RALEIGH, N.C. (AP) — Americans have grown accustomed to hearing apologies from everyone from cheating car-makers to cheating presidents, but a Fortune 500 chemical company with a pollution problem in North Carolina is following a different model: don't apologize, don't explain.

For six months, Wilmington, Delaware-based Chemours Co. has faced questions about an unregulated chemical with unknown health risks that flowed from the company's plant into the Cape Fear River, which provides drinking water for hundreds of thousands of people.

The company has said virtually nothing in its own defense a...