A House subcommittee yesterday sharply criticized the Consumer Product Safety Commission for failing to investigate and act prompty once it received information on the potential dangers of Tris, a carcinogenic flame retardant used in children's sleepwear.

"I am concerned that millions of children may still be facing a threat from Tris-treated garments since, even after numerous washings, Tris continues to be available for skin absorption and ingestion," said Rep. John Moss (D-Calif.), chairman of the subcommittee on oversight and investigations.

In a 47-page report, the subcommittee charged that CPSC failed to investigate the hazard posed by Tris in a timely fashion, failed to act quickly once it became aware of the dangers posed by Tris, and failed to give consumers instructions on how to guard against the flame retardant's ill effects.

"This report highlights the CPSC's failure to make adequate use of the powers Congress gave it," Moss wrote in submitting the report. "We believe that Tris is merely one example of a far bigger problem confronting the agency, namely the regulation of chronic hazards in consumer products."

The report recommends that CPSC take immediate action to warn the public of the potential dangers of wearing Tris-treated sleepwear. "Although Tris is no longer being used in children's sleepwear, it has by no means been totally eliminated as a hazard to the public health," Moss wrote.

The report found that while CPSC has focused on "acute hazards such as lawn mowers and architectural glass, it has moved too slowly to develop a policy for chronic hazards . . ."

The use of Tris in children's sleepwear evolved from government concern about the flammability of the cotton which comprised about 85 per cent of the material used in such garments until the early 1970s.

In 1971, the Commerce Department issued standards on flammability which forced manufacturers to turn to other types of fabric, principally man-made fibers, combined with flame-retarding chemicals.

By 1973, Tris had become the most widely used retardant because of its effectiveness and low cost. Within the next two years, though, scientists at the National Cancer Institute and the Environmental Protection Agency began to suspect Tris as an agent in causing cancer.

Not until mid-1977, though, after a petition by the Environmental Defense Fund, did CPSC ban Tris treated children's clothing.

At the same time, CPSC rejected an EDF request to warn consumers of the potential threat from Tris-treated garmets, and later declared that after three washings, Tris-treated garments could be considered safe.

The report also criticizes the nation's major manufacturer of Tris-Michigan Chemical Co. - now a division of Velsicol Chemical Co. - for failing to test Tris adequately before marketing it, making misleading statements about the safety of Tris, and withholding toxicological information of potential Tris hazards.