Hormesis: implications for public policy regarding toxicants.

Protecting workers and the public from toxic chemicals, particularly carcinogens, has been a principal goal of public policy. In the absence of knowing by what mechanism of action a toxicant harms people, regulatory toxicology assumes that even tiny doses can cause harm. Risk aversion has led to legislation and regulation that seek to ban toxic chemicals or lower exposure to trivial levels. Contradicting this policy, many studies show health benefits from low-level exposure to toxicants, including some carcinogens. This is known as hormesis. Thus, hormesis could lead to a fundamental change in the policy for regulating toxic substances. In particular, all toxicants that benefit health at low-level exposures should face similar change in regulations for low-dose exposure. The result would be the dissolving of the source of differences in policy for carcinogens and noncarcinogens at low doses. Two questions must be answered before hormesis can be incorporated into regulatory policy. (a) Are there sensitive individuals who would be harmed at doses that would help most people? (b) Is the hormetic effect toxicant specific or would exposure to just a few toxicants achieve the full benefit from hormesis?

Benefit-cost analysis in public health.

This chapter gives an overview of benefit-cost analysis (BCA) and similar evaluation tools, such as cost-effectiveness analysis and technology-based standards, in the context of public health. We describe these evaluation tools, how they are used, their shortcomings, and how they should be interpreted. As with other powerful tools, they are subject to misuse and misinterpretation, even by professionals doing the analysis.

Parent preferences and prenatal testing for neural tube defects.

Previous analyses of prenatal screening for neural tube defects have generally found benefits to exceed costs. The usual screening battery follows an elevated maternal serum alpha-fetoprotein level with high-resolution ultrasound and/or amniocentesis. Current thinking focuses on weighing the risk of a false-negative (an abnormality missed) against the risk of an amniocentesis-induced fetal loss. This thinking neglects the risk of a false-positive (an unaffected fetus labeled abnormal) and individual parents' preferences concerning a false-negative vs a fetal loss. With these risks included, we find that high-resolution ultrasound is appropriate for all women with elevated serum alpha-fetoprotein. Women with moderately elevated serum alpha-fetoprotein who have negative ultrasound scans need no further testing, nor do women with highly elevated serum alpha-fetoprotein and positive ultrasound scans. Further testing using amniocentesis to confirm the ultrasound result is appropriate for women with moderately elevated serum alpha-fetoprotein and positive ultrasound scans, and for women with highly elevated serum alpha-fetoprotein and negative ultrasound scans. The actual cutoffs defining normal, moderately elevated, and highly elevated serum alpha-fetoprotein depend on several parameters, particularly the underlying prevalence of neural tube defects and the parents' preferences.

Should persons with diabetes be licensed to drive trucks?--Risk management.

How should a regulatory agency interpret a risk analysis that concludes there is a small increase in risk? The agency must decide on behalf of society whether the increased risk is large enough to justify banning the risky activity or taking some other step to lessen the risks. In a companion paper (Songer et al.), we conclude that licensing insulin using persons to drive commercial motor vehicles in interstate commerce would result in 42 additional crashes each year. Here we address risk management issues by interpreting the number of additional crashes and the relative risks of the prospective handicapped drivers. Are the number of additional crashes (42) significant? Is the increase in the annual crash risk (from 0.00785 to 0.032 for non-insulin dependent and 0.048 for insulin dependent persons) significant? Are the relative risks significant for all insulin using drivers (4.7)? For drivers with a history of severe hypoglycemic reactions (19.8)? How should society tradeoff risk increases for increases in opportunity for these handicapped persons? We review other social decisions concerning highway safety: Accepting the increasing risks of letting 16 year olds drive, allowing extremely light cars, allowing some unsafe highways, and allowing extremely unsafe driving conditions at some times of day. We conclude that the additional risks from insulin using persons are well within the current accepted range of risks.(ABSTRACT TRUNCATED AT 250 WORDS)

Public perception of the risks of floods: implications for communication.

Floods in the U.S. kill an average of 162 people each year and cause $3.4 billion in property damage. Flood control programs have been successful in lowering, but not eliminating, the risks to lives and property. Since the late 1960s, the federal government has emphasized flood insurance as a primary tool for improving location and flood-proofing decisions, as well as for reimbursing flood losses. Since only 12.7% of houses in flood plain areas are covered by flood insurance, the program has been ineffective. We interviewed people living in three communities that had recently been flooded. Most people had little knowledge of the cause of floods or what could be done to prevent damage. People who work and who are better educated know more and are more likely to have flood insurance. Current government publications about flood risks are not likely to be understood by those at risk. There is little effective communication about the nature and magnitude of the risks and what individuals can do to protect their lives and property and lower their financial risks. The risk management program should both emphasize communication and enforcement of the current law requiring people at risk who hold federally funded loans to be insured.

Risk analysis and risk management.

During the past several decades, the public has given increasing attention to environmental problems and increased their demands that these problems be solved. During this period, the difficulty and costs of solving the problems have become apparent. Environmental abatement programs must be effective in achieving the desired goals and efficient in achieving them at low cost. Risk analysis is necessary to quantify the benefits of proposed solutions in order to make them effective and efficient. The necessity for performing risk assessment stems from a presidential executive order, from a Supreme Court Decision, and from the public's demand for information about the extent of possible danger from a hazard, rather than knowing simply that it is a hazard. The science of risk analysis is an an early stage and so there are many uncertainties concerning interpretation of the estimates. This approach has sharpened the scientific questions and hastened improvements in scientific understanding. Risk analysis is most helpful when the analysis reflects the science, without intrusion of the risk assessor's values or attempts to force a risk management outcome by skewing the risk analysis.

Value-of-information analysis of testing strategies: estimating the effect of uncertainty about the proportion of chemicals that are true human carcinogens.

Choosing a cost-effective strategy for classifying chemicals as human carcinogens and non-carcinogens depends upon the costs of false positives (carcinogens erroneously treated as non-carcinogenic) and false negatives (non-carcinogens erroneously treated as carcinogenic); upon the accuracy (sensitivity and specificity) of the classification strategy; and upon the underlying proportion of carcinogens in the population of chemicals to be classified. If these values are known, value-of-information analyses can indicate the most cost-effective among three strategies: classify as carcinogenic without testing, classify as non-carcinogenic without testing, or choose the most cost-effective test and classify on the basis of the test result. When some or all of the values are uncertain, the analysis becomes more complex, but still helps to guide decisions among the three classification strategies.

Scientific and cost-effectiveness criteria in selecting batteries of short-term tests.

The scientific and cost-effectiveness criteria introduced in this paper can be applied to published datasets and current and proposed batteries of short-term tests. The reports in the current volume will provide a wealth of additional material for such evaluations, but more systematically obtained information will be necessary to assess both the internal and external validity of these tests. Individual tests and batteries of tests should be standardized, employ positive controls, generate results capable of quantitative analyses that may make dichotomous classification as "positive" and "negative" obsolete, be interpreted in light of mechanisms of action, and be cost-effective on a grand scale. For regulatory purposes our long-term goal should be to replace the whole animal lifetime bioassay with an appropriate and cost-effective set of short-term tests.

Injury as externality: an economic perspective of trauma.

Economists emphasize the costs in dollars or other desirable outcomes of additional safety in contrast to safety experts who remind people to design safe products and operate them safely. Society loses emotionally and financially from traumatic injury. The emotional loss must be balanced against allowing individuals free choice and encouraging them to develop judgment. Individuals are viewed as making their own best safety decisions, although they must have good information and face the correct indentives. Currently, society subsidizes risk taking in many ways, thereby discouraging safety. Health and life insurance ought to be required along with liability insurance, to correct the incentives to drivers. In addition, regulation is required to deal with physical externalities.

Cost-effectiveness of short-term tests for carcinogenicity.

Most chemicals to which we are exposed are not properly tested for carcinogenicity. The latest methods of in vitro testing provide a way of screening with sufficient accuracy to remedy this situation.

Characteristics of individuals who identify a regular source of medical care.

Having a source where medical services are regularly received is an antecedent to securing high quality medical care; it facilitates access and indicates that the individual is not alienated from the health care delivery system. In this paper we develop models to characterize individuals, both children and adults, who claim a regular source of care. The models are estimated using a logit analysis (since the dependent variable is 0-1) applied to survey data on residents of East Palo Alto, California. These data indicate that in this low-income, predominately black population the most important factor influencing whether a child will have a regular source of medical care is whether the parents have a regular source. For adults, the anticipated need for care (as measured by health status), time in community, and sex were all found to be important. The type of individual least likely to have a regular source of care is a low-income, unmarried male who is in good health and is a recent arrival to the community. The individuals most likely to need easy access to medical care and continuity of care are most likely to have a regular source of care, and vice versa.