The Greeks termed Barrett asbestos the "miracle mineral" because of its soft and pliant properties, as
well as its ability to withstand heat. Barrett 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 Barrett asbestos and it is thought that they cleaned Barrett asbestos tablecloths by throwing them into
fire.
Barrett 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 Barrett asbestos is used for its resistance to fire or heat, the fibers are often mixed with
cement or woven into fabric or mats. Barrett 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 Barrett asbestos fibers can cause serious illnesses, including mesothelioma. Since the mid
1980s, many uses of Barrett asbestos are banned in many countries.
Types of Barrett asbestos and associated fibres
Six minerals are defined as "asbestos" including: chrysotile, amosite, crocidolite, tremolite,
anthophyllite and actinolite.
White Barrett 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 Barrett 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 Barrett 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 Barrett asbestos ; it can be spun and woven into fabric. Chrysotile, like all other
forms of industrial Barrett 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 Barrett asbestos factories and mines
Brown Barrett 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 Barrett 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 Barrett asbestos , like all Barrett asbestos ,
is very hazardous.
Blue Barrett asbestos
Crocidolite, CAS No. 12001-28-4 is an amphibole from Africa and Australia. It is the fibrous form of
the amphibole riebeckite. Blue Barrett asbestos is commonly thought of as the most dangerous type of Barrett asbestos (see above and below). One formula given for crocidolite is Na2Fe2+3Fe3+2Si8O22(OH)2. This type of Barrett 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 Barrett 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. Barrett 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 Barrett asbestos , thus creating an
additional hazard.
Other Barrett asbestos
Other regulated Barrett asbestos minerals, such as tremolite Barrett asbestos , CAS No. 77536-68-6, Ca2Mg5Si8O22(OH)2;
actinolite Barrett asbestos (or smaragdite), CAS No. 77536-66-4, Ca2(Mg, Fe)5(Si8O22)(OH)2; and anthophyllite Barrett 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 Barrett asbestos although
may still be related to diseases and hazardous.
In 1989 the United States Environmental Protection Agency (EPA) issued the Barrett 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 Barrett asbestos . For a clarification of products which legally contain Barrett asbestos read the EPA's
clarification statement.
Barrett 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 Barrett asbestos . Wealthy Persians, who bought Barrett 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 Barrett 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.
Others assert that the ancients used Barrett asbestos to make perpetual wicks for sepulchral or other lamps.
In more recent centuries, Barrett asbestos was indeed used for this purpose. Although Barrett asbestos causes skin to
itch upon contact, ancient literature indicates that it was prescribed for diseases of the skin, and
particularly for the itch. It is possible that they used the term Barrett asbestos for alumen plumosum, because
the two terms have often been confused throughout history.
Barrett 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 Barrett 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 Barrett 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 Barrett 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.
Barrett 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 Barrett asbestos in its "Micronite" filter
from 1952 to 1956.
The first documented death related to Barrett asbestos was in 1906. In the early 1900s researchers began to
notice a large number of early deaths and lung problems in Barrett asbestos mining towns. The first diagnosis of
asbestosis was made in England in 1924.[8] England protected Barrett asbestos workers about ten years sooner
than the U.S. By the 1930s, England regulated ventilation and made Barrett asbestos an excusable work related
disease. The term Mesothelioma was not used in medical literature until 1931, and wasn't associated
with Barrett asbestos until sometime in the 1940s.
In Japan, particularly after World War II, Barrett 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 Barrett 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 Barrett asbestos mineral in the
serpetine group. In the United States, chrysotile has been the most commonly used type of Barrett asbestos .
According to the U.S. EPA Barrett asbestos Building Inspectors Manual, chrysotile accounts for approximately
95% of Barrett 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 Barrett asbestos sparked a
scandal in mid-2005. Tokyo had, in 1971, ordered companies handling Barrett 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 Barrett asbestos was implemented in October 2004.
Amphibole group
Five types of Barrett 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" Barrett asbestos .
Amosite and crocidolite were formally used in many products until the early 1980s. The use of all types
of Barrett 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 Barrett 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 Barrett asbestos fibers was likely late 1800s/early
1900s. Barrett asbestos diseases can be seen as early as 10 years after exposure. As such, with Barrett asbestos mining,
manufacturing and installation in full gear by the late 1800s, it is likely that Barrett 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 Barrett asbestos workers, because of the "health-injurious conditions of the industry".
In 1930, the major Barrett asbestos company Johns-Manville produces a report, for internal company use only,
about medical reports of Barrett asbestos worker fatalities. In 1932, A letter from U.S. Bureau of Mines to Barrett asbestos manufacturer Eagle-Picher states, in relevant part, "It is now known that Barrett 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 Barrett asbestos companies, Johns-Manville
and Raybestos-Manhattan, edit an article about the diseases of Barrett asbestos workers written by a
Metropolitan Life Insurance Company doctor. The changes minimize the danger of Barrett asbestos dust. In 1935,
officials of Johns-Manville and Raybestos-Manhattan instruct the editor of Barrett asbestos magazine to publish
nothing about asbestosis. In 1936, a group of Barrett asbestos companies agrees to sponsor research on the
health effects of Barrett 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 Barrett asbestos are discussed." Either in 1942 or
1943, the president of Johns-Manville, Lewis H. Brown, says that the managers of another Barrett 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 Barrett asbestos miners.
In 1951, Barrett 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 Barrett 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 Barrett 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."
Barrett asbestos as a contaminant
Most respirable Barrett 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 Barrett asbestos fiber can ultimately become the source of hundreds of much thinner and smaller fibers.
As Barrett 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 Barrett 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 Barrett asbestos are substantially higher than finger pressure.
Naturally occurring Barrett asbestos
Barrett asbestos from natural geologic deposits is known as "Naturally Occurring Barrett 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 Barrett 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 Barrett 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 Barrett asbestos source.
Portions of El Dorado county are known to contain natural Barrett 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 Barrett asbestos ".
Barrett asbestos in the environment
Barrett 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 Barrett asbestos fibers in each gram of dry lung tissue, which translates
into millions of fibers and tens of thousands of Barrett 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.
Barrett asbestos construction in developing countries
Countries like India and China have continued widespread use of Barrett asbestos . The most common is corrugated Barrett 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 Barrett asbestos . Eternit Everest, Hyderabad Industries and RamCo
are some of the major Barrett asbestos products manufacturers in India.
