What can I do if my guinea pigs keep digging up the absorbent training pads and chewing it worries me that they can get sick from it! Help!?

Stop using training pads

You have fleece over the pads I assume? Can you wrap the fleece around the base of the cage?
You could use a different absorbent layer. Uhaul blankets (the recycled denim kind) work great. You can also use towels or mattress pads.

Try bedding. It will help to absorb the mess and sprinkle in baking soda to get rid of the Oder

rodent teeth grow continually . they MUST gnaw to wear down the teeth or they grow too long for them to open their moth enough to eat then they starve to death .

I would not use pads like that. Better to use recycled paper litter and put the litter box in the corner where they most like to go to the bathroom.