Research and risk of asbestos

Research and risk of asbestos irishtimes.com

Research and risk of asbestos

Risk of Asbestos and Cancer

What is asbestos?

Asbestos is a group of minerals that appear naturally as a fiber bundle. These fibers are found in soil and rocks in many parts of the world. They are mostly made of silicon and oxygen, but they also contain other elements. There are 2 main types of asbestos:

Chrysotile asbestos, also known as white asbestos, is the most common type of asbestos in industrial applications. When viewed under a microscope, chrysotile asbestos fibers wrap themselves in a spiral, which is why this form of asbestos is also called serpentine or curly asbestos.

Amphibol asbestos fibers are straight and needle-like. There are several types of amphibole fibers, including amosite (brown asbestos), crocidolite (blue asbestos), tremolite, actinolite, and anthophyllite.

Both types of asbestos have been linked to cancer.

Asbestos fibers can be useful because they are strong, resistant to heat and many chemicals, and do not conduct electricity. As a result, asbestos has been used as an insulating material since ancient times. Since the industrial revolution, asbestos has been used to isolate factories, schools, homes and ships, and to make car brakes and clutch parts, roof shingles, ceilings and floor tiles, cement, textiles, and hundreds of other products.

During the first half of the 20th century, more evidence showed that breathing in asbestos caused scarring in the lungs. Exposure to asbestos dust in the workplace is not controlled at that time. Starting in England in the 1930s, steps were taken to protect workers in the asbestos industry by installing ventilation and disposal systems. However, in an effort to make large ships during World War II, a large number of workers were exposed to high levels of asbestos.

When asbestos-related cancers became known in the second half of the 20th century, steps were taken to reduce exposure, including setting exposure standards and laws that prohibit the use of asbestos in construction materials. There has been a dramatic decline in importing and using asbestos in the United States since the mid-1970s, and alternative insulation materials have been developed. As a result, asbestos exposure has dropped dramatically. However, it is still used in some products, and may still be exposed to asbestos in old buildings, water pipes and other arrangements. The use of asbestos has been banned in the European Union since 2005, although the ban does not require the elimination of existing asbestos. Still, heavy use of asbestos continues to occur in several countries.

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how are people exposed to asbestos?

People can be exposed to asbestos in various ways:

Inhaling asbestos: Most of the exposure comes from breathing in asbestos fibers in the air. This can occur during mining and processing of asbestos, when making products containing asbestos, or when installing asbestos insulation. This can also occur when old buildings are destroyed or renovated, or when old asbestos-containing materials begin to break down. In this situation, asbestos fibers tend to make dust made of small particles that can float in the air.

Swallowing asbestos: Asbestos fibers can also be swallowed. This can occur when people consume contaminated food or liquids (such as water flowing through asbestos cement pipes). This can also occur when people cough asbestos they breathe, and then swallow their saliva.

Many people are exposed to very low levels of asbestos that occur naturally in the outside air as a result of erosion of rocks containing asbestos. This risk is higher in areas where rocks have a higher asbestos content. In some areas, asbestos can be detected in water supplies and also in the air. It can enter the water through several sources, such as rock or soil erosion, corrosion of asbestos cement pipes, or damage to roofing materials containing asbestos which then enter sewers after rain.

However, people with the heaviest exposure are those who work in the asbestos industry, such as shipbuilding and insulation. Many of these people remember working on a thick cloud of asbestos dust, day after day.

Family members of asbestos workers can also be exposed to high levels of asbestos because fiber can be taken home to workers' clothes, and can then be inhaled by other people in the household.

Asbestos exposure is also a concern in old buildings. If building materials containing asbestos (such as longer insulation and ceiling and floor tiles) begin to break down over time, asbestos fibers can be found in the air in the room and can pose a health threat. There are no health risks if asbestos is bound to finished products that are intact, such as walls and tiles. As long as the material is not damaged or disturbed (for example, by drilling or renovation), the fiber is not released into the air. Maintenance workers who sweep and dispose of asbestos dust or handle materials containing damaged asbestos are often exposed to higher levels than others in these buildings. Removing asbestos from other homes and buildings can also cause some exposure, although modern asbestos reduction workers are trained to use appropriate protective equipment to minimize exposure.

Although asbestos use has declined in the United States, people can still be exposed to asbestos in the workplace. In recent years, the US Occupational Health and Safety Administration (OSHA) estimates that more than one million American employees in the construction and general industries sectors face significant asbestos exposure to the work.

Mining and the use of asbestos also still endanger health in other parts of the world. Mining in the Russian Federation, China, Kazakhstan, Brazil, Canada and Zimbabwe accounts for almost all of the world's asbestos production. Much of what is produced is used in the Russian Federation (and other countries in the former Soviet Union) and Asia, and its use is increasing in some regions. In 2005, the World Health Organization estimated that around 125 million people worldwide were exposed to asbestos in the workplace, although it was found to be related to cancer and other lung diseases for more than 60 years.

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Does asbestos cause cancer?

The researchers used two main types of studies to try to find out whether a substance causes cancer.

Study in people: One type of study looks at cancer rates in different groups of people. Such studies can compare cancer rates in a group exposed to a substance with cancer rates in a group that is not exposed to it, or compare it to cancer rates in the general population. But it is sometimes difficult to know what the results of this study mean, because many other factors can influence the results.

Laboratory research: In studies conducted in the laboratory, animals are exposed to a substance (often in very large doses) to see if it causes tumors or other health problems. The researchers might also expose normal cells on laboratory plates to substances to see if it causes the type of changes seen in cancer cells. It is not always clear whether the results of this type of study will apply to humans, but laboratory studies are a good way to find out whether a substance might cause cancer.

In most cases, these two types of studies do not provide their own evidence, so researchers usually see human and laboratory-based studies when trying to find out if something causes cancer.

Evidence from human and laboratory animal studies shows that asbestos can increase the risk of several types of cancer.

When asbestos fibers in the air are inhaled, they can stick to mucus in the throat, trachea (windpipe), or bronchi (large respiratory tract of the lungs) and may be cleansed by coughing or swallowing. But some fibers reach the ends of small airways in the lungs or penetrate into the outer layers of the lungs and chest wall (known as the pleura). This fiber can irritate cells in the lungs or pleura and eventually cause lung cancer or mesothelioma.