Mineral dusts and prevention of silicosis, vol 4; No.2, September 1997Global Elimination of Silicosis: The ILO/WHO International Programme,by Igor A. Fedotov |
Silicosis is a well-known fibrogenic lung disease. The occupational origin of silicosis was recognized as far back as the Hippocratic times. Despite all efforts to prevent it, this ancient disease still afflicts hundreds of thousands of miners and millions of other workers engaged in hazardous dusty occupations in many countries. With its potential to cause physical disability, silicosis continues to be one of the most important occupational health problems in the world.
Action needed
Today, society possesses all the necessary means to combat this preventable disease and there is no excuse for silicosis persistence throughout the world. In the absence of effective specific treatment of silicosis, the only approach towards the protection of workers' health is the control of exposure to silica-containing dusts. Concerted actions from all those concerned with workers' health are required for this purpose.
At the national level laws and regulations and their enforcement, adoption of occupational exposure limits (OELs) and relevant technical standards, governmental advisory services, an effective inspection, a well- organized reporting system, and a national action programme involving governmental institutions, industry and trade unions, are the necessary elements of a sound infrastructure which is necessary to combat silicosis.
At the enterprise level application of appropriate technologies to avoid the formation of silica-containing dust, use of engineering methods of dust control, compliance with prescribed OELs and technical standards, surveillance of work environment to assess effectiveness of preventive measures, surveillance of workers' health to detect early development of silicosis, use of personal protective equipment (as a temporary measure), health education and training are imperative. The cooperation between employers and workers is a prerequisite for a success.
Technical knowledge, professional expertise, qualified personnel trained in using appropriate technologies and methods of dust control, and access to relevant information are needed for everyday activities to prevent silicosis. An evaluation of technologies applied in various industrial processes where the exposure to silica is encountered and available methods of dust control is necessary to assess the efficiency of prevention and to be able to recommend effective measures and technical standards for a wider use (transfer of technology). Above all, epidemiological studies and research are needed to learn more about the development of silicosis to prevent it successfully.
Occupational exposure limits
In real working conditions, the concentrations of airborne particles vary greatly around an average value. The WHO Study Group (1986) recommended the health-based exposure limits for free crystalline silica and coal-mine dust as time-weighted average (8-hour shift, 40-hour working week, 35-year working life) concentrations of respirable dust sampled in the breathing zone (60-cm sphere around the worker's head). For other sampling conditions, the exposure limit values have to be converted accordingly. The tentative recommended limit for free crystalline silica is 40 ęg/m3. For coal-mine dust with a free silica content equal to or less than 7% (mass) of the respirable mixed dust fraction, the range of 0.5 to 4.0 mg/m3 is recommended, tentatively. Limits above 0.5 mg/m3 should be applied only when there is sufficient epidemiologic evidence that the particular coal-mine dust is relatively harmless, and there is a limited risk of developing radiographic category 1 simple pneumoconiosis during the whole working life (The 1980 ILO International Classification of Radiographs of Pneumoconioses). In the absence of such epidemiological data, a limit in the range of 0.5 to 4 mg of dust per m3 may be used by comparing a new mine with others with a similar grade and composition of coal and similar working conditions. For coal-mine dust with free crystalline silica content higher than 7% (mass) of the respirable mixed dust, the above-mentioned limit should be applied, i.e. 40 ęg/m3.
There is a need for further research to identify the extent to which fluctuations in concentrations around a time-weighted average may be acceptable. The results of latest studies will be discussed at the Ninth International Conference on Occupational Respiratory Diseases (13 16 October 1997, Kyoto, Japan), which the ILO is at present organizing.
The ILO/WHO International Programme
Over the years, the ILO and WHO have paid special attention to the prevention of silicosis. In order to promote a wide international cooperation in this field, a joint ILO/WHO Programme on Global Elimination of Silicosis was proposed by the Joint ILO/WHO Committee on Occupational Health (April 1995). The purpose of the Programme is to offer countries a framework for a broad international collaboration and to contribute to the elimination of silicosis as an occupational health problem worldwide.
By establishing the Programme, the ILO and WHO have shaped a policy perspective for their member States for a wide international collaboration which should be governed by a true partnership between industrialized countries and developing countries. Every efforts should be made to promote the exchange of technical information and expertise in order to attain the common goal of elimination of silicosis.
The immediate objective of the ILO/WHO International Programme is to promote the development by countries of National Programmes on Elimination of Silicosis to reduce significantly the incidence rate of silicosis by the year 2010.
The development objective of the ILO/WHO International Programme is to establish wide international cooperation on global elimination of silicosis to eliminate it as an occupational health problem by the year 2030.
The principal means of action of the Programme will be:
(i) to catalyse long-term efficient cooperation between industrialized countries, developing countries and international organizations;
(ii) to promote the establishment by countries of National Programmes on Elimination of Silicosis accompanied by National Action Plans;
(iii) to provide technical assistance to countries in developing models (blue prints) of National Programmes and National Action Plans on Elimination of Silicosis and support their implementation.
Despite many obstacles, the idea of global elimination of silicosis is technically feasible. Positive experience gained by a number of countries shows that it is possible to reduce significantly the incidence rate of silicosis by using appropriate technologies and methods of dust control. The use of these technologies and methods has proved to be effective and economically affordable. Assistance provided within the framework of the ILO/WHO International Programme will contribute to the upgrading of national capacities to prevent silicosis. Only through a very broad collaboration at the international level, supported by joint multidisciplinary efforts by occupational health professionals and from all economic sectors concerned in each country, can this goal of global elimination of silicosis be achieved.
Dr. Igor A. Fedotov
Occupational Health Specialist
SEC HYG, ILO
4, route des Morillons
CH-1211 Geneva 22
SWITZERLAND