Throw Your Cast Iron Pan Away Immediately If You Notice This

So what to do if your pan doesn't exactly look like it is rusted, but has changed color over time? You might think there's no way the change can be due to rust, especially because your pan has not been exposed to much humidity. In fact, you might think that discoloration is quite normal, especially in a piece of metal cookware you've had for years. Most discoloration is completely normal in cast iron. But since it is sometimes impossible to differentiate rust from discoloration, you might have a far more dangerous situation on your hands without realizing it.

Continuing to use a rusted pan (even if you think it's discolored instead) may put your health at risk in more ways than one. Rust sometimes varies in shade, so your cast iron pan may very well be covered in corrosion. Rust is hazardous because if consumed, it can lead to tetanus, but only if it has been around the bacteria Clostridium tetani (via Fox News). Since this is usually only found outside or around soil, you might not have an issue with tetanus per se, unless you have left your cast iron pan in the garage, or taken it outdoors. Rust can still be toxic if enough is ingested, especially if done so frequently for long periods of time.