What is Asbestos?
Asbestos was called "the magic mineral" because its unique chemical composition and physical properties made it suitable for use in thousands of products from floor tiles to road signs, from sewage pipes to insulating mattresses. Asbestos fibres can withstand the fiercest heat but are so soft and flexible that they can be spun and woven as easily as cotton. The term asbestos is derived from a Greek word meaning "inextinguishable, unquenchable or inconsumable." It is a generic name for a group of fibrous silicate minerals, the most common of which are detailed below.
Chrysotile:
Also known as white asbestos chrysotile is a member of the Serpentine group, so-named because the fibre is curly. Chrysotile fibres are the most flexible of all asbestos fibres and their resistance to alkaline attack makes chrysotile a useful reinforcing material in asbestos-cement building products. Chrysotile and has traditionally been the most widely used of all asbestos types, accounting for approximately 95% of asbestos mined annually. The import and use of chrysotile was banned in the UK in 1999.
Crocidolite:
Crocidolite is known colloquially as "blue" asbestos and is a member of the Amphibole group. The needle-like fibres are the strongest of all asbestos fibres and have a high resistance to acids. 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. Its import into the UK was banned in 1985.
Amosite:
Amosite is also known as brown asbestos and is, like crocidolite, a member of the Amphibole group. Its harsh, spiky fibres have good tensile strength and resistance to heat. Amosite has been principally used in the UK in the manufacture of insulation boards. The import of amosite into the UK was banned in 1985.
How Does Asbestos Kill?
As well as being ideally suited for multiple commercial uses, asbestos is also the "perfect carcinogen" as it acts as both a promoter and initiator of cancer. Experiments have shown that when an asbestos fibre enters a lung cell it can attract cancer-causing agents. Asbestos fibres are dangerous when inhaled and the dustiest processes are, in general, the most hazardous. That asbestos is a toxic material has been known for decades. Exposure to asbestos has been linked to several diseases including asbestosis, lung cancer and mesothelioma.
Asbestosis:
Evidence presented in 1907 to a government enquiry by Dr. Montague Murray described the first diagnosed case of fatal, non-tubercular, diffuse pulmonary fibrosis in an asbestos worker: asbestosis. Asbestosis is an irreversible and progressive lung condition which results from the inhalation of asbestos fibres over an extended period. In asbestosis, lung tissue is scarred and thickened by the abrasive action of the asbestos fibres in the alveoli, the air sacks. The latency period for asbestosis is usually at least ten years and the higher the exposure, the greater the chances of developing the disease. Asbestosis tends to be linked to heavy occupational exposure although cases of asbestosis among those not occupationally exposed have been known.
Lung Cancer:
An article which appeared in The Lancet in 1934 presented evidence of a link between asbestos and lung cancer. Dr. Richard Doll's landmark paper: Mortality from Lung Cancer in Asbestos Workers was published in 1955; Doll's research showed that the incidence of lung cancer among men at an asbestos factory in Rochdale was ten times the national norm. Asbestos-related lung cancer can occur from occupational or environmental exposure: it is virtually incurable. The chances of recovery for those whose lung cancer is caused by asbestos are worse because the lungs may already damaged by the dust. One type of lung cancer asbestos causes, undifferentiated, small-cell type, is the one with the least hope of treatment. The latency period for lung cancer associated with asbestos exposure is usually between fifteen and thirty-five years. An article in the Journal of the American Medical Association estimated that an asbestos insulation worker who smokes had ninety two times the chance of dying from lung cancer as a non-smoking, non-asbestos worker.
Mesothelioma:
Mesothelioma is a formerly rare, but increasingly common cancer of the lung or the abdominal cavity; the only known cause of mesothelioma is exposure to asbestos. Malignant mesothelioma can be contracted from very low exposures to asbestos and accounts for the majority of victims who contract an asbestos-related disease through environmental exposure. The latency period for mesothelioma is generally between thirty to fifty years although British courts have accepted a latency period as short as ten years. On average, mesothelioma patients survive for eighteen months to two years following diagnosis although some poeple survive considerably longer. Currently, there is no known cure.
A scientific paper published in 1960 by Dr. Christopher Wagner established the link between the occurrence of mesothelioma and asbestos exposure in South Africa. Co-written with Dr. Sleggs & Marchard, "Diffuse Pleural Mesothelioma and Asbestos Exposure in the North Western Cape Province" appeared in the British Journal of Industrial Medicine. In 1995 a routine analysis of British statistics by Professor Julian Peto of the Institute of Cancer Research uncovered a rapid acceleration in the number of British mesothelioma deaths which, he predicted, would continue to increase from 1,000 to 3,000 per year by the year 2024. According to Peto, the most worrying aspect is the discovery that the rate of mesothelioma deaths is rising in men aged 50 and younger and that most victims have only had secondary links with asbestos, often as construction workers, carpenters, plumbers or electricians.
What are the Implications for the Future?
Asbestos is a problem which crosses national borders and class divisions. With their long latency periods, asbestos diseases appear to transcend even time itself. How we identify, locate and deal with this legacy will determine whether future generations will continue to experience the painful deaths caused by exposure to the "magic mineral."
More information coming soon.