How verdicts are decided
Every verdict comes from veterinary sources such as the ASPCA Animal Poison Control Center and the Merck Veterinary Manual, cited on the food's page [1][2]. Dogs and cats get separate verdicts because the same food can affect them differently — onions and garlic, for example, are more dangerous for cats [2].
If a food isn't listed yet, don't feed it until you've checked with your vet.