One of the country's leading public health officials said yesterday that the health risks posed by dioxin -- the chemical that became notorious during the Love Canal and Agent Orange environmental crises of the 1970s -- may have been seriously overstated.

In testimony before the House Government Operations subcommittee on human resources and intergovernmental relations, U.S. Assistant Surgeon General Vernon N. Houk said that new evidence suggests dioxin may be only a weak carcinogen and that the limits on the release and cleanup of the chemical -- which have cost American society billions of dollars -- may be stricter than necessary.

"Before all of the human studies {on dioxin} became available it was reasonable to assume that this compound induced cancer in humans and that since we did not know its potency, it was decided to regulate it in a very conservative manner," said Houk, who directs the Centers for Disease Control's Center for Environmental Health. "Scientifically, in my opinion, the data that are now available no longer support that position."

Houk's comments, which came with the approval of the CDC director, represent one of the first signs that federal health officials may be willing to amend their position on dioxin and bring U.S. policy into line with that of other Western nations.

In the past few years, several European countries as well as Canada have recalculated dioxin's dangers, saying that the estimates of a safe daily dose of dioxin used by the United States may overstate the risks by as much as 1,000 times.

Two senior officials of the Environmental Protection Agency questioned Houk's views, telling congressmen that their agency is not as willing as is CDC to change its position on dioxin.

"It is important to note that this dioxin issue is a contentious one," said William H. Farland, director of the EPA's Office of Health and Environmental Assessment. Farland said when an EPA committee analyzed the chemical last year "there was a range of opinions" on how to evaluate its dangers.

Houk's remarks also brought criticism from subcommittee Chairman Ted Weiss (D-N.Y.), who charged that they were out of step with the position of other federal agencies.

"It seems to me nothing short of arrogance for you individually to run counter to the views of other federal agencies," Weiss said to Houk. "I don't see how government can work on that basis."

Another committee member, however, Rep. Richard K. Armey (R-Tex.), accused Weiss -- who has long championed whistle-blowers in federal agencies -- of holding a double standard.

"The implications of this double standard are obvious," Armey said. "If you're a federal scientist who agrees with the political conclusions of the subcommittee in the face of opposing agency views, you are regarded as a courageous hero who's willing to speak out for justice. On the other hand if you're a scientist who disagrees with the subcommittee's conclusions, you identify yourself as a target for suspicion."

Most of the dioxin controversy concerns two studies on rodents in the 1970s which showed the chemical be one of the most potent carcinogens ever found.

Recently, however, studies of humans exposed to dioxin have suggested that the chemical does not act the same in humans as in rodents.