Document mmNebdVDbrob6Bq1rQdVg1qnO

A PROSPECTIVE MEDICAL SURVEILLANCE PROGRAM FOR THE DETECTION AND PREVENTION OF INDUSTRIALLY RELATED CANCER* Richard A. Greenberg, Ph.D., M.P.H. Carlo H. Tamburro, M.D. Charles E. Kupchella, Ph.D. Cancer Center and Department of Community Health and Medicine University of Louisville Louisville, Kentucky I. INTRODUCTION The extent of occupational disease in the United States is unknown; one of the reasons for this is that we have not, as yet, developed the routine mechanisms for the collection, storage and analysis of the re quired data. Rose et al. (I), recently identified three major elements that must be developed to study the national occupational health: 1) uniform methods for maintaining medical surveillance of the incidence and prevalence of occupational disease; 2) a system for monitoring all aspects of the work environment that may contribute to occupational dis ease; and, 3) better application of existing methods and the development of better methods to establish scientifically the relationships between occupational disease and the work environment. We would like to discuss the elements of a system of medical sur veillance now being developed for a cohort of industrial workers known to have been exposed, in varying degrees, to a known carcinogen, vinyl chlor ide. Perhaps a brief history is in order. Since 1974, seven cases of angiosarcoma of the liver have been discovered at the B.F. Goodrich Chemi cal plant among workers exposed to vinyl chloride. The company has been *Thi research is supported by Contract No. N01-CN-55212 from the National Cancer Institute, Cancer Control Branch, and B.F. Goodrich Grant. 1921 BFG08586 tootggoz in operation in Louisville since 1941. Plant personnel represent a cross section of the working population with jobs ranging froa annual labor to highly skilled technical and professional positions. The average employee has approximately thirteen years service. There are currently about 1,200 eaployees. Although the number has changed continuously due to technology and economic conditions, the rate of change has been relatively low. In response to the discovery of anglosarcoaa in 1974, s screening program was Initiated as a joint effort of the B.F. Goodrich Company and the University of Louisville. This effort has since been expanded by a direct grant to the University of Louisville Cancer Center by a contract from the National Cancer Institute, Division of Cancer Control and Rehabi litation. In addition to aedlcal surveillance, the program Includes edu cation and psychosocial rehabilitation. II. MEDICAL SURVEILLANCE SYSTEMS The medical surveillance system is composed of four ordered levels of screening. Each increased level tends to improve the total precision but at an ever increasing cost and complexity. The ideal for these pro grams is to obtain a maximum capability of dlacovering potential occupa tionally-induced cancer (aensitlvity) at an economic and social cost acceptable to management, labor, federal regulatory agencies and the indi vidual employee. The program should also be readily transferable to other industries. Level I is the minimum needed for an effective surveillance system in an industrial environment; it is applicable in industries of limited economic capability and/or a low expected rate of industrial illness of cancer. It serves as the foundation for all additional levels of screen ing and surveillance. This level contains three siajor components: 1) the employees' work history. This should include a chronological summary of each job an employee has held within the industrial complex. 2) An expo sure history for each Job. This would be a subjective determination of which agents or chemicals are or have been associated with each particular job. This estimate is based upon all available data and should be as quantitative as knowledge of the operation will permit, i.e., it would usually be a binary or rank order statistic. 3) The aedlcal history. The medical history of each employee should be determined upon initial employ ment and should include previous hospitalizations and illness. Subsequent 1922 BFG08587 7m TG OK absences due to Illness should be recorded and should Include the cause of Illness. Final diagnosis for hospitalization should be obtained as part of the medical history. This would constitute the Morbidity data. In addition, when possible, the death certificates for current or former employees should be obtained as part of the final medical history. This would constitute the basis for the mortality data. Level II would add to the detailed medical history and would in clude a physical examination. Specific information and physical determi nations related to the suspected industrial problem would be obtained. The exposure data would be extended to Include area monitoring for sus pected Industrial toxins or carcinogens. The medical screening program would be instituted and would include simple laboratory screening, such as blood and urine determinations; biochemical studies, utilizing the simplest available methods of detecting specific system disorders; radio logical studies, consisting of cosmon procedures such as x-rays of the chest and limbs; and finally, specific functional studies, designed to screen those selected body systems most likely to be involved as a result of exposure to the industrial environment. At Level III, the exposure data would be expanded to include indi vidual monitoring in addition to area monitoring and subjective job eval uation. The medical screening system would utilize studies designed for more specific purposes aimed at a target system organ. For example, in the case of the hepatobiliary system, specific enzymes (serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase); substance clearances (indocyanine green, bile acids); and protein determinations (albumin, globulin, etc) would be utilized. In addition, radiological studies would now include more sophisticated techniques such as liver, spleen and lung scans. Finally, functional studies such as pulmonary ventilation, cardiac sionltoring, and muscle exercise testing, would be initiated. The fourth level of medical surveillance requires the addition of two more major elements: 1) an educational program designed to inform, educate and encourage participation of the employees in the screening pro cedures on a continuing and systematic basis. 2) A counseling and follow up program for psychosocial rehabilitation to assist asymptomatic indivi duals, identified as being at high risk of Industrial disease, and indi viduals incidentally discovered to have early Industrial or non-industrial related illness. Furthermore, counseling and assistance will be needed 1923 BFG08588 20301003 for the symptomatic employee who will require occupational rehabilitation to new or modified forms of employment. This latter component of the medical surveillance system will allow the proper orientation and Indivi dual adaptation to the medical screening procedures, both for employees and management. Due to the great complexity of the medical surveillance system, it is highly improbable that a Level III system can be carried out without a Level IV system. III. RESULTS The following are brief descriptions of our progress and current thinking as regards several of the important but non-medical aspects of our medical surveillance system. A. Exposure Dr. A.M. Fairlie, J.R. Kute, J.C. Schaap, R.L. Rowles and V.J. Wilcox of the B.F. Goodrich Company initiated the development of the following system for obtaining chemical exposures and employee work histories and for combining them according to job classification into various indices of length and severity of exposure: 1. JOB CLASSIFICATION CODE Each job classification in each building is given a separate job classification code. Codes also identify jobs outside the local plant, layoffs, termination and retirement. 2. EMPLOYEE WORK HISTORY The work history for each employee consists of the date he was assigned to each job, the job classification code for the new job and the job classification code for his last job. It includes, in chrono logical order, the employee's complete work history. 3. CHEMICAL EXPOSURE A six-point rank order scale of exposure is subjectively obtained once each year for each of the nineteen chemicals by each job classifica tion code. 4. EXPOSURE INDICES The employee work histories and the associated chemical exposures are combined by Job code to produce the fourteen indices of exposure per chemical. Thus far, our interest has concentrated on two of these indices: 1924 BFG08589 \,0 0 T 6 6 0 Z a. The Average Exposure Index Iq Average Exposure 111 Vi Where a.j - number of sooths at exposure level sad b. The Total Exposure ladex Total Exposure - I n.I. _ r ~i r 1 1 1 Ij Bj ^average exposure] We are also laterested in the Interaction ten defined by the product of these exposure indices: Interaction Exposure " 2 These two indices will be tabulated on a calendar year basis and for selected linear combinations of calendar years. B. The Evaluation of Screening The screening tests will be evaluated in terms of their usefulness in detecting overt disease and in terms of their ability to detect early abnormalities that may be indicative of future overt disease. To eval uate the ability of a screening test to detect disease, ve must be able to croas-classlfy employees according to whether the test indicates the pre sence or absence of disease and according to whether the disease is actually present. Given this information, we evaluate the test by esti mating its sensitivity and specificity. This can be done even in the presence of errors in the so-called true classification. Aa is well-knovn, in a population in which the prevalence of disease is low, we will obtain imprecise estimates of sensitivity but precise estimates of specificity. Laboratory experiments frith rats will parallel our surveillance program. The rats will be subject of identical screening procedures and then sacri ficed and autopslsd. Estimates of sensitivity and specificity will also be obtained for this population of rats. To study the ability of the screening tests to predict future disease, we will record current results snd trends snd compare them with the presence or absence of disease at some time in the future, say at yearly Intervals. 1925 BFG08590 A second us* of eh* screening tests will be to relate then to past exposure. If abnormal screening tests sre related to previous exposure, they aay also be related to future disease. Such findings could be con sidered sn early warning; they will also help for* the basis for epidemio logical studies end animal experiments. C. Early Warning Mortality and morbidity rates will be monitored and compared with our best estimates of expected rates. Excess rates with a - 251 will warn us of a possible risk factor, and appropriate action will be takep. Tor example, surveillance of 1,200 employees for three years would pro vide approximately a three-in-ten chance of detecting a four-fold increase in lung cancer in a subset of 250 employees. IV. DISCTJSSIOH The major facets of any surveillance system capable of detecting early occupational disease must Include each of the following: 1. Accurate records must be maintained on the work histories of all employees. 2. Information must be carefully ascertained and recorded concerning exposure to various agents for each area and job classification. 3. The health status of the employees must be continuously monitored and compared to that expected in a similar nonexposed population. This should Include both morbidity and mortality. 4. Screening tests capable of detecting early abnormalities must be given periodically, the results carefully main tained and compared with previous exposures and later with future health. A Level I surveillance system is the foundation for an expanded system and by Itself provides sufficient data to alert management and labor to the necessity of moving to a higher level. We are actively establishing a Level TV system. Work histories and job exposures are routinely being collected on all employees since 1926 BFG08591 60016602 January 1, 1974. Tbay will b updated quarterly. The first round of physical examinations and screening tests carried out under our super vision should be completed this coming simmer. The date being collected are being coded and stored on magnetic discs. Computer programs for the rapid access and analysis of the data are being written. Some prelimi nary analysis and evaluation will be begun this turner. V. SUMMARY A surveillance system designed to detect early occupational disease la being established for the B.F. Goodrich Chemical Company's Louisville plant. The system will routinely collect and maintain records of work histories and job exposures. It will monitor the health of employees through annual and semi-annual physical examinations and through semi annual and quarterly screening tests. The data are stored in computeraccessible form, and methods for the early warning of both overt and potential disease are being developed. REFERENCE 1. Rose, V.E., Lee, J.S., and Kusnetz, H.L. National Surveillance Network for Occupational Health. J. Occup. Med., ,12:193-197, 1970. \ 1927 BFG08592 &U0TG60Z