Human Health Risk Science and the Law

Both scientists and attorneys participate in the protection of public health. Toxicologists and epidemiologists study the effects of human exposure to chemicals, and analyze health risk by various methods. Lawyers rely on such information in making legal arguments for both cases and legislative activities.

Administrative environmental law, toxic tort litigation, worker’s compensation cases and product safety matters all pertain to the protection of public health and safety. Environmental laws, for instance, are in place to both prevent and rectify environmental contamination that could adversely impact personal and public health. The objective of toxic tort litigation, worker’s compensation cases, and product liability matters is to determine if individual harm has been caused by exposure to toxic agents, or from the use of defective products.

Environmental & Safety Law

Environmental and product safety laws can be understood as a legislative form of policy. Like policy, their goal is to protect the environment and public health and safety. Health risk analyses help establish environmental quality standards, chemical registration laws, and product safety standards, which are all classified as “preventative” measures.

On the other hand, “curative” environmental protection laws and programs include actions needed to clean up past environmental contamination. Such laws exist at both the State and Federal level, one example being the Federal “Superfund” law. Toxicologists, epidemiologists, and other scientists supply the health risk data upon which such standards and programs are based.

Toxicology

Toxicology is the study of adverse effects on living organisms caused by exposure to chemical, physical, or biological agents.

Toxicologists frequently perform toxicity-testing on laboratory animals. While useful, these studies require two major data extrapolations and are thus not directly applicable to human health risk assessment. First, there is uncertainty about whether responses seen in animals given high doses of a chemical are descriptive of human responses that could occur at lower doses of the same chemical. Second, one must account for the fact that not all humans are equally susceptible to chemicals. These two extrapolations introduce a significant degree of uncertainty regarding the use of animal data for human health risk assessment.

Toxicity testing data can also be obtained from controlled human exposure studies, thus avoiding problems associated with extrapolating animal test data. Since these tests require human volunteers as subjects, there are ethical limitations. Most controlled human exposure studies investigate acute exposure: common air pollutants such as ozone, carbon monoxide, nitrogen oxides, and sulfur dioxide. This type of research has been used extensively for setting National Ambient Air Quality Standards.

Epidemiology

Epidemiological studies investigate associations between toxic agent exposure and adverse health outcomes in the exposed population, which could range from workers in occupational settings, to the general public. Epidemiological approaches have one big advantage over animal testing methods— since epidemiologists study the patterns of disease incidence in human populations, their work necessarily deals with the “real world” health experiences of people. However, one limitation of such studies is that it is often difficult to control for other factors, or “confounders,” that could affect the validity of study results.

Worker’s Compensation

In toxic tort or worker’s compensation cases, an individual or group of individuals’ claims are argued on behalf of public health protection. When a toxicologist or epidemiologist is an expert witness in this type of case, his/her major task is to determine whether an alleged chemical exposure caused adverse health effects. This first requires an analysis of whether or not a chemical or microbial agent is capable of causing the effects claimed (general causation). Additionally, it must be shown that the Plaintiff’s exposure to the agents involved was of a great enough magnitude, frequency, and duration to have affected them personally (specific causation).

In summary, both the scientific and the legal communities have opportunities and responsibilities to protect public health. Toxicologists and epidemiologists can provide information about risks associated with exposure to agents in the workplace, or in the environment. Attorneys use that information to establish both environmental laws and product safety standards, and to aid their work in cases involving an alleged personal injury due to chemical or microbial exposure.