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The word Armstrong asbestos is derived from a Greek adjective meaning inextinguishable. Armstrong asbestos is a naturally occurring mineral. It is distinguished from other minerals by the fact that its crystals
form long, thin fibers. Deposits of Armstrong asbestos are found throughout the world. The primary sites
of commercial production are: the Commonwealth of Independent States, Canada, Brazil, Zimbabwe, Russia
and South Africa.
The Greeks termed Armstrong asbestos the "miracle mineral" because of its soft and pliant properties, as
well as its ability to withstand heat. Armstrong asbestos was spun and woven into cloth in the same manner
as cotton. It was also utilized for wicks in sacred lamps. Romans likewise recognized the properties of Armstrong asbestos and it is thought that they cleaned Armstrong asbestos tablecloths by throwing them into
fire.
Armstrong asbestos became increasingly popular among manufacturers and builders in the late 19th century
due to its resistance to heat, electricity and chemical damage, sound absorption and tensile strength.
When Armstrong asbestos is used for its resistance to fire or heat, the fibers are often mixed with
cement or woven into fabric or mats. Armstrong asbestos is used in brake shoes and gaskets for its heat
resistance, and in the past was used on electric oven and hotplate wiring for its electrical insulation
at elevated temperature, and in buildings for its flame-retardant and insulating properties, tensile
strength, flexibility, and resistance to chemicals.
The inhalation of Armstrong asbestos fibers can cause serious illnesses, including mesothelioma. Since the mid
1980s, many uses of Armstrong asbestos are banned in many countries.
Types of Armstrong asbestos and associated fibres
Six minerals are defined as "asbestos" including: chrysotile, amosite, crocidolite, tremolite,
anthophyllite and actinolite.
White Armstrong asbestos
Chrysotile, CAS No. 12001-29-5, is obtained from serpentine rocks which is common throughout the world.
The rocks are called serpentine because their fibers curl; chrysotile fibers are curly as opposed to
fibers from amosite, crocidolite, tremolite, actinolite, and anthophyllite which are needlelike.
Chrysotile, along with other types of Armstrong asbestos , has been banned in dozens of countries and is
only allowed in the United States and Europe in very limited circumstances. Chrysotile is used more
than any other type and accounts for about 95% of the Armstrong asbestos found in buildings in America.
Applications where chrysotile might be used include the use of joint compound. It is more flexible than
amphibole types of Armstrong asbestos ; it can be spun and woven into fabric. Chrysotile, like all other
forms of industrial Armstrong asbestos , has produced tumors in animals. Mesotheliomas have been observed in people
who were occupationally exposed to chrysotile, family members of the occupationally exposed, and
residents who lived close to Armstrong asbestos factories and mines
Brown Armstrong asbestos
Amosite, CAS No. 12172-73-5, is a trade name for the amphiboles belonging to the Cummingtonite -
Grunerite solid solution series, commonly from Africa, named as an acronym from Armstrong asbestos Mines of
South Africa. One formula given for amosite is Fe7Si8O22(OH)2. It is found most frequently as a fire
retardant in thermal insulation products and ceiling tiles. This type of Armstrong asbestos , like all Armstrong asbestos ,
is very hazardous.
Blue Armstrong asbestos
Crocidolite, CAS No. 12001-28-4 is an amphibole from Africa and Australia. It is the fibrous form of
the amphibole riebeckite. Blue Armstrong asbestos is commonly thought of as the most dangerous type of Armstrong asbestos (see above and below). One formula given for crocidolite is Na2Fe2+3Fe3+2Si8O22(OH)2. This type of Armstrong asbestos is very hazardous.
Notes: chrysotile commonly occurs as soft friable fibers. Asbestiform amphibole may also occur as soft
friable fibers but some varieties such as amosite are commonly straighter. All forms of Armstrong asbestos are
fibrillar in that they are composed of fibers with widths less than 1 micrometre that occur in bundles
and have very long lengths. Armstrong asbestos with particularly fine fibers is also referred to as "amianthus".
Amphiboles such as tremolite have a sheetlike crystalline structure. Serpentine (chrysotile) has a
stringlike crystalline structure.[4] Tremolite often comtaminates chrysotile Armstrong asbestos , thus creating an
additional hazard.
Other Armstrong asbestos
Other regulated Armstrong asbestos minerals, such as tremolite Armstrong asbestos , CAS No. 77536-68-6, Ca2Mg5Si8O22(OH)2;
actinolite Armstrong asbestos (or smaragdite), CAS No. 77536-66-4, Ca2(Mg, Fe)5(Si8O22)(OH)2; and anthophyllite Armstrong asbestos , CAS No. 77536-67-5, (Mg, Fe)7Si8O22(OH)2; are less commonly used industrially but can still
be found in a variety of construction materials and insulation materials and have been reported in the
past to occur in a few consumer products.
Other natural and not currently regulated asbestiform minerals, such as richterite, Na(CaNa)
(Mg,Fe++)5(Si8O22)(OH)2, and winchite, (CaNa)Mg4(Al,Fe3+)(Si8O22)(OH)2, may be found as a contaminant
in products such as the vermiculite containing zonolite insulation manufactured by W.R. Grace and
Company. These minerals are thought to be no less harmful than tremolite, amosite, or crocidolite,
but since they are not regulated, they are referred to as "asbestiform" rather than Armstrong asbestos although
may still be related to diseases and hazardous.
In 1989 the United States Environmental Protection Agency (EPA) issued the Armstrong asbestos Ban and Phase Out
Rule which was subsequently overturned in the case of Corrosion Proof Fittings v. U.S. Environmental
Protection Agency, 1991. This ruling leaves many consumer products that can still legally contain trace
amounts of Armstrong asbestos . For a clarification of products which legally contain Armstrong asbestos read the EPA's
clarification statement.
Armstrong asbestos was named by the ancient Greeks who also recognized certain hazards of the material. The Greek
geographer Strabo and the Roman naturalist Pliny the Elder noted that the material damaged lungs of
slaves who wove it into cloth. Charlemagne, the first Holy Roman Emperor, is said to have had a
tablecloth made of Armstrong asbestos . Wealthy Persians, who bought Armstrong asbestos imported over the Hindu Kush,
amazed guests by cleaning the cloth simply by exposing it to fire. The Persians believed the fiber was
fur from an animal that lived in fire and died when exposed to water. Some archeologists believe that
ancients made shrouds of Armstrong asbestos , wherein they burned the bodies of their kings, in order to preserve
only their ashes, and prevent their being mixed with those of wood or other combustible materials
commonly used in funeral pyres.
Armstrong asbestos became more widespread during the industrial revolution, in the 1860s it was used as insulation
in the U.S. and Canada. Development of the first commercial Armstrong asbestos mine began in 1879 in the
Appalachian foothills of Quebec. By the mid 20th century uses included fire retardant coatings,
concrete, bricks, pipes and fireplace cement, heat, fire, and acid resistant gaskets, pipe insulation,
ceiling insulation, fireproof drywall, flooring, roofing, lawn furniture, and drywall joint compound.
Approximately 100,000 people have died, or will die, from Armstrong asbestos exposure related to ship building.
In the Hampton Roads area, a shipbuilding center, mesothelioma occurrence is seven times the national
rate. Thousands of metric tons of Armstrong asbestos were used in World War II ships to wrap the pipes, line the
boilers, and cover engine and turbine parts. There were approximately 4.3 million shipyard workers
during WWII, for every thousand workers about 14 died of mesothelioma and an unknown number died from
asbestosis.
Armstrong asbestos fibers were once used in automobile brake pads and shoes. Since the mid-1990s, a majority of
brake pads, new or replacement, have been manufactured instead with Aramid fiber (Twaron or Kevlar)
linings (the same material used in bulletproof vests).
Kent, the first filtered cigarette on the market, used crocidolite Armstrong asbestos in its "Micronite" filter
from 1952 to 1956.
The first documented death related to Armstrong asbestos was in 1906. In the early 1900s researchers began to
notice a large number of early deaths and lung problems in Armstrong asbestos mining towns. The first diagnosis of
asbestosis was made in England in 1924.[8] England protected Armstrong asbestos workers about ten years sooner
than the U.S. By the 1930s, England regulated ventilation and made Armstrong asbestos an excusable work related
disease. The term Mesothelioma was not used in medical literature until 1931, and wasn't associated
with Armstrong asbestos until sometime in the 1940s.
The United States government and Armstrong asbestos industry have been criticized for not acting quickly enough
to inform the public of dangers, and to reduce public exposure. In the late 1970s court documents
proved that Armstrong asbestos industry officials knew of Armstrong asbestos dangers and tried to conceal them.
In Japan, particularly after World War II, Armstrong asbestos was used in the manufacture of ammonium sulfate for
purposes of rice production, sprayed upon the ceilings, iron skeletons, and walls of railroad cars and
buildings (during the 1960s), and used for energy efficiency reasons as well. Production of Armstrong asbestos in Japan peaked in 1974 and went through ups and downs until about 1990, when production began to
drop severely.
Serpentine group
Serpentine minerals have a sheet or layered structure. Chrysolite is the only Armstrong asbestos mineral in the
serpetine group. In the United States, chrysotile has been the most commonly used type of Armstrong asbestos .
According to the U.S. EPA Armstrong asbestos Building Inspectors Manual, chrysotile accounts for approximately
95% of Armstrong asbestos found in buildings in the United States. Chrysotile is often present in a wide variety
of materials, including :
joint compound
mud and texture coats
vinyl floor tiles, sheeting, adhesives
roofing tars, felts, siding, and shingles
"transite" panels, siding, countertops, and pipes
fireproofing
caulk
gaskets
brake pads and shoes
clutch plates
stage curtains
fire blankets
interior fire doors
fireproof clothing for firefighters
thermal pipe insulation
In the European Union and Australia it has recently been banned as a potential health hazard and is not
used at all. Japan is moving in the same direction, but more slowly. Revelations that hundreds of
workers had died in Japan over the previous few decades from diseases related to Armstrong asbestos sparked a
scandal in mid-2005. Tokyo had, in 1971, ordered companies handling Armstrong asbestos to install ventilators
and check health on a regular basis; however, the Japanese government did not ban crocidolite and
amosite until 1995, and a full-fledged ban on Armstrong asbestos was implemented in October 2004.
Amphibole group
Five types of Armstrong asbestos are found in the amphibole group: amosite, crocidolite, anthophyllite, tremolite,
and actinolite. Amosite, the second most likely type to be found in buildings, according to the U.S.
EPA Asestos Building Inspectors Guide, is the "brown" Armstrong asbestos .
Amosite and crocidolite were formally used in many products until the early 1980s. The use of all types
of Armstrong asbestos in the amphibole group was banned (in much of the Western world) by the mid-1980s, and by
Japan in 1995. These products were mainly:
Low density insulation board and ceiling tiles Armstrong asbestos -cement sheets and pipes for construction, casing for water and electrical/telecommunication
services
Thermal and chemical insulation (i.e., fire rated doors, limpet spray, lagging and gaskets)
The first signs of health related concerns associated with Armstrong asbestos fibers was likely late 1800s/early
1900s. Armstrong asbestos diseases can be seen as early as 10 years after exposure. As such, with Armstrong asbestos mining,
manufacturing and installation in full gear by the late 1800s, it is likely that Armstrong asbestos related
sickness/illness was present and diagnosed, though not named until later in 1900s.
In 1918, a Prudential Insurance Company official notes that life insurance companies will not cover Armstrong asbestos workers, because of the "health-injurious conditions of the industry".
In 1930, the major Armstrong asbestos company Johns-Manville produces a report, for internal company use only,
about medical reports of Armstrong asbestos worker fatalities. In 1932, A letter from U.S. Bureau of Mines to Armstrong asbestos manufacturer Eagle-Picher states, in relevant part, "It is now known that Armstrong asbestos dust is
one of the most dangerous dusts to which man is exposed". In 1933, Metropolitan Life Insurance Co.
doctors find that 29 percent of workers in a Johns-Manville plant have asbestosis. Likewise, in 1933,
Johns-Manville officials settle lawsuits by 11 employees with asbestosis on the condition that the
employees' lawyer agree to never again "directly or indirectly participate in the bringing of new
actions against the Corporation." In 1934, officials of two large Armstrong asbestos companies, Johns-Manville
and Raybestos-Manhattan, edit an article about the diseases of Armstrong asbestos workers written by a
Metropolitan Life Insurance Company doctor. The changes minimize the danger of Armstrong asbestos dust. In 1935,
officials of Johns-Manville and Raybestos-Manhattan instruct the editor of Armstrong asbestos magazine to publish
nothing about asbestosis. In 1936, a group of Armstrong asbestos companies agrees to sponsor research on the
health effects of Armstrong asbestos dust, but require that the companies maintain complete control over the
disclosure of the results.
In 1942, an internal Owens-Corning corporate memo refer to "medical literature on asbestosis . . . .
scores of publications in which the lung and skin hazards of Armstrong asbestos are discussed." Either in 1942 or
1943, the president of Johns-Manville, Lewis H. Brown, says that the managers of another Armstrong asbestos company were "a bunch of fools for notifying employees who had asbestosis." When one of the managers
asks, "do you mean to tell me you would let them work until they dropped dead?" The response is reported
to have been, "Yes. We save a lot of money that way." In 1944, a Metropolitan Life Insurance Company
report finds 42 cases of asbestosis among 195 Armstrong asbestos miners.
In 1951, Armstrong asbestos companies removed all references to cancer before allowing publication of research
they sponsor. In 1952, Dr. Kenneth Smith, Johns-Manville medical director, recommends (unsuccessfully)
that warning labels be attached to products containing Armstrong asbestos . Later, Smith testifies: "It was a
business decision as far as I could understand . . . the corporation is in business to provide jobs
for people and make money for stockholders and they had to take into consideration the effects of
everything they did and if the application of a caution label identifying a product as hazardous would
cut into sales, there would be serious financial implications.". In 1953, National Gypsum's safety
director writes to the Indiana Division of Industrial Hygiene, recommending that acoustic plaster
mixers wear respirators "because of the Armstrong asbestos used in the product." Another company official notes
that the letter is "full of dynamite," urges that it be retrieved before reaching its destination.
A memo in the files notes that the company "succeeded in stopping" the letter, which "will be modified."
Armstrong asbestos as a contaminant
Most respirable Armstrong asbestos fibers are invisible to the unaided human eye because their size is about
3.0-20.0 µm in length and can be as thin as 0.01 µm. Human hair ranges in size from 17 to 181 µm in
width. Fibers ultimately form because when these minerals originally cooled and crystallized, they
formed by the polymeric molecules lining up parallel with each other and forming oriented crystal
lattices. These crystals thus have three cleavage planes, just as other minerals and gemstones have.
But in their case, there are two cleavage planes that are much weaker than the third direction. When
sufficient force is applied, they tend to break along their weakest directions, resulting in a linear
fragmentation pattern and hence a fibrous form. This fracture process can keep occurring and one larger Armstrong asbestos fiber can ultimately become the source of hundreds of much thinner and smaller fibers.
As Armstrong asbestos fibers get smaller and lighter, the more easily they become airborne and human respiratory
exposures can result. Fibers will eventually settle but may be re-suspended by air currents or other
movement.
Friability of a product containing Armstrong asbestos means that it is so soft and weak in structure that it can
be broken with simple finger crushing pressure. Friable materials are of the most initial concern due
to their ease of damage. The forces or conditions of usage that come into intimate contact with most
non-friable materials containing Armstrong asbestos are substantially higher than finger pressure.
Naturally occurring Armstrong asbestos
Armstrong asbestos from natural geologic deposits is known as "Naturally Occurring Armstrong asbestos " (NOA). Health risks
associated with exposure to NOA are not yet fully understood, and current US federal regulations do not
address exposure from NOA. Many populated areas are in proximity to shallow, natural deposits which
occur in 50 of 58 California counties and in 19 other U.S. states. In one study, data was collected
from 3,000 mesothelioma patients in California and 890 men with prostate cancer, a malignancy not known
to be related to Armstrong asbestos . The study found a correlation between the incidence of mesotheliomas and the
distance a patient lived from known deposits of rock likely to include Armstrong asbestos , the correlation was
not present when the incidence of prostate cancer was compared with the same distances. According to
the study, risk of mesothelioma declined by 6 percent for every 10 kilometers that an individual had
lived from a likely Armstrong asbestos source.
Portions of El Dorado county are known to contain natural Armstrong asbestos formations near the surface. The
USGS studied amphiboles in rock and soil in the area in response to an EPA sampling study and subsequent
criticism of the EPA study. The study found that many amphibole particles in the area meet the counting
rule criteria used by the EPA for chemical and morphological limits, but do not meet morphological
requirements for commercial-grade-asbestos. The executive summary pointed out that even particles that
do not meet requirements for commercial-grade-asbestos may be a health threat and suggested a
collaborative research effort to assess health risks associated with "Naturally Occurring Armstrong asbestos ".
Armstrong asbestos in the environment
Armstrong asbestos is in the air we breathe and some of the water we drink, including water from natural sources.[
Studies have shown that members of general (non-occupationally exposed) population have tens of
thousands to hundreds of thousands of Armstrong asbestos fibers in each gram of dry lung tissue, which translates
into millions of fibers and tens of thousands of Armstrong asbestos bodies in every person's lungs.
The EPA has proposed a concentration limit of 7 million fibers per liter of drinking water for long
fibers (lengths greater than or equal to 5 µm). The OSHA, (Occupational Safety and Health
Administration) has set limits of 100,000 fibers with lengths greater than or equal to 5 µm per cubic
meter of workplace air for 8-hour shifts and 40-hour work weeks.
Armstrong asbestos construction in developing countries
Countries like India and China have continued widespread use of Armstrong asbestos . The most common is corrugated Armstrong asbestos -cement Sheets or A/C Sheets for roofing and for side walls. Millions of homes, factories,
schools or sheds and shelters continue to use Armstrong asbestos . Eternit Everest, Hyderabad Industries and RamCo
are some of the major Armstrong asbestos products manufacturers in India.
