They come from farms just like the crickets you buy why would they be full of toxins? You really don't know where your pet store feeders come from do you? Big fat earth worms are great food for turtles but would not feed many to them vary any herps diet except snakes we all know what snakes eat.if somebody tells you they are organic worms they are crazy just trying to rip you off.i raise all my own feeders because of cost.