By Jackson Orem
Asbestos are minerals occurring naturally as bundles of fibres in soil and rocks all over the world. They are composed of silicon and oxygen in combination with other elements. There are many types of asbestos, but two are most common, that is Chrysotile and Amphibole asbestos.
Chrysotile asbestos are white in colour and commonly used in heavy industries. They comprise fibres in form of spirals hence also called serpentine or curly asbestos.
Amphibole asbestos on the other hand, is needle-like. Both types of common asbestos have been linked to cancer. The main desirable qualities of asbestos has been their strength, resistance to heat, chemical corrosion and being poor conductors of electricity. Hence due to these qualities, asbestos has found many uses since the industrial revolution as insulators, automobile brakes and clutches, roofing shingles, ceiling and floor tiles, cement, textiles and many others.
However, due to growing evidence during the first half of the 20th century about health hazards resulting from inhalation and damage to lungs from dusts in workplaces, steps were taken to protect workers in the asbestos industry. In particular due recognition of asbestos as a cause of cancers.
Objective measures have been instituted to reduce exposure, including establishing exposure standards and laws that banned the use of asbestos in construction materials. Best still, alternative insulating materials have since been developed. With decrease exposure to asbestos at work places, there have been dramatic declines in health hazards, including cancers among industrial workers in occupation previously associated with heavy exposures in developed countries.
There are a number of ways by which people get exposed to asbestos; namely inhalation of asbestos fibres in the air such as during the mining and processing of asbestos, in manufacturing of asbestos-containing products or during installation of insulations.
Another major exposure is from demolition work of old buildings. In all these situations, dust from asbestos fibres floating as particles in air are inhaled. The other common route of exposure is through swallowing of asbestos fibres in contaminated food or liquids through asbestos cement pipes). Swallowing can also occur by coughing up asbestos from the lung and swallowing through the saliva.
Naturally, there may be some low level of asbestos in our outdoor environment from erosion of asbestos-containing rocks or other surfaces. The risk of this is higher in areas where rocks have higher asbestos content. It should be understood that the heaviest exposure occur among industrial workers such as shipbuilding and insulation industries to the extent that even family members of these workers can also be exposed to high levels of asbestos because the fibres can be carried home on the workers’ clothing and can then be inhaled by others in the household.
What about asbestos exposure from old building which is our biggest concern in Uganda? The risk here is in older buildings, which show signs of decomposition with evidence of break down, posing risk of asbestos fibres being blown indoors. However, there is no health risk if the asbestos materials are intact without damage or evidence of disturbance.
In this regard, maintenance workers of old asbestos structures have considerable risks comparable to that of industrial workers due to asbestos dust. Therefore, asbestos removal from buildings must be done by trained well-protected workers, equipped to minimise exposure. Asbestos has been classified as a known human carcinogen (a substance that causes cancer) by the International Agency for Research on Cancer (IARC).
According to IARC, there is sufficient evidence that asbestos causes mesothelioma (a relatively rare cancer of the thin membranes that line the chest and abdomen) and cancers of the lung, larynx and ovary. Although rare, mesothelioma is the most common form of cancer associated with asbestos exposure.
Evidence from studies in both people and lab animals has confirmed increase risk for some types of cancer due to asbestos.
When asbestos fibres are inhaled, they reach the small airways in the lungs or penetrate outer lining of the lung and chest wall causing irritation eventually causing lung cancer or mesothelioma.
Further inhalation in workers exposed to asbestos who also smoke increases the risk for the lung cancer to a greater extent than non-smokers. There is also an increased risk of mesothelioma among family members of workers and people living in neighbourhoods near asbestos factories and mines.
Studies have also found clear links between workplace exposure to asbestos and cancers of the larynx (voice box).
Does asbestos cause any other health problems? The major health problem caused by asbestos exposure, aside from cancer, is a lung disease called asbestosis. When a person breathes high levels of asbestos over time, some of the fibres lodge deep in the lungs.
Irritation caused by the fibres can eventually lead to scarring (fibrosis) in the lungs. This can make it hard to breathe. The main symptoms of asbestosis are shortness of breath and a chronic cough. When asbestosis occurs, it is typically 10 to 20 years after the initial exposure to asbestos. The disease can get worse over time. While some people may not have serious symptoms, others may be seriously disabled by breathing problems. Unfortunately there is no effective treatment for this disease.
It is good that the public in Uganda is getting concerned about the continued use of asbestos sheets, although suffice to say the risk of this exposure for causing cancers generally low. Although any exposure to asbestos potentially can lead to adverse health effect as stated earlier, especially at individual level, this risk is low at the population level in Uganda. The presence of asbestos in home building materials does not pose a health risk unless the material is broken, deteriorating or disturbed in such a way that airborne asbestos fibres are produced. The potential for this to occur is heightened only when asbestos-containing material is being broken, or when it is being nailed/ hammered.
In the absence of major mining, industrial or commercial use in Uganda our major potential risk is from house roofings, which as stated earlier is low risk exposure. In other words there is unlikely to be an outbreak of asbestos related health problem in Uganda.
None the less to prevent the few and in between individual risks or cases that might occur measures need to be put in place. The ban on exploration, mining and industrial use of asbestos or related products, including importation in Uganda should be in place and enforced. There should, therefore, be in place a plan for systematically scaling down exposure from housing. This should include ascertaining the magnitude of exposure in this category through identification and cataloguing asbestos structures in the country both in public and private use and there status.
There should be a guided national decommissioning plan purposed to protect the public and the environment. This requires review and alignment of existing legislations and polices such as occupational and housing safety standards, together with the requisite financial commitment. That said, adhoc and unco-ordinated decommissioning in piece meal by individuals and entities without a comprehensive national action framework to guide and coordinate actions will lead to creating more harm than good.
The writer is the executive director, Uganda Cancer Institute