Although the sale and production of Children's sleepwear treated with Tris, a flame retardant found to cause cancer in animals, was banned in April 1977, confusion still plagues many parents on the whole subject of pajamas, chemicals and safety.

"I just avoid the issue by putting the kids to bed in long johns or my husband's tee-shirts," says a mother of two. "I haven't bought any new nightclothes in three years."

But according to a spokesman for the U.S. Consumer Product Safety Commission (CPSC), which ordered the Tris ban, "There is no Tristreated clothing on the market today."

In the District, the city's Consumer Protection Office has not conducted a survey of local stores since the fall of 1977. "At that time, we found no stores that were selling pajamas with Tris," said information officer Ethiopia Liggins, "and we are certain that is still the case. We have had no complaints from consumers on the matter.

Parents need not fear, however, that the pajamas they buy are dangerously flammable, according to experts. Children's sleepwear now being sold are of synthetics that are flame retardant because of the elements used to make up the fabric.

The Environmental Defense Fund (EDF), the consumer organization in Washington that led the fight to get Tris-treated nightwear off the market, agrees that children's sleepwear being sold today is free of hazardous flame retardants, but it is concerned about old, treated, sleepwear still in use in many households.

"I think we're out of the woods on the new stuff," said EDF staff attorney Robert Rauch, "but I am personally concerned that old garments can still pose a hazard. It is fair to say that a fair amount of garments treated with Tris and Fyrol (another flame retardant that is structually similar to Tris) are still in circulation, and should be disposed of.

"Ideally, any sleepwear manufactured between 1972 and 1977 should be wrapped in a separate package and thrown in the trash," Rauch said. "Don't give it to anybody else or use it for rags."

Another EDF spokesman, Dr. Robert Harris, said the organization's concern over used Tris-treated pajamas results from tests and analyses performed by Drs. Arlene Blum and Bruce Ames of the University of California, Evan Horning of Baylor College in Houston and Ralph Dougherty of Florida State University.

In a study made in 1978, horning and Doherty determined that Tris can be absorbed into the skin of children wearing treated sleepwear, even after the garments have been washed 10 times. They reported that dibromopropanol, a Tris byproduct first found by Blum and Ames in the urine of a child wearing a new Tristreated garment in early 1977, was detected in the urine of 10 children wearing treated garments, some of which had been washed many times.

At the time of the findings were released, Horning told a reporter that although most of the chemical is excreted from the body fairly soon, "we think some stays in the body fat, though we still must work on this."

Harris said that after five or six washings, Tris in treated fabrics does "level out." But he said no determination has been made on how much risk the remaining Tris poses, "how much is absorbed or what the retention time is."

No Tris-related cancer has been reported in humans yet, Harris said, but early tests on mice showed that Tris could cause systemic cancer affecting at least four organs, including the kidneys.

Fred Shippee of the American Apparel Manufacturers Association also confirmed that no Tris-treated sleepwear is for sale in the District or elsewhere now. What was left in the hands of manufacturers and retailers has been disposed of in landfills, he said, or was exported before that was prohibited by the federal government. Much of the treated fabric is still in storage, awaiting Congressional action on whether the government would cover losses sustained by business because of the Tris ban, he added.

Shippee disagreed strongly with the EDF suggestion that consumers get rid of old, Tris-treated sleepwear.

"I think that's lousy advice," Shippee said. He found the EDF's comments "inappropriate" since the issue of used, treated sleepwear had been resolved in an out-of-court settlement between the EDF and the CPSC in the summer of 1977.

At that time, the EDF argued that the Tris ban should be extended to include used sleepwear already in the hands of consumers. The CPSC declined to extend the ban, but did agree to tell the public that even after repeated washings some Tris might remain, and that continued use of treated garments was up to individual consumers.

In any event, consumer planning to buy new nightclothes for their kids can be assured that garments in sizes 0 to 14 meet federal flammability standards, said a CPSC representative.

Most sleepwear sold now is made from 100 percent polyester. Nylon and nylon tricot have a share of the market, and some modacrylics, sold under the brand names, SEF and Cordelan, are still around, Shippee said.

None of these fabrics is treated with flames retardant chemicals, but each is constructed in such a way to make it flame retardant.

Instructions on most garments state that detergent, not soap, should be used in laundering to retain flame retardent properties. Soap is fatty in nature, and thus flammable, Shippey said, and residues left on the fabric surface could be hazardous.

Acetates and triacetates, two blends that relied heavily on Tris have disappeared from the market. Cotton sleepwear for children is not being produced, Shippee said, because "flammability standards can't be met without the use of chemicals."

Although Harris at the EDF says he is not "overly worried" about the fabrics now used in children's nightwear, "nothing is risk free. There are chemicals of some type in almost all fabrics, but no one is asking hard questions about wearing apparel" for children or adults.

What do Harris' children sleep in? "My mother-in-law makes their nightclothes - out of pure cotton."