Visit almost any anti-GMO website and you will find alarming headlines about the alleged dangers of GMO foods. They kill pigs, cows and sheep on farms and in lab studies! Humans are next!

“Monsanto MON -0.15%’s GMO Feed Creates Horrific Physical Ailments in Animals,” screams a typical article, in AlterNet, a popular anti-GMO site. It touts “new research” but as is typical of such articles and such sites, it neither quotes a study nor links to any independent research.

Although there have been more than 2,000 studies documenting that biotechnology does not pose an unusual threat to human health and genetically modified foods are as safe or safer than conventional or organic foods, questions remain in the minds of many consumers.

What does the research say?

Animal feeding studies are the basis for evaluating the safety of GMO crops. One-off studies of lab animals have occasionally shown some problems. Gilles-Eric Séralini, in his retracted GM corn study (later republished in a non-peer-reviewed anti-GMO journal), claimed rats fed genetically engineered corn developed grotesque cancerous tumors—the kind no farmer would miss among his animals if this cause-effect was genuinely in place.

Anti-GMO crusader Jeffrey Smith, on his personal website, the Institute for Responsible Technology, lists more than a dozen cases in which he claims animals fed GMOs exhibited abnormal conditions, including cancer and early death. He also references his own self-published book, and anecdotal evidence that pigs fed GM feed turned sterile or had false pregnancies and sheep that grazed on BT cotton plants often died.

“Nearly every independent animal feeding safety study on GM foods shows adverse or unexplained effects,” he writes. “But we were not supposed to know about these problems…the biotech industry works overtime to try to hide them.”