What sound or visual indication necessitates immediate discarding of canned goods due to *Clostridium botulinum* toxin risk?

Bulging, deeply dented, cracked, or leaking cans

Canned goods are shelf-stable because they are sealed to destroy microorganisms; however, physical damage or improper processing can indicate dangerous contamination, particularly by *Clostridium botulinum*, which produces deadly toxins. Any signs of physical compromise on the container are immediate red flags requiring disposal. This includes cans that are bulging, which suggests gas production from bacterial activity inside; cans exhibiting deep dents, cracks, or leakage, which compromise the sterile seal. While a gentle hiss upon opening is often normal, resulting from the vacuum seal releasing, any loud hissing or forceful spurting of contents is also a major indicator of danger, signaling pressure build-up within the sealed environment.