The Food and Drug Administration is warning the public not to eat, sell or serve certain Great Value raw frozen shrimp sold at Walmart due to possible contamination with Cesium-137, a radioactive isotope.

U.S. Customs and Border Protection alerted the FDA about possible Cesium-137, or Cs-137, detected in shipping containers at four U.S. ports, the FDA said Tuesday in a press release. Testing on frozen shrimp from the distributor, Indonesia's BMS Foods, also tested positive, the FDA said.

However, no shrimp that has tested positive for Cesium-137 has entered the U.S. food supply, according to the FDA.