Sippy cups, those seemingly indestructible vessels that toddlers use to quench their thirst have a problem: mold can accumulate.

I used to clean ours with toothpics or thin metal skewers, but that was after hundreds of uses.

Mayborn USA is recalling more than 3 million of their spill-proof Tommee Tippee Sippee cups. The recall affects five types of cups: First Sips Transition cup, Trainer Sippee cup, Sippee cup (including Cute Quips), Sportee bottle and Insulated Swiggle/Sippee tumblers.

All of them have a removable valve, which the Consumer Product Safety Commission says can develop mold if not cleaned well. The agency said 68 kids have gotten sick.

Their symptoms include vomiting and diarrhea, consistent with drinking from a cup containing mold.