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The Medical Society of the County of New York
Occupational Safety and Health
STATEMENT OF ERNEST E. DIXON, TABERSHAW ASSOCIATES,
ROCKVILLE, MD. Dr. Dixon. Thank you.
I am Dr. Ernest M. Dixon, a private practitioner in the medical specialty of occupational medicine. I appear today at the invitation of the subcommittee to testify on medical and genetic screening programs in the workplace.
In recent years the value of health monitoring of workers has become recognized as being of increased importance. Many of the NIOSH recommendations and OSHA standards associated with substance exposures have specific recommendations for medical surveillance. These include specified tests which are uniquely characteristic of, or helpful in, establishing a diagnosis—and in providing an experiential baseline level in the worker prior to working with potentially hazardous materials. Also, where it is known that certain health conditions predispose to increased susceptibility, above that of normal individuals—to a given exposure, screening or testing to determine the presence or absence of the predisposing condition may be undertaken.
General health evaluation prior to exposure is of considerable importance. Since test results for individuals may vary over a wide range of normal values, knowing the baseline level of an individual may be of critical importance. Also, a departure from an individual's normal level, even though still in the normal range, may be of greater significance than a single value classified as abnormal. For example, a person who normally has a high red blood count may show a change even though he's in the normal range at a low level in the range of normal and that would be significant, whereas the single reading itself would not be.
General health evaluations, notwithstanding the benefits of special screening procedures, remains the method of choice. It should include a medical history, physical examination, laboratory and other tests, such as chest X-ray, pulmonary function, audiogram, electrocardiogram, et cetera, as may be indicated. Such assessments can establish a general baseline and create a health profile that provides the fundamental basis for worker selection and place
ment to avoid undue risks. To this basic health evaluation should be added any pathognomonic or other specialized tests which may be appropriate for the given exposure. Most of these examination and testing measures are conventional clinical procedures and, as such, are well established as to accuracy, standardization, ranges, et cetera. Unfortunately, however, despite substantial new developments in clinical laboratory science, there are all too few substances for which there are specific tests.
Of special interest and concern is the relatively new area of screening for genetic abnormalities. This is an area which is rapidly developing and is the subject of extensive research. Much is known about the genetic basis and nature of many disorders and there is a moderate amount of information on genetic abnormalities in test systems induced by toxic agents. The use of screening tests to predetermined genetically increased susceptibility to potentially harmful physical or toxic agents in humans is, however, extremely limited at present. I can list only four or five for which there is an established basis, and to summarize them hurriedly, one is the serum antitrypsim tests for respiratory irritants; and the glucose-6-phosphate dehydrogenase test which can detect antimalarial and other drugs and potentially hemolytic chemicals; the hemoglobin S in sickle cell anemia which can produce problems with deficient oxygen at high altitude and possible or probable nitro and amino chemical compounds; and the whole allergic reactions field due to allergens which vary all the way from pollens to chemicals such as toluene diisocyanate.
In addition to these well established procedures, which are determined by clinical means-and I want to emphasize clinical means—there are a group of newer short-term genetic monitoring tests for chromosomal aberrations. These may determine mutations, which are heritable changes in cells, or genetic damage, which may be either reparable or lethal to the cell instead of inducing heritable change. Among the testing methods are cytogenetics, sister chromatid exchange, body fluid analysis, testing of sperm cells and detection of somatic cell variants. Most of the cytogenetic studies in industry have been recent-during the past decade-and are directed at assessing the degree of chromosomal aberration occurring in cells-generally cultured lymphocytes-in individuals subsequent to work exposure to chemicals such as benzene, vinyl chloride monomer, and epichlorhydrin.
Without going into any of the specifics of testing techniques and difficulties therein, it is fair to say that all of the studies done thus far are seriously flawed due to the complexity and inadequate control of the many variables, improper experimental design, incorrect epidemiologic interpretation, inadequate validation, lack of standardization, nonreproducibility and genetically irrelevant end points. In some instances studies have been undertaken to develop a baseline of the frequency of aberrations in nonexposed groups. However, I know of no instance in which a reliable conclusion has resulted.
In view of all the confounding difficulties and inherent uncertainties, at least thus far in their development, such genetic tests must be relegated to the category of the experimental, that is, as research tools only. None of these short-term tests have achieved
the status of clinical tests—and unless or until such does occur they cannot be assigned any interpretive or predictive value. It is a testing modality which warrants further research-and I would urge it-but it must be limited to research status only until the many problems have been resolved and reasonable reliability has been achieved. Genetic testing has had extremely limited use in industry thus far and has been essentially limited to research study only, to my knowledge.
Clinical health surveillance or medical screening, on the other hand, has a long-established basis of scientific legitimacy and validity. It is used quite extensively in industry today and is especially prevalent in industries having obvious potential hazards to health. Its utility, however, is wholly contingent upon examinations being tailored by experts in occupational medicine to monitor selectively and to interpret properly the results. Only through such surveillance programs correlated with work histories and exposure data is it possible to assure worker health. This includes consideration of future expected exposure and work information to aid in proper placement and past data to assess for the presence or absence of adverse health effects from past work. It requires physicians knowledgeable in the specialty of occupational health to tailor programs appropriately and to interpret the results. All too often, individuals who are experts in a given test technology or physicians lacking occupational health skills are called upon to render such judgments. The dilemmas that can result when unqualified individuals make the decisions are evident in some regulatory standards and in the public decisionmaking arenas. Many organizations, with do-good intent, have pressed for or against a special measure without any depth of understanding of the complex issues involved and have unwisely influenced policy decisions. Similarly, those with a mission and dedication in pursuit of promoting a method or procedure may be so zealous and persuasive as to influence decisionmakers to make wrong choices.
A conscientiously administered medical surveillance program is the keystone to assuring the health of workers. A properly implemented program to assess general health and to examine specifically the organ system functions at risk is the only means available to assure that individuals can safely undertake potentially hazardous work or that they have not suffered any adverse health effects. Despite all preventive and precautionary measures that can be undertaken, it is only by demonstrating no adverse health effects in workers that assurance of safety can be established. Conversely, detection of adverse effects, hopefully at as early a time as possible, is a signal for taking more effective precautionary and remedial actions. Confidential, high-quality medical examination programs correlated with work and exposure history by means of a systems approach can now provide a highly effective means of protecting the individual and groups of workers. The data base systems approach to health surveillance today offers a whole new vista of improved technologic capability. As new testing methods that can be helpful are developed they should be added to the armamentarium of medical surveillance technology, but only as they become fully validated.
Based on the suggested areas of comment and special questions posed for this inquiry, it is evident that the committee is searching to determine which methods and procedures are proper and useful, how to avoid possible abuses and the efficacy of protection that medical surveillance can provide.
In my earlier comments, I have attempted to describe an overview of medical and genetic testing as it exists today. My view of genetic testing is that it is in its infancy and is generally in appropriate today, except as a research tool. I favor its development and proper use when it becomes established because we need every technologic advance possible to assist us in attaining enhanced predictive and diagnostic capability. I consider conventional medical testing to be highly effective and appropriate. The new occupational health management systems which include medical surveillance programs can be highly effective in the hands of and when directed by skilled occupational health specialists.
If an individual is discovered to have a genetic deficit or other medical abnormality which would put him at a risk greater than normal individuals, added protective measures or precluding him from exposure to the special hazard is obviously the reasonable approach. Concern for an individual who is known to be hypersusceptible to adverse effects from any agent requires protection from exposure beyond that which normal individuals may tolerate readily. Control of the degree of exposure should be the primary objective, if it is possible and feasible to achieve, but an individual should not be assigned to work if it is not possible to assure his own safety or if it would jeopardize others. Any approach to solving problems of this nature should be individualized and strictly practical and not by broad categorical or policy solutions which could be discriminatory. Companies with which I am familiar generally take the highly individualized approach within the limits of knowledge and preclude broad discriminatory policies and actions as much as possible. This mandates that examinations be selectively designed with knowledge of the job requirements, utilize tests with established merit, and with interpretation of the results by experts and professionals who have sufficient information to sustain their conclusions.
Among the legitimate issues to be accomplished by testing are determinations regarding: physical capacity to do the job without harm to self, others, or property; potential harm to the individual worker and his offspring; productivity; and liability.
It should be kept in mind that medical surveillance occurs in two principal categories:
One, initial or preplacement examinations which are done to establish a baseline for future reference and to determine if the individual can physically perform the intended work and whether or not there is any health condition which might require special precautionary care or job placement consideration.
Two, periodic examinations after engaging in work to assure that no adverse health effects are developing or, if so, that they are detected sufficiently early to permit remedial action and preclude lasting ill consequences.
In my judgment, the benefits in worker health protection afforded by properly and fairly conducted health surveillance far outweighs any risk that discriminatory decisions might pose. However, there are ethical and social dilemmas to be addressed. When it comes to a health problem of an individual posing a hazard to other individuals or property, there can never be a decision to accept the latter. When the deliberation involves only a hazard to the individual, the decision is less easy or clear-cut. Even if we exclude employer liability as an issue, the moral aspects cannot be denied or easily resolved.
Is the harm of not being able to work at a specific task because of a health problem worse than being allowed to do the work and assuming the consequences of an adverse health effect? Even if we could quantify the severity-discomfort, mild or severe disability, death-it, offers little help in answering the question. The physician feels compelled to urge avoidance of any risk to health. There is a parallel in the case of the physician insisting on surgery for appendicitis but the patient refusing; should the physician or the State force the individual to undergo surgery?
In industry, the role of the physician is primarily advisory to management but his recommendation should be given great weight. Where there are other issues of concern to management, such as productivity, management must make the decision. In my judgment, in instances of hazard to self or others, the knowledgeable physician's determination should be accepted. But who is to decide whether or not an individual can work? This is an issue that is never decided easily.
Certainly both sides should be informed of the physician's recommendations. But ultimately, who decides? If a dispute arises, it would be best for a judgment to be made by a panel or board of review of neutral specialists in occupational medicine. Physicians in other medical specialities lack the perspective and technical skill to adequately make the “whole worker” assessment. Unqualified people too often are the arbiters. By utilizing available expertise, the best knowledge and judgment can be brought to bear on these problems effectively. I do not believe that workers should be permitted to assume the risks of bodily harm just because they are shielded from the risks of financial loss.
Limiting workplace exposures to the greatest extent feasible is always the first preference for eliminating or minimizing health risks. In some instances of hypersusceptibility, the degree of control that would have to be achieved may be unattainable by available engineering measures or be prohibitively costly. If the costs are excessive and impinge seriously on the financial health of the enterprise, the benefit to a few could be outweighed by the harm to the majority of workers and it might be better to place hypersusceptible workers elsewhere. Also, if the nature of the hazard is potentially severe for the unusually susceptible worker, it would not be in his best interest to permit him to work in such circumstances.
I have tried to cover briefly the general considerations on medical and genetic screening, testing and surveillance. In my judgment, proper programs of testing, in which qualified specialists in occupational health tailor programs broadly enough to assess general health levels and to specifically measure the function of organ systems at risk, constitute the most effective measures for health