Backyard chickens: Fun for the entire family! That is, until your kids get arsenic poisoning from them.

The Utah Department of Health tracked worrisome levels of arsenic in two kids’ urine to the family’s backyard chicken coop, reports Judy Fahys in the Salt Lake Tribune (hat tip to Cookie Jill). More specifically, to the arsenic-based additive called roxarsone that (along with others) is commonly used in animal feed, and that somehow wound up in the eggs from those chickens. The kids were eagerly eating a dozen eggs or so a week each from their hens.

Used in combination with antibiotics, arsenic helps keep chickens, turkeys, and pigs from getting sick in crowded conditions, and also makes them grow bigger, faster. While this sounds nuts — feeding a notorious poison to animals you plan to eat — the poultry industry, along with Food and Drug Administration officials, is quick to point out that there are two kinds of arsenic: inorganic, aka the cancer-causing “bad” kind, which occurs naturally in the environment in combination with other elements such as oxygen, chlorine, and sulfur; and organic. No, not the kind you can get from Whole Foods: in this case “organic” refers to compounds containing carbon, or hydrogen. Organic arsenic is considered less toxic, and that’s what’s used in animal feed, usually in the form of roxarsone.

The key word there is “less.” FDA spokesperson Ira Allen wrote in an email to me that:

FDA completed food safety assessments in conjunction with the approval of the arsenic-containing animal drug products. As part of that assessment process, FDA established tolerances for the presence of arsenic in animal-derived food. For example, the tolerance for total arsenic in uncooked muscle tissue from chickens is 0.5 parts per million (ppm). FDA does not at this time have evidence that residues of total arsenic in animal-derived food are exceeding the established tolerances.

The timing for this little news development is quite interesting. In November 2009, Rep. Steve Israel (D-N.Y.) introduced a bill, the “Poison-Free Poultry Act of 2009,” that called for a ban on roxarsone. The following month, the Center for Food Safety joined with the Institute for Agriculture and Trade Policy (IATP) to file a petition [PDF] with the FDA, requesting that it stop approving all arsenic-containing compounds used in animal feed, not just roxarsone. A dozen or so additional groups joined the petition.

Why ban arsenic as an additive, if it’s so safe? Well, a few years ago, IATP had conducted some independent tests of chicken sold under various brands and found detectable levels of arsenic [PDF] in most of them — including one of the two USDA Certified Organic brands tested, even though organic regulations prohibit the use of arsenic in feed. While the levels of the others were not above the threshold set by the FDA, as the IATP and the Center for Food Safety argue in the petition, “Banning arsenic-containing compounds in feed additives would provide an easy solution to lighten the burden on public health.”

It’s kind of a no-brainer. “Science has indicated that arsenic is not necessary for a large-scale chicken production,” says Paige Tomaselli, a staff attorney with the Center for Food Safety who helped draft the petition. “They don’t use it in Europe, and it creates an unnecessary risk: organic can convert to inorganic in the soil and the manure. We think it’s an unnecessary practice.”

Back to those arsenic-laced eggs in Utah. No one has apparently ever checked to see how much arsenic from chicken feed might end up in eggs, whether those from battery hens or the seemingly wholesome kind children gather from their backyard birds. The IATP only tested muscle tissue and liver.

Though it’s important to note that the Utah kids showed none of the symptoms of arsenic poisoning, the daughter’s urine levels revealed double the arsenic that the FDA considers toxic, and the boy was 75 percent above that limit. Which, if you’re a parent, might cause you to kinda freak out.

By law the FDA has 180 days to respond to arsenic-in-feed petition — that is, until this past June 9. According to Tomaselli, about a week before time was up, the FDA contacted the Center and IATP and said that “they were considering the issue, but ‘due to the complexity of the issues raised,’ they would need more time. We hope that they will act on it soon.”

In response to my asking about the status of the petition in regards to the possible poisoning of the Utah kids, the FDA’s Ira Allen replied that:

Based on the scientific information available at the time, previous assessments of arsenic-containing animal drug products assumed that organic arsenic was not significantly metabolized in the live chicken (i.e., the arsenic remained in the organic form). However, recent studies have called that assumption into question. FDA is evaluating reports suggesting that organic arsenic may convert to inorganic forms in the digestive track, litter, or soils. FDA is actively gathering additional information to address these emerging questions. FDA will initiate the appropriate action once a determination is made as to whether the approved uses of arsenic-containing drugs in animal feed pose a risk to public health.

The question I wish the agency would ask is, what benefit — to industry, obviously, as there is none for consumers — could possibly outweigh putting the public at risk at all by feeding a potential carcinogen to our food animals?

But as we wait for the FDA to stop clucking around, all you backyard chicken fanciers might want to shell out the extra dough for certified organic layer rations for your birds. Or maybe ease off on eating their eggs.