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Case study: Wismut - A Uranium Exposure Revisited

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Historical Development

The Erz mountains have been mined since the twelfth century, and beginning in 1470 silver mining brought the area to prominence. Around the year 1500 the first reports of a specific disease among miners appeared in Agricola’s writings. In 1879 this disease was recognized by Haerting and Hesse as lung cancer, but at that time what caused it was not clear. In 1925 “Schneeberg lung cancer” was added to the list of occupational diseases.

The material from which Marie Curie isolated the elements radium and polonium came from the slag heap of the Joachimstal (Jachymov) in Bohemia. In 1936 Rajewsky’s radon measurements near Schneeberg confirmed the already assumed connection between radon in the mining shafts and lung cancer.

In 1945 the Soviet Union intensified its atomic weapons research programme. The search for uranium was extended to the Erz Mountains, as the conditions for mining were better there than in the Soviet deposits. After initial inquiries, the whole area was placed under Soviet military administration and declared a restricted zone.

From 1946 to 1990 the Soviet Wismut Company (SAG), later the Soviet-German Wismut Company (SDAG), carried out uranium mining in Thuringia and Saxony (figure 1). At the time the Soviet Union was under pressure to obtain sufficient quantities of uranium to construct the first Soviet atomic bomb. Appropriate equipment was not available, so achieving the necessary level of uranium production was possible only by disregarding safety measures. Working conditions were especially bad in the years 1946 to 1954. According to an SAG Wismut health report, 1,281 miners had fatal accidents and 20,000 suffered injuries or other detrimental effects to their health just in the second half of 1949.

Figure 1.  Mining areas of SDAG Wismut in East Germany

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In post-war Germany, the Soviet Union considered uranium mining a form of reparations. Prisoners, conscripts and “volunteers” were mobilized, but at first there were hardly any skilled personnel. In all, Wismut employed between 400,000 and 500,000 people (figure 2).

Figure 2. Wismut employees 1946-90

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Bad working conditions, the lack of suitable technology and intense work pressure led to extremely high numbers of accidents and illnesses. The working conditions gradually improved beginning in 1953, when German participation in the Soviet company began.

Dry-drilling, which produced high levels of dust, was employed from 1946 to 1955. No artificial ventilation was available, resulting in high radon concentrations. In addition, the workers’ health was adversely affected by the extremely heavy labour due to the lack of equipment, the lack of safety gear and long work shifts (200 hours per month).

Figure 3. Exposure records of former SDAG Wismut

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The exposure level varied over time and from shaft to shaft. The systematic measurement of the exposure also ensued in different phases, as is shown in figure 3. The exposures to ionizing radiation (shown in Working Level Months (WLM)) can be given only very roughly (table 1). Today, comparisons with radiation-exposure situations in other countries, measurements made under experimental conditions and assessments of written records permit a more precise statement of the exposure level.

Table 1. Estimates of radiation exposure (Working Level Months/Year) in the Wismut mines

Year

WLM/Year

1946–1955

30–300

1956–1960

10–100

1961–1965

5–50

1966–1970

3–25

1971–1975

2–10

1976–1989

1–4

 

In addition to intensive exposure to rock dust, other factors relevant to illnesses were present, such as uranium dust, arsenic, asbestos and emissions from explosives. There were physical effects from noise, hand-arm vibrations and whole-body vibrations. Under these conditions, silicoses and radiation-related bronchial carcinomas dominate the record of occupational diseases from 1952 to 1990 (table 2).

Table 2. Comprehensive overview of known occupational diseases in Wismut uranium mines 1952-90

 

List No. BKVO 1

Absolute number

%

Diseases due to quartz

40

14,733

47.8

Malignant tumours or pretumours from ionizing radiation

92

5,276

17.1

Diseases due to partial body vibration

54

Diseases of tendons and extremity joints

71–72

4,950

16.0

Impaired hearing due to noise

50

4,664

15.1

Skin diseases

80

601

1.9

Other

628

2.1

Total

 

30,852

100

1 Occupational disease classification of the former GDR.
Source: Wismut Health System Annual Reports.

 

Although over time the health services of SAG/SDAG Wismut provided increasing levels of comprehensive care for the miners, including annual medical examinations, the effects on health of extracting the ore were not systematically analysed. Production and working conditions were kept strictly secret; the Wismut companies were autonomous and organizationally were a “state within a state”.

The full magnitude of the events became known only in 1989-90 with the end of the German Democratic Republic (GDR). In December 1990 uranium mining was discontinued in Germany. Since 1991 the Berufsgenossenschaften (preventing, recording and compensating industrial and trade associations), as the statutory accident insurance carrier have been responsible for recording and compensating all accidents and occupational diseases related to the former Wismut operation. This means that the associations are responsible for providing affected individuals with the best possible medical care and for collecting all relevant occupational health and safety information.

In 1990, approximately 600 claims for bronchial carcinoma were still pending with the Wismut social insurance system; some 1,700 cases of lung cancer had been turned down in earlier years. Since 1991 these claims have been pursued or reopened by the responsible Berufsgenossenschaften. On the basis of scientific projections (Jacobi, Henrichs and Barclay 1992; Wichmann, Brüske-Hohlfeld and Mohner 1995), it is estimated that in the next ten years between 200 and 300 cases of bronchial carcinomas per year will be recognized as resulting from working at Wismut.

The Present: After the Change

The production and working conditions at SDAG Wismut left their mark on both the employees and the environment in Thuringia and Saxony. In accordance with the law of the Federal Republic of Germany, the federal government took over responsibility for cleaning up the environment in the affected region. The costs of these activities for the period 1991-2005 have been estimated at DM 13 billion.

After the GDR joined the Federal Republic of Germany in 1990, the Berufsgenossenschaften, as statutory accident insurance carriers, became responsible for managing occupational diseases in the former GDR. In light of the particular conditions at Wismut, the Berufsgenossenschaften decided to form a special unit to handle occupational safety and health for the Wismut complex. To the extent possible, while respecting legal regulations protecting the privacy of personal data, the Berufsgenossenschaften secured records on former working conditions. Thus when the company was dissolved for economic reasons all evidence that could possibly serve to substantiate the claims of employees in case of illness would not be lost. The “Wismut Central Care Office” (ZeBWis) was established by the Federation on 1 January 1992 and bears responsibility for occupational medical treatment, early detection and rehabilitation.

From ZeBWis’s goal of providing appropriate occupational medical care to former uranium mining employees, four essential health surveillance tasks emerged:

  • organizing mass screening examinations for early diagnosis and treatment of diseases
  • documenting the screening findings and linking them with data from the occupational disease detection procedures
  • scientifically analysing the data
  • support of research on early detection and treatment of disease.

 

Screening is provided to the exposed workers in order to assure early diagnosis whenever possible. Ethical, scientific and economic aspects of such screening procedures require a thorough discussion which is beyond the scope of this article.

A programme of occupational medicine was developed, based on the well-founded trade association principles for special occupational medical examinations. Integrated into this were examination methods known from mining and radiation protection. The component parts of the programme follow from the main agents of exposure: dust, radiation and other hazardous materials.

The ongoing medical surveillance of former Wismut employees is aimed primarily at early detection and treatment of bronchial carcinomas resulting from exposure to radiation or other carcinogenic materials. Whereas the connections between ionizing radiation and lung cancers are proven with adequate certainty, the effects on health of long-term, low-dosage radiation exposure have been less researched. Current knowledge is based on extrapolations of data from survivors of the atomic bombings of Hiroshima and Nagasaki, as well as data obtained from other international studies of uranium miners.

The situation in Thuringia and Saxony is exceptional in that significantly more people underwent a much broader range of exposures. Therefore, a wealth of scientific knowledge can be gained from this experience. To what degree radiation works synergistically with exposure to carcinogens like arsenic, asbestos or diesel motor emissions in causing lung cancer should be scientifically examined using newly obtained data. The early detection of bronchial carcinomas through the introduction of state-of-the-art examination techniques should be an important part of the prospective scientific research.

Available Data from the Wismut Health System

In response to the extreme accident and health problems it faced, Wismut established its own health service, which provided, among other things, annual medical screening examinations, including chest x rays. In later years additional occupational disease examination units were set up. Since the Wismut health service took over not only occupational medicine, but also full medical care for employees and their dependents, by 1990 SDAG Wismut had collected comprehensive health information on many former and current Wismut employees. In addition to complete information on the occupational medical examinations, and a complete archive of occupational diseases, a comprehensive x-ray archive exists with over 792,000 x rays.

In Stollberg the Wismut health system had a central pathology department in which comprehensive histological and pathological material was collected from the miners, as well as from the inhabitants of the area. In 1994 this material was given to the German Cancer Research Center (DKFZ) in Heidelberg for safekeeping and research purposes. A portion of the records of the former health system was first taken over by the statutory accident insurance system. For this purpose, ZeBWis established a temporary archive at Shaft 371 in Hartenstein (Saxony).

These records are used for processing insurance claims, for preparing and administering occupational medical care and for scientific study. In addition to being used by the Berufsgenossenschaften, the records are available to experts and to authorized physicians in the context of their clinical work with and management of each former employee.

The core of these archives consists of the complete files of occupational diseases (45,000) which were taken over, together with the corresponding occupational disease tracing files (28,000), the tracing files for monitoring dust-endangered persons (200,000), as well as targeted documentary records with the results of the occupational medical fitness and monitoring examinations. In addition, the autopsy records of Stollberg Pathology are kept in this ZeBWis archive.

These last-mentioned records, as well as the occupational disease tracing files, have in the meantime been prepared for data processing. Both these forms of documentation will be used for extracting data for a 60,000-person comprehensive epidemiological study by the federal ministry for the environment.

In addition to the data on exposure to radon and radon by-products, the records on the exposure of former employees to other agents are of special interest to the Berufsgenossenschaften. Thus the present-day Wismut GmbH has measurement results available for viewing, in list form, from the early 1970s to the present for silicogenic dusts, asbestos dusts, heavy metal dusts, wood dusts, explosives dusts, toxic vapours, welding fumes, diesel motor emissions, noise, partial- and whole-body vibrations and heavy physical labour. For the years 1987 to 1990 the individual measurements are archived in electronic media.

This is important information for retrospective analysis of the exposures in Wismut’s uranium mining operations. It also constitutes the basis for constructing a job-exposure matrix which assigns exposures to tasks for research purposes.

To round out the picture, further records are stored in the department that safeguards health data at Wismut GmbH, including: patient files of former out-patients, accident reports by the former company and by occupational safety inspections, clinical occupational medical records, biological exposure tests, occupational medical rehabilitation and neoplastic disease reports.

However, not all Wismut archives—primarily paper files—were designed for centralized evaluation. Thus, with the dissolution of SDAG Wismut on 31 December 1990, and the dissolution of the Wismut company health system, the question was posed of what to do with these unique records.

Digression: Incorporating the Holdings

The first task for ZeBWis was to define the people who worked underground or in the preparation plants and to determine their current location. The holdings comprise some 300,000 people. Few of the company’s records were in a form that could be used in data processing. Thus it was necessary to tread the wearisome path of viewing one card at a time. The card files from nearly 20 locations had to be collected.

The next step was to collect the vital statistics and addresses of these people. Information from old personnel and wage records was not useful for this. Old addresses were often no longer valid, in part because a blanket renaming of streets, squares and roads took place after the unification treaty was signed. The Central Inhabitant Registry of the former GDR was also not useful, as by this time the information was no longer complete.

Finding these people was eventually made possible with the assistance of the Association of German Pension Insurance Carriers, through which addresses for nearly 150,000 people were collected to communicate the offer of free occupational medical care.

To give the examining doctor an impression of the hazards and exposure that the patient was subject to from the so-called occupational or work case history a job-exposure matrix was constructed.

Occupational Medical Care

Approximately 125 specially trained occupational physicians with experience in diagnosing dust- and radiation-caused diseases were recruited for the examinations. They work under the direction of ZeBWis and are spread throughout the Federal Republic to ensure that the affected individuals can obtain the indicated examination near their current place of residence. Due to intensive training of the participating physicians, standard high-quality examinations are performed at all examination locations. By distributing uniform documentation forms ahead of time, it is ensured that all relevant information is collected according to set standards and is entered into ZeBWis’s data centres. By optimizing the number of files, every examining doctor carries out an adequate number of exams every year and thereby remains practised and experienced in the examination programme. Through regular exchange of information and continuing education, the physicians always have access to current information. All examining physicians are experienced in assessing chest x rays in accordance with the 1980 ILO guidelines (International Labour Organization 1980).

The data pool, which is growing as a result of the ongoing examinations, is geared to acquaint physicians and risk assessment experts in the occupational disease detection programme with relevant preliminary findings. It furthermore provides a basis for addressing specific symptoms or diseases that appear under defined risk situations.

The Future

Comparing the number of people who worked for Wismut underground and/or in preparation plants with the number who were employed in uranium mining in the Western world, it is evident that, even with big gaps, the data on hand present an extraordinary basis for gaining new scientific understanding. Whereas the 1994 overview by Lubin et al. (1994) on the risk of lung cancer covered approximately 60,000 affected individuals and about 2,700 cases of lung cancer in 11 studies, the data from some 300,000 former Wismut employees are now available. At least 6,500 have died to date from radiation-caused lung cancer. Furthermore, Wismut never collected the exposure information on a great number of persons exposed either to ionizing radiation or other agents.

As precise information as possible on exposure is necessary for optimal occupational disease diagnosis as well as for scientific research. This is taken into account in two research projects that are being sponsored or carried out by the Berufsgenossenschaften. A job-exposure matrix was prepared by consolidating available site measurements, analysing geological data, using information on production figures and, in some cases, reconstructing working conditions in the early years of Wismut. Data of this type are a prerequisite for developing a better understanding, through cohort studies or case-control studies, of the nature and extent of illnesses that result from uranium mining. Understanding the effect of long-term, low-level radiation doses and the cumulative effects of radiation, dust and other carcinogenic materials might also be improved in this manner. Studies of this are now beginning or are being planned. With the help of biological specimens that were collected in Wismut’s former pathology laboratories, scientific knowledge can also be obtained about the type of lung cancer and also about the interactive effects between silicogenic dusts and radiation, as well as other carcinogenic hazardous materials that are inhaled or ingested. Such plans are being pursued at this time by the DKFZ. Collaboration on this issue is now underway between the German research facilities and other research groups such as the US NIOSH and the National Cancer Institute (NCI). Corresponding work groups in countries like the Czech Republic, France and Canada are also cooperating in studying the exposure data.

To what extent malignancies other than lung cancer may develop from radiation exposure during uranium ore mining is poorly understood. At the request of the trade associations, a model of this was developed (Jacobi and Roth 1995) to establish under what conditions cancers of the mouth and throat, liver, kidneys, skin or bones can be caused by working conditions such as those at Wismut.

 

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Contents

Preface
Part I. The Body
Part II. Health Care
Part III. Management & Policy
Part IV. Tools and Approaches
Biological Monitoring
Epidemiology and Statistics
Ergonomics
Occupational Hygiene
Personal Protection
Record Systems and Surveillance
Toxicology
Part V. Psychosocial and Organizational Factors
Part VI. General Hazards
Part VII. The Environment
Part VIII. Accidents and Safety Management
Part IX. Chemicals
Part X. Industries Based on Biological Resources
Part XI. Industries Based on Natural Resources
Part XII. Chemical Industries
Part XIII. Manufacturing Industries
Part XIV. Textile and Apparel Industries
Part XV. Transport Industries
Part XVI. Construction
Part XVII. Services and Trade
Part XVIII. Guides

Record Systems and Surveillance References

Agricola, G. 1556. De Re Metallica. Translated by HC Hoover and LH Hoover. 1950. New York: Dover.

Ahrens, W, KH Jöckel, P Brochard, U Bolm-Audorf, K Grossgarten, Y Iwatsubo, E Orlowski, H Pohlabeln, and F Berrino. 1993. Retrospective assessment of asbestos exposure. l. Case-control analysis in a study of lung cancer: Efficiency of job-specific questionnaires and job-exposure-matrices. Int J Epidemiol 1993 Suppl. 2:S83-S95.

Alho, J, T Kauppinen, and E Sundquist. 1988. Use of exposure registration in the prevention of occupational cancer in Finland. Am J Ind Med 13:581-592.

American National Standards Institute (ANSI). 1963. American National Standard Method of Recording Basic Facts Relating to the Nature and Occurrence of Work Injuries. New York: ANSI.

Baker, EL. 1986. Comprehensive Plan for Surveillance of Occupational Illness and Injury in the United States. Washington, DC: NIOSH.

Baker, EL, PA Honchar, and LJ Fine. 1989. Surveillance in occupational illness and injury: Concepts and content. Am J Public Health 79:9-11.

Baker, EL, JM Melius, and JD Millar. 1988. Surveillance of occupational illness and injury in the United States: Current perspectives and future directions. J Publ Health Policy 9:198-221.

Baser, ME and D Marion. 1990. A statewide case registry for surveillance of occupational heavy metals absorption. Am J Public Health 80:162-164.

Bennett, B. 1990. World Register of Cases of Angiosarcoma of the Liver (ASL) due to Vinyl Chloride Monomer: ICI Registry.

Brackbill, RM, TM Frazier, and S Shilling. 1988. Smoking characteristics of workers, 1978-1980. Am J Ind Med 13:4-41.

Burdoff, A. 1995. Reducing random measurement-error in assessing postural load on the back in epidemiologic surveys. Scand J Work Environ Health 21:15-23.

Bureau of Labor Statistics (BLS). 1986. Record Keeping Guidelines for Occupational Injuries and Illnesses. Washington, DC: US Department of Labor.

—. 1989. California Work Injuries and Illness. Washington, DC: US Department of Labor.

—. 1992. Occupational Injury and Illness Classification Manual. Washington, DC: US Department of Labor.

—. 1993a. Occupational Injuries and Illnesses in the United States by Industry, 1991. Washington, DC: US Department of Labor.

—. 1993b. Survey of Occupational Injuries and Illnesses. Washington, DC: US Department of Labor.

—. 1994. Survey of Occupational Injuries and Illnesses, 1992. Washington, DC: US Department of Labor.

Bureau of the Census. 1992. Alphabetic List of Industries and Occupations. Washington, DC: US Government Printing Office.

—. 1993. Current Population Survey, January through December 1993 (Machine-Readable Data Files). Washington, DC: Bureau of the Census.

Burstein, JM and BS Levy. 1994. The teaching of occupational health in United States medical schools. Little improvement in nine years. Am J Public Health 84:846-849.

Castorino, J and L Rosenstock. 1992. Physician shortage in occupational and environmental medicine. Ann Intern Med 113:983-986.

Checkoway, H, NE Pearce, and DJ Crawford-Brown. 1989. Research Methods in Occupational Epidemiology. New York: Oxford Univ. Press.

Chowdhury, NH, C Fowler, and FJ Mycroft. 1994. Adult blood lead epidemiology and surveillance—United States, 1992-1994. Morb Mortal Weekly Rep 43:483-485.

Coenen, W. 1981. Measurement strategies and documentation concepts for collecting hazardous work materials. Modern accident prevention (in German). Mod Unfallverhütung:52-57.

Coenen, W and LH Engels. 1993. Mastering the risks on the job. Research for developing new preventive strategies (in German). BG 2:88-91.

Craft, B, D Spundin, R Spirtas, and V Behrens. 1977. Draft report of a task force on occupational health surveillance. In Hazard Surveillance in Occupational Disease, edited by J Froines, DH Wegman, and E Eisen. Am J Pub Health 79 (Supplement) 1989.

Dubrow, R, JP Sestito, NR Lalich, CA Burnett, and JA Salg. 1987. Death certificate-based occupational mortality surveillance in the United States. Am J Ind Med 11:329-342.

Figgs, LW, M Dosemeci, and A Blair. 1995. United States non-Hodgkin’s lymphoma surveillance by occupation 1984-1989: A twenty-four-state death certificate study. Am J Ind Med 27:817-835.

Frazier, TM, NR Lalich, and DH Pederson. 1983. Uses of computer generated maps in occupational hazard and mortality surveillance. Scand J Work Environ Health 9:148-154.

Freund, E, PJ Seligman, TL Chorba, SK Safford, JG Drachmann, and HF Hull. 1989. Mandatory reporting of occupational diseases by clinicians. JAMA 262:3041-3044.

Froines, JR, DH Wegman, and CA Dellenbaugh. 1986. An approach to the characterization of silica exposure in US industry. Am J Ind Med 10:345-361.

Froines, JR, S Baron, DH Wegman, and S O’Rourke. 1990. Characterization of the airborne concentrations of lead in US industry. Am J Ind Med 18:1-17.

Gallagher, RF, WJ Threlfall, PR Band, and JJ Spinelli. 1989. Occupational Mortality in British Columbia 1950-1984. Vancouver: Cancer Control Agency of British Columbia.

Guralnick, L. 1962. Mortality by occupation and industry among men 20-46 years of age: United States, 1950. Vital Statistics-Special Reports 53 (2). Washington, DC: National Center for Health Statistics.

—. 1963a. Mortality by industry and cause of death among men 20 to 40 years of age: United States, 1950. Vital Statistics-Special Reports, 53(4). Washington, DC: National Center for Health Statistics.

—. 1963b. Mortality by occupation and cause of death among men 20 to 64 years of age: United States, 1950. Vital Statistics-Special Reports 53(3). Washington, DC: National Center for Health Statistics.

Halperin, WE and TM Frazier. 1985. Surveillance for the effects of workplace exposure. Ann Rev Public Health 6:419-432.

Hansen, DJ and LW Whitehead. 1988. The influence of task and location on solvent exposures in a printing plant. Am Ind Hyg Assoc J 49:259-265.

Haerting, FH and W Hesse. 1879. Der Lungenkrebs, die Bergkrankheit in den Schneeberger Gruben Vierteljahrsschr gerichtl. Medizin und Öffentl. Gesundheitswesen 31:296-307.

Institute of Medicine. 1988. Role of the Primary Care Physician in Occupational and Environmental Medicine. Washington, DC: National Academy Press.

International Agency for Research on Cancer (IARC). 1990. Phenoxy acid herbicides and contaminants: Description of the IARC international register of workers. Am J Ind Med 18:39-45.

International Labour Organization (ILO). 1980. Guidelines for the Use of ILO International Classification of Radiographs of Pneumoconioses. Occupational Safety and Health Series, No. 22. Geneva: ILO.

Jacobi, W, K Henrichs, and D Barclay. 1992. Verursachungswahrscheinlichkeit von Lungenkrebs durch die berufliche Strahlenexposition von Uran-Bergarbeitem der Wismut AG. Neuherberg: GSF—Bericht S-14/92.

Jacobi, W and P Roth. 1995. Risiko und Verursachungs-Wahrscheinlichkeit von extrapulmonalen Krebserkrankungen durch die berufliche Strahlenexposition von Beschäftigten der ehemaligen. Neuherberg: GSF—Bericht S-4/95.

Kauppinen, T, M Kogevinas, E Johnson, H Becher, PA Bertazzi, HB de Mesquita, D Coggon, L Green, M Littorin, and E Lynge. 1993. Chemical exposure in manufacture of phenoxy herbicides and chlorophenols and in spraying of phenoxy herbicides. Am J Ind Med 23:903-920.

Landrigan, PJ. 1989. Improving the surveillance of occupational disease. Am J Public Health 79:1601-1602.

Lee, HS and WH Phoon. 1989. Occupational asthma in Singapore. J Occup Med, Singapore 1:22-27.

Linet, MS, H Malker, and JK McLaughlin. 1988. Leukemias and occupation in Sweden. A registry-based analysis. Am J Ind Med 14:319-330.

Lubin, JH, JD Boise, RW Hornung, C Edling, GR Howe, E Kunz, RA Kusiak, HI Morrison, EP Radford, JM Samet, M Tirmarche, A Woodward, TS Xiang, and DA Pierce. 1994. Radon and Lung Cancer Risk: A Joint Analysis of 11 Underground Miners Studies. Bethesda, MD: National Institute of Health (NIH).

Markowitz, S. 1992. The role of surveillance in occupational health. In Environmental and Occupational Medicine, edited by W Rom.

Markowitz, SB, E Fischer, MD Fahs, J Shapiro, and P Landrigan. 1989. Occupational disease in New York State. Am J Ind Med 16:417-435.

Matte, TD, RE Hoffman, KD Rosenman, and M Stanbury. 1990. Surveillance of occupational asthma under the SENSOR model. Chest 98:173S-178S.

McDowell, ME. 1983. Leukemia mortality in electrical workers in England and Wales. Lancet 1:246.

Melius, JM, JP Sestito, and PJ Seligman. 1989. Occupational disease surveillance with existing data sources. Am J Public Health 79:46-52.

Milham, S. 1982. Mortality from leukemia in workers exposed to electrical and magnetic fields. New Engl J Med 307:249.

—. 1983. Occupational Mortality in Washington State 1950-1979. NIOSH publication No. 83-116. Springfield, Va: National Technical Information Service.

Muldoon, JT, LA Wintermeyer, JA Eure, L Fuortes, JA Merchant, LSF Van, and TB Richards. 1987. Occupational disease surveillance data sources 1985. Am J Public Health 77:1006-1008.

National Research Council (NRC). 1984. Toxicity Testing Strategies to Determine Needs and Priorities. Washington, DC: National Academic Press.

Office of Management and Budget (OMB). 1987. Standard Industrial Classification Manual. Washington, DC: US Government Printing Office.

OSHA. 1970. The Occupational Safety and Health Act of 1970 Public Law 91-596 91st US Congress.

Ott, G. 1993. Strategic proposals for measurement technique in occurrences of damage (in German). Dräger Heft 355:2-5.

Pearce, NE, RA Sheppard, JK Howard, J Fraser, and BM Lilley. 1985. Leukemia in electrical workers in New Zealand. Lancet ii:811-812.

Phoon, WH. 1989. Occupational diseases in Singapore. J Occup Med, Singapore 1:17-21.

Pollack, ES and DG Keimig (eds.). 1987. Counting Injuries and Illnesses in the Workplace: Proposals for a Better System. Washington, DC: National Academy Press.

Rajewsky, B. 1939. Bericht über die Schneeberger Untersuchungen. Zeitschrift für Krebsforschung 49:315-340.

Rappaport, SM. 1991. Assessment of long-term exposures to toxic substances in air. Ann Occup Hyg 35:61-121.

Registrar General. 1986. Occupation Mortality, Decennial Supplement for England and Wales, 1979-1980, 1982-1983 Part I Commentary. Series DS, No. 6. London: Her Majesty’s Stationery Office.

Robinson, C, F Stern, W Halperin, H Venable, M Petersen, T Frazier, C Burnett, N Lalich, J Salg, and J Sestito. 1995. Assessment of mortality in the construction industry in the United States, 1984-1986. Am J Ind Med 28:49-70.

Roche, LM. 1993. Use of employer illness reports for occupational disease surveillance among public employees in New Jersey. J Occup Med 35:581-586.

Rosenman, KD. 1988. Use of hospital discharge data in the surveillance of occupational disease. Am J Ind Med 13:281-289.

Rosenstock, L. 1981. Occupational medicine: Too long neglected. Ann Intern Med 95:994.

Rothman, KJ. 1986. Modern Epidemiology. Boston: Little, Brown & Co.

Seifert, B. 1987. Measurement strategy and measurement procedure for investigations of inside air. Measurement technique and Environmental protection (in German). 2:M61-M65.

Selikoff, IJ. 1982. Disability Compensation for Asbestos-Associated Disease in the United States. New York: Mt. Sinai School of Medicine.

Selikoff, IJ, EC Hammond, and H Seidman. 1979. Mortality experience of insulation workers in the United States and Canada, 1943-1976. Ann NY Acad Sci 330:91-116.

Selikoff, IJ and H Seidman. 1991. Asbestos-associated deaths among insulation workers in the United States and Canada, 1967-1987. Ann NY Acad Sci 643:1-14.

Seta, JA and DS Sundin. 1984. Trends of a decade—A perspective on occupational hazard surveillance 1970-1983. Morb Mortal Weekly Rep 34(2):15SS-24SS.

Shilling, S and RM Brackbill. 1987. Occupational health and safety risks and potential health consequences perceived by US workers. Publ Health Rep 102:36-46.

Slighter, R. 1994. Personal communication, United States Office of Worker’s Compensation Program, September 13, 1994.

Tanaka, S, DK Wild, PJ Seligman, WE Halperin, VJ Behrens, and V Putz-Anderson. 1995. Prevalence and work-relatedness of self-reported carpal tunnel syndrome among US workers—Analysis of the occupational health supplement data of 1988 national health interview survey. Am J Ind Med 27:451-470.

Teschke, K, SA Marion, A Jin, RA Fenske, and C van Netten. 1994. Strategies for determining occupational exposure in risk assessment. A review and a proposal for assessing fungicide exposures in the lumber industry. Am Ind Hyg Assoc J 55:443-449.

Ullrich, D. 1995. Methods for determining indoor air pollution. Indoor air quality (in German). BIA-Report 2/95,91-96.

US Department of Health and Human Services (USDHHS). 1980. Industrial Characteristics of Persons Reporting Morbidity During the Health Interview Surveys Conducted in 1969-1974. Washington, DC: USDHHS.

—. July 1993. Vital and Health Statistics Health Conditions among the Currently Employed: United States 1988. Washington, DC: USDHHS.

—. July 1994. Vital and Health Statistics Plan and Operation of the Third National Health and Nutrition Examination Survey, 1988-94. Vol. No. 32. Washington, DC: USDHHS.

US Department of Labor (USDOL). 1980. An Interim Report to Congress on Occupational Diseases. Washington, DC: US Government Printing Office.

US Public Health Services (USPHS). 1989. The International Classification of Diseases, 9th Revision, Clinical Modification. Washington, DC: US Government Printing Office.

Wegman, DH. 1992. Hazard surveillance. Chap. 6 in Public Health Surveillance, edited by W Halperin, EL Baker, and RR Ronson. New York: Van Nostrand Reinhold.

Wegman, DH and JR Froines. 1985. Surveillance needs for occupational health. Am J Public Health 75:1259-1261.

Welch, L. 1989. The role of occupational health clinics in surveillance of occupational disease. Am J Public Health 79:58-60.

Wichmann, HE, I Brüske-Hohlfeld, and M Mohner. 1995. Stichprobenerhebung und Auswertung von Personaldaten der Wismut Hauptverband der gewerblichen Berufsgenossenschaften. Forschungsbericht 617.0-WI-02, Sankt Augustin.

World Health Organization (WHO). 1977. Manual of the International Statistical Classification of Diseases, Injuries, and Causes of Death, Based on the Recommendations of the Ninth Revision Conference, 1975. Geneva: WHO.