation was detected in any of these analyses." By contrast, all lung cancer cases were smokers, and there was a clear dose-response relationship between amount of smoking and lung cancer.