The U.S. Food and Drug Administration is investigating reports of radioactive contamination in frozen shrimp imported from Indonesia.

Customs and Border Protection detected the radioisotope Cesium-137 at four U.S. ports. The FDA later confirmed the isotope in one sample of breaded shrimp, prompting the agency to block entry of all contaminated shipments.

The FDA has also urged Walmart to recall certain lots of Great Value raw frozen shrimp linked to the contamination. The affected products carry the item code 7383108 and a best-by date of March 15, 2027.

Officials are working with Indonesian authorities to determine the source of the contamination. Consumers are advised not to eat or serve shrimp from the recalled lots and to safely dispose of any products that match the description.