Asbestos was used in some products 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.
Crocidolite, also known as blue or green asbestos, is a member
of the Amphibole group. The needle like (or acicular) fibres are
the strongest of all asbestos fibres and have a high resistance to
acids. Crocidolite was used in yarn and rope lagging from the 1880s
until the mid 1960s and in preformed thermal insulation from the
mid 1920s until 1950. The high bulk volume of crocidolite makes it
suitable for use in sprayed insulation. Crocidolite is known to be
the most lethal of all the asbestos types. The "import (into the
UK), supply and use of crude, fibre, flake, powder or waste
crocidolite or amosite" wasn't actually banned until 1985, although
strict guidelines had regulated its use since 1969. Crocidolite,
CAS No. 12001-28-4 is an amphibole found primarily in southern
Africa, but also in Australia. It is the fibrous form of the
amphibole riebeckite. Note: Riebeckite is not named after Jan van
Riebeck - but rather Emil Riebeck, the German geologist who
discovered it in Yemen on the Arabian Peninsula. One formula given
for crocidolite is
Na2Fe5Si8O22(OH)2.The
name is said to come from the nearby Crocodile River. Another
origin may be from the Greek word for "wooly" which also sounds
similar.
Historic usage
Asbestos was named by the ancient Greeks. The ancients already
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 asbestos. Wealthy Persians, who bought asbestos
imported over the Hindu Kush, amazed guests by cleaning the cloth
by simply exposing it to fire. Some of the Persians believed the
fiber was fur from an animal named samandar that lived in fire and
died when exposed to water. While traveling to China, Marco Polo
described observing miraculous garments that were cleaned by being
placed in fires. These garments were likely made from asbestos.
Some archeologists believe that ancients made shrouds of
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 asbestos to
make perpetual wicks for sepulchral or other lamps. In more recent
centuries, asbestos was indeed used for this purpose. Although
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
asbestos for alumen plumosum, because the two terms have often been
confused throughout history.
Recent usage
Asbestos became more widespread during the industrial
revolution; in the 1866 it was used as insulation in the U.S. and
Canada. Development of the first commercial asbestos mine began in
1874 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 in the United States have died, or will die, from
asbestos exposure related to ship building. In the Hampton Roads
area, a shipbuilding center, mesothelioma occurrence is seven times
the national rate. Thousands of tons of 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 in the United States during WWII; for every thousand
workers about fourteen died of mesothelioma and an unknown number
died from asbestosis. Asbestos fibers were once used in automobile
brake pads, shoes, and clutch discs. Since the mid-1990s, a
majority of brake pads, new or replacement, have been manufactured
instead with linings made of ceramic, carbon, metallic and Aramid
fiber (Twaron or Kevlar—the same material used in bulletproof
vests). Kent, the first filtered cigarette on the market, used
crocidolite asbestos in its "Micronite" filter from 1952 to 1956.
The first documented death related to asbestos was in 1906. In the
early 1900s researchers began to notice a large number of early
deaths and lung problems in asbestos mining towns. The first
diagnosis of asbestosis was made in the UK in 1924. By the 1930s,
the UK regulated ventilation and made asbestosis an excusable work
related disease, about ten years sooner than the U.S. The term
Mesothelioma was first used in medical literature until 1931; its
association with asbestos was first noted sometime in the
1940s.
Mesothelioma, more precisely malignant mesothelioma, is a rare
form of cancer that develops from the protective lining that covers
many of the body's internal organs, the mesothelium. It is usually
caused by exposure to asbestos. Symptoms or signs of mesothelioma
may not appear until 20 to 50 years (or more) after exposure to
asbestos. Shortness of breath, cough, and pain in the chest due to
an accumulation of fluid in the pleural space (pleural effusion)
are often symptoms of pleural mesothelioma. Steve Mc Queen was one
of the more famous deaths from this form of cancer.
The United States government and 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 asbestos industry officials knew of asbestos
dangers since the 1930s and had concealed them from the public. In
Japan, particularly after World War II, 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 asbestos in Japan peaked
in 1974 and went through ups and downs until about 1990, when
production began to drop severely. In Australia, asbestos was
widely used in construction and other industries between 1945 and
1980. From the 1970s there was increasing concern about the dangers
of asbestos and its use was phased out. Mining ceased in 1983, The
use of asbestos was phased out in 1989 and banned entirely in 2004.
The dangers of asbestos are now well known in Australia and there
is help and support for sufferers from asbestosis or
mesothelioma.
In order to substantiate your visit and be able to claim this
Earthcache, a number of questions need to be answered and submitted
to the cache developer, via e-mail.
You should also post a photograph on the site with your log of
your GPSr near GZ.
1. As you drive along the Kaapsehoop/Nelspruit road – you
will see a lot of evidence of asbestos mining. Describe some of the
signs of mining you observed (see waypoints in cache).
2. Look closely at the exposed outcrop here where you have
stopped. Look at the shape and colour of the “crystals”
in the rocks. Look specifically for any rock that looks fibrous
– see if you can break or get a freshly exposed rock.
3. Describe any asbestos related incidents in your log that you
remember from you own life (appliances you used, school experiments
etc.).
4. Describe any other interesting things you saw while doing
this cache.
NOTE: You may log your visit prior to approval, but e-mail
submissions that do not meet the above criteria will be
deleted.
