American Journal of Law & Medicine

Environment and health: vital intersection or contested territory?


The effects of environmental exposure, broadly defined as any exposure from outside the body, on human health are unquestionably the most important determinants of public health. While important genetic determinants of disease exert their effects irrespective of exposure from outside the body, these do not contribute as much to the overall public health burden of disease as factors such as tobacco smoke, poor quality water, inadequate or contaminated food, occupational exposures to dusts and chemicals, motor vehicle accidents, interpersonal violence, air pollution, and other factors external to the body. (1) In many cases, genetic predisposition and environmental exposures combined cause disease in an individual, so it may be impossible to separate out individual biological contributions from various external factors. Nevertheless, it is widely understood that public health concerns populations and communities, and that environmental determinants of health have been paramount throughout human history. (2)

Much of the scientific documentation of the impact of the environment on health has been produced in epidemiologic studies. The origins of the field of epidemiology are often traced to Dr. John Snow, who studied the patterns of cholera in London in the mid-nineteenth century. (3) His research, which included examining differential patterns of death in neighborhoods served by particular water companies, hypothesizing a cause, (4) testing the hypothesis against alternative explanations, and recommending action to prevent community exposure to contaminated water, is still seen as a paradigm for modern public health practice. (5) While epidemiology is still considered the fundamental science of public health, and all schools of public health require students to take epidemiology courses, (6) in recent years there has been a tendency toward reductionist and individual-level explanations of disease causation. (7) Modern examples of the interplay between environmental toxic exposures and human health impacts abound, (8) but this Article focuses on the examples of childhood lead poisoning and cancer to illustrate the connections and controversies in this area of public health.

Furthermore, the relation between environmental exposures and disease has been the subject of lawsuits claiming harm from low-level toxic exposures to substances such as lead and synthetic chemicals. (9) These disputes are often sharply contested and occasionally break new legal ground. (10) In the last decade, the U.S. Supreme Court has attempted to provide guidance to the courts on how to handle scientific evidence in such cases, including Daubert v. Merrell Dow Pharmaceuticals, Inc. (11) This has led to some major obstacles for plaintiffs attempting to get their cases before juries in many parts of the United States. (12) The future of toxic tort litigation will rest, in part, on how the courts understand the scientific process and the evaluation of scientific literature, and how they interpret their "gate-keeping" role. (13) In this Article, we describe how epidemiologists draw scientific inferences about causation and contrast this with post-Daubert tort practices.


The earliest cases of childhood lead poisoning undoubtedly occurred many centuries ago. Lead pipes and pots were used for carrying water, cooking, preserving wine, and lead poisoning was recognized as a health hazard from the era of Hippocrates, approximately 400 B.C. (14) Subsequently, lead was a component of pottery glazes and other manufactured goods leading to periodic outbreaks of lead poisoning long before the modern era. (15) From a public health perspective, however, childhood lead poisoning has been reported as a widespread problem only in the past one hundred years or so. (16) The earliest cases were associated with ingestion of lead-based paint in homes and with the burning of lead batteries for fuel in poor communities during the winter. (17) In the United States, the first efforts to determine the full extent of the problem of childhood lead poisoning were in Baltimore, Maryland. (18) These early studies focused on the gross effects of high-level exposure and a condition called "plumbism," characterized by acute gastrointestinal symptoms, neurological symptoms such as seizures, and occasionally coma or even death. (19) Efforts to reduce exposure were focused on peeling paint in dilapidated inner-city housing and blood levels of clinical concern were reported in the medical literature. (20)

In the 1960s and 1970s, additional research showed that subtle effects, such as diminished IQ and behavioral and learning problems, were occurring at lower levels of exposure (see Appendix A). (21) This led to more intensive efforts to identify children at risk of these health effects, and a national plan to reduce childhood lead poisoning by eliminating lead-based paint for household use. (22) Unfortunately, a massive amount of lead was already present in the environment due to previous applications of lead paint and from exhaust from automobiles burning gasoline with lead additives (23). Efforts to remove lead paint hazards from older housing were minimally successful in the 1970s and 1980S, (24) and achieved only moderate gains in communities with additional sources of funds from federal agencies. (25)

In some states, such as Massachusetts and Maryland, local laws and state-level initiatives have led to more comprehensive childhood blood lead screening programs and abatement of lead paint hazards. (26) For example, Massachusetts has a very high estimated percentage of screening in high-risk communities and has removed or reduced lead paint hazards in thousands of dwellings where young children live. (27) This proactive approach resulted from the combined activities of pediatricians and primary healthcare providers, local and state health departments, and property owners. (28) This state-level program also provides for the training and licensing of lead paint removal workers and contractors. (29) The number of units inspected and where lead paint hazards have been abated has been impressive, but other states have been less aggressive and less successful over the past two decades. (30)

The second major source of lead in young children's environment has been leaded gasoline. (31) This source is equally widespread, although less concentrated than lead-based paint. (32) The history of the use of lead as an additive to reduce engine knock in automobile engines has been well documented, (33) and is an example of scientific information dismissed in the interests of promoting an industry. Concern about this source of childhood lead exposure compelled Congress to ban leaded gasoline in the 1970s under the Clean Air Act. (34) At about the same time, the Consumer Product Safety Commission severely restricted the amount of lead allowed in household paint. (35) Thus, in the 1970s the federal government likewise took aim at the two largest sources of lead in the United States. Since that time, the amount of lead in children's blood has steadily declined (see Appendix B) and is one of the clear cut examples of how regulatory action can have an immediate positive impact on children's exposure to an environmental hazard.

As more has been learned about the harmful effects of lead in developing children, the blood lead levels that are considered "undue lead absorption" have come down correspondingly. For example, the level of concern in the early 1970s was 40 micrograms per 100 milliliters of whole blood; the Centers for Disease Control and Prevention ("CDC") lowered this level to 30 micrograms per 100 milliliters by the late 1970s, and eventually to 10 micrograms by the late 1990s. (36) Based on current knowledge, the CDC's position is that "no threshold has been determined regarding lead's harmful effects on children's learning or behavior." (37) In the late 1970s, the National Health and Nutrition Examination Survey estimated that 88.2% of children between the ages of one and five in the United States had blood lead levels greater than 10 mcg. (38) By the late 1980s, this survey indicated that the percentage of U.S. children with this blood lead level had declined to 8.6%. (39) The latest available survey data, from the years 1999-2000, indicates that this percentage is now 2.2%, or 434,000 children in the United States. (40) The 1991 public health goal for the nation of reducing to zero the number of children with blood lead levels greater than 25 micrograms by the year 2000 was not met, and the CDC has now set a new goal of reducing the number of children with levels greater than 10 micrograms by the year 2010. (41)

In conjunction with the increased knowledge about the sources and effects of lead on young children, legislation and judicial precedent have established legal remedies for victims of lead poisoning. For example, the Massachusetts statute (42) and associated regulations (43) provide for fines and civil actions to require property owners to remove lead paint hazards from homes where children under age six reside. (44) This law has been used for three decades to require de-leading, and occasionally has forced rental property owners to enter into consent decrees to make major renovations to deteriorating properties. In addition, attorneys have brought civil actions for damages to clients who were lead poisoned and have suffered neurological effects. The largest settlement of such a case in Massachusetts was announced in September 2003; the property management company agreed to pay $4 million to four individuals who had resided in a hazardous property in the mid-1980s and subsequently were unable to finish high school or get jobs. (45)

The lesson of childhood lead poisoning is largely one of unheeded early warnings, (46) followed by widespread adverse effects in children throughout the United States, and subsequent legal and regulatory steps to reduce the hazard many years later. The example serves as a cautionary tale in public health schools and literature, and the legal remedies may serve as a warning about future failures to act in time to prevent harm. (47)


The correlation of workplace and community exposures and increased cancer risk has been one of the most urgent environmental health issues of the past quarter century. In the United States, much of the concern has focused on toxic chemicals and radiation, both ionizing and non-ionizing, and their relationship to cancer clusters in communities, factories and sometimes schools. Citizens' organizations have focused on dramatic examples, such as incidents in Times Beach, Missouri (48) and Love Canal, New York, (49) both of which were evacuated because of community exposure to dioxin; others have learned from workplace experiences such as the Oak Ridge National Laboratory in Tennessee, where excess radiation has increased the risk of leukemia deaths in the workforce. (50) Similar concerns followed a disastrous explosion at a chemical plant in Seveso, Italy (51) and the nuclear power plant disaster in Chernobyl, Ukraine. But numerous less-publicized examples have occurred in communities throughout North America, and healthcare and legal professionals are increasingly asked to evaluate the causes and consequences of these worrisome events for communities. (53) This Part addresses three aspects of the problem: the background of cancer incidence and mortality against which local clusters are assessed, the types of exposures which are known or suspected causes of such clusters, and the implications for healthcare or legal professionals who wish to provide guidance for concerned patients or communities.


Over the past quarter century, the incidence of cancer in the United States has risen steadily, from an age-adjusted rate of 385 cancer diagnoses per 100,000 citizens in 1973 to 476 per 100,000 in 1999. (54) The age-adjusted cancer mortality rates in the United States increased during this period as well, yet have recently declined largely because of improved treatments for some cancers and declining lung cancer mortality in males. (55) While there have been some improvements in the cancer patterns overall, it is instructive to examine some important trends in specific cancer types which may be due to avoidable exposures.

Table 1 shows the major types of cancer for which there are significant trends in both incidence and mortality.

The decreasing incidence and mortality from stomach cancer has been repeatedly noted, and has been associated with improved methods of storing and preserving food. (57) Likewise, the decreasing incidence and mortality due to cervical cancer is most likely the result of widespread screening efforts and early diagnosis and treatment. (58) On the other hand, cancers for which incidence and mortality continue to increase appear to be similarly avoidable. Lung cancer, particularly in females, non-Hodgkin's lymphoma, melanoma of the skin, multiple myeloma and several other, less common malignancies have continually increased. (59) Each of these seems to be largely the result of avoidable exposures. For instance, lung cancer is primarily due to exposure to cigarette smoke, (60) melanoma of the skin is strongly linked to frequent exposure to ultraviolet light, (61) and non-Hodgkin's lymphoma has been associated with environmental and occupational exposure to carcinogens. …

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