Nicholas Kristof covers this in his latest New York Times opinion piece.
After looking into industrial raised chicken practices here's what he found:
That’s because my topic today is a pair of new scientific studies suggesting that poultry on factory farms are routinely fed caffeine, active ingredients of Tylenol and Benadryl, banned antibiotics and even arsenic.He was pretty floored by this:
Likewise, I grew up on a farm, and thought I knew what to expect in my food. But Benadryl? Arsenic? These studies don’t mean that you should dump the contents of your refrigerator, but they do raise serious questions about the food we eat and how we should shop.
Kristof concludes that his family is better off eating organic. But there's "organic" and then there's "organic." Organic is, unfortunately, now just another label, and doesn't necessarily mean you'll be avoiding unwanted drugs, hormones and chemicals in your food.
Eating organic, is, of course, better than eating non-organic, but in the end you're best bet is buying directly from a farmer where you can question exactly how the food was produced. Second best is looking into the farming practices of individual producers to find out exactly how "organic" their product is.