|
29 ELR 10185 | Environmental Law Reporter | copyright © 1999 | All rights reserved Multimedia Exposure Modeling in the CourtroomRolf R. von Oppenfeld and Mark E. FreezeEditors' Summary: The increasing number of toxic tort lawsuits in the courts today causes litigants to use a vast array of scientific methodologies and exposure models, which in turn add to the already high level of confusion among attorneys, judges, witnesses, and juries in the toxic tort courtroom. As a result, toxic tort lawyers must become experts in several scientific disciplines and be thoroughly familiar with state-of-the-art scientific data and studies in order to convince courts to exclude as much of their opponents' science — and to admit as much of their own science — as possible. This Article addresses the role of exposure modeling in establishing or refuting claims in toxic tort litigation that exposures to toxins have caused or increased the risk of illness or injury. The Article illustrates the delicate balance that a lawyer must consider when attempting to meet the increased role for lawyers established under Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579, 23 ELR 20979 (1993), when presenting complex scientific evidence to jurors. The authors begin with an overview of toxic tort litigation and then examine various factors, methodologies, and uncertainties that litigants must take into account when performing exposure assessments and formulating trial strategies. The Article closes by discussing the courtroom presentation of exposure models and other scientific evidence. The authors are members of the "Team for Environmental, Science, and Technology Law" or "TESTLaw" Practice Group, a national environmental law practice within the law firm von Oppenfeld, Hiser & Freeze, P.C., with regional offices in Phoenix, Arizona, and Columbia, South Carolina. Rolf R. von Oppenfeld practices primarily in the areas of environmental law and litigation. Mark E. Freeze has extensive experience in Comprehensive Environmental Response, Compensation, and Liability Act and toxic tort litigation. Throughout the United States, toxic tort lawsuits have proliferated at an alarming rate in recent years. Among the more prevalent substances forming the basis for this litigation are: Agent Orange, arc welding fumes, asbestos, polychlorinated biphenyls, trichloroethylene, and medical devices (e.g., intrauterine devices). To illustrate the magnitude of toxic tort litigation, over 100,000 claims have been filed over the last 20 years in state and federal courts by victims who have contracted one of the many asbestos-related diseases. Furthermore, there have been over 200,000 claimants who have asserted injury due to the Dalkon shield intrauterine device.1 Generally, toxic tort litigation involves common-law claims that exposures to hazardous substances either have caused serious illness among plaintiffs or placed them at an increased risk of developing some illness. Typically, toxic tort litigation is replete with scientific data and testimony. Consequently, a toxic tort lawyer must become an expert in several scientific disciplines and be thoroughly familiar with state-of-the-art scientific data and studies in order to be prepared to argue on two fronts in any case: (1) to exclude as much of the opponent's science as possible, and (2) to admit as much of the client's supporting science as possible.2 The introduction of scientific evidence into the courtroom can be perplexing. As a result, various court personnel including attorneys, judges, witnesses, and juries may find it difficult to carry out their responsibilities. Lawyers may feel they need to match opponent expert testimony number for number. Expert witnesses may have trouble framing their opinions in terms appropriate in a legal context. Furthermore, juries composed of citizens of differing scientific backgrounds may be confused by scientific testimony, and judges may find themselves presiding over legal and scientific dilemmas.3 There is a great disparity between the ease with which [29 ELR 10186] toxic tort litigation may arise and the difficulties in resolving the connection between the suspected toxin and the health effects that may be associated with exposure. Such difficulties have created a great deal of confusion in the courts.4 In toxic tort cases, "litigation may reflect scientific controversy, but it also may help to create it."5 The scientific methodologies and exposure models chosen by litigants when presenting toxic tort evidence adds to this confusion. Depending on the models chosen, a jury will be presented with varying assessments and estimations of exposure to substances alleged by the plaintiff to be harmful. Conservative analyses and methodologies, such as those used by the U.S. Environmental Protection Agency (EPA), often lead to overestimations of actual or potential harm. Conversely, other approaches and models may lead to an underestimation of risk or harm. This Article addresses the role of exposure modeling in establishing or refuting claims in toxic tort litigation that exposures to toxins have caused or increased the risk of illness or injury. The Article begins with an overview of toxic tort litigation and its relevant factors in order to explain the various procedural and evidentiary complexities associated with this form of litigation. The Article then examines various factors, methodologies, and uncertainties that litigants must take into account when performing exposure assessments and formulating trial strategies. Because most jurors have limited scientific backgrounds, toxic tort lawyers must carefully present scientific evidence in a way that is meaningful and comprehensible to jurors. Therefore, this Article also discusses the courtroom presentation of exposure models and other scientific evidence. The discussion of courtroom presentation is particularly relevant in light of the U.S. Supreme Court' Daubert decision expanding the role for attorneys with regard to the admission of expert scientific testimony and evidence. This Article illustrates the delicate balance that a lawyer must consider when attempting to meet the increased role for lawyers established under Daubert when presenting complex scientific evidence to jurors. There is generally no such thing as a "typical" toxic tort. Toxic tort litigation is a complex area of the law due to the numerous variables that exist in any particular case. Included among these variables are: thousands of toxic substances that produce varied effects; substances that are released from a variety of mediums and handled by numerous individuals; the uniqueness of each individual's response to an exposure; the length of time, due to long latency periods, from exposure until the observation of clinical manifestations; the variety of bases on which litigation may be pursued and defended, including common-law negligence principles, state and federal statutes, and other governmentally imposed regulations; the confusing nature of documenting exposures because an exposure may occur by a multitude of routes including inhalation, ingestion, or dermal exposure, singularly or in combination; and finally, causation, which is a significant complication when attempting to prove liability.6 Compounding these difficulties is the fact that toxic tort cases are replete with expert scientific and medical testimony assessing exposure, causation, and symptoms. This expert testimony is often at odds with the "expertise" of juries composed of citizens with little or no scientific background. Perhaps no issue illustrates the difficulty and complexity of toxic tort litigation more than the notion of causation. Due to long latency periods before the manifestation of injuries, an often limited scientific knowledge about the nature of those injuries,uncertainty about the mechanism of action of many toxins, questions about amounts and durations of exposure, as well as many other issues, toxic tort claims historically have not been successful.7 Ideally, in order to demonstrate that a given toxin was a link in the causal chain that led to an individual's illness or injury, one would need to trace every step in the biology of the development of the disease, including the role played by the toxin.8 Due to the fact that the biological mechanisms of most diseases are understood rudimentarily at best, other processes are required in order to make an inference of causation. In the absence of direct evidence, scientific methods and experimentation are used to infer causation.9 There is a vast array of literature that examines the notion of causation as it relates to toxic tort litigation.10 In order to assess causation of injury or illness in toxic tort litigation, one must first show that a person or persons were exposed to the toxin in question. An Introduction to Exposure Modeling in the Courtroom Exposure is defined as the "contact of an organism with a chemical or physical agent."11 The magnitude of exposure to an agent is determined by measuring or estimating the amount of the agent available at various exchange boundaries (i.e., lungs, gut, and skin) during a specified period of time. Through the use of an exposure assessment, one can make a determination or estimation of the magnitude, frequency, duration, and route of exposure of an organism to various pollutants.12 These estimates can be generated directly from monitoring contaminant levels measured in the environment and in biological organisms, or indirectly from modeling results or reasoned estimates.13 It is important that [29 ELR 10187] litigants understand the advantages and disadvantages of using monitoring and modeling data in the courtroom. Monitoring data generally will be the preferred option, because modeling is usually based on various assumptions and may provide limited data for an estimation of the various concentrations to which people may have been exposed. Sophisticated mathematical modeling can be extremely resource intensive. For parties with limited financial resources, this can prevent an accurate assessment of the actual exposures encountered and severely hinder their case. However, litigants may encounter problems if they rely solely on monitoring data. Improper monitoring can inaccurately predict human exposure levels. This is evident when exposure estimates are based on relatively few measurements.14 A toxic exposure assessment attempts to identify the pathways by which a chemical may reach individuals, to estimate the amounts of a chemical that an individual is likely to be exposed to, and to provide an estimate of the number of individuals who are likely to be exposed.15 Stated another way, an exposure assessment attempts to answer the questions, "How much of a pollutant is out there?" and "To what amounts were persons exposed?"16 There are a variety of ways to measure toxic exposure and its associated health effects, including examining human disease incidence rates in order to estimate likely exposure levels or simulating exposure with models that predict relative degrees of toxicity.17 By evaluating the various components of exposure, an expert can construct reasonable scenarios for each problem area characterizing exposures by different populations. In toxic tort litigation, it is the role of the jury to sort through these various scenarios in rendering a verdict as to whether exposure to the pollutant in question has caused an injury or illness. It is imperative for attorneys, judges, and juries to have a working understanding of the exposure assessment and modeling process in order to view evidence competently and objectively in toxic tort litigation. Through the use of exposure modeling and its mathematical formulas, litigants can depict exposure values to illustrate graphically exposure levels to a particular substance or pollutant. Some of the various exposure model formulas that are used in conducting exposure assessments are shown in Figures 1 through 4.18 These models were presented in chapter six of EPA's Risk Assessment Guidance for Superfund: Human Health Evaluation Manual.19 The associated variable definitions and terminology are presented as well. It should be noted that "intake" is often considered by EPA to be synonymous with "exposure" in the sense that intake may be defined as "a measure of exposure expressed as the mass of a substance in contact with the exchange boundary per unit body weight, per unit time (e.g., milligrams (mg) chemical/kilograms (kg)-day). Other terms often used to signify intake include normalized exposure rate, administered dose, and applied dose."20 RESIDENTIAL EXPOSURE: INGESTION OF CHEMICALS IN DRINKING WATER (AND BEVERAGES MADE USING DRINKING WATER) Equation: Intake (mg/kg-day) = (CW x IR x EF x ED)/(BW x AT) CW = Chemical Concentration in Water (mg/liter) IR = Ingestion Rate (liters/day) EF = Exposure Frequency (days/year) ED = Exposure Duration (years) AT = Average Time (period over which exposure is averaged — days) Source: Risk Assessment Guidance for Superfund: Human Health Evaluation Manual, Part A, Chapter 6. RESIDENTIAL EXPOSURE: INGESTION OF CHEMICALS IN SOIL Equation: Intake (mg/kg-day) = (CS x IR x CF x FI x EF x ED)/(BW x AT) CS = Chemical Concentration in Soil (mg/kg) IR = Ingestion Rate (mg soil/day) CF = Conversion Factor (10<-6> kg/mg) FI = Fraction Ingested from Contaminated Source (unitless) ED = Exposure Duration (years) AT = Average Time (period over which exposure is averaged — days) Source: Risk Assessment Guidance for Superfund: Human Health Evaluation Manual, Part A, Chapter 6. RESIDENTIAL EXPOSURE: INGESTION OF DERMAL CONTACT WITH CHEMICALS IN SOIL Absorbed Dose (mg/kg-day) = (CS x CF x SA x AF x ABS x EF x ED)/(BW x AT) CS = Chemical Concentration in Soil (mg/kg) CF = Conversion Factor (10<-6> kg/mg) SA = Skin Surface Area Available for Contact (cm2/event) AF = Soil to Skin Adherence Factor (mg/cm2) ABS = Absorption Factor (unitless) EF = Exposure Frequency (events/year) ED = Exposure Duration (years) AT = Averaging Time (period over which exposure is averaged — days) Source: Risk Assessment Guidance for Superfund: Human Health Evaluation Manual, Part A, Chapter 6. RESIDENTIAL EXPOSURE: INHALATION OF AIRBORNE (VAPOR PHASE) CHEMICALS Equation: Intake (mg/kg-day) = (CA x IR x ET x EF x ED)/(BW x AT) CA = Contaminant Concentration in Air (mg/m3) IR = Inhalation Rate (m3/hour) ET = Exposure Time (hours/day) EF = Exposure Frequency (days/year) ED = Exposure Duration (years) AT = Averaging Time (period over which exposure is averaged — days) Source: Risk Assessment Guidance for Superfund: Human Health Evaluation Manual, Part A, Chapter 6. When presenting a claim of injury to a jury, plaintiffs seek to maximize the number of exposures and the variables associated with exposure in order to strengthen their claims that such exposure caused an illness or increased the risk of illness. Conversely, defense counsel seeks to minimize such exposures and variables. Exposure Assessments and Their Relevance to Toxic Tort Litigation Before discussing some of the various models used by litigants and the rationale and methodologies associated with those models, a brief overview of the steps in the exposure assessment process and their courtroom implications in toxic tort litigation is useful. [] Exposure Pathways. When engaged in toxic tort litigation, it is imperative that litigants understand the various means by which a person or persons may be exposed to toxins. Plaintiffs may be exposed to toxins through a multitude of pathways including ingestion, inhalation, dermal absorption, or a combination of these routes. Activity patterns play a large role in determining the pathways of exposure.21 Ingestion of contaminants may result due to inadvertent consumption of contaminated soils or sediment, or through the consumption of drinking water, surface water, or wildlife. Dermal contact often occurs as a result of direct contact of the skin with either contaminated sediments, riverplain soils, or overlying water. Inhalation of airborne vapors or dust may introduce contaminants into the respiratory systems.22 A matrix of potential exposure pathways gathered from chapter six of the Risk Assessment Guidance for Superfund: Human Health Evaluation Manual is shown in Figure 5.23 MATRIX OF POTENTIAL EXPOSURE ROUTES
C = exposure in children may be significantly greater than in adults A = exposure to adults (highest exposure is likely to occur during occupational activities) — = exposure of this population via this route is not likely to occur When adjudicating a claim of injury or illness in a toxic tort case, plaintiffs and defendants must be aware of these pathway differences and the physiological and biological factors associated with each. For example, the ingestion exposure pathways often result in higher exposure estimates than the dermal or inhalation pathways because of the greater absorption of contaminants through the gastrointestinal tract as compared with absorption through the skin, and the relatively high levels of intake of contaminants in soil, water, and food as compared with inhalation of contaminants.24 In measuring the assorted routes of exposure, standard assumptions are often made by litigants in determining modeling calculations. For example, EPA includes the standard assumption that the average adult consumes 2 liters of water per day and 20 cubic meters of air per day.25 However, [29 ELR 10188] there is actually a wide degree of variability in these rates.26 The use of various exposure models and assumptions will highlight these differences. Problem areas related to exposure in toxic tort litigation concern the existence of multiple exposure pathways. An additional complicating factor is that the toxicity of a substance may vary according to the different exposure routes. For example, asbestos is known to be carcinogenic when inhaled. However, it cannot be absorbed through the skin and has not been conclusively shown to be carcinogenic if ingested.27 Absent supporting data regarding the toxicity, metabolism, and absorption via different exposure routes, it is often assumed that adverse effects from different exposure routes are equivalent. However, this assumption should not be made without considering all available data.28 Therefore, when identifying relevant exposure pathways, it is necessary for litigants to consider the toxicities of the pollutants at issue via the different exposure routes that are being investigated. Through the use of expert testimony, such toxicities will be maximized or minimized by opposing counsel. [] Sources and Releases. When engaged in toxic tort litigation, information concerning the concentrations and quantities of released toxins is critical in assessing exposure. Furthermore, an understanding of the location and timing of releases of potential pollutants is critical in order to assess and accurately measure exposures. The absence or presence of a pollutant at a particular site at a particular time plays a large role in determining whether the litigants were exposed to the pollutant. Monitoring or computer modeling can assist litigants in estimating the sources and amounts of pollutants released from the source and the amount of pollutants found at different distances from the source.29 [] Fate and Transport of Pollution. The fate and transport of pollutants are critical in assessing potential or actual toxic tort liability. The final destination (fate) and the route that the toxin in question takes (transport) provide information for determining the pollutant concentrations that plaintiffs are likely to be exposed to in toxic tort cases.30 Once again, the parties to litigation may base estimations of these concentrations on monitoring and modeling data. Whether relying on monitoring, modeling, or a combination thereof, it is important for litigants to consider the dilution, dispersion, mobility, persistence, and degradation of the substances in the environment before exposure.31 Should the fate and transport of toxins be modeled from release to exposure, uncertainties in these factors may be elevated due to the increased time and distance to exposure. Furthermore, even if ambient concentration data are available, contaminant concentrations can change between the monitoring location and the point of exposure.32 Because the burden of proof in civil toxic tort litigation is so fine (i.e., a preponderance of the evidence), counsel must consider all possible uncertainties relating to the fate and transport of pollution. Such uncertainties can mean the difference between a multimillion dollar judgment or complete absolution from liability. [] Human Contact. When attempting to prove causation in toxic tort litigation, it is necessary for plaintiffs to show actual human contact with the contaminants at issue. As a result, it is essential for litigants to estimate the duration and magnitude of the contact, and calculate the size and distribution of the populations at risk. Sometimes this merely entails a cursory examination of geographical data. For example, showing contact for persons living adjacent to a facility releasing toxins might not involve a detailed analysis. However, due to the various pathways by which toxins may come into contact with humans (i.e., groundwater, surfacewater, air dispersion, etc.), more remote points of human contact may exist where the amounts and concentrations of contaminant determination is not as straightforward. In order to maximize or minimize the number of exposures, attorneys must consider all potential points of human contact in their assessment of the evidence. The models, methodologies, and assumptions employed by the litigants will determine whether the plaintiff has presented sufficient evidence of contact to the toxins alleged to have caused an illness or injury. Other elements that may complicate a demonstration of human contact with various pollutants include behavioral and sensitivity factors. In attempting to demonstrate that the requisite amount of contact has occurred, litigants must consider behavioral factors. For example, time and location factors vary widely for individuals. Some people spend a greater amount of time indoors as opposed to outdoors.33 Attorneys must adequately convey this type of information in the courtroom to judges and juries in order to demonstrate that the plaintiffs did or did not have adequate contact with a pollutant. To illustrate, a plaintiff claiming injuries or illness resulting from exposure to asbestos may have a harder time convincing a jury that he or she has been injured should opposing counsel demonstrate that the plaintiff spends an inordinate amount of time indoors, sheltered from any sources of asbestos pollution. Similarly, some humans are more sensitive to particular contaminants than others and may experience adverse health effects at concentration levels lower than those causing adverse effects in members of the general public.34 Often referred to as the "thin skull doctrine," defense attorneys must be acutely aware of highly sensitive populations such as pregnant women, infants, or asthmatics when presenting evidence of toxic exposure before the court. Juries are often sympathetic to such highly sensitive persons and the resulting verdicts may reflect this compassion. [] Uncertainties. Finally, exposure assessments and modeling are not an exact science. Because the use of exposure modeling and its meaning in toxic tort litigation are subject to wide interpretations and uncertainty, the use of uncertainty analysis should be discussed. The goal of an analysis [29 ELR 10189] of uncertainties is "to provide decisionmakers with the complete spectrum of information concerning the quality of a concentration estimate, including the potential variability in the estimated concentration, the inherent variability in the input parameters, data gaps, and the effect these gaps have on the accuracy or reasonableness of the concentration estimates developed."35 Such an analysis will allow decision-makers to better weigh the concentration results in the context of other factors being considered in toxic tort litigation.36 In the context of toxic tort litigation, the jury is the ultimate decisionmaker.37 Exposure Models and Litigation Plaintiffs and defendants in litigation are confronted on a regular basis with the issues of the relevance, admissibility, and utility of scientific evidence. Toxic tort litigation is no exception. As previously stated, the complexities associated with toxic tort cases in establishing causation, injuries, and responsible parties add to this confusion.38 The discussion that follows will examine various methodologies used in the courtroom by litigants in presenting exposure models and the assumptions associated with these methodologies. To date, "almost all human health risk assessments have used conservative 'point' estimates to characterizethe hazards associated with exposure to chemicals in the environment."39 The methodology used by an exposure expert can have a profound impact on the expert's conclusions and the credibility of those conclusions. Conservative point estimates of exposures may produce drastically different data as to whether the plaintiff has demonstrated to a jury the requisite level of exposure. Conversely, the use of more sophisticated probabilistic analyses may produce entirely different perceptions as to whether a plaintiff was exposed to pollutants in an amount and duration contributing to the incidence of disease. The following discussion presents an examination of deterministic assumptions made by EPA and other regulatory agencies. It addresses several of the various assumptions that are employed in exposure modeling calculations. In toxic tort litigation, each party's stance with respect to governmental data is fact-sensitive and will depend on the chemical and exposure levels at issue on a case-by-case basis. Should the toxin in a particular case be detected in an amount below a governmentally imposed level, the defendant will argue that the exposure was therefore de minimis and harmless. On the other hand, if the toxin exceeds the standard, the plaintiff will offer this fact as proof of wrongdoing. Often the defense will argue that the governmental standard is irrelevant and inadmissible. As a result, the impact of governmental assessments may vary from case to case.40 Deterministic Versus Probabilistic Methodologies and Exposure The federal government regulates the environment through EPA and EPA's interpretation of various statutes relating to air and water pollution, waste disposal, and hazardous and toxic substances. Included among these statutes are the Clean Air Act,41 the Clean Water Act,42 the Toxic Substances Control Act,43 the Resource Conservation and Recovery Act,44 and the Comprehensive Environmental Response, Compensation, and Liability Act.45 On a local and state level, environmental regulation may occur either independently or in conjunction with federal law. Furthermore, toxic substances and pollutants may be regulated by other agencies such as the Occupational Safety and Health Administration. Consequently, the same chemical may have differing levels of safe exposure depending on the context in which it is being regulated.46 Based on varying exposure limits, a government agency's assessment of a chemical product may "almost provide an incentive to bring toxic tort litigation."47 [] Government Policy and Regulations. Traditionally, government or legislative action has had very little effect on tort liability. As a result, plaintiffs were previously barred from using policy or regulations in order to prove hazard or fault.48 Recently, however, plaintiffs have increasingly tried to introduce government policy and regulations as evidence to support a claim that exposure to a particular substance has resulted in an injury or illness.49 Evidence of this type is considered to be effective, "since government policy and regulations imply official recognition of the hazards of a material or safe levels of exposure with minimal or no independent evidence."50 As a result, defendants are charged with carefully circumscribed tort liability "on the basis of a prophylactic regulatory scheme designed to provide the broadest protection to the public."51 Such a strategy is based on scientific assumptions and the use of mathematical risk models to protect the public from levels of exposure where little or no empirical data exist associating exposure with adverse health effects. A wide variety of models are available for use in exposure assessments. The EPA Exposure Methods Handbook describes some of the models available and provides guidance in selecting the appropriate modeling techniques. The use of these models and the variables associated with intake and exposure calculations [29 ELR 10190] is crucial in toxic tort litigation. Plaintiffs' strategy in introducing such evidence can be effective, because research has shown that charges of defendants' noncompliance with applicable government standards dispose juries quite negatively toward defendants.52 The choice of exposure factors and variables is crucial in toxic tort cases. The use of exposure modeling in conducting toxic exposure assessments may be used by litigants to predict whether concentrations of chemicals in the environment are of concern and whether there have been exposures at levels of concern to the plaintiffs in toxic tort litigation. The discussion that follows examines how the differences in exposure variables used in modeling techniques and the use of regulatory assumptions can be used by counsel in toxic tort litigation in order to influence judges and juries. [] Plaintiff Strategies. As mentioned above, in order to maximize exposure, plaintiffs often resort to reliance on conservative governmentally imposed standards of maximum allowable exposure levels as proof that by exceeding this threshold level of exposure, the defendant caused or increased the likelihood of disease. Scientifically objective assessments of exposure factors should be a goal in determining the risks associated with exposures to chemicals in toxic tort litigation. However, the conservatism employed by EPA and other agencies in determining exposure modeling variables and conducting risk assessments often causes the true levels of exposure to toxins to be overstated. Some commentators have suggested that such an overstatement of risk may be by a factor of 1,000 or more.53 As such, this methodology presents a powerful weapon for plaintiffs in toxic tort litigation when examining the levels of exposure. When conducting exposure assessments through modeling data, EPA may overestimate the actual risks posed by the exposure of humans to various materials. There are several reasons that EPA methodology may overstate these risks, including (1) the use of broad assumptions instead of site-specific data, (2) the use of theoretical worst-case values for modeling variables, and (3) the use of "point estimates" to characterize those variables.54 In the event that these potential overestimations are made in conjunction with each variable in a modeling equation, the resulting "multiplier effect" may yield an unreasonable estimate of exposure and health risks. Through the use of modeling, plaintiffs may use such exposure estimations to establish prima facie evidence of a defendant's wrongdoing by showing that a governmentally mandated safe exposure level was exceeded. EPA's approach to conducting exposure assessments is based on assumptions that often lead to an inflated risk estimate. The models presented in Figures 1 through 4 present a few of the more common exposure equations examining intake.55 The data gathered and applied to variables such as chemical concentration, ingestion rates, inhalation rates, exposure frequency, and duration, to name a few, play a crucial role in litigation in determining the various exposures and intakes that plaintiffs may have encountered. Reliance by EPA on a number of standardized assumptions and models in performing exposure assessments in which the presence of a substance is often equated to exposure, regardless of whether there is any actual exposure or a realistic likelihood of exposure, often results in an overestimation of exposure.56 As a practical example, the assumptions often used in Superfund site exposure models and assessments can be used to illustrate this notion. The usual practice of EPA is to sample and analyze soil and water, identify contaminants, and then construct theoretical current and future exposure scenarios that maximize exposure.57 Some of the various assumptions that have been made at Superfund sites include the following: frequency of exposure is assumed to be every day for 30 years; substance concentrations in groundwater are assumed to be total, not dissolved concentrations from unfiltered samples; substance concentrations are assumed to remain constant throughout the duration of exposure; individuals are assumed to consume 100 percent of their drinking water from "contaminated" wells at home; and adults are assumed to consume 100 milligrams per day (mg/day) of the most contaminated surface soil per day while children consume 200 mg/day (burrowing infant assumption).58 Applying larger variable values will often overstate the actual exposure level. Many of the elements of these assumptions "do not exist, will never exist, and are extreme even when taken in isolation."59 However, when armed with such statistics and calculations, plaintiffs have powerful testimony and evidence that the exposure levels are excessive and the health risk associated with those exposures are compensable. In addition to the assumptions stated above, regulatory agencies often use theoretical worst-case values for many of the variables in exposure model equations. For example, two important variables used in soil sampling are the chemical concentration of the contaminant in the soil, and the amount of soil that a person contacts and ingests.60 EPA regularly uses an upper-bound, worst-case estimate such as the 95th percentile or the 95 percent upper confidence level on the mean as a conservative estimate of exposure.61 However, the combination of several upper-bound estimates does not result in an exposure estimate at the 95th percentile. For example, a combination of three variables at their 95th percentile will result in a value that is actually at the 99.8th percentile.62 Once again, a plaintiff using such data has a powerful case that the requisite level of exposure to chemicals has occurred. Another factor often beneficial to plaintiffs in toxic tort litigation is the use of "point estimates" in order to characterize the hazards associated with exposure to chemicals in the environment. At present, virtually all state and federal guidelines for conducting risk assessments rely on point estimates of risk in making environmental decisions.63 An example [29 ELR 10191] of the use of point estimates is how EPA estimates groundwater concentrations at Superfund sites. When conducting exposure assessments at Superfund sites, EPA obtains groundwater sample data through hydrogeological studies and water distribution analysis at various levels and locations at a site. However, instead of using an average figure to examine contaminant concentration, EPA uses upper-bound concentration data from the most contaminated portions of the site. This results in an assumption that the entire site is as contaminated as the most contaminated areas. Furthermore, an ingestion rate of 2 liters/day (average adult consumption is 1.4 liters/day) from the most contaminated groundwater at asite is assumed. Based on these factors and other assumptions used in the exposure model present in Figure 1, an overestimation of exposure is likely to occur.64 The potential for overestimating exposure by compounding overly conservative assumptions is shown in Table 1.65 These data were gathered from Exaggerating Risk: How EPA's Risk Assessments Distort the Facts at Superfund Sites Throughout the United States.66 These data differentiate EPA's method of estimating exposure based on point estimates to a more reasonable point estimate of polynuclear aromatic hydrocarbon intake by an adult. Based on expert testimony and presentation of these figures, a powerful case can be made that exposure levels exceeded governmentally set standards and, therefore, present prima facie evidence of fault. For juries often composed of citizens with little or no scientific or statistical background, these numbers can present a skewed version of the actual exposure and the health risks associated with that exposure. Furthermore, juries often come to the case predisposed to believe that exposure to toxic chemicals has caused injury. Therefore, plaintiffs will almost always attempt to focus the attention of the jury on the injured plaintiff. It should be pointed out that the larger the potential damages in a case, the more likely that plaintiffs will develop their own models, rather than rely on the government's models. In so doing, they will often use even more conservative assumptions than EPA. CALCULATION OF ESTIMATE OF INTAKE OF SOIL CONTAINING POLYNUCLEAR AROMATIC HYDROCARBONS BY AN ADULT Intake = (CC x IR x CF x AC x AF x BF x FE x DE)/(BW x AT), where: CC = Chemical concentration in the soil IR = Rate of ingestion of soil AC = Amount of contaminated soil
[] Defense Strategies. In toxic tort scenarios, the defense has several approaches with which to minimize the effect of plaintiff testimony and evidence. If the pollutant at issue in a particular case is detected at a level below a governmentally imposed standard, the defendant will likely assert the government's standard claiming that the exposure was de minimis and harmless. However, in the event that the toxin does exceed the government standard, the defense must frame their argument differently. Generally, the defense will argue that the government standard is irrelevant and inadmissible.67 When presenting exposure evidence and models, the defense will seek to minimize the number and levels of exposure as well as the relevant variables associated with the models employed in the exposure assessment. A more probabilistic approach to assessing exposure may be preferred by defendants when confronted with governmentally established exposure guidelines. A probabilistic technique such as a Monte Carlo simulation addresses the main deficiencies of the point estimate approach because it provides a great deal of additional information concerning exposure and the possible incidence of disease. Instead of merely presenting point estimates of exposure, the Monte Carlo simulation characterizes a range of potential exposures and their likelihood of occurrence.68 Probabilistic approaches use a group of possible values for each exposure variable, thereby reducing the discussion of what constitutes the best point estimate. Furthermore, probabilistic methods can be used by the defense to incorporate all ingestion, inhalation, or dermal absorption values into frequency of their occurrence.69 For example, the conservative scenario of soil consumption per day in children established by EPA is 200 mg/day. However, through the use of Monte Carlo methods, this ingestion rate can be arranged to reflect a range of values. Recent data indicate that 50 percent of children ingest no more than 9 to 40 mg/day of soil from sources such as household dust, dirt in foods, and direct soil contact.70 In addition, some have suggested an arithmetic mean value of 16 mg/day.71 When applied to the model shown in Figure 2, using a conservative, worst-case value will result in a much greater exposure due to the greater ingestion rate variable in the calculation. Therefore, a defendant must seek to minimize such exposure inputs. The purpose of this minimization is twofold. One, minimization of exposure may present a more realistic measurement of the exposure that actually occurred. Two, juries are likely to equate a higher exposure value with causation of injury. A 1991 study commissioned by the Chemical Manufacturers Association evaluated EPA's existing Superfund exposure assessment assumptions, statistically analyzed the uncertainty of the existing exposure assessment methods, and evaluated and recommended modifications or alternative approaches to disease uncertainty. The exposure estimates derived from point estimates were compared with exposure estimates taken from a Monte Carlo simulation using both EPA assumptions and data derived from more recent peer-reviewed research. The 95th percentile exposure values derived from the Monte Carlo analysis showed lower likely exposures than values derived from EPA single point estimates. The results of this are presented in Table 2.72 EXPOSURE ESTIMATES FOR FOUR SAMPLE SCENARIOS
Additional strategies that a defendant may employ include presenting alternative causation theories for plaintiffs' injuries. A defendant would also be well advised to ask the judge to bifurcate the trial into two phases. Phase one would concentrate on whether there had been exposure and whether the exposure was sufficient to cause injury. Phase 2 would concentrate on plaintiffs' specific injury and damages. By so doing, the defendant can focus the jury's attention on the exposure question, rather than on the injured plaintiff. [] A Case Study in Toxic Tort Litigation: O'Dell v. Hercules, Inc.73 A recent case illustrates the differing interpretations of exposure that may occur during toxic tort litigation. In Hercules, residents of Jacksonville, Arkansas, brought suit against Hercules, Inc., alleging that the defendant had taken chemicals to a landfill over a 10-year period during its operations as a herbicide manufacturing plant. Hercules primarily manufactured Agent Orange for the federal government. The plaintiffs alleged that Hercules and a subsequent owner of the plant (Vertac Chemical Corporation) had been negligent and conducted ultrahazardous activities at the site. They claimed that exposure to the chemicals had caused various ailments ranging from nosebleeds to cancer and birth defects. They also claimed that exposure had led to an increased risk of contracting cancer in the future.74 Both sides to the litigation employed experts to testify as to the varying amounts of exposure encountered and the health effects associated with those amounts. The outcome turned on the quantification and use of exposure estimates and the methodologies to which they were applied. The plaintiff's experts spoke of the risks associated with the pollutants in general terms such as "dioxin is carcinogenic." Furthermore, the plaintiffs relied on animal studies to support these statements, but they did not attempt to quantify their exposure levels to show whether they could have received a dose sufficient to cause any adverse symptoms. Conversely, through the use of exposure models and testimony, the defense consistently focused on the specific dosages to which the plaintiffs may have been exposed and showed that these potential doses were insufficient to cause illness or injury.75 In Hercules, 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) was detected in landfills in an amount exceeding the one part per billion (ppb) level of concern established by the Centers for Disease Control. The plaintiffs focused on this as evidence of harm. However, to counteract this evidence, Hercules established that the 1 ppb level far overstated the real risk of exposure. Hercules demonstrated that a more accurate level of exposure that would increase an individual's risk of contracting cancer by one chance in a million was 122 ppb. Upon cross-examination, the plaintiff's expert admitted that the 1 ppb level of concern had been based on conservative assumptions regarding soil ingestion, and that the actual level of concern should be adjusted upward to 7.8 ppb to reflect more realistic levels of ingestion. However, the expert admitted that the 122 ppb level is that which would result from an assumption that TCDD is a promoter of cancer and from the use of a threshold model of risk assessment. After establishing the 122 ppb threshold level, the defense had no trouble showing that the plaintiffs were not exposed to risk because no quantities of TCDD exceeding 122 ppb were observed. Based on this and other evidence, a jury found for Hercules.76 Hercules demonstrates the importance of considering various exposure scenarios and levels, and convincing a jury that the exposure levels with which they are presented are more realistic and probable than those assessments presented by opposing counsel. Exceeding governmentally imposed regulations is not fatal to a case. Properly educating jury members on complex scientific matters through coherent testimony is perhaps the most critical factor in persuasion. Because most jurors have a limited scientific and mathematical background, the presentation of this evidence and testimony in an intelligible manner is crucial. Assessment and Presentation of Uncertainty There is inevitably a certain degree of doubt as to how well an exposure model or its mathematical expression (e.g., air dispersion models, water distribution models, etc.) approximates the true relationships between site-specific environmental conditions. In an ideal situation, the use of a fully validated model that considers the interrelationships of every parameter would be preferred. However, generally there are only rudimentary, partially validated models that are customarily used. Consequently, one must identify various assumptions associated with exposure models such as linearity, homogeneity, and steady-state relationships in order to identify how these factors affect exposure and risk estimates.77 Varying assumptions about the functional relationships between variables (i.e., sensitivity analysis) can be used to measure the amount of uncertainty presented by the model.78 The goal of an analysis of uncertainty is to "provide decisionmakers with the complete spectrum of information concerning the quality of a concentration estimate, including the potential variability in concentration measurements, input parameters, and data gaps."79 Analysis of uncertainties will allow the decisionmaker to better evaluate concentration results in the context of other factors being considered.80 The basic causes of uncertainty in exposure modeling are varied. The more prominent causes include measurement errors; generic data gathering such as using similar chemical properties to fill in gaps about an unknown substance; the natural variability of environmental concentrations due to factors such as wind, temperature, and water flow; modeling uncertainties; disagreements in professional judgment; and sampling errors.81 Probabilistic assessments are more conducive to sensitivity and quantitative uncertainty analysis than the deterministic approach. An accurate sensitivity analysis requires an [29 ELR 10193] accurate estimate of variance within a particular data set. A probabilistic approach can more accurately supply such information.82 Sensitivity analysis allows for the testing of an output variable to the possible variation in input variables.83 Thus, it can allow attorneys and experts to better identify the variables that predominate in the results and give a more precise insight as to the risk estimate associated with a model. By identifying the influential input variables, more resources can be directed to reduce their uncertainties and thus reduce the output uncertainty.84 In the context of establishing or refuting the requisite preponderance of the evidence burden of proof in a civil toxic tort matter, such uncertainty reduction is a powerful tool. Because toxic tort litigation often hinges on probabilities, the reduction of the uncertainty in these assessments is critical in successfully prosecuting or defending toxic tort litigation. Scientific Evidence and Expert Testimony in the Courtroom One of the major factors distinguishing toxic tort litigation from other forms of litigation is its complexity. Typically, the outcome of toxic tort litigation is based on the effectiveness of expert testimony in assessing exposure to hazardous substances and causation. Rarely can a single expert address all of the necessary scientific issues. Toxic tort cases often encompass "widely divergent disciplines such as epidemiology, toxicology, hydrology, meteorology, and medicine."85 Experts employed in toxic tort cases may range from highly respected, well-known experts who can offer opinions within the mainstream of science to experts whose credentials are dubious and whose theories lack general scientific support. The following discussion focuses on the role of scientific evidence in the courtroom. It examines the evolution of admissibility of scientific testimony and evidence due to changing legal principles and precedence. It also addresses the presentation of exposure models and other scientific evidence to jurors and their perceptions regarding such evidence. Finally, because jurors are the ultimate decisionmakers in toxic tort litigation, the following discussion examines their comprehension and perceptions of toxic tort evidence and their role in deciding the "battle of the experts." Traditional Evidentiary Standards According to traditional evidentiary standards, expert scientific testimony is allowable when: (1) the expert possesses a background that gives him or her special knowledge about the applicable subject matter; (2) the testimony would be helpful to a trier of fact; and (3) the expert's testimony is based on facts, data, or methods relied on by other experts in the field.86 It is frequently through expert opinion testimony that exposure modeling evidence is presented to juries. Individuals whose expertise has been approved by the court typically will explain their opinion about the exposure at issue. The plaintiffs present their experts and the defendants present experts of their own. When opinions differ, which is virtually always, the jury must decide the weight to attach to the testimony. The expert opinion method of educating juries on the complexities and interpretations of exposure evidence seems sensible. Problems arise, however, because not all experts hold the same standard of scientific validity or ethics. In other words, some litigants are willing to pay large sums of money for experts with sufficiently impressive credentials to say favorable things about the litigant's position. Unfortunately, some experts can be induced by such financial incentives to say remarkable things, including things not well-founded in science. An attorney has two ways of responding to such testimony presented by opposing experts: (1) appealing to the judge to exclude the expert's testimony, and (2) undermining the expert's testimony in the minds of the jury with cross-examination and contrary expert opinion. For many years, courts admitted expert opinion only if it was based on scientific methods generally accepted as reliable in the relevant scientific community.87 This standard, known as the Frye test, was named after a 1923 case which prohibited the introduction of expert opinion evidence based on methodology that diverged significantly from the procedures accepted by recognized authorities in the field.88 Using the Frye rule, litigants could prevent "lone nut" scientists from presenting unique theories of evidence to juries. However, the rule could also prevent sound opinions from being heard in court simply because they were based on new theories. For nearly half a century, Frye served fairly well to exclude unreliable or unconventional evidence from court-rooms.89 In the 1960s and 1970s, however, the rule came under attackfrom lawyers who viewed the rule as "elitist and unhelpful" in complex cases involving new pollutants and unfamiliar hazards. Critics argued that alleged toxic tort victims should not be denied compensation just because the plaintiff's offer of proof did not meet the standards of acceptance by a broader scientific community.90 An Evolving Standard of Evidence In 1975, Rule 702 of the Federal Rules of Evidence was developed. In relevant part, it provides: "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."91 In 1993, the Supreme Court struck down the Frye test. In Daubert, the Supreme Court held that the Federal Rules of Evidence superseded Frye, and that proposed experts may testify to any scientific knowledge that will assist the trier of fact.92 The Court went [29 ELR 10194] on to suggest that a trial court would need to make a "preliminary assessment of whether the reasoning or methodology underlying the testimony is scientifically valid and of whether that reasoning or methodology properly can be applied to the facts in issue."93 Daubert suggests that the methodology or technique underlying a scientific statement can be evaluated on the basis of its susceptibility to empirical testing, the peer review it has received, its publication, its rate of error, the existence of standards controlling its operation, and its general acceptance in the relevant scientific community. Thus, under Frye, an attorney wishing to have expert scientific testimony excluded would present evidence to the judge that the opinion the expert was going to express was based on science not generally accepted by his or her peers. Under Daubert, an attorney must delve directly into the substantive merits of the expert's methodology in order to undermine the scientific validity of the expert's proposed testimony sufficiently to have it excluded from trial. This new standard requires greater scientific sophistication on the part of attorneys than did the Frye rule. In December 1997, in General Electric Co. v. Joiner,94 the Supreme Court both reaffirmed Daubert and held that the standard of review that federal appellate courts must give to district court decisions on the question of admissibility of scientific evidence is the traditional abuse-of-discretion standard. In Joiner, the Supreme Court reversed the Eleventh Circuit holding that applied a "particularly stringent standard of review."95 It should be noted that Daubert construes theFederal Rules of Evidence. Thus, it is not directly binding on state courts. However, because many states have adopted the Frye test, Daubert may affect numerous state standards for the admission of expert scientific testimony and evidence. At this date, the extent to which Daubert and Joiner will affect trial practice is largely unknown. Through multimedia exposure modeling by the parties, a jury is presented with a multitude of questions and issues. These issues include: whether the plaintiffs were exposed to toxic chemicals at all; if so, what were the durations of exposure; what were the estimated doses; and which, if any, defendants are responsible for the exposures? Effectively educating a jury about complex scientific matters is imperative in order to prevail at trial. In recent years, the judicial system has experienced a fundamental change in many of the civil cases that it must resolve. The explosion of toxic tort litigation has fueled this change. Many of these toxic tort cases involve multiple claims for similar injuries and multiple defendants. Commentators have expressed concern about the competence of civil juries to render equitable verdicts in highly complex cases replete with scientific testimony.96 Among the critics was former Chief Justice Warren Burger who suggested that "jurors lack the ability to deal with the complex issues often presented in federal civil trials."97 The predominance of probabilistic evidence and testimony in toxic tort litigation often may lead the jury to "misunderstand the nature of this evidence or place an inordinate amount of weight on its probative value."98 A jury may treat an expert's testimony and numbers as the absolute truth. Exposure modeling and its various methodologies rely heavily on statistical and mathematical relationships and other demonstrative evidence in assessing the degree or probability that the plaintiff was exposed to the chemical at issue. Jurors may have difficulty understanding that probabilistic evidence merely establishes a statistical association of exposure in a particular population. Mock jury studies focusing on probabilistic evidence have shown that jurors often fail to process small probabilities adequately and "fail to distinguish between probabilities of 1 in 1000, 1 in 10,000, and 1 in 100,000."99 As a result, it is crucial for litigants to properly educate jury members about the implications of the scientific and exposure evidence at issue. Once a jury accepts a witness' explanation of scientific or technical concepts, it will be more likely that the jury will accept the expert's opinions. When presenting exposure modeling evidence to a jury, it is important for counsel to present the witness asa reliable, knowledgeable person whose testimony flows logically from the facts and is easily understandable to jurors.100 An expert testifying about exposure evidence should be properly qualified on the issue that they are going to help decide. The persuasiveness of an expert's background should be maximized while minimizing the tedium. For example, prior experience in assessing exposure scenarios, professional accomplishments, and education should be elicited. The proper preparation of the expert is crucial to jury understanding of exposure issues. According to Faust F. Rossi, "experts who calculate things present the most difficult demonstrative evidence problems. What many of these experts do for a living sounds like it will be difficult to understand."101 Many people have an aversion to math, and this can create problems for the exposure expert. Furthermore, numerous people are uncomfortable when dealing with abstract evidence such as formulas, estimations, and numerical representations.102 Because juries are often composed of citizens with little or no scientific understanding, it is necessary for exposure experts to attempt to reduce their modeling presentations to understandable terms and everyday language. Once a jury accepts the witness' explanation of scientific or mathematical concepts, it should be that much easier for the jury to accept his or her opinions.103 The Hercules case, discussed above, presents an excellent illustration of the power and persuasion of expert testimony in toxic tort litigation. In presenting expert testimony, [29 ELR 10195] the plaintiff's expert relied on highly technical language in his testimony without explaining it to the jury. Furthermore, many plaintiff experts appeared to lack candor in their testimony, often giving unresponsive answers to questions on cross-examination. On the other hand, defense counsel presented experts who were willing to admit certain facts brought out on cross-examination as being true, but who were also able to explain why those facts did not alter their conclusions that the levels of chemicals found in the landfills did not present a risk to the plaintiffs. In addition, Hercules' experts simplified much of the highly technical information to a level that was comprehensible to jurors. In particular, Hercules' risk assessment expert used lay language and adopted an anecdotal manner in presenting scientific studies. He explained that many substances people use in everyday life are carcinogenic. However, when exposed to small doses most people do not consider these substances to be harmful.104 Jury Perceptions of Exposure Evidence in Toxic Tort Litigation Over the past two decades, information has been gathered in order to better understand how juror characteristics shape perceptions of toxic and environmental issues. Based on data gathered at actual trials as well as at mock trials, quantitative and qualitative evidence documenting juror perceptions and predispositions have been generated by numerousjury consultants. According to Dr. George Speckart of Bodaken Associates, "arguments against the toxicity of a given substance are likely to be futile, since almost all jurors are receptive to the notion that an unfamiliar chemical presents health hazards. The key variable in determining verdict is the perceived degree of exposure, not toxicity."105 Other research conducted by jury consultants is more ambiguous. According to studies conducted by Starr Litigation Services of Phoenix, Arizona, 90 percent of jurors polled in various toxic tort cases and mock trials indicated that "there is no safe dose of some toxic chemicals."106 Furthermore, 75 percent of jurors polled believed that "most chemicals, with repeated exposure, cause cancer."107 According to Starr, jurors place a great deal of faith in government standards of exposure levels with roughly 80 percent of jurors polled believing that "any level of exposure to a chemical deemed hazardous by the United States government is too much exposure."108 Because plaintiffs often rely on governmentally imposed dose standards in toxic tort litigation, this juror perception of governmental and other regulatory standards can be powerful evidence for a defendant to overcome. Indeed, Starr's experience indicates that a defense claim that a plaintiff was exposed to an insignificant dose to cause harm is a challenging defense to proffer effectively. The explosion of toxic tort litigation has led to increased reliance on scientific expert testimony in the courtroom in order to demonstrate a requisite level of exposure (or lack thereof) to toxic chemicals. Through the use of multimedia exposure modeling, plaintiffs seek to develop evidence maximizing exposures and thus strengthen their claims that such exposures have caused illness or injury. In doing so, they often rely on government methodologies in order to support a claim that exposure to a substance was hazardous. Conversely, the use of exposure experts and methodologies by the defense is necessary in order to evaluate the plaintiffs' expert opinions and offer rebuttal opinions where warranted. Inappropriate assumptions in plaintiffs' or government methodologies must be challenged. Effective presentation of difficult scientific concepts thus has increased significance in a court system composed of jurors who often have very little back ground in science or statistical probabilities. As a result, the methodologies chosen by the expert, together with the justification provided for the jury, can have a profound impact on juror perceptions of the conclusions reached by the expert and, just as importantly, the credibility of those conclusions. 1. See Thomas W. Henderson, Toxic Tort Litigation: Medical and Scientific Principles of Causation, 132 AM. J. EPIDEMTOLOGY 869 (1992). 2. James D. Pagliaro & Amelia C. Benton, Courtroom Science: Toxic Tort Battle ground, 3 Toxics L. Rep. (BNA) 1336 (Mar. 22, 1989). 3. See Andrew W. Young, Book Note, 7 HARV. J.L. & TECH. 223 (1993) (reviewing KENNETH R. FOSTER ET AL., PHANTOM RISK: SCIENTIFIC INFERENCE AND THE LAW (1993)). 4. See KENNETH R. FOSTER ET AL., PHANTOM RISK: SCIENTIFIC INFERENCE AND THE LAW 2 (1993). 5. Id. at 1. 6. See Charles J. Muchmore & George R. Sorenson, What Is a Toxic Tort?, published in Arizona State Bar Convention Proceedings of Symposium on Environmental Litigation 1 (1990). 7. See Michael Dore, Causation, in LAW OF TOXIC TORTS: LITIGATION DEFENSE INSURANCE 24-1 (Environmental Law Series, 1992). 8. See Michael D. Green, Expert Witnesses and Sufficiency of Evidence in Toxic Substances Litigation: The Legacy of Agent Orange and Bendectin Litigation, 86 NW. U. L. REV. 643, 644 (1992). 9. See id. at 645. 10. See, e.g., Melissa Moore Thompson, Causal Inference in Epidemiology: Implications for Toxic Tort Litigation, 71 N.C. L. REV. 247 (1992); Andrew A. Marino & Lawrence E. Marino, The Scientific Basis of Causality in Toxic Tort Cases, 21 DAYTON L. REV. 1 (1995). 11. Proposed Guidelines for Exposure-Related Measurements, 53 Fed. Reg. 48830 (Dec. 2, 1988) (emphasis added). 12. See U.S. EPA, RISK ASSESSMENT GUIDANCE FOR SUPERFUND: HUMAN HEALTH EVALUATION MANUAL pt. A 6-1 (1989) [hereinafter RISK ASSESSMENT GUIDANCE FOR SUPERFUND]. 13. See U.S. EPA, ASSESSING ENVIRONMENTAL RISKS TO HUMAN HEALTH (visited Feb. 11, 1999) http://www.epa.gov/docs/futures/risk/roadmap/rmap/chap4.txt.html [hereinafter ASSESSING ENVIRONMENTAL RISKS TO HUMAN HEALTH]. 14. See id. 15. See HAZARDOUS WASTE CLEANUP PROJECT, EXAGGERATING RISK 8 (1993) [hereinafter EXAGGERATING RISK]. 16. See THOMAS MURRAY, U.S. EPA, EXPOSURE ASSESSMENT (visited Feb. 11, 1999) http://www.epa.gov/opptintr/cie/expose.htm. 17. See Exposure Assessments Based on Models Not Always Good Predictors, Scientist Warns, 6 Toxics L. Rep. (BNA) 839 (Dec. 11, 1991). 18. See figs. 1-4 infra. 19. See RISK ASSESSMENT GUIDANCE FOR SUPERFUND, supra note 12, at 6-35, 6-40, 6-41, 6-44. 20. Id. at 6-4. 21. See ASSESSING ENVIRONMENTAL RISKS TO HUMAN HEALTH, supra note 13. 22. See U.S. EPA, RISK ASSESSMENT AND MODELING OVERVIEW DOCUMENT (1993) http://www.epa.gov/grtlakes/arcs/EPA-905-R93-007/EPA-905-R93-007.html [hereinafter RISK ASSESSMENT AND MODELING OVERVIEW DOCUMENT]. 23. See RISK ASSESSMENT GUIDANCE FOR SUPERFUND, supra note 12, at 6-18; fig. 5 infra. 24. See RISK ASSESSMENT AND MODELING OVERVIEW DOCUMENT, supra note 22. 25. See infra notes 54-59 and accompanying text. 26. See U.S. EPA, EXPOSURE FACTORS HANDBOOK 2-3, 3-6 (1989). 27. See ASSESSING ENVIRONMENTAL RISKS TO HUMAN HEALTH, supra note 13. 28. See id. 29. Further discussion on the monitoring and modeling methods used in assessing exposure in toxic tort litigation are presented infra. 30. See ASSESSING ENVIRONMENTAL RISKS TO HUMAN HEALTH, supra note 13. 31. See id. 32. See id. 33. See id. 34. See id. 35. U.S. EPA, EXPOSURE ASSESSMENT METHODS HANDBOOK 2-1 (1989) [hereinafter EXPOSURE ASSESSMENT METHODS HANDBOOK]. 36. See id. 37. Therefore, a discussion of the nature of uncertainty and its impact on toxic tort litigation is presented infra. 38. See supra notes 6-10 and accompanying text. 39. Brent Finley & Dennis Paustenbach, The Benefits of Probabilistic Exposure Assessment: Three Case Studies Involving Contaminated Air, Water, and Soil, 14 RISK ANALYSIS 53 (1994). 40. See Ellen Relkin, The Sword or the Shield: Use of Governmental Regulations, Exposure Standards and Toxicological Data in Toxic Tort Litigation, 6 DICK. J. ENVTL. L. & POL'Y 3 (1997). 41. 42 U.S.C. §§ 7401-7671q, ELR STAT. CAA §§ 101-618. 42. 33 U.S.C. §§ 1251-1387, ELR STAT. FWPCA §§ 101-607. 43. 15 U.S.C. §§ 2601-2692, ELR STAT. TSCA §§ 2-412. 44. 42 U.S.C. §§ 6901-6992k, ELR STAT. RCRA §§ 1001-11012. 45. Id. §§ 9601-9675, ELR STAT. CERCLA §§ 101-405; Relkin, supra note 40, at 2. 46. See Relkin, supra note 40, at 2. 47. John Endicott, Using Government Health Assessment Documents in Defending Toxic Tort Litigation, 9 Toxics L. Rep. (BNA) 198 n. 1 (July 20, 1994) (citing Anthony Thompson & Traci Stegemann. Current Hazard Identification Programs: Potential Societal and Regulatory Consequences, 8 Toxics L. Rep. (BNA) 417 (Sept. 8, 1993). 48. See Pagliaro & Benton, supra note 2, at 1336. 49. See id. 50. See id. 51. See id. 52. See id. 53. See EXAGGERATING RISK, supra note 15, at 1; S.J. MILLOY, NATIONAL ENVIRONMENTAL POLICY INSTITUTE, SCIENCE-BASED RISK ASSESSMENT: A PIECE OF THE SUPERFUND PUZZLE 32 (1995). 54. See EXAGGERATING RISK, supra note 15, at 1-2. 55. See figs. 1-4 infra. 56. See EXAGGERATING RISK, supra note 15, at 2. 57. See id. at 14. 58. See id. at 16; MILLOY, supra note 53, at 33, 36. 59. EXAGGERATING RISK, supra note 15, at 10. 60. See fig. 2 infra. 61. See EXAGGERATING RISK, supra note 15, at 13, 16. 62. See MILLOY, supra note 53, at 32. 63. See Finley & Paustenbach, supra note 39, at 54. 64. See fig. 1 infra. 65. See tbl. 1 infra. 66. See EXAGGERATING RISK, supra note 15, at 41. 67. Relkin, supra note 40, at 3. 68. See Finley & Paustenbach, supra note 39, at 55. 69. See id. at 55-56. 70. See Edward J. Calabrese et al., How Much Soil Do Young Children Ingest: An Epidemiologic Study, 10 REG. TOXICOLOGY & PHARMACOLOGY 123 (1989); Scott Davis et al., Quantitative Estimates of Soil Ingestion in Normal Children Between the Ages of 2 and 7 Years: Population-Based Estimates Using Aluminum, Silicon, and Titanium as Soil Tracer Elements, 45 ARCHIVES ENVTL. HEALTH 112 (1990); Edward J. Calabrese et al., Preliminary Adult Soil Ingestion Estimates: Results of a Pilot Study, 12 REG. TOXICOLOGY & PHARMACOLOGY 88 (1990); Edward J. Calabrese & Edward J. Stanek III, Soil Ingestion Estimation in Children and Adults: A Dominant Influence in Site-Specific Risk Assessment, 28 ELR 10660 (Nov. 1998). 71. See Edward J. Stanek III & Edward J. Calabrese, A Guide to Interpreting Soil Ingestion Studies. 1. Development of a Model to Estimate the Soil Ingestion Detection Level of Soil Ingestion Studies, 13 REG. TOXICOLOGY & PHARMACOLOGY 263 (1991); Edward J. Calabrese & Edward J. Stanek III, A Guide to Interpreting Soil Ingestion Studies. II. Qualitative and Quantitative Evidence of Soil Ingestion, 13 REG. TOXICOLOGY & PHARMACOLOGY 278 (1991); Calabrese & Stanek, Soil Ingestion Estimation in Children and Adults: A Dominant Influence in Site-Specific Risk Assessment, supra note 70. 72. See EXAGGERATING RISK, supra note 15, at 23; tbl. 2 infra. a Percent of Monte Carlo simulations exceeding EPA default values. b First value is default value - 95th percentile; second value is default value/95th percentile. 73. O'Dell v. Hercules, Inc., 904 F.2d 1194 (8th Cir. 1990). 74. See Eugene G. Partain et al., A Defendant's Verdict in a Dioxin Exposure Case: O'Dell v. Hercules, Inc., 2 Toxics L. Rep. (BNA) 1402 (May 18, 1988). 75. See id. 76. See id. 77. See RISK ASSESSMENT GUIDANCE FOR SUPERFUND, supra note 12, at 8-19. 78. See id. 79. See EXPOSURE ASSESSMENT METHODS HANDBOOK, supra note 35, at 2-1. 80. See id. 81. See id. at 2-1 to 2-3. 82. See Finley & Paustenbach, supra note 39, at 56. 83. See EXPOSURE ASSESSMENT METHODS HANDBOOK, supra note 35, at 2-4. 84. See id. 85. FAUST F. ROSSI, AMERICAN BAR ASS'N, EXPERT WITNESSES 453 (1991). 86. See Peter A. Bell, Strict Scrutiny of Scientific Evidence: A Bad Idea Whose Time Has Come (Part II), 6 Toxics L. Rep. (BNA) 1047 (Jan. 29, 1992). 87. See FOSTER ET AL., supra note 4, at 38. 88. See Frye v. United States, 293 F. 1013 (D.C. Cir. 1923). 89. See FOSTER ET AL., supra note 4, at 38. 90. See id. 91. FED. R. EVID. 702. 92. 509 U.S. 579, 23 ELR 20979 (1993). 93. Id. at 592, 23 ELR at 20982. 94. 118 S. Ct. 512, 28 ELR 20227 (1997). 95. Id. at 514, 28 ELR at 20228. 96. See Irwin A. Horowitz & Kenneth S. Bordens, An Experimental Investigation of Procedural Issues in Complex Tort Trials, 14 LAW & HUM. BEHAV. 269, 270 (1990). 97. Joe S. Cecil et al., Citizen Comprehension of Difficult Issues: Lessons From Civil Jury Trials, 40 AM. U. L. REV. 727, 733 (1991). 98. Wayne Roth-Nelson & Kathey Verdeal, Risk Evidence in Toxic Torts, 2 ENVTL. LAW. 405, 437 (1996). 99. Id. at 441. 100. See ROSSI, supra note 85, at 204. 101. Id. at 252-53. 102. See id. at 253. 103. See id. at 204. 104. See Partain et al., supra note 74, at 1402. 105. Interview with George R. Speckart, Research Associate, Bodaken Associates, in Los Angeles, Cal. (June 9, 1997). 106. Memorandum from Starr Litigation Services, Inc. to The TESTLaw Practice Group (Sept. 22, 1997) (on file with authors). 107. Id. 108. Interview with Nora Bensko, Analyst, Starr Litigation Services, Inc., in Phoenix, Ariz. (Sept. 22, 1997). 29 ELR 10185 | Environmental Law Reporter | copyright © 1999 | All rights reserved |