An industrial process for making glass fibers was first patented in
Russia in 1840.[1, pg.292] At the Columbian Exposition in Chicago in
1893, Edward Libbey, an American, exhibited lamp shades, a dress, and
other articles woven from glass fibers. In 1915, the Allied Forces
blockaded Germany, creating an asbestos shortage which resulted in
commercial production of fiber glass in the U.S., as an asbestos
substitute. (Asbestos is a naturally-occurring fibrous material that
can be woven into cloth, does not burn readily, has excellent
properties for thermal insulation, and therefore came into commercial
use during this century.[2, pgs.390-392] Fiber glass has many of the
same characteristics as asbestos.)
In 1938, the Owens Corning Fiberglas Company was formed, and three
years later, in 1941, evidence of pulmonary [lung] disease was reported
by Walter J. Siebert, who investigated the health of workers in
cooperation with Owens Corning.[1, pg.292] That same year another
investigator reported finding "no hazard to the lungs" of workers
exposed to glass fibers in the air. Scientific disagreement of this
sort has characterized the study of fiber glass ever since; meanwhile
fiber glass production has increased steadily.
That same year (1941), the U.S. Patent Office issued patents for 353
glass wool products. Glass wool, fiber glass, fiberglas, fibrous glass,
and glass fibers are all names for the same thing: thin, needle-shaped
rods of glass, which nature does not make but humans do.
Fiber glass is now used for thermal insulation of industrial buildings
and homes; as acoustic insulation; as fireproofing; as a reinforcing
material in plastics, cement, and textiles; in automotive components;
in gaskets and seals; in filters for air and fluids; and for many other
miscellaneous uses. More than 30,000 commercial products now contain
As asbestos has been phased out because of health concerns, fiber glass
production in the U.S. has been rising. In 1975, U.S. production of
fiber glass was 247.88 million kilograms (545.3 million pounds); by
1984 it had risen to 632.88 million kilograms (1392.3 million pounds).
[1, pg.302] If that rate of growth (10.4% per year) held steady, then
production of fiber glass in the U.S. in 1995 would be 4365 million
Fiber glass is now causing serious health concerns among U.S. officials
and health researchers. As we reported in REHW #74, in a series of
papers published from 1969 to 1977, Dr. Mearl F. Stanton of the
National Cancer Institute found that glass fibers less then 3
micrometers in diameter and greater than 20 micrometers in length are
"potent carcinogens" in rats; and, he said in 1974, "it is unlikely
that different mechanisms are operative in man." A micrometer is a
millionth of a meter (and a meter is about three feet). Since that
time, studies have continued to appear, showing that fibers of this
size not only cause cancer in laboratory animals, but also cause
changes in the activity and chemical composition of cells, leading to
changes in the genetic structure and in the cellular immune system.
Although these cell changes may be more common (and possibly more
important) than cancer, it is the cancer-causing potential of glass
fibers that has attracted most attention.
In 1970, Dr. Stanton announced that "it is certain that in the pleura
of the rat, fibrous glass of small diameter is a potent carcinogen."
The pleura is the outer casing of the lungs; cancer of the pleura in
humans is called mesothelioma and it is caused by asbestos fibers.
Stanton continued his research and showed that when glass fibers are
manufactured as small as asbestos fibers, glass causes cancer in
laboratory animals just as asbestos does. Asbestos is a potent human
carcinogen, which will have killed an estimated 300,000 American
workers by the end of this century. The finding that fiber glass
causes diseases similar to asbestos was chilling news in the early
1970s, and an additional 25 years of research has not made the problem
seem less serious. Workers in fiber glass manufacturing plants are
exposed to concentrations of fibers far lower than the concentrations
to which asbestos workers were exposed, yet several industry-sponsored
epidemiological studies of fiber glass workers in the U.S., Canada, and
Europe have reported statistically significant increases in lung
The International Agency for Research on Cancer (IARC), of the World
Health Organization, listed fiber glass as a "probable [human]
carcinogen" in 1987. In 1990, the members of the U.S. National
Toxicology Program (NTP) --representatives of 10 federal health
agencies --concluded unanimously that fiber glass "may reasonably be
anticipated to be a carcinogen" in humans. NTP members were
preparing to list fiber glass that way in the SEVENTH ANNUAL (1992)
REPORT ON CARCINOGENS, the NTP's annual listing of cancer-causing
substances, which is mandated by Public Law 95-622. But industry
As we reported in REHW#367, four major manufacturers of fiber glass
insulation campaigned for three years to prevent their product from
being labeled a carcinogen by NTP (see REHW #367). They managed to
delay the publication of the NTP's SEVENTH ANNUAL REPORT ON CARCINOGENS
for more than two years, but on June 24, 1994, the Secretary of Health
and Human Services (HHS), Donna E. Shalala, signed the REPORT and sent
it to Congress, thus making it official policy of the U.S. government
that fiber glass is "reasonably anticipated to be a carcinogen." In the
U.S., fiber glass must now be labeled a carcinogen.
Announcing this decision, government officials tried to play down its
significance. Bill Grigg, a spokesperson for the U.S. Public Health
Service (a subdivision of Health and Human Services) told the
WASHINGTON POST, "There are no human data I'm aware of that would
indicate there's any problem that would involve any consumer or
worker." To make such a statement, Mr. Grigg had to ignore at least
six epidemiological studies showing statistically-significant increases
in lung cancer among production workers in fiber glass factories.
Indeed, according to researchers in the Occupational Safety and Health
Administration (OSHA, another division of Health and Human Services)
fiber for fiber, fiber glass is a more potent carcinogen than asbestos.
Fiber glass --a material that nature does not make --is now measurable
everywhere in the air. The air in cities, rural areas,[1, pgs.311-314]
and remote mountain tops now contains measurable concentrations of
fiber glass. If the dose-response curve is a straight line (that is to
say, if half as much fiber glass causes half as much cancer) and if
there is no threshold dose (no dose below which the cancer hazard
disappears), then exposing the Earth's 5.7 billion human inhabitants to
low concentrations of fiber glass will inevitably take its toll by
causing excess cancers in some portion of the population.
According to OSHA researchers, an 8-hour exposure to 0.043 glass fibers
per cubic centimeter of air is sufficient to cause lung cancer in one-
in-every-thousand exposed workers during a 45-year working lifetime.[8,
pg.580] In rural areas, the concentration of fiber glass in outdoor air
is reported to be 0.00004 fibers per cubic centimeter, about 1000 times
below the amount thought to endanger one-in-every-thousand fiber glass
workers.[1, pg.314] But people in rural areas breathe the air 24 hours
a day, not 8 hours. Furthermore, a human lifetime is 70 years, not the
45 years assumed for a "work lifetime." Moreover, one-in-a-thousand is
not adequate protection for the general public; U.S. Environmental
Protection Agency uses one-in-100,000 or one-in-a-million as a standard
for public exposures. (And, finally, in urban air, there's 10 to 40
times as much fiber glass as in rural air.) Therefore, the amount of
fiber glass in the outdoor air in the U.S. and Europe (and presumably
elsewhere) already seems higher than prudent public health policies
would permit. Assuming a straight-line dose-response curve and no
threshold, we believe there is ample reason to be concerned about the
human health hazards posed by fiber glass in the general environment.
(And this says nothing about the hazards to wildlife.)
It has been 25 years since researchers at the National Cancer Institute
concluded that fiber glass is a potent carcinogen in experimental
animals. During that time, additional research has confirmed those
findings again and again. During the same period, the amount of
fiber glass manufactured has increased rapidly year after year. Ninety
percent of American homes now contain fiber glass insulation. All of
this fiber glass will eventually be released into the environment
unless special (and very expensive) precautions are taken to prevent
its release. We believe the likelihood of Americans taking such
precautions is nil. Billions of pounds of fiber glass now in buildings
will eventually be dumped into landfills, from which it will leak out
slowly as time passes. Elevated concentrations of fiber glass are
already measurable in the air above landfills today.
In 1991, PATTY'S INDUSTRIAL HYGIENE AND TOXICOLOGY, a standard
reference book on work-place safety and health, said about fiber glass,
"...it is prudent for industrial hygienists to treat these materials
with the same precautions as asbestos."[1, pg. 324] How do we treat
asbestos? In the U.S., all new uses of asbestos have been banned. A ban
of fiber glass is long overdue.
 Jaswant Singh and Michael A. Coffman, "Man-Made Mineral Fibers," in
George D. Clayton and Florence E. Clayton, editors, PATTY'S INDUSTRIAL
HYGIENE AND TOXICOLOGY FOURTH EDITION, VOLUME 1, PART B (New York: John
Wiley & Sons, 1991), pgs. 289-327.
 Michael A. Coffman and Jaswant Singh, "Asbestos Management in
Buildings," in George D. Clayton and Florence E. Clayton, editors,
PATTY'S INDUSTRIAL HYGIENE AND TOXICOLOGY FOURTH EDITION, VOLUME 1,
PART B (New York: John Wiley & Sons, 1991), pgs. 387-420.
 The annual list of carcinogens is drawn up by an inter-agency
Working Group for the Annual Reports on Carcinogens, which includes
representatives from the Agency for Toxic Substances and Disease
Registry (ATSDR); the Centers for Disease Control (CDC); the National
Institute for Occupational Safety and Health (NIOSH); the Consumer
Product Safety Commission (CPSC); the U.S. Environmental Protection
Agency (EPA); the Food and Drug Administration (FDA); the National
Cancer Institute (NCI); the National Institute of Environmental Health
Sciences (NIEHS); the National Library of Medicine (NLM); and the
Occupational Safety and Health Administration (OSHA).
 Reported in Katherine and Peter Montague, "Fiber Glass,"
ENVIRONMENT Vol. 16 (September 1974), pgs. 6-9.
 Philip J. Landrigan, "Commentary: Environmental Disease--A
Preventable Epidemic," AMERICAN JOURNAL OF PUBLIC HEALTH Vol. 82 (July
1992), pg. 941.
 See Peter F. Infante and others, "Fibrous Glass and Cancer,"
AMERICAN JOURNAL OF INDUSTRIAL MEDICINE Vol. 26 (1994), pgs. 559-584,
which reviews the following studies, among others: L. Simonato and
others, "The International Agency for Research on Cancer Historical
Cohort of MMMF Production Workers in Seven European Countries:
Extension of the Follow-Up," ANNALS OF OCCUPATIONAL HYGIENE Vol. 31,
No. 4B (1987), pgs. 603-623; Philip E. Enterline and others, "Mortality
Update of a Cohort of U.S. Man-Made Mineral Fibre Workers," ANNALS OF
OCCUPATIONAL HYGIENE Vol. 31, No. 4B (1987), pgs. 625-656; Harry S.
Shannon and others, "Mortality Experience of Ontario Glass Fibre
Workers--Extended Follow-Up," ANNALS OF OCCUPATIONAL HYGIENE Vol. 31,
No. 4B (1987), pgs. 657-662; and John R. Goldsmith, "Comparative
Epidemiology of Men Exposed to Asbestos and Man-Made Mineral Fibers,"
AMERICAN JOURNAL OF INDUSTRIAL MEDICINE Vol. 10 (1986), pgs. 543-552;
G.M. Marsh and others, "Mortality Among a Cohort of US Man-Made Mineral
Fiber Workers: 1985 Follow-Up," JOURNAL OF OCCUPATIONAL MEDICINE Vol.
32 (1990), pgs. 594-604; P. Boffetta and others, "Lung Cancer Mortality
Among Workers in the European Production of Man-Made Mineral Fibers--A
Poisson Regression Analysis," SCANDINAVIAN JOURNAL OF WORK,
ENVIRONMENT, AND HEALTH Vol. 18 (1992), pgs. 279-286.
 Frank Swoboda and Maryann Haggerty, "U.S. Suspects Figerglass as
Carcinogen, Calls Insulation Safe," WASHINGTON POST July 2, 1994, pg.
 Peter F. Infante and others, "Fibrous Glass and Cancer," AMERICAN
JOURNAL OF INDUSTRIAL MEDICINE Vol. 26 (1994), pgs. 559-584.
Special thanks to the advocacy organization, Victims of Fiberglass
(VOF), for keeping us informed about these issues over the years. VOF
publishes an excellent newsletter, FIBERGLASS ROOTS OF CANCER; contact
Bob Horowitz, Victims of Fiberglass, P.O. Box 894, Bryte, CA 95605-
0894; phone (916) 371-0656.
Descriptor terms: fiber glass; man-made mineral fibers; carcinogens;
cancer; lung cancer; studies; epidemiology; energy conservation;
insulation; asbestos; iarc; who; world health organization; ntp;
victims of fiberglass; hhs; osha;