ne person who thinks Houston has suffered as a result is environmental attorney Jim Blackburn. A longtime activist whose thick mustache and bulldog manner give him the air of a take-no-prisoners football coach, Blackburn is one of the Texas Medical Center's leading critics. "I don't think that the TMC has been effective at any level in terms of examining urban air toxicity," he says. "I see them as a silent partner in the attack on Houston from an air-quality standpoint."

The research community's silence "is very disheartening when you have the best medical center in the world," says Pamela Berger, who now works in the mayor's environmental policy office. "It's pretty bad."

Unquestionably, there are many bona fide difficulties inherent in designing and running studies of community toxics exposure. The subject is notoriously complex; it's difficult to control for the many lifestyle and other variables that might affect citizens' health in addition to (or in synergy with) their exposure to pollutants. For a place with obvious air quality issues, Harris County's air pollution monitoring system is spotty at best. And research grant money from industry and federal sources alike is not only extremely tight, but also often targeted toward more narrowly focused studies at the molecular level.

But these are the kinds of difficulties a leading medical institution should be able to surmount. More to the point, other research institutes are doing groundbreaking toxics exposure work right in their own communities.

Harvard's landmark "Six City" study on the effects of tiny airborne particles such as soot included the nearby community of Watertown, Massachusetts. The study took fifteen years, tracked the health of 8,000 people, and has helped shape national policy on particle pollution. At Johns Hopkins, researchers have begun an investigation of exposure to volatile organic compounds in industrial South Baltimore. Columbia University researchers are studying air toxics exposure of high school students in New York City and Los Angeles. Columbia also has an innovative program underway in poor communities in New York City and Poland to investigate the effects of toxics on children exposed in the womb.

Are Texas Medical Center researchers being told outright not to run these kinds of studies? Probably not -- although two scientists contacted for this article recounted incidents in which they were given a clear negative message. When he was on the faculty at the UT School of Public Health in the 1960s, now-retired pathologist David Marrack floated a proposal to examine the relationships between respiratory illness and exposure to toxics. "I was told, 'We don't think that's a good thing to investigate,'" Marrack recalls. "I understood that it wasn't good for my [professional] health to do it."

More recently, Marvin Legator planned a trip to Austin in the early 1990s to speak to residents concerned about benzene exposures from a nearby tank farm. Legator, a UTMB researcher now semiretired, was warned by his superiors that if he made the trip, he might not have a job when he returned. (Legator says that since then, the institution has supported his research, including several studies on workplace exposure to butadiene.)

But for the most part, the pressure is much more subtle, says M.D. Anderson's Lovell Jones. Jones, who combines the attitude of an unrecalcitrant activist with a measured, professorial delivery, will not name names. He makes it clear, however, that the climate within the Texas Medical Center is hostile to community-based health-effects studies. "You get the message in a number of ways, such as [lab and office] space and financial support of what you're doing," Jones says. "Institutions have ways of making your life either easier or more difficult."

Researchers who do try to swim against the tide can meet with baffling obstacles. Consider UTMB's recent refusal to cooperate with Winnie Hamilton, a Baylor scientist who wanted to study mercury exposure among low-income pregnant women on the Gulf Coast. Hamilton had the funding lined up, and essentially all UTMB had to do was distribute a questionnaire to women visiting its maternal health clinics. But a UTMB administrator refused, explaining that the staff was busy "implementing some very exciting teletechnology projects into the already crowded workday."

Jonathan Ward says it's not hard to see why a place like Texas Medical has a hands-off attitude. "A public institution that's chartered to provide health care and do research is benefiting from funds from particular kinds of organizations," says Ward. "They're probably not going to go out and do things that upset those organizations."

David Marrack is still more blunt: "The medical institutions are beholden to industry for their grant funds," he says. "There is political pressure not to investigate things that go too close to home."

The pressure doesn't always come from within the institutions. Researchers know that any scientist whose findings point to problems with specific chemicals can expect a no-holds-barred attack from industry; they can recite example after example from around the country. Many sources mentioned Jack Killian, a former medical director at a Dow Chemical plant on the Gulf Coast in the 1970s. When Killian began to see chromosomal damage in workers, which he attributed to benzene, the company shut down his lab and hired other researchers to discredit his methods. Eventually Killian left, and the lab was turned into a cafeteria. "That's clearly the message for new investigators," comments Harvard scientist Joel Schwartz, who has professional connections with the Houston medical research community. "You don't want to get into this. You're gonna get harassed for the rest of your life."