Cable Leaking
iPod touch (4th generation), iOS 6.1.6
I do not recall that specific problem being posted here before.
Since it is a 30-pin cable I doubt it is still under the one-year warranty.
However, if you want you can make an appointment at the Genius Bar of an Apple store.
No health risks unless you eat it. Sounds like the plasticizer used to make the wire coating pliable or in the plug end is breaking down. That can happen with cheap cables.
Thank you for your reply. As bobjbkln has said, buying another cable won't cost much so it's not worth taking it to the Genius Bar. I'm more concerned with why it happened so I can make sure my other cables don't get affected and to make sure there aren't any health risks.
30 pin cables can be purchased for very little money on eBay or Amazon. For a dollar or two you can solve your problem.
Cable Leaking