The FDA said its sweeping test results showed America’s infant formula supply was safe. But a Spotlight on America investigation found the agency did not test the formula samples for disease-causing pathogens — even as it investigated an infant botulism outbreak.

At least 52 babies were hospitalized during two outbreaks linked to ByHeart and Nara Organics formulas. Parents whose children became seriously ill are now demanding answers about what the FDA knew and why warning signs did not prompt additional action.

The FDA said its investigation into the source of the contamination remains ongoing. Both formula companies said they are changing suppliers and strengthening testing and safety measures.