Medical Monitoring Following Chemical Exposures

Thursday, July 1, 2004 - 01:00

Ronald E. Gots, M.D., Ph.D.
International Center for Toxicology and Medicine

Individuals may be exposed to various potentially toxic materials, either in the air or in the drinking water. The sources of contamination may be leaking underground gasoline tanks, waste site fugitive emissions, smoke stack emissions, explosions, fires, and contaminated drinking water from various earlier disposal practices or accidental spills. Along with claims for money damages, plaintiffs who have suffered such exposure may demand medical monitoring or surveillance, based upon the proposition that their exposures have created a risk and, therefore, a need for regular clinical evaluations.

The claimants' rationale for demanding medical monitoring seems, at first blush, unimpeachable. Checkups, it is reasoned, will identify any chemically-induced injuries currently present or as soon as they occur in the future. Like motherhood and apple pie, such requests seem eminently reasonable. Often, however, the requested studies make little sense when they are examined critically for clinical merit. With the scope of these requests expanding and the price tags ranging often in the thousands of dollars per claimant each year for life, a serious analysis of requested testing is clearly in order.

There are only two theoretical medical or scientific justifications for such monitoring. The first is that a study can determine whether effects might occur in the future; this calls for a scientific investigation or experiment, rather than a medically-established justification. The second would be to identify early the presence of disease in an individual so that prompt intervention might take place. This is the customary argument put forth in the context of toxic tort claims.

Scientific Investigation As Predictors Of Future Risk

When individuals have been exposed only to very low levels of allegedly toxic materials from waste sites in the air or drinking water, the investigations are exceedingly difficult to perform (some say impossible) and to interpret. This is so for a number of reasons, the most important being that finding unexposed persons to compare with people exposed to very low levels of chemicals - i.e., parts per billion - is practically impossible since these are background levels to which we are all exposed. The second reason is that it is almost impossible to control for other factors which could produce effects when the study exposure levels are so low. Carcinogens naturally occurring in foods, for example, are present at these low exposures levels and vary from person to person depending upon diet, a factor which cannot be controlled. Thus, though studies of exposed individuals are being attempted, they are fraught with enormous methodological problems.

Even if such a study can be performed and intended results can be achieved, whether it can be the basis of a claim for damages in a toxic tort action is highly questionable. An epidemiological investigation is not designed to check into the health of a specific individual (i.e., a claimant). Nor is it based upon medical or scientific certainties. Just the opposite: it is by its very nature investigative, designed to determine whether an effect might occur, rather than to find the effect which is known to occur. It is experimental, uncertain, speculative, and based upon possibilities.

Monitoring To Detect Disease

Although there is little medical precedent for monitoring populations exposed to low-level environmental contaminants, there are several related fields of medicine that can help us understand monitoring. One is occupational medicine, where workers are exposed day in and day out, for their entire working lives, to many of these environmental contaminants, at much greater doses. The others include basic toxicology; our knowledge of clinical medicine; and the nature and value of specific medical examinations and tests.

Testing in the occupational setting provides significant guidance to an understanding of medical monitoring. Exposed workers undergo certain prescribed evaluations focused upon the specific chemical hazards. Thus, lead plant workers are given routine hematological and neurological (the target organs lead) tests, as well as biological monitoring of lead levels in urine and blood. Similarly, those exposed to certain levels of asbestos, silica or isocyanates will undergo routine pulmonary functions testing. These and scores of other occupationally-specific evaluations are central to the field of occupational medicine.

To understand why common requests for medical monitoring in toxic tort claims do not follow normal clinical or toxicology principles, consider two factors: the first is the circumstances of exposure; the second is the nature and purpose of the commonly recommended testing. Typically "mass tort" litigation involves low-level exposures - exposures which have generally ended or have been reduced substantially by the time of the litigation. For instance, small amounts of thrichloroethylene or bezene may have been detected in a community's drinking water, following which a new water source was provided. Volatile organic compounds (VOCs) in excess of state or federal standards may be emitted from a neighborhood stack which was subsequently cleaned up. Firemen fighting a transformer fire can be exposed to PCBs - an acute self limited event. These situations are representative of commonly seen claims.

Using the workplace as a precedent no future monitoring would be warranted or recommended in any of the situations described above. Monitoring of workers after employment ends (and thus, exposure ends) is rarely indicated unless a present problem exists, such as an inordinately high blood level of worrisome chemical or early asbestosis. Even then, monitoring is only indicated if it is likely to reveal a long term effect. In cases like those involved in mass tort actions exposure has generally ended and there is almost never evidence of elevated chemical levels in individuals requiring such follow up studies.

A Need For Monitoring?

Considering the issues of medical monitoring, one needs to ask a series of questions: What are we monitoring? Why are we monitoring it? What is it likely to show given the exposure circumstances of the claimants? And, most importantly, did the chemical exposures create a special need for the monitoring?

As a rule, requests for medical monitoring ask, non-selectively, for comprehensive physical examinations and a wide variety of laboratory testing. Many of these requests are parts of customary annual physical examinations and good routine health maintenance: breast examinations, pap smears, and sigmoidoscopies in people over forty, for example. In other words, the requested tests are of potential value to anyone, with or without the chemical exposures, and are not needed because of any new or more intense risks posed by the exposure or peculiar to the circumstances of the claim. To understand this more completely, and to better assess the utility of requesting testing, we need to examine the subparts of suggested medical monitoring programs.

The medical monitoring sought in hazardous waste claims consists of three parts of activities or studies: (1) routine examinations and tests,(2) organ specific tests; and (3) cancer or mutagenicity tests.

Routine examinations include a physical exam, a urinalysis, and standard blood tests. The customary battery of blood chemistry profiles includes (among others) reading for serum sodium, potassium calcium, and uric acid. There is no imaginable way that environmentally transmitted chemical exposures could ever, even theoretically, affect these blood tests. Thus, it is essential that each test requested be examined critically to assess and challenge its relevance to the exposure at issue.

The second group of tests may be called "organ specific" studies. They include tests for kidney and liver functioning, cardiac activity, and immunological and neurological levels. In some instances, the subject chemical may be toxic to those organ systems and, therefore, the tests are seemingly relevant to the extant exposures. However, toxicology and occupational medicine properly recognize the criticality of dosage and temporal relationships to organ toxicity. This is central to the discipline of toxicology and must be familiar to attorneys dealing with toxicological claims.

We know that levels of tricholoroethylene (TCE) produce cardiac arrythmias. We know how much benzene it takes to produce an aplastic anemia. We also know how long after exposure ends the likelihood of potential toxicity persists. Thus, if an individual ingested some TCE and has no evidence of current neurological or hepatic injury, he won't develop any in the future from that exposure and future monitoring of those parameters is not indicated. Most hazardous waste claims, in which exposure levels are quite low and generally over by the time of the claims, do not meet these requirements.

Monitoring For Risks Of Cancer

The third type of testing is for cancer and mutations. Only rarely is exposure-related cancer risk of sufficient magnitude and specificity to recommend regular testing. A valid example is the recommended chest x-rays is individuals with asbestosis, particularly if they are smokers. By contrast, in workers with moderate workplace exposure to benzene (hundred of times higher than the worst hazardous waste exposures yet), monitoring for leukemia after one's working life has ended is not recommended by medical authorities or federal agencies.

Other types of cancer testing are routine and part of proper health maintenance- breast examinations, mammography, Pap smear, and sigmoidoscopy, for example. These have nothing to do with any chemical exposures - industrial chemicals are not known to cause the sorts of cancer that are the target of these common tests - yet, they are generally requested by claimants. Other frequently requested tests are of an experimental nature and have not known clinical value. These include chromosomal studies, sister chromatid exchange studies, chromosomal banding, and odd antigen studies. For the most part they have little sensitivity or selectivity and are more laboratory research tools than clinically accepted tests. If these or any other tests provided good predictive value for cancer, all of us would get them every year. The reason we don't, and our doctors don't recommend that we do, is that they provide no valuable information.

One of the arguments given for carrying out tests for cancer or birth defects is based upon allegations of increased risk attendant the exposure. The first response to that allegation is discussed above - can the test actually predict anything? The second response is based upon the inapplicability of regulatory-based risk assessment methodology to individuals.


In sum, there are few, if any, circumstances in which tests for cancer, mutations - or any other sort of health risk - are indicated as a result of hazardous waste exposure. To assess the need in each case, each requested test needs to be reviewed for a number of features: its pertinence to the chemical in question; its relevance to the dose; its predictive value; its established clinical efficacy; and its general acceptance in the medical community. When the defense attorney breaks apart these issues, test by test, their lack of value in this situation soon becomes apparent.

Ronald E. Gots, M.D., Ph.D., is CEO of the International Center for Toxicology and Medicine (ICTM). Questions about this article may be addressed to him at (310) 519-0300 or