At most petting farms and carnivals children can be seen excitedly gathered around the chicken coops. They are enthralled with the iconic animals that have roamed the happy farms of Old McDonald and Babe. However, chickens may not be as safe and cuddly as many children–or their parents–assume.

The results of a Utah investigation into the astronomically high levels of arsenic in two local children led to a startling discovery. The kids’ arsenic levels came from their backyard chickens.

Further investigation led to the real culprit, which was the feed being given to their feathery pets. This widely-used and completely legal chicken feed contains high levels of arsenic additives in the form of roxarsone.

Roxarsone is used in many different chicken feeds in order to prevent the birds from contracting parasitic diseases. The U.S. Food and Drug Administration (FDA) allows the additive because it is the natural variety of arsenic and thought to be less dangerous. However, roxarsone may be more dangerous than previously thought, judging by the high levels of arsenic poisoning in these two Utah children.

Though many city children only get to see chickens at petting farms and carnivals, chickens are starting to creep off of country farms and into residential neighborhoods. This particular type of chicken is called the “Backyard Chicken” and is steadily gaining popularity. As Food Safety News reported in June, many cities are starting to allow chickens onto even very small residential properties of 5,000 square feet.

This raises the question, should roxarsone be allowed in the feed of animals infiltrating the backyards of our neighborhoods? reported the results of a researcher at Duquesne University who found evidence that arsenic converts to the inorganic and highly poisonous kind when it is mixed with chicken manure.

Chicken manure is often later used as fertilizer and can leak into waterways.

Christine McNaughton, the toxologist working on the two arsenic cases told the Salt Lake City Tribune, “For anyone who has backyard chickens, this is an issue.”

The Minneapolis based Institute for Agriculture and Trade Policy is petitioning the FDA to ban the arsenic additives. David Wallinga, a director at the Institute, stated, “Because we’ve turned a blind eye to what we put in our animal feed, we’re putting our children at risk.”

Arsenic additives are banned in Europe.