Some packages of Great Value frozen shrimp sold at Walmart are at risk for potential for Cesium-137 contamination, the FDA says.

The US Food and Drug Administration on Tuesday urged the public not to eat certain bags of frozen raw shrimp sold at Walmart, citing concerns about unsanitary conditions and radioactive contamination found in shipments from the same supplier.

The FDA detected Cesium-137, a radioactive isotope, in one shipment of Great Value frozen raw shrimp to Walmart. It said the affected shipment wasn’t sold.