The Consumer Product Safety Commission is investigating some 100 clothing manufacturers in New York City and the Southeast to see if they are attempting to export children's garments treated with Tris, a substance said to cause cancer in animals.

Late last week the CPSC extended its year-old ban on the sale of such treated clothing to exports. The move was seen as a reaction to recent reports that many manufacturers were dumping the goods overseas at distress prices.

According to CPSC spokeswoman Heidi Bowers, agents from the commission's compliance and enforcement division will attempt to discover what firms are trying sill to export the goods, and then institute a number of actions aimed at stopping the sales.

Court orders, seizures of the clothing and criminal sanctions all are being considered, Bowers said.

Last week several manufacturers told the Washington Post that they had shipped millions of dollars worth of the garments to such places as Venezuela and Mexico. Clothing normally would be sold for $30 or more a dozen was old for about $5 a dozen.

Many manufacturers were tired of waiting for federal funds to compensate them for approximately $50 million in losses built up when they had to buy back the affected garments because of the domestic ban imposed by the CPSC last year.

The ban was imposed after the Environmental Defense Fund warned the CPSC of the alleged carcinogenic nature of Tris, a flame retardant which the government had ordered clothing manufacturers to put in childrens clothing as a safety measure.

The House is expected soon to pass a bill to compensate the companies involved. It has passed the Senate.

Last October the CPSC ruled that it did not have authority to ban exports.But last week it reversed that stand, based on a legal opinion from staff attorneys. The move was not unexpected because the political make-up of the agency also has been reversed in recent months, and the new Democratic commissioners, now in the majority, have expressed a desire to be consistant with the administration human rights policy overseas.