WASHINGTON—U.S. congressional investigators found “dangerous levels of toxic heavy metals” in certain baby foods that could cause neurological damage, a House Oversight subcommittee said in a report released on Thursday. The panel examined baby foods made by Nurture Inc., Hain Celestial Group Inc., Beech-Nut Nutrition, and Gerber, it said, adding that it was “greatly concerned” that Walmart Inc., Campbell Soup Co. and Sprout Organic Foods refused to cooperate with the investigation. The report said internal company standards “permit dangerously high levels of toxic heavy metals, and documents revealed that the manufacturers have often sold foods that exceeded those levels.” Campbell said in a statement on its website that its products are safe and cited the lack of a current FDA standard for heavy metals in baby food. The company said it thought it had been “full partners” in the study with congressional researchers. Walmart did not immediately respond to a …