The Consumer Product Safety Commission voted unanimously yesterday to do away with the part of its children's sleepwear standards that led manufacturers to use the controversial fire-retarding chemical Tris.

If the commission reaffirms its vote next month, manufacturers will be able to use many nylon and polyester fabrics in children's sleepwear without treating them with any fire-retarding chemicals, a commission spokeswoman said.

Up until April, Tris was commonly used on polyester fabrics to get them past a flame test required by the commission.

The commission banned the sale of garments treated with Tris on April 7 after tests showed Tris caused cancer in animals.

That ban sparked a storm of protest from clothing manufacturers and retail stores, who argued that they often had no way to determine what chemicals the manufacturers of the cloth were using, and that they were bearing an unfair economic burden because of the ban on sales.

Their protests led to an overturning of the commission ban by the Fourth U.S. Circuit Court of APpeals in Richmond. It said the commission had acted "arbitrarily and capriciously" in banning only the sale of Tris-treated garments, and not the use of the chemical as well.

Yesterday's action does not affect the need for fire-retarding chemicals other than Tris on cotton garments, which before the Tris controversy accounted for only 10 per cent of the children's sleepwear market but 80 per cent of the burn injuries, the commission spokeswoman said.

The commission took three separate votes yesterday.

The most important was a unanimous vote to scrap a test which require that an artificial fabric withstand three seconds exposure to a flame without melting enough to drip.

"In our research we could find no basis for that requirement in protecting kids," said Dr. Robert Harris of the Environmental Defense Fund. "The stanards are to prevent sleepwater from going up in flames. Polyester doesn't do that anyway, even when not treated. So you don't need chemicals. Polyester is an inherently flame-resistant fiber."

In a second vote, this time 3 to 2, the commission dropped requirements for any flammability standards at all for infant clothing sizes 0-1. "Accident data did not indicate many injuries to the 0-1 age group," the commission said. ". . . Presumably children 0-1, on their own accord, are not as likely to be exposed to such ignition sources as matches and ranges as are older children."

The third vote scrapped a test for lace, ruffles and other trim in which the trim had to be held vertically over the flame. That means, a commission spokesman said, that trim will be used only horizontally on childrens' sleepwear if the vote is reaffirmed next month.