Chevron v. Echazabal: a sobering decision for environmental health research. (Correspondence).

A recent Supreme Court decision (Chevron v. Echazabal) may have important implications for environmental health research (1). Risk-factor research has made important contributions to workplace health and safety. Systematic evaluation of the impact of chemical and physical agents on disease occurrence has provided information for the development of policies for controlling injury and disease. Research has focused predominantly on the impact of external risk factors on workers. With the advancement of molecular genetic methods, researchers have begun to identify individual risk factors believed to affect the occurrence of disease. Considerable attention has been given to identifying biological markers--markers of susceptibility, exposure, or effect--that enable better characterization of disease risk resulting from exposure. Studies investigating gene-environment interactions have identified DNA markers (e.g., polymorphisms in metabolic enzymes and allelic variation associated with hypersensitivity) associated with elevated risk for occupational disease.

In Chevron v. Echazabal, the court addressed issues central to the Americans with Disabilities Act (ADA). The ADA is cited by some commentators as offering individuals protection from genetic discrimination (2,3). Others have questioned whether regulations promulgated under the ADA by the Equal Employment Opportunity Commission offer such protection (4,5). The recent decision addresses the case of a refinery worker who was denied employment due to chronic liver disease, which was eventually identified as hepatitis C. Chevron sought to exclude the individual based on the rationale that his liver function was impaired and would be subject to further damage if he experienced chemical exposures characteristic of refinery work. Conceptually, a preplacement examination using a liver function assay resulted in the identification of a biological marker that the employer interpreted to suggest a heightened susceptibility to disability from workplace exposure.

At the heart of this ruling is the court's interpretation of the direct threat provision of the ADA. A direct threat is defined as a significant risk of substantial harm that cannot be eliminated by reasonable accommodation (6). An individual may be refused employment if a direct threat can be established. Historically, there has been ambiguity over the scope of the direct threat defense (5). In a previous ruling [Echazabal v. Chevron (7)], the Ninth Circuit Court held that the direct threat defense was not available to Chevron because Echazabal only presented a risk to himself. The court reasoned that a direct threat only applies when the individual's condition poses a direct threat to others. In other words, the circuit court affirmed the notion of health as a discretionary right in which the individual may chose to assume certain risks so long at they do not have the potential to harm others. The recent Supreme Court decision rejects this reasoning and reverses the circuit court's judgment. Individuals who pose a risk exclusively to themselves may be excluded from a job as long the employer relies on reasonable medical judgment and accounts for the duration of the risk and the nature, severity, likelihood, and imminence of the potential harm (6).

In this example, Chevron produced evidence identifying a severe disease in a prospective employee and concluded that Echazabal's liver function was subject to further damage under job conditions in the refinery. Conceptually, Chevron based its position, and the court concurred unanimously, on the identification of biological evidence of clinical disease. Basing workplace exclusion on evidence of clinical disease is substantively different from the identification of DNA markers associated with elevated risk for occupational illness, and perhaps the court would recognize such a difference and rule differently in the later example. However, the difference between a DNA marker of disease and susceptibility is not always clear. It is conceivable that if the DNA marker was sufficiently predictive of an individual's risk of a severe disease, then the basis for a direct threat exclusion may exist (8). Although this scenario is speculative, the Supreme Court has unanimously stated that a direct threat to self may serve as the basis for workplace exclusion.

This is a sobering decision for researchers involved in risk factor research, some of whom have articulated the belief that assumption of risk is a discretionary right of workers. Researchers and institutional review boards should be mindful of this decision when considering future research into individual risk factors, particularly for occupational disease.

Geoffrey Lomax
University of California-Berkeley
School of Public Health
Center for Occupational and
Environmental Health
Berkeley, California
E-mail: [e-mail]

REFERENCES AND NOTES

(1.) Chevron U.S.A. Inc. v. Echzabal. Case No. 00-1406, U.S. Supreme Court, Washington, DC, 2002.

(2.) Natowicz MR, Alper JK, Alper JS. Genetic discrimination and the law. Am J Hum Genet 50(3):465-475 (1992).

(3.) Miller PS. Genetic discrimination in the workplace. J Law Med Ethics 28(3):189-197 (1998).

(4.) Holtzman NA, Rothstein M. Reply to Natowicz et al. [Letter] Am J Hum Genet 51:897 (1992).

(5.) Rothstein MA. Genetics and the Work Force of the Next Hundred Years. Columbia Business Law Review (3):371-402 (2000).

(6.) Equal Employment Opportunity Commission. Regulations to Implement the Equal Employment Provisions of the Americans with Disabilities Act. 29CFR1630.2(r) (2001).

(7.) Echazabal v. Chevron U.S.A. Inc. Case No. 98-55551, U.S. Court of Appeals for the Ninth Circuit, Pasadena, CA, 2000.

(8.) Rothstein M. Personal communication.