Science gap at the EPA

By Bonner Cohen
Copyright 1999 Washington Times
October 31, 1999

Every now and then, an event occurs that is of such magnitude that in its wake things are simply not the same as they once were. Such may be the outcome of a landmark study in the Oct. 28 issue of the British science journal Nature. Scientists have uncovered a hole in our knowledge of many of the chemicals we regulate that is so deep that what has passed for reliable data about them are flawed at best, perhaps even entirely useless.

According to the study's lead author, microbiologist David Lewis, an area of science that revolutionized the pharmaceutical industry decades ago and made drugs safer has been overlooked by environmental regulators charged with protecting public health and the environment. Potentially, everything from plastics to pesticides could be engineered to make pollution far less harmful. "If EPA had focused on making pollution safer through scientific research instead of just regulating industry to death, we would be leaving our children a much safer world," Mr. Lewis says.

While the study's title, "Influence of Environmental Change on Degradation of Chiral Pollutants in Soil," seems innocuous enough, its findings are another matter. The study deals with chirality, a characteristic exhibited by chemicals with asymmetric molecules. The asymmetry causes molecules of the same chemical to exist as mirror images of one another. Since many of the building blocks of living organisms - including sugars, amino acids and proteins - are also chiral, the effects of chiral pollutants depend on how well the toxic portions of the pollutant fit together with molecules of living things.

"Our study emphasizes the fact that much of the historical environmental data collected on pollutants is unreliable because so many of the chemicals are chiral, and the data do not distinguish which mirror images of certain chemicals were present and which were harmless," says Mr. Lewis. "The good news is that trace amounts of many of the environmental pollutants EPA is most worried about - including some DDT derivatives, PCBs and plasticizers - aren't as bad as previously thought."

"On the other hand, he warns, "measures intended to protect the environment, such as using treated sewage sludge as a fertilizer, will likely increase the persistence of the more toxic forms of some pesticides."

The study explores molecular shapes and how the environment affects the persistence of pollutants. When shapes of pollutant molecules do not permit a close fit with molecules in living things, they cannot interact very well, meaning that these chemicals pose a less-serious threat. "It's like trying to shake someone's right hand with your left hand," Mr. Lewis explains.

Knowing which molecules are ill-fitting mirror images, or enantiomers, as scientists call them, can be extremely helpful. Mr. Lewis points out that 50 of the top 100 best-selling drugs - including barbiturates, Ritalin and ibuprofen - are marketed after removing the enantiomers with harmful side-effects, such as birth defects found three decades ago with the drug thalidomide.

The problem with pollutants, according to the study,is two-fold: First, very few chemicals now considered major pollutants have been evaluated for their chirality at all; second, environmental changes appear to alter which mirror images persist in the environment by affecting the soil microbes responsible for breaking down the chemicals.

According to the Nature study, global environmental changes, such as tropical deforestation and nutrient pollution, will significantly alter the risks posed by many pollutants - making the effects of some worse and others less harmful. "Without knowing how chiral pollutants will be affected, environmental measures aimed at reducing the effects of pollution are being formulated largely in the dark," Mr. Lewis says. Current assessments of the risks many pollutants pose to public health and the environment, therefore, are unreliable."

Incredibly, in all the data on which EPA bases its regulations, the agency has never considered the fact that many of the chemicals it regulates are chiral, with each individual form having completely different effects on living organisms. Because EPA does not include chirality in its risk assessments, how valid are the agency's findings on, say, pesticides, approximately one-fourth of which are chiral? As the study's authors point out, current methods of determining which chemicals pose threats to the environment may be worthless in many cases.

Faulty risk assessments lead to flawed environmental policies. Currently, EPA is embroiled in a growing controversy over sludge. Since 1993, the agency has allowed so-called Class B municipal sludge, consisting mostly of human waste, to be spread as fertilizer on crops. While EPA maintains the practice is safe, many of its scientists have warned that applying this complex mixture of pathogens and chemical pollutants is fraught with many unknown pitfalls.

Their concerns are underscored by the unexpected finding in the Nature study that sludge could increase the risks associated with some pollutants. Unexplained deaths linked to sludge are turning up across the country, including those of an 11-year-old boy in Pennsylvania, a 26-year-old man in New Hampshire and hundreds of dairy cows on two Georgia farms. Earlier this year, the United Mine Workers of America requested, and got, an investigation by the Centers for Disease Control and Prevention (CDC) into severe illnesses coal miners are suffering after exposure to sludge applied for mine reclamation. All of this has EPA scrambling to deal with a public health and environmental problem of its own making.

As fate would have it, the study's lead author was among the many EPA scientists who tried to warn the agency about sludge. For daring to criticize EPA'slack of science, Mr. Lewis, as part of a legal settlement with the agency, has been temporarily assigned to the University of Georgia to await termination by EPA. But as the Nature study gains currency, EPA may discover that it's easier to get rid of a good scientist than it is to avoid the consequences of all the poor science it keeps.

Bonner R. Cohen is a senior fellow at the Lexington Institute in Arlington.

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