HOUSTON—A congressional committee has told the Environmental Protection Agency that letting a Port Arthur incinerator import toxic waste from Mexico would “effectively create an open border” for disposing a banned chemical compound in the United States.

The EPA has indicated it will approve Veolia Environmental Services importing up to 20,000 tons of PCBs, or polychlorinated biphenyls, which the U.S. prohibits from being imported.

The House Committee on Energy and Commerce, which oversees the EPA, raised issues with the Veoila’s proposal in a letter Monday to the federal agency’s chief administrator.

The committee’s concerns included the risk to residents of the Gulf Coast refinery town and surrounding Jefferson County, the availability of alternative disposal methods and the plant’s safety record.

“The people of Southeast Texas already live with a large concentration of industries, and they deserve to know why the EPA intends to exempt this facility from the federal ban on importing toxic PCBs,” said Rep. Gene Green, D-Houston, a committee member.

An EPA spokeswoman said the agency had received the letter and would give it careful consideration. The agency has until Aug. 4 to respond to the committee, the Houston Chronicle reported Tuesday.

Mitch Osborne, the Veolia plant’s general manager, said he had not had a chance to read the committee’s letter but defended the facility’s record. Company officials said smokestack tests show the incinerator destroys more than 99 percent of the material that it burns.

“If we didn’t believe that we could do this safely, then we wouldn’t be going through this political firestorm,” he said.

Federal law bans the import of PCBs, but the EPA has the power to grant exemptions on a case-by-case basis for up to a year.