Raw kidney beans contain relatively high amounts of phytohemagglutinin, and thus are more toxic than most other bean varieties if not pre-soaked and subsequently heated to the boiling point for at least 10 minutes. The US Food and Drug Administration recommends boiling for 30 minutes to ensure they reach a sufficient temperature long enough to completely destroy the toxin.Cooking at the lower temperature of 80 °C (176 °F), such as in a slow cooker, can increase this danger and raise the toxin concentration up to fivefold.Canned red kidney beans, though, are safe to use immediately.