Some of the area's major department stores and several children's shops will give cash refunds to parents who return unworn sleepwear treated with the flame-retardant chemical Tris, a potential cancer-causing substance, according to a survey by the city's Office of Consumer Protection.

In the survey, conducted last week among 21 stores in downtown, Georgetown and the nearby Maryland suburbs, the office found that 12 made cash refunds, seven other said they never sold pajamas treated with Tris and the other two, K-Mart and Lord and Taylor, told the office to send written questions to their corporation headquarters, said Edith Barksdale-Sloan, director of the consumer office.

Stores who will make refunds for both used and unused clothes are Garfinckel's (which no longer carries clothes treated with Tris), Gaint, Sears, McBrides, Morton's, J. C. Penney, Woodward and Lothrop, Saks Fifth Avenue (if used clothes are clean). Beyda Petites (if the manufacturer accepts used garments) and Ida's Department Store, 5601 Georgia Ave. NW. Hecht's will make refunds only on unused clothes.

"I strongly urge those parents who have recently purchased children's sleepwear to contact the stores where they were purchased to see if they have been treated with Tris," Mrs. Barksdale-Sloan said.

Seven stores told the consumer office they never sold Tris-treated pajamas - Jelleff's; Mufphy's Woolco; the Esther Shop, 1407 F St. NW; Frances Reilly, of Georgetown; Just So, 3301 New Mexico Ave. NW, and Les Lutin, Inc., 1663 Wisconsin Ave. NW.

The Consumer Product Safety Commission is scheduled to vote Thursday on whether to ban production of polyster children's sleepwear containing Tris.