Industry released 5 percent more toxic chemicals into the environment in 2002 than the year before, the Environmental Protection Agency reported yesterday.

The latest statistics, compiled in the agency's annual Toxic Release Inventory, represent a setback: In 2001, according to the inventory, toxic emissions had declined by about 16 percent. Environmental groups, moreover, charged yesterday that polluters were releasing four to five times more toxic material than they reported.

Kim Nelson, who directs the EPA's Environmental Information Office, said much of last year's increase was caused by an Arizona-based copper smelting facility that closed and had to dispose of significant waste material. Without that facility, she said, emissions dropped by 3 percent nationwide.

"This is a very broad and far-reaching effort the agency has implemented to inform the American public about toxics," Nelson said.

Under a 1986 law targeting 650 chemicals, companies must report to the EPA how much of each they release annually, and the agency reports these figures to the public. The federal government does not directly monitor the release of all emissions, though it has recently taken enforcement action against facilities that missed the EPA's July 1 reporting deadline.

The 2002 figures marked the first time since 1997 that reported emissions increased. Releases of lead increased 3.2 percent and mercury jumped by 10 percent, though Nelson attributed the mercury increase to a single gold mine. However, emissions of dioxin, a carcinogenic byproduct of various industrial processes, fell by 5 percent.

Phil Clapp, president of the National Environmental Trust, disputed the EPA's explanation of the 2002 increase. "The growth in emissions is too big to be explained away by pointing at a smelter here or a factory there," he said. "This is an across-the-board increase in pollution."

In addition, two environmental groups released a study yesterday that suggested the government figures sharply understated emissions. They based their critique on findings by the Texas Commission on Environmental Quality, which determined the concentration of toxic substances in the air around refineries and chemical plants was far higher than the figures reported to state and federal authorities.

Extrapolating to other states, the groups concluded that industry was underestimating releases of carcinogens such as benzene and butadiene by as much as 400 or 500 percent.

"The public is being exposed to far more toxins than the EPA is reporting," said Environmental Integrity Project counsel Kelly Haragan, whose group co-wrote the report with a Texas air quality group. "EPA has known for a long time its numbers are inaccurate."

The EPA's Nelson said that the agency had "no evidence of significant trends" in underreporting, adding that critics have unrealistic standards. "The law doesn't require precise monitoring of every single chemical at every single facility in the country," she said.

Frank Maisano, spokesman for the Electric Reliability Coordinating Council, a utility group, said mercury pollution will decline as soon as the Bush administration is able to change the rules for power plant emissions. Many Democrats and environmental groups charge that the Bush proposal would weaken regulations that compel plants to install new pollution controls when they modernize facilities.

"What it shows is we really need EPA to move forward with its efforts to regulate emissions, as they have proposed to do," Maisano said.