Tests for hazardous substances and pollutants on samples from all over the United States may have been compromised by a pattern of falsifications at a plant owned by TRC Cos., a federal prosecutor said Thursday.

TRC and a former executive pleaded guilty in U.S. District Court, St. Louis, to filing false reports on tests done on samples for the Environmental Protection Agency.Test samples from all over the United States were subjected to falsification at the company's former Metatrace laboratory in St. Louis County for two years, said James Martin, the assistant U.S. attorney prosecuting the case.

"This was an ongoing practice from August 1987 to August of 1989," Martin said. As for the cost to the EPA, Martin said, "That number hasn't been determined yet . . . the exact damage to the government is still being determined."

"They did samples from all around the country," he added.

However, the company pleaded guilty to just one count, Martin said.

Still, the company could be fined up to $500,000 for the one count it pleaded to and also could be forced to pay an as yet undetermined amount of reimbursement for any damage the government suffered, Martin said.

Martin said a pattern of falsifications in "an ongoing practice" ocurred at TRC's Metatrace laboratory.

The executive who pleaded guilty also to one count, Kenneth Baughman, was formerly project manager for the company. Although he is a cooperating witness in the continuing investigation, Baughman could face up to a $250,000 fine and five years in jail, Martin said.

Martin said his office was still investigating the false reports and whether any other individuals would be charged.

Typically, the falsifications involved the "backdating" of test reports so that tests carried out after a 10-day time limit had elapsed appeared to have been done in the proper time, Martin said.

He said a computer clock was set back "to manipulate the (apparent) holding time" of samples.