Health risks abound in modern life. But are the decisions we make to preserve our health supported by solid science? Not always. As a result, it's become more challenging than ever to make informed choices about prevention and treatment.
Consider the recent clinical trial demonstrating that the cholesterol-lowering drug Zetia (and a drug that contains it, Vytorin) does not effectively reduce fatty deposits in arteries. These findings raise doubts and concerns about a basic tenet in medicine: Lowering cholesterol will lower the incidence of heart disease.
Our analysis of critical published studies supports the contention that elevated blood serum cholesterol levels do not correlate well with an increase in coronary heart disease. In fact, within a given population, individuals with normal and elevated cholesterol have essentially the same incidence of coronary heart disease. We found that for 999 out of 1,000 individuals each year, whether they have elevated cholesterol or normal cholesterol has no effect on the development of coronary heart disease.
The alarm bells ring almost daily. News reports deliver authoritative and unequivocal warnings about the dangers of high cholesterol, environmental contaminants and some prescription drugs. With great conviction, experts tell us we can protect ourselves by taking tests to detect cancer and by swallowing statin drugs and antioxidant vitamins.
An unmistakable veneer of certainty is attached to such advice. But peel away that veneer, and you'll find a shadowy realm filled with uncertainty. Some recent examples:
There has been general agreement in the medical community for decades that diabetics should lower their blood sugar to decrease their risk of dying from heart disease. But results of a recent federal study have cast doubt on that premise. In fact, the study found that lowering blood sugar levels resulted in a significantly higher death rate.
Statins, the top-selling prescription drugs in the world, are being used to reduce the levels of "bad" cholesterol in the blood. But some researchers are now telling us that it's the "good" cholesterol that's really important.
The highly touted painkiller Vioxx was taken off the market when it was determined that there were increased numbers of heart attacks in individuals taking this drug.
Acceptable exposure to carcinogenic contaminants, such as dioxin and benzene, is based on not exceeding the arbitrary value of one additional cancer per million people - a value never originally intended to be used for regulatory compliance.
Dozens of other examples can be found in which medical decisions and environmental actions lack scientific evidence. Why has this happened?
In large part, the blame can be linked to public expectations. Because researchers in the past have made astonishing strides in medicine and environmental health, consumers and public officials have come to expect similar "miracle breakthroughs" for a wider array of ills.
Yet, in recent decades, a subtle but critical shift in focus has taken place. Rather than continuing to concentrate on diseases such as polio and malaria, where a direct cause is known, researchers have turned more often to chronic debilitating ailments, such as heart disease, cancer and diabetes, and to the effects of low levels of environmental contaminants such as dioxin and PCBs.
Precise cause-and-effect relationships for many of these diseases remain elusive. Experts rely on risk factors, so the level of uncertainty has risen, severely limiting our ability to make confident decisions regarding health issues. The scientific, regulatory and medical communities have been forced to turn to an analytical technique known as risk assessment to determine what to do.
The uncertainty inherent in risk assessment has been problematic. According to risk assessment specialists, doctors and other authorities need to explain uncertainty to patients and communities. But this rarely occurs, and the reasons are rooted in our need for concrete answers.
Uncertainty causes anxiety, particularly when it involves our health. Environmental scientists, physicians and drug companies try to respond by giving us what we want. Frequently, the level of uncertainty surrounding their research is overlooked.
When we are not properly informed about uncertainty, we cannot make decisions about medical or environmental risks based on solid evidence. Today, we are too often asked to rely on uncertain scientific findings in making such choices. As a result, errors of interpretation are common, and the dissemination of misleading or even deceptive health benefits and risk information is widespread.
Having health information - including information about uncertainty - available in a readily understandable format will enable us to determine what level of benefits and/or risks we find acceptable when it comes to preserving our health.
As a difficult but necessary first step, health professionals must acknowledge that the public has a right to this information. But at the same time, consumers must take an active role in digging beneath the illusion of certainty that continues to cloud medical and environmental decisions.
Erik Rifkin, a Baltimore-based environmental consultant, and Edward J. Bouwer, chairman of the department of geography and environmental engineering at the Johns Hopkins University, are national experts in human health risk assessment. They are authors of the book "The Illusion of Certainty: Health Benefits and Risks."