The Consumer Product Safety Commission has determined that at least one manufacturer shipped children's nightwear to Puerto Rico containing Tris, a chemical banned by the CPSC as a potential carcinogen.

Although several hundred of these garments may have been sold, the CPSC has made no effort so far to warn consumers.

The CPSC investigation only covered the four major department store chains. There is a possibility that Tris-treated nightwear also is being sold in the hundreds of smaller clothing stores scattered around the island, a local CPSC inspector, Edgardo San Miguel acknowledged.

Tris was used as a flame-retardent on childrens' pajamas until it was banned in April 1977. As part of the United States, Puerto Rico is automatically included in a product ban.

Published allegations that Tris treated sleepwear was being sold in Puerto Rico spurred the CPSC investigation in early May. Twelve samples of children's pajamas were collected and sent to the CPSC lab in Washington.

One garment, manufactured by Confee Pajamas of New Bedford, Mass., and sold at a New York department store chain in San Juan tested positive.

The store immediately pulled all unsold Confee products off the shelves and has shipped them back to the factory, buyer Rafaelita Navarro said.

No effort has been made to notify consumers, however, although test results were known in mid-May.

CPSC compliance officer Elizabeth Jones explained that only about one-third, or 600 to 700 garments, in the Confee shipments to Puerto Rico were Tris-treated. The factory cannot identify which are the Tris-treated styles until it receives the returned shipment, she said.

Furthermore, part of the Confee stock is supplied by Springs Mills, in South Carolina, which has obtained an injunction prohibiting the CPSC from enforcing the Tris ban against its fabrics. Some of the garments in the Puerto Rican shipments may have been supplied by Springs Mills.

After these questions are answered, the CPSC can then ask New York Department Stores to put up signs warning consumers.

"There are lots of problems in dealing with Tris-treated garments. So far we have gotten cooperation from the store and the factory, and we are hoping it continues," Jones said. "It is a sticky situation."

According to Navarro, New York Department Stores received four shipments from Confee over the past two years, each with about 1,200 garments. The Tris-treated garment was taken from a 1978 shipment.

About one-fourth of the first 1978 shipment was sold, she estimated, while the second shipment was still in the warehouse. The store also returned the remnants of its 1977 shipments to protect itself, she explained.

Interviewed by telephone at the Confee factory, company president Nat Kleger said only two styles in the 1978 shipment contained Tris. He will not know how many of these garments were sent in 1978 or whether the 1977 shipments contain Tris, until he receives the returns, he said.

Asked why the garments were sent to Puerto Rico, Kleger claimed it was because of "confusion."

"We always consider a shipment to Puerto Rico as an export, because you had to take it to the docks and put it on a boat," he explained, "not considering it was a territory.

"Most of the manufacturers shipping there were doing it because of a misunderstanding," he said, "until it came to light in a Fairchilds' publication."

Asked if the CPSC will take punitive action against Confee, Jones said the decision will not be made for several months.

She claimed the Confee shipments were "unique." It would be next to impossible to visit the smaller stores with the CPSC's limited resources, she said.

"There is no real reason to believe Tris-treated products are being dumped in Puerto Rico," she said."There is always the possibility that some small store in Puerto Rico or the United States still has the product, but for the most part, retailers and manufacturers got the notification and managed to get it off the shelves.

The CPSC is now working on a bill to include foreign exports as part of a product ban.

Meanwhile, according to Kleger, companies can continue exports if they notify the federal government which in turn notifies the foreign government of the country receiving the shipment. For all practical purposes, these regulations are cutting off any exports, he explained.