Asbestos in Bulgaria History, Current Use and Perspectives
Bulgaria has its asbestos deposits (antophylite and tremolite) as well as regions with natural asbestos admixtures in soil and endemic findings of pleural plaques.
The prevalence of endemic pleural plaques has been surveyed in 1973-1978 through a fluorographic examination of the entire population of the endemic region, older than 14. The survey covered 96059 subjects revealing 720 individuals with pleural plaques (1). The majority of the findings (94.6%) were in persons older than 40. The incidence of plaques was greater for antophylite. The existence of regions with asbestos injuries caused by natural admixtures of the mineral in soil has been confirmed in other countries as well (Russia, Cuba, Austria, Greece, Turkey). Figure 1 displays the location of acknowledged endemic regions in the Balkan states.
|
Figure 1
The substantial production and use of asbestos products in the period 1960-1990 realized at poor technical and technological level of dust prevention outlined the hygienic aspect of the problem.
The annual asbestos consumption in Bulgaria by 1980 (5) is shown in Table 1. Chrysotile is input in asbestos-cement products (pipes, plates, panels), in asbestos-perlite insulation shells, blocks, segments, in asbestos textile articles (ropes, cords, fillings, tissues), in squirted insulations of industrial equipment, in friction products, pressed materials for electronics, in diaphragms for electrolysis in chemical industry.
|
Asbestos type |
Annual usage (tons) |
|
chrysotile |
32000 (imported mainly from Russia and Canada) |
|
crocidolite |
1000 (imported from South Africa) |
|
anthophylite, tremolite |
7000 (Bulgarian production) |
Crocidolite is used as a component in some types of asbestos-cement pipes. The Bulgarian asbestos raw material is input in insulation putties of pipelines, turbines, furnaces, etc. in energetics and metallurgy. The production of Bulgarian asbestos and of major asbestos-containing products and the relevant number of enterprises are presented in Table 2.
|
Production type |
Number of plants |
|
Exploitation of the deposits of: antophylite and tremolite |
3 underground 2 ground |
|
Initial processing of the raw material |
2 |
|
Production of asbestos-cement |
6 |
|
Production of asbestos perlite |
1 |
|
Production of asbestos textile materials |
1 |
|
Production of friction materials |
1 plant and several shop facilities |
|
Production of the pressed materials |
3 - 4 shop facilities |
A wide range of ready-made imported asbestos products is used together with Bulgarian products (9)- Table 3.
|
Industry type |
Asbestos products |
|
Chemical and food processing |
filter stocks |
|
Ship-building, chemical industry, energetics |
insulation and fitting materials,some of them containing amosite (navylight, marinite) |
Hygienic control on asbestos dust has been performed since 1977 (5,13). The measurement and assessment of asbestos concentration in working environment was initially made by stationary two-stage sampling and determination of asbestos contents in total dust and its respirable fraction by mass. For this purpose a method was developed and corresponding threshold limit values (TLVs) by mass conforming with those of the former USSR were implemented. A microscopic method in phase contrast for determination of the count concentration of respirable asbestos fibers (l > 5 mm, d < 3 mm, l/d ³ 3) was studied, approbated and implemented. It was further improved to conform with WHO referent method (15). On this basis values for maximal threshold limit values for concentrations were introduced, borrowed from the UK, which became the leading ones for Bulgaria. Following the development of scientific knowledge, the TLV for count concentration of chrysotile has been diminished several times (13, 14) intending to reach that of the EU in 2001.
|
Figure 2
The control of air dust pollution up to 1998 has been executed by the bodies of the State Sanitary Control at the Ministry of Health and after that by the bodies of the Ministry of Labor and Social Policy. Asbestos dust measuring is performed by specialized laboratories at the Hygiene Epidemiology Inspectorates and the "Solid particles in the working environment" at the National Center of Hygiene, Medical Ecology and Nutrition, which is the methodological advisor of the national network. The number of exposed workers is about 25 thousand individuals (1).
There is a system for medical monitoring of exposed workers - 8 regional departments for prevention, service and diagnostics of pneumoconiosis and a Center for occupational diseases, which is a national methodological and advisory body. The diagnosis of asbestos-induced lung diseases is made at specialized diagnostic commissions for occupational lung diseases involving specialists in occupational lung diseases, occupational medicine and radiologists, competent in ILO International Radiological Classification of Pneumoconioses, Geneva-1980.
Diagnostic criteria for asbestosis, asbestos induced pleural thickenings and pleural plaques:
Compulsory criteria:
Five and more years of work environment exposure to asbestos or asbestos containing dust.
Duration of the latency period to appearance of asbestosis - 10 and more years from the beginning of asbestos exposure
X-ray findings of s, t, and s/t small irregular opacities of Category 2/1 to 3/3+ on anterior-posterior conventional chest radiography in cases with asbestosis
Pleural fibrosis and pleural plaques on chest x-ray in first oblique position
Low value of diffusion capacity (DLCO, DM) in cases with asbestosis
Low value of static ventilatory parameters (VC, FVC, TLC etc) in cases with advanced asbestosis or pleural damages
Additional criteria:
t or s/t irregular opacities and subpleural curveline shadows on chest high resolution computed tomography (HRCT), and pleural thickenings and pleural plaques on conventional chest CT (accounted by Kraus et all. Classification for pneumoconiotic findings on chest HRCT)
Pleural echography in cases with pleural thickenings, pleural plaques and pleural effusion
Perfusion scintigraphy in cases with asbestosis
Fibrobronchoscopy with transbronchial lung biopsy (TBLB), pleural biopsy (PB) etc. in difficult diagnosed cases with pulmonary or pleural impairments with histological and mineralogical estimation
Diagnostic criteria for lung cancer and malignant pleural mesothelioma:
Appearance of lung cancer in pulmonary area with asbestos induced pulmonary fibrosis, estimated by TBLB
Malignant pleural mesothelioma in pleural fibrotic area or pleural hyalinosis estimated according to PB
Asbestos bodies ore asbestos fibers in area of lung malignant process or pleural malignant tumor.
The data from conducted by 1989 measurements of asbestos dust at the work place show systematically high average shift concentrations of fibers at dust-releasing operations in all major productions in the country (13) Table 4.
|
DUST RELEASING OPERATIONS |
AVERAGE SHIFT FIBRE CONCENTRATION (f/cm3) |
|
Primary asbestos material processing; |
5 - 30 |
|
Torque converting and destroying asbestos insulations |
4-12 |
|
Preparation of asbestos putties |
2 |
|
Unpacking and dosing asbestos materials and mechanical processing of asbestos products in asbestos-cement industry; |
|
|
Dosing, combing, twisting in asbestos-textile production; |
1-8 |
|
Polishing gaskets and grinding of waste material |
1-6 |
The data from systematic 15-year monitoring of 9142 workers (1967-1982) evidence 206 cases with asbestosis and 492 cases with pre-morbid changes (1). Figure 3 presents the structure of occupational morbidity for asbestosis up to 1982. The greatest rate belongs to insulation workers and workers in power-repair (37%) followed by miners and workers in primary processing of asbestos raw material (21%), asbestos-cement production (16%), asboplasts (10%), asbestos textile (10%) and about 10% - others. Five cases of lung cancer are recorded among subjects with lung asbestosis
|
Figure 3
At considering those facts and because of the proven pathogenic effect of asbestos dust, the issue of prevention of human asbestos exposure and environmental pollution is a national priority. Measures for limitation of the asbestos problem are being implemented through Ordinance N 12/93 of the Ministry of Health (MoH), developed according the basics of ILO Convention No. 162, regulating sanitary rules at import, manufacture and use of asbestos and asbestos-containing materials and products. This Ordinance bans:
import and use of crocidolite and amosite;
production and use of asbestos materials and products which have safe and accessible substitutes;
use of asbestos-cement materials for construction of living buildings, health and education facilities, kindergartens, sport and leisure facilities;
construction of squirted asbestos insulations and covers;
transport and storage of asbestos in the open and re-use of asbestos product packages.
Permit regime is being introduced for import, manufacture, use and demolition of asbestos materials. There are requirements for the employers to control asbestos dust in the working environment and organized emission sources; to provide protective garments and respiratory masks to the workers; to certify and label the production. In this sense Ordinance 12/93 of the Ministry of Health stipulates measures for protection of workplace and ambient environment from asbestos pollution, transposing to a great degree the major provisions of Directives 83/477/EC and 87/217/EC (6,7).
The implemented measures lead to:
canceling the output and manufacture of Bulgarian asbestos material as well as asbestos-cement (only one factory left working) and asbestos-textile production.
restriction of the variety of imported asbestos materials to fitting boards, insulations, special paddings for petrochemical, chemical industry, energetics and friction products, mainly for heavy duty trucks;
decreased volume of existing productions and respective decrease of the number of exposed workers;
mitigation of asbestos exposure of major occupations to values below national TLVs (13) Table 5.
wide introduction of less dangerous materials - alternatives to asbestos.
|
Occupation |
Average shift concentration C (fibres/cm3) |
|
1 |
2 |
|
Production of asbestos Milling - Feeding operator |
0.45 |
|
Manufacture of asbestos-cement products** asbestos dosing operator |
0.2 - 0.9; 0.2 |
|
Manufacture of asbestos-cement products raw materials department (board operator) |
0.1 |
|
Asbestos-textile products manufacturing preparation of asbestos mixtures* |
1.5 |
|
Asbestos brake production
feeding, mixing and stirring operator |
0.6 |
|
Cutting fittings for petrochemical industry
cutter (fittings) |
0.4 |
|
Non-ferrous metallurgy
pouring (replacing asbestos insulating screens) |
0.5 |
|
Thermal power plant destroying turbine asbestos insulation |
6.5 |
* Closed in 1996
** Closed in 1999
The low values of asbestos fibres concentrations in the air are due to the implemented control measures and to the substantially decreased production volume, result of the country transition to market economy.
The number of newly detected cases with asbestos-induced lung diseases is small (11). Table 6 presents provisional data for the total number of subjects with asbestos-induced lung asbestosis and pleural asbestos injuries over the period 1980 2000.
|
Year |
1980 |
1985 |
1990 |
1995 |
2000 |
|
Total number of patients |
161 |
136 |
201 |
196 |
193 |
Having in mind the substantial number of workers exposed to asbestos these data could be considered as decreased. It can be supposed that there is a significant hidden morbidity and incidence rate probably due to organizational, financial and legal reasons as well as to insufficient number of specialists.
In the 80s mesothelioma was very rarely encountered in the country (2). It is not a problem of endemic regions while occupationally exposed workers, mainly from asbestos-cement manufacture who have been in contact with crocidolite, are expected to develop mesothelioma in 1 to 4% after a latent period of 20 to 40 years (2).
Table 7 illustrates all number of cases with malignant pleural mesothelioma in Bulgaria in 1991, 1992, 1993, and 1997 years (4).
|
|
1991 |
1992 |
1993 |
1997 |
||||||||
|
m* |
f** |
total |
m* |
f** |
total |
m* |
f** |
total |
m* |
f** |
total |
|
Number of Cases |
4 |
2 |
6 |
5 |
4 |
9 |
9 |
5 |
14 |
11 |
5 |
16 |
|
Incidence Rate per 100000 |
0.09 |
0.04 |
0.07 |
0.12 |
0.09 |
0.11 |
0.22 |
0.12 |
0.17 |
0.27 |
0.12 |
0. 19 |
* male
** female
There is a clear trend of increase in the number, and in the incidence rates (IR) per 100000 individuals. The absolute number and IR predominate in male, than in female population. Unfortunately there is no information on asbestos exposure of newly detected subjects with malignant pleural mesothelioma. The prevailing number of them, though, come from regions with occupational use of asbestos which suggests possible relationship between their increasing number and occupational asbestos exposure.
The preparation of the country for EU accession imposed the adoption of a number of regulations in the field of human health protection at work with dangerous substances, including asbestos:
Act for Safe and Health Work Place Conditions (State Gazette No.124, 1997, amended No.86, 1999);
Act for Protection from Adverse Effects of Chemical Substances, Preparations and Products (State Gazette No.10, 2000);
Ordinance No. 7 on minimal requirements for healthy and safe work place conditions and at use of production equipment (State Gazette No. 88, 1999);
Ordinance for notification, registration, confirming, appealing and reporting of occupational diseases (State Gazette No. 33, 2001);
Ordinance of the Ministry of Health No. 5, 1988 for the activity of the departments for prevention, diagnostics and servicing of pneumoconiosis in the country, which is to be reviewed;
Draft for updating Ordinance 12/93 in conformity with the requirements of EU Directives in the field of working environment. The draft ordinance bans all types of amphibolic asbestos, as well as certain chrysotile-containing products. The TLVs are equalized with those of EU. More strict rules are introduced for provision of safety at destroying buildings containing asbestos materials or demolishing asbestos products from buildings, constructions, installations and ships;
Draft Ordinance for ban and restrictions of particularly dangerous substances, including asbestos;
Draft Ordinance for environmental protection from asbestos pollution transposing the main provisions of Directive 87/217/EEC.
In 2000 the National Labor Inspectorate at the Ministry of Labor and Social Policy carried out a national campaign on checking the work place conditions at work with asbestos. The results (12) showed that the amount of import and use of asbestos was about 2000 tons per year. Some 4400 workers are directly exposed to asbestos dust. In Bulgaria 434 firms work continuously and 315 episodically with asbestos mainly in chemical, metallurgical, cement, glass and ceramics industry, energetics, transport enterprises, construction and furnace repair, water supply, etc. About 130 companies in the country have substituted asbestos with asbestos-free materials.
At present furnace repairs and disassembling of asbestos insulations from industrial equipment as well as destroying of old buildings containing asbestos materials constitute a problem, as these activities are performed without special preparation and dust prevention equipment.
In conclusion, the volume of asbestos use in the country during the last 10 years is reduced to 2000 tons/year, the occupational exposure to asbestos dust brought down to levels below TLV for the majority of workers in contact with asbestos, and their number diminished down to about 4500 subjects. This enables an optimistic prognosis concerning occupational asbestos-related health risk.
Current highlights for further actions in this direction are:
Development of a National program for continuous mitigation and canceling the use of asbestos in Bulgaria;
implementation of rules for provision of safety at breaking down buildings containing asbestos materials;
Overall coverage of workers previously and currently exposed to asbestos and subjects with asbestos-related diseases;
Early diagnostics of asbestos-related with application of all modern methods with a view on timely cancellation of asbestos exposure;
Provision of adequate forms for training of employers, workers, trade unionists, manufacturers, importers and distributors of asbestos and asbestos-containing materials and the public on the health risk from inhaling asbestos dust and preventive strategies;
Participation of Republic of Bulgaria in funded international projects on quality assurance at measurement and assessment of asbestos exposure, as well as prevention and early diagnostics of asbestosis and asbestos-induced lung and other diseases.
References
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Burilkov T. Profesionalni belodrobni bolesti.Medicina I fiskultura ,Sofia, 1990
Burilkov, T. D., Mihailova, L. D. In: Asbestos Medical Research, Vol. 4 of the Source book on Asbestos Diseases: Medical, Legal and Engineering Aspects, edited by: George, A., Peters, J. D., C. S. P., P. E.. Garland law Publishing New York & London
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Council Directives 83/477/ЕС and 91/382/ЕС - On the protection of workers from the risks related to exposure to asbestos at work.
Council Directive 87/217/EEC On the prevention end reduction of environmental pollution by asbestos.
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June 8, 2001
