San Francisco Chronicle

Precautionary Principle a Risky Gambit

Risk reduction must be weighed

The recently passed Precautionary Principle ordinance purports to make San Francisco a leader by "challenging traditional assumptions about risk management." In truth, it will likely be bad for the city, public health and the environment.

The precautionary principle is routinely described as "better safe than sorry." Risk reduction is a laudable goal, but only when weighed against the risks of not taking certain actions. The trick is balancing the two. The city needs a policy of risk management and mitigation, not a mandate for the elimination of risk, which is simply impossible.

The ordinance mandates "selection of the alternative that presents the least potential threat to human health." But what if the least riskiest option also confers the least benefit? Although it has now been added (but only once), the word "benefit" did not appear in the original ordinance. San Franciscans should know better.

AIDS activists here have had to fight the FDA tooth and nail over drug approvals because the FDA believes potential risks outweigh potential benefits.

That is, the FDA practices the precautionary principle.

Of course, many chemicals pose health risks, and we should do everything we can to lessen their impact on our lives and to find alternatives. But not at the expense of inferior alternatives that result in greater harm to human health or the environment. Activists have targeted genetically modified organisms because they carry an uncertain risk. But many of those organisms drastically reduce pesticide use, a good thing by the activists' own standards.

Here's how Chronicle columnist Ruth Rosen described the Precautionary Principle ordinance ("Better safe than sorry," June 19): "When science cannot yet fully establish a cause-and-effect relationship, but can provide reasonable evidence of harm, this principle urges us to take precautionary measures. In other words, if we wait until we're absolutely certain, we've probably waited too long."

It sounds just as reasonable to say: "When science cannot yet fully establish a cause-and-effect relationship, but can provide reasonable evidence of benefit, this principle urges us to act." In fact, both approaches are meaningless unless risk and benefit, including cost, are taken into account.

San Francisco is a dangerous place to cross the street, yet thousands of people do it every day. Applying the precautionary principle, however, pedestrians would have to be certain that no car loomed around the corner. They would never get out the front door.

Obviously, there are different scales of risks. It is more dangerous to cross 19th Avenue at rush hour than a secluded cul-de-sac at lunchtime. But if all risk is unacceptable, as it is for proponents of the precautionary principle, both would be treated the same way, which is irrational.

Perhaps the most infamous example of risk reduction at all costs occurred in Peru in 1991. After a U.S. EPA study found evidence of an increase in cancer risk from a chlorine byproduct, officials in Peru stopped using chlorine to disinfect drinking water, resulting in a widespread cholera outbreak that killed thousands. Innumerable cases show that the elimination of "dangerous" risks would result in a lower standard of health and well-being.

By setting an unattainable benchmark, San Francisco's Precautionary Principle ordinance has no way to measure success. To be truly on the cutting edge of risk management, the city should institute some performance measures that take risk, benefit and cost into account. The goal should not be risk reduction alone but a net improvement in human health and safety.

In these days of cash-strapped cities and states, we need the maximum benefit possible. That means scientifically rigorous assessments of risk that consider whatever means are available to improve health and environmental safety.

Michael De Alessi is director of natural resource policy at Reason Foundation

Michael De Alessi is Fellow





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