It’s a common belief/myth, but it’s not true – generally. If the liver is from an unhealthy animal, then, yes it may contain toxins, particularly heavy metals, but then, so would all the other organs and meat of that same animal and you shouldn’t eat any part of it. And whether or not the food the chicken eats is organic isn’t really relevant, there are heavy metals in organic food too. Pesticide accumulation which is a primary concern with non-organic feed is not an issue specific to the liver. The liver does filter, but its job isn’t to store toxins for some imagined future use, it processes them, renders them inert, and gets rid of them. Still, liver is not something that you should eat as a regular daily diet, while it’s nutrient rich, it’s got high levels of Vitamin A and copper, in particular, and were you to make a daily diet of it, it could be a problem. As an occasional treat, it’s no more “toxic” than any other type of meat.