Introduction
The recent Fifth District case of Donaldson v. Central Illinois Public Service Company, 2000 Ill.App. Lexis 316 (5th District, May 10, 2000), undermined an already complicated standard relating to scientific proof of medical causation in toxic tort cases. The Fifth District, along with a number of other appellate courts, have created confusion with respect to the role of the trial court in reviewing the admissibility of this type of evidence. This article looks at various federal and state court approaches to the admission of scientific evidence in toxic tort cases and discusses the application of the "scientific method" to various types of evidence which have been historically tendered to establish causation in toxic tort cases.

Federal and state courts in Illinois have authored several recent decisions which may significantly expand the relief which can be sought by injured plaintiffs in toxic tort cases filed in this state. For example, medical monitoring claims have been filed in increasing numbers all over the country, including Illinois, out of concern over the possibility that soil and water contamination from hazardous waste sites pose a significant health risk to surrounding population centers. Several federal courts applying Illinois law have recognized the validity of this type of claim. Illinois courts have also recently recognized that where a defendant negligently acts to increase the risk that an underlying injury, disease or condition will result in death or long-term morbidity, the element of causation is established, even where it is probable that death and/or other morbidity would have occurred in the absence of the defendant's conduct.

Arguments have been made that adoption of relaxed standards of causation and/or expansion of the types of relief which may be sought, in toxic tort cases, may cause a flood of unlimited and unpredictable litigation.

The aforementioned questions are complicated by conflicts in the way that various Illinois courts approach scientific proof of medical causation. Various federal and Illinois state courts disagree on whether, and to what extent, the trial court as "gatekeeper" should initially review and scrutinize questions relating to admissibility of scientific evidence on causation issues. Illinois state courts further differ as to the extent to which the trial court should "second guess" the underlying scientific basis for an expert's opinion.

Conflicts between Illinois appellate and federal courts, reviewing cases arising in this state, have led to inconsistent rulings in cases presenting almost identical scientific analysis and evidence, as well as the introduction of "junk science" to prove a "cognizable injury". In light of the potential expansion of toxic tort law in this state, Illinois courts must address differences in their approach to proof of medical causation so as to insure the application of both a uniform legal standard and frame work for review. Serious consideration should be given to adoption of the use of principles of the scientific method, by all courts, to insure the creation of these uniform standards and frame work.

Illinois has recently relaxed causation requirements in several different areas. In Holton v. Memorial Hospital, the Illinois Supreme Court held that in a medical malpractice action, a defendant may be liable where his conduct increases the risk of harm to the plaintiff³. In Holton, supra, the Supreme Court held that plaintiff met his burden or proof on the causation element by establishing that defendant's conduct diminished his chance of recovery, even where it was more probable than not that he would have died from his underlying disease⁴.

The expansion of Holton, supra, to toxic tort actions would seem to be a logical step in the evolution of the law of causation. Several foreign courts have recently noted that the modern trend in toxic tort cases has been to relax standards governing the demonstration of medical causation. These courts appear to have accepted the suggestion that plaintiff's injury in a toxic tort case may be more subtle and sophisticated as compared to other actions⁵.

Recently, in Donaldson v. Central Illinois Public Services Corporation, et al.⁶, a toxic tort case, the Fifth District suggested that when the cause or etiology of a specific disease is not known or is otherwise unclear, proof of causation is not as stringent⁷. Where there exists limited knowledge of a malady, medical testimony pertaining to causation may not be unqualified or unequivocal⁸. Curiously, the court, while suggesting that a relaxed standard be applied with respect to proof of causation in toxic tort cases, goes on to state that at the very least it should be no more stringent than in other types of cases⁹.

Toxic tort litigation normally arises out of three or four different factual scenarios. The first type of action consists of a straight products liability action in which plaintiff claims an exposure to asbestos, chlorine, solvents or substances, due to inadequate warnings or a defect in the product¹⁰.

The second type of action arises out of improper storage and/or disposal of hazardous material on property. In this situation people actually using the property for some purpose and/or neighbors, claim exposure and injury due to the leeching or escape of hazardous material into the soil or underlying aquifer. Personal injury claims arising out of this scenario are usually brought under a negligence/premises liability theory. However, these claims may also be brought against product manufacturers and suppliers, as well as hazardous waste generators, transporters or disposal companies¹¹.

The third type of action arises from worker's compensation cases wherein the employer is alleged to have willfully or intentionally exposed employees to hazardous substances¹².

In toxic tort cases, the plaintiff commonly attempts to claim either a direct physical injury, damage arising out of fear of future injury, and/or necessary medical expenses for monitoring in the future. The law in this area is increasingly recognizing claims for damage arising in the absence of a defined physical injury.

Illinois state courts have not directly addressed the issue as to whether a plaintiff can recover medical monitoring expenses in a toxic tort case¹³. However, in Carey v. Kerr McGee Corporation¹⁴, a federal trial judge for the Northern District held that under Illinois law as predicted by that court, a claimant alleging exposure to a toxic substance may obtain recovery for reasonable medical monitoring costs without being required to prove a present physical injury. The court correctly noted that the trend in the United States is to recognize this type of claim¹⁵. The court distinguished claims for medical monitoring expenses from claims arising out of an "increased risk of contracting disease"¹⁶. The court noted that claims for medical monitoring do not seek future damages in contrast to claims for "increased risk for contracting a latent disease".¹⁷

While the court in Carey was probably correct in suggesting that the modern trend is to recognize claims for medical monitoring, authority is split as to whether plaintiff must demonstrate a physical injury in order to bring this claim¹⁸. The more representative view appears to suggest that the need to periodically monitor is in and of itself a "cognizable" injury¹⁹. In medical monitoring cases which require demonstration of physical injury, confusion exists as to what constitutes an injury under the law. The question of whether plaintiff has suffered physical injury normally arises where plaintiff is able to demonstrate subclinical or physiological changes secondary to chemical exposure but no clear physical harm or adverse affect²⁰.

In most cases where plaintiff is seeking damages for medical monitoring, the following must be established: (1) a significant exposure, (2) a significantly increased risk of serious latent disease, (3) that medical monitoring is reasonably necessary, (4) that techniques exist that suggest that early detection and treatment is beneficial, (5) that defendant was negligent, and (6) that defendant's negligence caused the exposure.

Medical monitoring cases present a series of complex questions relating to causation issues. Those issues include: (1) whether plaintiff suffered a significant exposure, (2) whether the exposure significantly increased plaintiff's risk of serious disease, (3) whether early detection and treatment would be beneficial, and (4) whether defendant's fault caused the exposure²¹.

Illinois courts have up to this point in time been reticent to recognize claims for emotional distress due to "increased risk of a latent disease" from exposure to a hazardous substance²². However, recent decisions by both our supreme and appellate courts may give plaintiffs some basis to successfully argue this cause of action in the future²³. The causation issues associated with the claims where a plaintiff suggests "increased risk of a latent disease" are complex and would, to a large degree, mirror causation issues arising out of medical monitoring claims. If Illinois courts were to recognize plaintiff's right to recover damages for increased risk of suffering a latent disease and/or fear of contracting a disease, causation issues would necessarily include: (a) whether plaintiff suffered a significant exposure, (b) whether the exposure significantly increased plaintiff's risk of serious disease, (c) whether defendant's fault caused the chemical exposure, and (d) proof of physical impact or objective proof of mental distress. (Examples being the necessity of hospitalization and/or medical care.)²⁴.

Insofar as Illinois may be heading toward recognizing claims which do not require a showing of a defined physical injury, application of sound procedures and standards of review to scientific evidence in the area will become increasingly important. Illinois appellate courts have for the most part recognized that the Supreme Court of this state has declined to adopt the Daubert test in place of the Frye test relating to admissibility of scientific evidence on causation issues²⁸. Unfortunately, individual appellate districts then go on to apply varying approaches to the determination of whether scientific evidence will be admissible, under standards which appear to be set by the individual courts hearing the case. Some courts require extensive hearings concerning the credibility and admissibility of scientific evidence on causation²⁹. Other courts rule on the basis of written submissions³⁰. The Fifth District has recently questioned whether a pre-trial hearing is even required³¹.

If scientific, technical or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training or education may testify thereto in the form of an opinion or otherwise.

While the principles enunciated in Federal Rule 702 do not appear at first blush to be significantly different than those referenced in Frye, federal courts applying Rule 702 have imposed vigorous standards of review to prevent juries from considering what has come to be known as "junk science".

The Seventh Circuit, acknowledging the Daubert decision, has enacted a two step approach for the District Courts to undertake in determining the admissibility of expert testimony on causation issues in toxic tort cases under Rule 702³⁶. First, the court must consider whether the testimony pertains to scientific knowledge; that is whether it is subject to the "scientific method". The court must exclude evidence which is unscientific speculation even when offered by a genuine scientist. The proffered expert testimony must be derived by scientific method and must fit the case. In other words, a scientific expert is an expert who relies on the application of scientific principles rather than on skill or experienced based observation for the bases of his opinions. Second, the District Court must determine whether the testimony assists the trier of fact³⁷. In essence, the District Court, as "gatekeeper", must apply the principles of the "scientific method" when initially determining whether to allow the jury to consider causation testimony rather than merely allowing the jury to weigh its credibility based upon vigorous cross-examination, contrary evidence and court instruction.

Questions frequently arise as to what defines "scientific method" in terms of the above frame work for evaluating the validity of scientific evidence. The Federal Judicial Center has produced the "Reference Manual on Scientific Evidence" for use by the federal court system. The manual includes an evidentiary frame work which educates judges on relevant issues including toxicology and chemical exposure³⁸.

While a complete discussion of the application of the scientific method to proposed evidence is beyond the scope of this article, review of several court opinions is important in gaining a basic understanding of the level of scrutiny which a District Court must apply to these issues, as well as an understanding of the conflict which arises between federal and state courts hearing cases originating in this State.

In Wintz v. Northrop Corporation³⁹, plaintiff sought damages for injuries allegedly suffered as a result of a minor plaintiff's in-utero exposure to bromine. The appellate court considered whether the proffered testimony of plaintiff's toxicologist was improperly excluded. The court also considered whether the plaintiff had failed to raise a material issue of fact on the issue of causation so as to defeat summary judgment.

In Wintz, the minor plaintiff's mother was exposed to certain chemicals as a result of her employment, where she was required to mix certain chemicals. The minor plaintiff was born with severe neurological morbidity. After the minor plaintiff's birth, upon learning of maternal exposure to bromine, treating physicians ordered chemistries which demonstrated that the infant had elevated levels of bromine in her system. Testing was also performed on the infant's mother which also revealed elevated levels of bromine.

The defendant, through a geneticist, argued that plaintiff demonstrated classic signs of a genetic disorder known as Prader Willy Syndrome (PWS). PWS is a genetic disorder caused by deletion of genetic material from the father's chromosomes and has never been associated with environmental exposure.

The plaintiff hired a toxicologist to opine that the baby's injuries were caused by exposure to bromine. The court noted that plaintiff's expert had a Master's Degree in chemistry and experience in the area of toxicology. Plaintiff's expert relied on testimony by treating physicians demonstrating elevated levels of the chemical in the baby's system and animal studies suggesting that at high doses, bromine may have teratogenic effects.

The court, in scrutinizing opinions by plaintiff's toxicologist, reviewed the Federal Judicial Center's Reference Manual on Scientific Evidence. The court citing to the chapter entitled "Reference Guide on Toxicology", concluded that three assessments should have been made by plaintiff's toxicologist as a premise for any opinion:

First, the toxicologist should analyze whether the disease can be related to chemical exposure by a biologically plausible theory. Second, the expert should examine if plaintiff was exposed to the chemical in a manner that can lead to absorption into the body. Finally, the expert should offer an opinion as to whether the dose to which the plaintiff was exposed is sufficient to cause the disease⁴⁰

The court recognized that plaintiff's experts had evidence that the minor plaintiff's mother had worked with bromine, but never determined the frequency, the quantity, or the form that the infant's mother was exposed to bromine on the job. Plaintiff's experts never attempted to correlate any specific dose received by the minor plaintiff's mother with plaintiff's symptoms. Plaintiff's experts did not properly analyze the dose required to produce injury in humans. Plaintiff's experts failed to cite to any human studies suggesting that bromine could cause injuries like those allegedly suffered by the minor plaintiff. The court ultimately barred plaintiff's toxicological evidence and granted defendant summary judgment⁴¹.

In Abdishi v. Phillip Morris⁴² , a District Court dealt with the issue of whether opinions by plaintiff's experts, that the plaintiff's injuries resulted from cigarettes contaminated with MITC smoked by the plaintiff, should be admitted into evidence. After an exhaustive review of the qualifications and testimony of plaintiff's experts, the court found the testimony to be inadmissible. The court noted that while plaintiff's experts were qualified as toxicologists, they failed to demonstrate the requisite expertise on MITC, its toxicity in humans, as well as expertise to rule out other medical causes for the injuries claimed by the plaintiff⁴³. Plaintiff's experts also failed to use scientific methodology in researching the issues and forming conclusions.

The court found that plaintiff's expert toxicologists had failed to perform any analysis concerning the extent of exposure of the plaintiff to the chemical agent in question. The court rejected the experts' suggestion that the dose to which plaintiff was exposed was obviously sufficient to cause injury by reason that plaintiff demonstrated symptomatology consistent with exposure; particularly in light of the fact that the expert failed to obtain any quantitative data on the issue or correlate such data with research denoting the dose necessary to cause harm in humans⁴⁴. The court noted that plaintiff's experts were not relying on human studies, but on anecdotal reports and animal studies. Plaintiff's experts did not take any steps to validate the literature relied upon. They failed to determine if the literature had been subjected to peer review. They failed to do a complete survey of all the literature in the area. They failed to personally assess the literature relied upon for bias, confounding factors, and other deficiencies in the scientific method. They failed to rule out potential alternative causes for the symptoms experienced by the plaintiff⁴⁵.

In Donaldson, supra⁴⁶, the Fifth District Appellate Court held that a cause and effect relationship need not be clearly established by animal or epidemiological studies in order to admit expert testimony that a causal relationship exists. The court initially noted that in Illinois, an expert does not need to quantify the specific level of exposure to a chemical agent to testify to causation; he must simply be able to point to some evidence of exposure⁴⁷. The court went on to suggest that plaintiff need not establish causality by statistical analysis or sophisticated study; the plaintiff's case possibly being the first of its kind, caught by an expert alert enough to recognize causation⁴⁸.

In Donaldson, the evidence presented by plaintiff consisted of a suggestion that the incidence of cases of neuroblastoma in Taylorville was statistically above normal. The plaintiff's case was otherwise based on extrapolation of data linking the chemical to cancers other than the type of cancer at issue. The court recognized that there were no human or animal studies suggesting that the chemical at issue could cause the type of cancer suffered by plaintiff. The court accepted at face value testimony by plaintiff's expert that the "extrapolation method" was accepted by the scientific community without any literature or other support for this assertion. The fact that plaintiff's experts had resorted to extrapolation methodology rather than pointing to a single epidemiological or animal study "affected" the weight of the testimony not its admissibility⁴⁰.

The court in Donaldson specifically rejected alternative standards of review for admissibility of scientific evidence expressed by the Fourth District in Harris, infra, as not conforming to the Frye test and as otherwise inconsistent with Supreme Court decisions which had rejected Daubert⁵⁰. The court was openly critical of other appellate courts following Daubert, suggesting that these judges were "boxed into" working within a structure that had not functioned well and which otherwise defeated the intent of the Supreme Court in deciding Daubert to encourage liberal admissibility⁵¹.

In Harris v. Cropmate⁵², the Fourth District also rejected an invitation by defendant to adopt Daubert. However, the Fourth District did recognize that Daubert offered several useful "nuggets" helpful in the assessment of admissibility of scientific evidence⁵³. The Fourth District, citing Professor Graham's Textbook on Evidence, adopted what it characterized as a "Frye plus reliability standard" for admission of "novel scientific evidence"⁵⁴. The Fourth District recommended an analytical framework in applying the aforementioned standard consisting of the following series of inquiry: (1) What evidence is being offered? (2) Will the evidence assist the trier of fact? (3) If so, does the evidence constitute scientific evidence? (4) If so, is the evidence novel or does it involve firmly established scientific method? (5) If novel, is it reasonably relied upon by the relevant scientific community to which the opinion witness belongs?⁵⁵

The court noted that while it must rely on the community of experts to help it decide the admissibility of scientific evidence, it may not delegate its authority as "gatekeeper" to that scientific community⁵⁶.

The court noted that in conducting a Frye evidentiary hearing, it may consider the following: (a) scientific publications and law review articles, (b) prior judicial decisions, (c) practical application of the method, (d) expert testimony, (e) acceptance of the method by the relevant scientific community, and (f) attitudes of fellow scientists. In determining whether the evidence is reliable, the court may consider (1) the ability to empirically test the method, (2) peer review of the method, (3) potential errors in applying the method, (4) reliability of underlying data, (5) a witness' experience with the specific scientific issue, (6) whether the witness reached conclusions after performing requisite research, or in the alternative, did the witness merely perform research to confirm opinions previously derived⁵⁷.

The Harris case dealt with whether crop damage suffered by plaintiff was as a result of a herbicide known as 2-4-D or a disease known as anthracnose. Testimony on the causation issue was largely based on the relative expertise of various witnesses, their personal observation of the fields in question, and testing of herbicide levels in the fields at issue. Despite an extensive discussion of admissibility standards for scientific evidence and the Daubert decision, the court concluded that much of the testimony of the experts involved did not constitute "scientific evidence" otherwise subject to the Frye review standard in that it did not purport to rely on scientific principle or methodology on the issue of causation⁵⁸.

The Fifth District Appellate Court's recent opinion in Donaldson, supra, is the most extreme example to date of the trend, exemplified by recent decisions by certain Illinois Appellate Court, to reduce and/or effectively eliminate the role of the trial court in overseeing admission of scientific evidence on causation issues relating to exposure, dose response and adverse health effects potentially attributable to a given chemical agent. A review of the Donaldson decision requires reconsideration by our state, appellate and supreme courts concerning the adoption of a standard of review insuring application and use of the "scientific method" and reaffirmation of the trial court's role in the review of this type of evidence.

Review and application of the "scientific method" insures that a party will be presenting the most credibile argument available on causation issues. The need to adopt procedures to insure proper application of the scientific method to scrutinize toxic tort cases is clear, in light of the potential recognition of claims for "medical monitoring" and/or "fear of disease" type injuries in the future. An analysis of the various types of evidence customarily used in toxic tort cases to prove causation, as well as principles underlying the "scientific method" used to scrutinize this evidence, is important in terms of correctly guiding our state courts in future cases.

A sixteenth century Swiss chemist once wrote: "Tis the dose that makes the poison."⁵⁹ This principle, that a high enough dose of any substance will cause adverse health effects and its antithesis, forms the basis for the initial assessment of whether exposure to a given substance caused harm.

An exposure analysis must be tailored to the facts of a given case. The analysis performed, when a chemical exposure is alleged to have occurred as a result of leeching of chemicals from an underground storage tank, for example, is significantly different than a situation where the plaintiff suffers an alleged occupational exposure while working directly with the chemical agent. Insofar as causation issues arise in all of the various types of toxic tort cases which may be filed, this discussion of the application of "scientific method" to causation evidence will enunciate general principles of analysis.

In cases where exposure is alleged to have occurred from environmental contamination (soil and aquifer contamination), state and federal governmental agencies often require a "risk analysis" as part of remediation⁶⁰. In evaluating the human risk posed by contamination of a site, litigants must collect data on the principle hazardous constituents causing contamination. The second step is an "exposure assessment" necessitating investigation of potential pathways of exposure and development of data defining cumulative daily intake for each of the principle hazardous constituents.

If the pathway analysis suggests that a receptor (plant, animal or human) is not subject to exposure to constituent chemicals at toxic levels, plaintiff may have a difficult time suggesting that his or her injuries were due to exposure to those chemicals⁶¹.

The third phase of risk analysis is normally referred to as a "toxicity assessment." This assessment typically involves review of the literature describing dose/response relationships and adverse health effects which would normally be predicted following an exposure to one or more of the principle hazardous constituents. This data is combined in the final stage which is normally referred to as the "risk characterization" analysis. A "risk characterization" analysis is performed for each potential exposure pathway by each respective hazardous constituent⁶².

A review of the risk assessment necessarily requires an analysis in terms of efforts to maintain quality assurance and controls before a party should rely upon the assessment to suggest causation. The failure of a given expert to obtain, review, and critique this data, if available, should result in exclusion of the evidence on causation issues.

In cases where the alleged exposure is due to direct contact with the chemical agent in question, a similar but different analysis should be undertaken. The modern science of industrial hygiene has worked to quantitate, as well as promulgate the dose or level of exposure necessary for a given chemical to cause disease or injury. Studies have been done with respect to both occupational and non-occupational exposures. Care should be taken to use the applicable study depending upon the nature of the exposure suggested.

One must also consider the “human pathway” by which exposure has occurred. In other words, was the substance inhaled, ingested and/or absorbed through the skin? Whether a substance causes adverse health effects, the extent to which it may cause health effects, the organs susceptible to health risk, and the dose necessary to cause adverse effects may depend upon the pathway by which the person has been exposed to the agent.

There is resource data available to litigants on exposure issues. For example, the American Conference of Governmental Industrial Hygienist (ACGIH) publishes exposure data on a yearly basis for a variety of different substances. The term “threshold limit value” refers to a measured airborne concentration of a given substance below which disease or injury is not deemed to occur⁶³.

Analogues terms have been adopted by various governmental agencies which also publish exposure data, including the Occupational Safety and Health Administration (OSHA), the National Institute for Occupational Safety and Health (NIOSH) and the American National Standard Institute (ANSI) to describe and quantify concentrations of a given substance necessary to cause adverse health effects⁶⁴.

Threshold limit values are set annually by the ACGIH and may change over time. Different agencies may assign slightly different values to a particular chemical in terms of their minimum necessary exposure valuations.

In cases where airborne concentration of chemicals have been monitored, compliance with the threshold limit value over time may suggest against the proposition that a plaintiff’s injuries were caused by a chemical exposure⁶⁵. The best evidence of compliance with threshold limit values may be demonstrated by review of personal monitoring data on the plaintiff, work site sampling of similarly situated workers or review of literature analyzing exposure in similar work settings. However, work site sampling of similarly situated workers or review of literature analyzing exposure in similar work settings are secondary sources which must be critically reviewed in terms of each individual plaintiff. Anecdotal data, if available, may be considered, but great caution should be exercised before reliance is placed on this type of data due to its inherent unreliability.

After data on exposure has been collected, critiqued and analyzed, studies should be made of available data on dose/response relationships and adverse health effects associated with a given chemical agent. Examples of data available on these issues may include human studies, census data, epidemiological studies, anecdotal reports, state and local governmental data and animal studies. The credibility of any opinion on causation issues depends both on the type of study available to support a party’s position, as well as a critical analysis of the validity of the study or studies relied upon.

Examples of general questions which should be considered as to any study which a party may seek to use to prove causation include: (a) whether it was subject to peer review? (b) whether it was properly controlled? (c) whether it was subject to bias? (d) whether it was a primary or secondary source? (e) whether there were confounding factors present? (f) whether its conclusions were consistent with other similar studies? and (g) whether it defined a specific dose/response relationship in deriving conclusions and/or set forth the nature of exposure.

An illustration as to why a critical analysis of individual studies is important includes the fact that many epidemiological studies are inconclusive due to limited population sizes actually studied and/or inadequate information on dose/response and/or the nature of the exposure. Limited population sizes may affect the ability to assess an alleged association between the chemical and a given adverse health effect, in that the author may not be able to state his conclusions with statistical significance. Larger studies may improve the ability to do a statistical evaluation as to the accuracy of results.

A second illustration of why a critical analysis of individual studies is important relates to the fact that chemicals other than the chemical of concern may have been ingested in the population studied. For example, use of cigarettes, alcohol and/or other environmental exposures by the subject population may constitute confounding factors in that it may be unclear which agent actually caused the adverse health effect. In many studies, authors will point out limitations in their findings (i.e., that their findings were not statistically significant, lack of control, presence of confounding factors, etc.).

Individual human studies may be relied upon where they characterize the relationship between the concentration of the chemical at issue and elicited health effects. The studies should suggest the dose necessary to cause an adverse health effect. These studies may also suggest more overt symptoms which should be present at various concentrations before more subtle permanent injury can be suggested. The failure of an individual plaintiff to demonstrate other symptoms associated with toxicity from exposure to a given chemical may call into question whether the chemical played a part in causing the alleged adverse health effects. Care should be taken where studies demonstrate elevation of isolated blood or urine chemistries, but do not suggest injury. Absent corroborating evidence, a study that demonstrates alteration in chemistries (an adaptation response), which is not otherwise corroborated by other studies suggesting adverse health effects, should not be relied upon to establish cause. Studies which suggest subclinical effects should also be viewed with skepticism, particularly in the absence of additional well founded corroborating studies suggesting adverse health effects. A review of studies purporting to be human studies should be made to determine whether and to what extent extrapolation was made from animal studies by the author in coming to his conclusions.

Courts have generally recognized that human epidemiological studies, which are otherwise well founded, are the most valuable evidence in proving or disproving causation. Epidemiological studies consist of studies in human populations over time who have been exposed to the chemical agent at issue. They may be retrospective or prospective. Generally, a prospective study is less susceptible to bias, lack of control and other confounding factors. In determining whether epidemiological studies are of value in suggesting that a given chemical causes specific injury or disease, one should determine whether results of other epidemiological studies are consistent. For example, epidemiological studies on a given chemical may contradict one another, adversely effecting their credibility.

Toxicological studies of high level exposures in laboratory animals may be helpful in corroborating or contradicting epidemiological and/or human studies proffered to prove or disprove causation. Absent corroboration by human data, it may be difficult to extrapolate data useful in either proving or disproving causation from animal studies. Normally, animal studies use exceptionally high doses which may negate their usefulness in suggesting causation in human beings. Differences in the way a given animal metabolizes an agent may also effect the usefulness of animal studies in proving causation. However, it should be noted that several toxicologists suggest that there are means of adjusting for differences in metabolation between animals and humans in certain models.

In animal studies, an evaluation should be made of the propensity of the animal toward spontaneous tumor formation which may limit predictive value. An animal’s response to specific metabolites of the chemical agent may suggest against a plausible biological mechanism of injury in humans and limit the usefulness of the study.

Another source of potential information includes adverse health classification, by chemical, by various governmental agencies or organizations. For example, several governmental organizations classify chemicals in terms of their potential to cause cancer. Governmental agencies which classify chemicals in this manner include the Environmental Protection Agency (EPA), Occupational Safety & Health Administration (OSHA) and National Institute of Occupational Safety & Health (NIOSH). State agencies and public health services have also studied the adverse health effects of various chemicals from time to time. Attention should be paid to the fact that from time to time, governmental agencies reclassify chemicals in terms of their ability to produce adverse health effects and/or, at times, withdraw a position such that a thorough study of the history of the classification by a given governmental agency is necessary.

Private agencies publish classifications, for given chemicals by adverse health effect. Examples of such agencies include the International Agency for Research on Cancer (IARC), the American Conference of Governmental Industrial Hygienist (ACGIH), and the National Cancer Institute (NCI). From time to time, these agencies change and/or withdraw their position on a given chemical. Litigants must review the history of classification by individual organization, as well as the data relied upon in coming to the classification.

The Internet continues to expand its base of information relating to toxic tort litigation (beyond medline). For example, ToxNet contains files focusing on toxicology. ToxNet includes files such as the Hazardous Substance Data Bank, the Integrated Risk Information System, Registry of Toxic Effects of Chemical Substances, and the Chemical Carcinogenic Research Information System. A review of MSDS sheets and technical data sheets put out by various chemical manufacturers and chemical manufacturing organizations may also be helpful. The industry in which the chemical is used might also publish useful information.

Some experts, where there is no direct evidence of cause and effect, extrapolate data from studies of other members of the chemical class in evaluating the chemical at issue. For example, we have encountered experts who have attempted to use studies on one chlorinated solvent (trichloroethylene) to establish a causal connection for a given adverse health effect resulting from exposure to a different chlorinated solvent (perchloroethylene). Most well qualified toxicologists view such an attempt with great skepticism in that the characteristics and toxicity of different chemicals, even of the same class, or for that matter, even different isomers of the same chemical formula, can vary greatly.

Experts have also attempted to extrapolate data based upon adverse health effects on different organ systems. It must be noted that metabolization of a given chemical may be organ specific and/or metabolites may be completely excreted, such that the extrapolation is scientifically invalid. The absence of evidence of injury and/or adverse health effects in the organ systems known to be affected by a given chemical in a given plaintiff, in addition to the injury alleged, would also seem to suggest against use of the extrapolation method.

Extrapolation of data from studies suggesting similar adverse health effects in organ systems other than that effected systems would most likely be rejected by our federal courts. Federal courts have historically taken a dim view of extrapolation, absent corroborating valid scientific evidence. Obviously, based upon the state court decisions referenced in this publication, admission of such evidence may depend upon the district in which the case is pending.

Given the uncertainty in these areas, the Illinois Supreme Court needs to enunciate a procedural framework for the review of scientific evidence relating to proof of medical causation, as well as the level of scrutiny which a trial court should exercise in assessing the reliability of this type of evidence and whether to admit same. A strong argument can be made that even if our Supreme Court continues to refuse to recognize Daubert, adoption to some degree of principles underlying the scientific method in the analysis of scientific evidence will promote uniformity of outcome in state courts called on to decide issues relating to the admissibility of medical causation evidence. A pronouncement by the Supreme Court on this issue will also promote uniformity of decision between federal and state courts, thereby hopefully alleviating forum shopping, as well as insuring that cases are decided based upon credible scientific evidence.

ENDNOTES
/1/ Smith v. Chicago Limousine Service, 109 Ill.App.2d 755, 441 N.E.2d 81 (1982).

/2/ Wiedman v. Industrial Erectors Inc., 137 Ill.App.3d 47, 483 N.E.2d 990, 997 (1st Dist., 1985).

/3/ 176 Ill.2d 95, 679 N.E.2d 1202 (1997).

/4/ Id.

/5/ Landigren v. Celetex, 127 N.J. 404, 605 A2d 1079 (1992); James v. Chevron USA Inc., 301 N.J. Super 512, 694 A2d 270 (1997).

/6/ Donaldson v. Central Illinois Public Services Company, 2000 Ill.App. Lexis 316 (May 10, 2000).

/7/ Lexis slip decision, pg. 14.

/8/ Lexis slip decision, pg. 15.

/9/ Id.

/10/ Werckenthein v. Bucher Petro Chemical Co., 248 Ill.App.3d 282, 618 N.E.2d 902 (1993).

/11/ Donaldson v. Central Illinois Public Service Company, et al., 2000 Ill.App. Lexis 316 (5th District) (5/10/00).

/12/ Limanowski v. Ashland Chemical Co., 275 Ill.App.3d 115, 655 N.E.2d 1049 (1994).

/13/ . Carey, et al. v. Kerr McGee Chemical Corporation, 999 F.S. 1109 (1998).

/14/ Id.

/15/ Carey, supra, Lexis slip decision at pg. 9.

/16/ Id.

/17/ Id.

/18/ Barnes v. American Tobacco, 161 F.3d 127 (3d Cir. Pa.,1998).

/19/ Barnes, supra, at page 139.

/20/ Barnes, supra, at page 139.

/21/ Barnes, supra, at pages 152, 153.

/22/ Majea v. Northwestern, 183 Ill. 2d 407, 701 N.E. 2d 1084 (1998); Wehmeier v. UNR Industries inc., 213 Ill.App.3d 6, 572 N.E.2d 320 (4th Dist., 1991).

/23/ Holton v. Memorial Hospital, supra

/24/ Potter v. Fire Stone Tire & Rubber Co., 25 Cal. Rptr.2d 550, 863 P2d 795 (Cal., 1993); Welsh v. Commonwealth Edison, 306 Ill.App.3d 148, 713 N.E.2d 679(1st Dist., 1999).

/25/ See “Life After Daubert”, Illinois Bar Journal, Vol. 8, No. 3, pg. 134 (March 2000).

/26/ People v. Miller, 173 Ill.2d 167, 670 N.e.2d 721 (1996); Donaldson, supra; Harris v. Cropmate, 302 Ill.App.3d 364, 706 N.E.2d 55 (1999).

/27/ Dotto v. Okan, 269 Ill.App.3d 808, 646 N.E.2d 1277 (1st Dist., 1995); (Adopting Daubert); Donaldson, supra; (Rejecting Daubert; Harris, supra; (Adopting a compromise denoted as the “Frye Plus Reliability” standard).

/28/ See Footnotes 26 and 27.

/29/ Dotto, supra.

/30/ Duran v. Cullinan, 286 Ill.App.3d 1005, 677 N.E.2d 999 (1997).

/31/ Donaldson, supra.

/32/ 293 Fed. 1013, 1014 (D.C. Cir. 1923).

/33/ Id.

/34/ 113 S Ct. 2786; 509 US 579 (1993).

/35/ Id.

/36/ Wintz v. Northrup Corporation, 110 F.3d 408 (7th Cir., 1997).

/37/ Wintz, supra, at pg. 512.

/38/ Federal Judicial Center Reference Manual (1994).

/39/ 110 F.3d 508 (7th Cir., 1997).

/40/ Wintz, supra, at pg. 513.

/41/ Id.

/42/ 1999 US Dist. Lexis 14903 (1999).

/43/ Lexis slip opinion at page 5 of 12.

/44/ Lexis slip opinion at page 9 of 12.

/45/ Lexis slip opinion at page 7 of 12.

/46/ 2000 Ill.App. Lexis 316 (May 10, 2000).

/47/ Lexis slip decision at page 16 of 23.

/48/ Lexis slip opinion at page 15 of 23

/49/ Lexis slip opinion at page 13 of 23

/50/ Id.

/51/ Id. see also Harris, 302 Ill.App. 2d at pg. 366.

/52/ 302 Ill.App.3d 364, 706 N.E.2d 55 (4th Dist., 1999).

/53/ Harris, supra, at pg. 369.

/54/ Harris, supra, at pg. 368.

/55/ Harris, supra, at pg. 368-372.

/56/ Harris, supra, at pg. 371.

/57/ Id.

/58/ Harris, supra, at pg. 372

/59/ Paracelsus born Theuphrastus Bombastus Von Hohen Hein (1493).

/60/Risk Based Correction Action (RBCA) is based on the science of risk assessment. Guidelines of this type have published by EPA(Risk Assessment Guidelines for Superfund (RAGS) (EPA 540-1-89-002 (Dec., 1989)).

/61/ Id.

/62/ Id.

/63/ Threshold limit value and TLU are copyrighted by ACGIH.

/64/ Permissible Exposure Limit (PEL) and Short Term Exposure Limits (STEL) were adopted by OSHA.

/65/ Threshold limit values for 1961 ACGIH (1961).

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