Viewpoint

Dangerous Asbestos

By Tim Frederikson

Over the past year there has been a great deal of publicity concerning the dangers of asbestos and its effects on people exposed to it. Claims for compensation have been laid and further actions are pending from many industrial sectors where asbestos is used -- construction, the automotive industry and fertiliser manufacture, to name a few.

Asbestos is the name given to a group of impure magnesium silicate minerals. Their fibrous form and characteristics make them useful in the manufacture of items requiring heat resistance and flexibility. They are found in a wide range of products, including brake-shoes, insulation panels, firefighters' gloves and paints.

In New Zealand, several types of asbestos were processed and used for many years with varying hazards, ranging from high to extreme.

The health hazard occurs because asbestos fibres can be inhaled into the lungs. The fibres can't be broken down by body fluids or removed by current technology. Each fibre has a hooked end which catches in lung tissue, lodging it there for life. The body attempts to protect itself by forming tissue around the area where the hook has punctured the lung tissue. This becomes a continual process and the lungs eventually become covered with this growing scar tissue or tumor. Eventually the lungs can no longer process oxygen because of their reduced active area, and the person dies. Depending upon the amount inhaled and the period of exposure, signs of this occupational disease can occur 10 to 40 years following the last exposure.

There is a further health hazard peculiar to those workers whose exposure results from asbestos grinding or mining operations. Mesothelioma is a similarly debilitating form of lung disease. The difference lies in the size and shape of the inhaled particle, with mesothelioma caused by asbestos dust rather than fibres. The dust is just as impossible to shift from deep in the lungs but, instead of forming scar tissue around the particle, the body creates a heavy yellow fluid which it attempts to cough out. Sadly, this fluid continues to slowly fill the lung's air sacs, gradually suffocating the victim.

For many years, the apparent durability and flame resistance of asbestos made asbestos a common construction material. However, time and damage would cause the material to revert to its fibrous or powdery state.

People concerned about possible exposure and material can now contact their local Health Protection Unit or Occupational Safety & Health office for advice and assistance.

As far as health effects are concerned, the situation is more difficult because of the long time between exposure and the onset of symptoms. A series of lung function tests can show if any impairment is present. X-rays do not usually show abnormalities until the lungs have decreased in their capacity and so are not a reliable indication of asbestosis.

Substitutes for asbestos are available but these often do not have the latter's full range of useful properties. In addition, some have their own health hazards.

Tim Frederikson is a chemical safety consultant.