Why don't people get ill from eating liver, an organ full of poisons?

MA:

I was enjoying a hefty helping of liver and onions the other day, and I began to wonder how people can safely eat that organ. I know the human liver filters out poisons from our system. I would assume cow and chicken livers do the same thing. So why don't people get ill from eating an organ full of poisons?

-- L, chowing down

Gunk that goes through the liver doesn't hang around there too long. The liver is a hard-working processor of blood and producer of bile to aid digestion. What it stores are vitamins and minerals, especially iron, which is why it got its healthful rep in the first place. But if you scan USDA inspection reports for cattle they've sampled at slaughter, you'll see that traces of antibiotics and other chemical enhancements fed to cows can end up in their tissue, and levels in the liver are usually higher than levels in muscle. So if you're spooked by that kind of thing, cow's feet with onions would probably be a better choice than liver and onions.