An example may be useful here. It is known that individuals who have one copy of certain mutations in the gene that codes for alpha-1-antitrypsin (A1AT) (i.e., are heterozygous) are more susceptible to lung damage when exposed to certain inhalants, ranging from chemicals typically used and produced in industry to smog and tobacco smoke (Ranes and Stoller, 2005). On its face, it seems obvious that such individuals should not experience these potential harmful exposures. But questions about how to achieve this goal quickly arise.

One might think that people with mutations in A1AT would simply choose to avoid being in harmful environments. However, a great deal of evidence demonstrates that knowledge of risk does not lead inexorably to health-promoting behavior change (Marteau and Lerman, 2001), and at times it may lead to harmful responses. The possible explanations for these apparently suboptimal outcomes are many. In some cases, susceptible individuals simply choose to ignore the risk of toxic exposures. Some argue that protecting susceptible individuals by providing health care if they become ill or by cleaning the environment creates “moral hazard”—the possibility that predisposed people would engage in socially undesirable, unhealthy activities because they are insulated from the consequences. The argument in this case would be that people with mutations in A1AT do not avoid exposing themselves to risk because they know they will receive treatment if they become ill.

Some decisions not to avoid potentially harmful exposures, however, result from trade-offs that are made with other goals. Some people with these mutations may find that they can earn a living wage only if they live in a smoggy city or work in sites with harmful fumes. They can be faced with choosing between optimizing their health and meeting their immediate needs and those of their families. Also, the personal protective equipment that could ameliorate some of the risk to such susceptible individuals can be onerous and expensive. However, no matter what the reason for lack of avoidance, it does seem likely that most people do not choose ill health as a matter of preference. Moreover, relatively little research has been done to show how to increase health-promoting behavior in these type of situations.

Nor is it clear that protecting only those who have greater risk is necessarily the best policy. Exposures to smoke and toxic fumes are potentially harmful to a large part of the population, not just to those who are particularly susceptible. Reducing such exposures, then, could improve the health of the public generally, not just those members of the public with mutations in A1AT or other susceptibilities. As a result, environmental regulation has taken a variety of approaches, sometimes requiring individual protective measures, but frequently trying to reduce exposures for everyone. This has led to noticeable improvements in air and water quality over the past 50 years, with benefits going beyond good



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