If you saw “Arsenic in Our Chicken?,” Nick Kristof’s much-read New York Times column from earlier this month, you’ve heard about the widespread use of some unexpected additives in chicken farming.

Studies released this year detected caffeine, acetaminophen (the active ingredient in Tylenol), fluoxetine (the active ingredient in Prozac), various antibiotics, arsenic, and more in feather meal, a substance made from ground poultry feathers and used in animal feed. The findings were the results of studies by the Johns Hopkins Center for a Livable Future and Arizona State University.

“I grew up on a farm, and I thought I knew what to expect in my food. But Benadryl? Arsenic?” Kristof wrote. The studies, he added, “raise serious questions about the food we eat and how we should shop.”