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Asbestos - A Major Health Hazard for WorkersAsbestos is a generic term applied to a naturally occurring silicate mineral that is a known carcinogen – a substance that can cause cancer. Asbestos was used for its heat resistant properties in many products, mainly in buildings, ships and vehicles, in the 1950's, 1960's and 1970's. There are two main types of asbestos: serpentine and amphibole. The serpentine fibre has a curved or wavy appearance (snake-like) and is more likely to break into long and thin particles. Almost 90% of asbestos that occurs today belongs to this type. Chrysotile or white asbestos is a kind of serpentine. The amphibole fibres are straight and long. They include amosite (brown asbestos), crocidolite (blue asbestos), actinolite and anthophyllite. Asbestos containing materials are referred to as either friable or bonded. Friable asbestos is in the form of a powder, or can be crumbled, pulverized or reduced to powder by hand pressure when dry. Friable asbestos-containing materials include sprayed asbestos insulation, pipe and boiler insulation and non-bonded asbestos fabric. Bonded asbestos is difficult to damage by hand and includes materials such as asbestos-cement sheets, roof tiles, vinyl floor tiles and electrical switchboards. The use of amosite (brown asbestos) and crocidolite (blue asbestos) was banned in Australia in the mid 1980's. Chrysotile (white asbestos), which was used mainly for the manufacture of packing and friction materials such as brake and clutch linings, has been banned since the 31st December, 2003. Asbestos is a carcinogenic substance. Health risks arise from the inhalation of asbestos fibres into the lungs. Larger fibres are usually cleared by normal physiological processes but smaller fibres (less than 3 microns) may cause serious health effects, such as asbestosis, mesothelioma, lung cancer and pleural disease, that can take up to fifty years to develop. The risk is greater with increased exposure and even minor exposures can have serious health effects. Exposures in the past were very high in some industries, particularly asbestos mining and asbestos-cement manufacturing, that no longer occur in Australia. As awareness increases about the serious health effects of asbestos, it has become evident that the widespread use of asbestos in buildings in the 1950s, 1960s and 1970s continues to be a problem. For example, sprayed asbestos will deteriorate over time, and if uncontrolled will crumble and send fibres into the air where they could be breathed in by people in the surrounding area and even circulated around a building by air conditioning systems. The demolition of buildings with asbestos insulation or lagging has the potential for the release of massive amounts of asbestos fibre unless stringent precautions are taken. Workers who are involved in asbestos removal or who carry out dust-forming operations (such as handling, sawing, sanding, grinding, drilling, turning or general maintenance and renovation) are most at risk. The most likely sources of asbestos exposure today are:
There are four major health effects caused by exposure to asbestos:
Asbestosis is a chronic chest disease that is caused by inhalation of high concentrations of asbestos fibres. The condition can develop 10 to 20 years after initial exposure. Asbestos fibres initially damage cell membranes in the lungs. As a result, the lung tissue becomes hardened and forms scars (fibrosis). In the initial stages, asbestos-related fibrosis is mostly in the outer lung tissues. As the disease progresses, fibrosis becomes widespread throughout the lung. The hardening lung tissue restricts oxygen intake, making breathing difficult. Fibrosis also lessens the lungs' ability to process oxygen and remove carbon dioxide waste. This is known as restrictive lung disease as it reduces the total lung capacity. A person suffering from asbestosis is vulnerable to pneumonia and bronchitis and can die from their effects. What are the symptoms? Shortness of breath on exertion is usually the earliest symptom of asbestosis. However, a few patients may first present with a dry cough or chest pain unrelated to exercise. As the disease progresses, shortness of breath (dyspnoea) becomes more evident, may be present at rest, and may be associated with a productive cough. Other symptoms include persistent coughing, chest pain, phlegm, lung infections, pulmonary hypertension and heart failure. Detection In a lung X-ray, early abnormalities of asbestosis are difficult to detect. In more advanced asbestosis, the chest X-ray is obviously abnormal and is characterised by predominantly irregular opacity and/or linear shadows, which are particularly evident in the lower lobes of the lung. It can also present as a cloudy or ground glass appearance in the X-ray. Benign Pleural Disease commonly occurs before fibrosis. It happens in the lining of the lung (pleura). Patches of thickening of the pleural membrane are known as pleural plaques. The plaques show up on an X-ray and are an indictor of past asbestos exposure. While worrying to many workers, they are not in themselves a cause of lung disease. Mesothelioma is a cancer of the lung lining (pleura). It can result from even low level exposures. Crocidolite (blue asbestos) and amosite (brown or grey asbestos) have the most potent documented effects in producing this tumor. This type of cancer can take between 30 to 45 years to develop after initial exposure to asbestos. It is an aggressive cancer and is extremely painful. Mesothelioma can lead to death within a few months and sufferers rarely live longer than 12-18 months. What are the symptoms? The usual symptoms of a person with a pleural mesothelioma are chest pain and shortness of breath. The pain is described as dull and aching, but it can be very severe. The shortness of breath is rapidly progressive and may be due to lung compression or restriction of respiratory movement by the tumour. Some asbestos fibres can penetrate through the lung to the stomach or bowel. Mesothelioma can also occur in the abdominal cavity (peritoneum). Diffuse abdominal pain, abdominal swelling or progressive loss of weight may also be experienced. Detection and treatment A routine chest X-ray may lead to the diagnosis of an asymptomatic pleural mesothelioma. There is no effective treatment currently available. To date, chemotherapy and radiotherapy have not proved useful. However, research is being done in Australia to find new ways of treating mesothelioma. These include gene therapy and manipulating enzymes to control the progression of pleural mesothelioma. Lung cancer (of the bronchial tubes, lung and alveoli) can also develop after exposure to asbestos. Asbestos is one of a large number of agents linked to the development of lung cancer. Workers who were exposed to asbestos and who smoked or were exposed to second-hand smoke run a much greater risk of getting lung cancer. The risk is eight times higher than other smokers, seventeen times higher than asbestos workers who did not smoke and eighty-seven times higher than the general non-smoking public. The risk of lung cancer appears to be greatest when asbestosis is also present. What are the symptoms? The earliest symptom is an irritative cough with increasing sputum production. Further symptoms include blood tinged sputum and coughing up clear blood. Chest pain can also be experienced as well as chest infections that fail to clear up within two or three weeks. Detection and treatment X rays can show evidence of lung cancer. Examination of sputum samples is also a valuable aid in diagnosing the cause of the cancer, particularly in the case of bronchial carcinoma. Currently the best hope of recovery from lung cancer is surgical removal of the early lesions. Prognosis for more widespread lung cancer is poor. Smoking and asbestos
The health effects of asbestos strike at smokers and non-smokers alike. But cigarette smoking greatly increases the risk of death from lung cancer in people who are exposed to asbestos. Workers exposed to asbestos are 10 times more likely to develop lung cancer than unexposed general population. In workers who smoke and have a high exposure to asbestos this risk of lung cancer can be up to 100 times. Use of asbestos
Schedule 2 of the National Model Regulations for the Control of Workplace Hazardous Substances allows for the prohibition of use of specific substances where the risks to employees' health are significant and where no other control is adequate. In 2001, Schedule 2 was amended to include chrysotile asbestos so that from 31 December 2003 it is illegal to use, re-use or sell any products containing any form of asbestos in Australia. State and Territory legislation has been updated accordingly. Importing or exporting of asbestos is also banned. The ban does not apply to asbestos products that are already in place but when they are replaced, non-asbestos alternatives must be used. Any stockpiles of asbestos-containing products must be safely disposed of. There are a few exemptions that apply for a transitional period only for some uses of asbestos where no safe alternatives currently exist. Contact WorkCover for further information on exemptions. Working with asbestos-containing materials
In NSW, asbestos is regulated under the Occupational Health and Safety Act 2000. The Occupational Health and Safety Regulation, 2001 stipulates the requirements for working with asbestos and the removal of asbestos. An employer must identify and implement measures to prevent the uncontrolled disturbance of asbestos-containing material while construction work is carried out. Water blasting of asbestos containing material is prohibited. An employer must also ensure that employees and other persons contracted to carry out asbestos work are informed of the dangers involved and of precautions that should be taken. A license is required to carry out asbestos removal work unless the purpose is to: (i) obtain a sample for analysis; (ii) remove friable asbestos, at the persons usual place of work, at a frequency of one hour per week or less, or (iii) remove undamaged bonded asbestos with a total surface area of less than 200 square metres. A controller of premises must ensure that a register is kept, in which the type, condition and location of all asbestos and asbestos-containing material in any place of work is recorded. Exposure Standards
The National Occupational Health and Safety Commission [NOHSC: 1003 (1995) Updated 2003] has set the following exposure standards which state the maximum airborne asbestos fibre levels that workers can be exposed to:
The exposure standards represent airborne concentrations which, according to current knowledge, should neither impair the health of nor cause undue discomfort to nearly all workers. However it should be noted that the exposure standards do not represent `no-effect' levels which guarantee protection to every worker. The above TWA exposure standards apply to long-term exposure to a substance over an eight-hour day, for a five-day working week. Sample identification
A sample of about 100g to 250g of material is collected and sealed in an appropriate container or plastic bag and clearly labelled with its location, time and date of collection and the name of the person collecting the sample. If the suspected asbestos is located in a number of areas or layers, then multiple samples should be collected. Care must be taken to avoid exposure during collection of the sample (see safe working methods). Special laboratory techniques are required to identify asbestos. Air monitoring to determine exposure levels
Asbestos monitoring must be done by a qualified occupational hygienist and follow the procedures under the Membrane Filter Method for Estimating Airborne Asbestos Dust (NOHSC 1988). Testing for the number of asbestos fibres in a sample must be done by a laboratory accredited by NATA (the laboratory testing authority) for asbestos counting. There are two types of sampling: Occupational Sampling and Environmental Sampling.
A sample of air is collected from the worker's breathing zone and the number of fibres in a set volume of air are counted under a microscope to determine exposure levels. The results are compared against the current occupational exposure standard for airborne asbestos fibres Air sampling is done to assess the effectiveness of controls within the working area and outside the operations. These samples from the area measure background levels of asbestos and should be taken extensively during asbestos removal operations. An adequate number of samples must be taken to confirm safe levels before workers or the public are allowed to access areas from where asbestos has been removed. Ensuring the health of workers
Under the NSW Occupational Health and Safety Regulation 2001, the constructor (or removal contractor) must arrange for medical examinations for workers exposed to asbestos in removal or other construction work. These must be conducted by an authorised medical officer and the report and x-ray sent to the NSW Dust Diseases Board for its records. The results of the examination must be notified in writing to the constructor and the worker. The Workers Health Centre has doctors who are authorised medical officers under these regulations and can arrange for medical examinations and workplace screenings for asbestos exposure. Useful References
For further information and advice contact the Workers Health Centre
02 9749 7666 admin@workershealth.com.au Facts 031 © Workers Health Centre, 2004 |
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