All packaging – glass, aluminum, paper and plastics (such as polystyrene) – contains substances that can “migrate” in very tiny amounts to foods or beverages. That’s one of the reasons why FDA regulates food packaging in the first place – to be confident that the amount of substances that might actually migrate is safe.
Test data submitted to FDA indicated that the migration of styrene from polystyrene foodservice products is tiny and expected to be significantly below the safety limits set by FDA itself – 10,000 times less than FDA’s acceptable daily intake level.