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

A widening seafood safety scare has prompted federal officials to expand a nationwide shrimp recall for the second time in a week. Walmart’s popular Great Value brand to the growing list of products pulled from store shelves over concerns about possible radioactive contamination.

The FDA advises consumers not to eat certain shrimp products from Walmart over possible radioactive contamination. What to know about the recall.