TCS Daily


Bush EPA Prescribes A Dose Of Reason For Poison Policy

By Kenneth Green - March 26, 2001 12:00 AM

When the subject is toxicological;
One must sometimes become pedagogical;
And examine the rules;
And the common-sense tools;
That produce a perspective that's logical.


The media is abuzz over the announcement that the Bush Environmental Protection Agency will revoke the Clinton EPA's decision to lower the safe drinking water standard for arsenic. Rather than lowering the standard from the current level of 50 parts per billion (ppb) down to 10 parts per billion, EPA Administrator Christine Todd Whitman announced that EPA will leave the standard at the current level, established in 1975, while considering a standard lower than 50 ppb, but higher than 10 ppb.

Old school, panic-based environmental advocates are verbally rending their garments. "This decision will force millions of Americans to continue to drink arsenic-laced water," says Erik Olson, attorney at the Natural Resources Defense Council. Sen. John Kerry, D-Mass., asserts that the decision "would turn back the clock on safety standards to the days when Harry Truman was in the White House and President Bush and I were in grade school."

But is the mourning warranted? Not necessarily. As the first rule of toxicology points out, "The dose makes the poison." True, one would not wish to take a large dose of arsenic. But then, virtually nobody is. According to EPA, arsenic levels are already below 50 parts per billion (ppb) in all community water systems with surface water supplies and are infrequently exceeded by community water systems with ground water supplies. In a 1992 study, EPA estimated that only 1 percent of all public water systems would have arsenic levels greater than 20 ppb. And according to the U.S. Geologic Survey, 87 percent of all systems have arsenic levels below 5 ppb. Still, some chemicals can be quite toxic at very low levels. So how dangerous is exposure to low levels of arsenic in drinking water?

Since one can't experimentally detect cancers in humans being exposed to such low doses of arsenic, scientists estimate the dose suspected of causing cancer in humans based on either high exposure cases in humans, or experiments with laboratory animals. In such experiments, animals are fed high doses of toxins, such as arsenic, and then scientists estimate what an equivalent dose might do to humans.

In choosing to lower the standard. the Clinton-EPA relied on animal studies and a high-dose exposure incident in Taiwan (more than 250 ppb), and chose to assume that you could do a straight extrapolation from high exposures to low, as though there was no safe dose for arsenic, even one molecule.

But that's not necessarily a good assumption. For one thing, the entire lining of your digestive system is "sloughed off" every few days, taking all of the cells exposed to anything toxic right out of your body. That not only protects you from arsenic, but from cancer causing chemicals in your coffee, peanut butter, steak, and veggies. And that's only the obvious defense. Your body also has mechanisms to pull toxins out of your blood if they get that far; barriers to prevent toxins from getting into cells; barriers to prevent them from getting into the nucleus of the cell; mechanisms to purge proteins that become damaged by toxins; mechanisms to fix your DNA if it is damaged, and the list goes on. The human body is quite able to handle low doses of most natural toxins.

Unlike the Clean Air Act, the Safe Drinking Water Act requires the EPA to consider cost when setting standards because Congress, in most environmental rules, recognizes that high-cost regulations can impoverish people, and do more harm than good. But if the Clinton-EPA chose the gloomiest scenario for risk from arsenic, they picked the rosiest scenario for the costs of removing it from drinking water. In calculating the cost of their proposed new standard, the Clinton-EPA focused only on the costs to large suppliers (who get benefits of scale), but ignored the costs to the many small suppliers, who don't get such benefits. They also ignored the costs that the new standard would have on the cleanup of Superfund sites, which are automatically subject to whatever standard is passed pursuant to laws such as the Safe Drinking Water Act, even if the contaminated site will never be used as a source of drinking water.

If rule number one for toxicologists is "The Dose Makes the Poison," rule number one for risk managers and policymakers should be, "First, Do No Harm." And misdirecting resources to address nearly non-existent risks when other risks go under attended does considerable harm. So does wasting resources and weakening the economy, which is the wellspring of safety, health, and environmental protection.

Using worst-case assumptions on risk, but best-case assumptions on cost leads to distorted safety investments and overprotective standards. In a society where we have limited public health resources, we can't afford to waste. Taking the arsenic standard back for reconsideration using more reasonable assumptions to craft more reasonable policy is a most reasonable act.

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