Mineral dusts and silicosis

Dr. Wajira M. Palipane

M.Med. (Occupational Medicine - National University of Singapore)

Rapid population growth, industrial development and urbanisation coupled with the increasing desire of the mankind for better standard of living challenge the workers safety in many economic sectors mainly, construction, manufacturing, mining and agriculture.

Dust is associated with most of the human activities thereby workers at any type of work place are exposed to dust. Dust material, which arises from the mechanical comminution of coarser material during grinding, drilling, blasting milling or handling.

Dust can be either toxic to human body or simply a nuisance. Nuisance dusts arise from substances that do not exert toxic effects. Toxic dusts like silica dust, asbestos dusts, graphite dust, can be harmful to human beings, mainly to their lungs. The occupational origin of silicosis had been recognised as far back as the times of Nance. Therefore, silicosis is considered as one of the oldest occupational diseases known.

Quartz dust is present in several industrial activities. Silicosis is the most common "pneumoconiosis" worldwide. Silicosis is caused by exposures to any dust which contains free silica. Free silica is a very dominant fibrogenic agent which causes fibrosis of the lung tissue.

Despite all efforts by world bodies such as WHO and ILO to prevent silicosis this ancient disease still plagues tens of thousands of miners and workers engaged in hazardous dusty occupations in many countries. Silicosis continues to be one of the most important occupational diseases worldwide.

Silicosis develops gradually over a period of nearly ten years of exposure to free silica. The seventy of the disease however depends on several factors such has the nature of the dust, its concentration and duration of exposure and individual susceptibility of those who are exposed.

The prevalence of silicosis in Sri Lanka is said to be very low but some research workers say it is not prevalent in this country. My personal point of view is, we need to do a large scale epidemiological study on those who are exposed to hazardous dusts containing free silica to assess the real situation of silicosis in Sri Lanka.

Exposure to silica dusts exists in several industries in Sri Lanka including mining, foundries, ceramic industry , quarries and sand blasting etc. Therefore I dare not say that silicosis is not prevalent in Sri Lanka.

In real working conditions the concentrations of airborne particles vary significantly. The WHO recommended exposures limit for free crystalline silica is 40 micrograms per cubic metre of air. The ILO and WHO have paid special attention in order to prevent silicosis worldwide.

The joint ILO/WHO programme on Global Elimination of silicosis was proposed by the joint ILO/WHO committee on occupational Health in April 1995. The objective of this programme was to assist the countries for as broad international collaboration and to contribute to the elimination of silicosis as an occupational health problem worldwide.

For this programme to be effective a wide international collaboration and strong partnership between industrialised countries and developing countries are mandatory. Genuine efforts should be taken to promote the exchange of technical information and expertise between industrialised countries and developing countries.

The major strategies of this programme are:

To promote effective and long term cooperation between industrialised, developing countries and international organisation.

To promote establishment of national programs on elimination of silicosis by individual countries. To provide technical assistance and expertise to countries in their national action plans.