Sad news. Just goes to show you shouldn't leave your baby alone with a dog, regardless of how nice/dosile the dog is.
If i had to guess, it would be the lab. At 6 months they arent that big, but compared to a baby, they would be real big.
Labs are great dogs (i have one) but they are crazy about food. If i give Dakota a bone or something, he goes fucking psycho if i try and take it off him. He's bitten me a few times on the hand, hurt quite a fair bit. I dunno if they are all like that, or whether he's just nuts
Either way, i wouldnt let a baby/toddler/small kid near a lab eating. An accident waiting to happen.