The pigs living in pens at the University of Guelph in Ontario are, well, unique. It’s nothing to do with their appearance — cute and pink, they look like any other Yorkshire pigs. The difference is in their genetic makeup, and, subsequently, their “cleaner” manure.

Normally, a pig can’t break down phytate, a phosphorus-rich compound found in the cereal grains they eat. That means as much as 75 percent of the phosphorus in the animal’s feed goes undigested and ends up in its manure. That becomes a problem when large numbers of pigs are concentrated on ranches. “The bulk of phosphorus passes through the pig and can get into freshwater sources, leading to extensive algal growth,” says Cecil Forsberg, leader of the university’s pig project.

To solve this long-standing environmental pollution problem, Forsberg and colleagues genetically engineered pigs, dubbed Enviropigs, which digest more phosphorus. By introducing a bacterial gene for the enzyme phytase into Enviropigs’ genome, the pigs secrete the enzyme in their saliva and expel up to 60 percent less phosphorus in their manure than their non-transgenic counterparts.

Enviropigs are just one type of genetically engineered animal living in experimental labs in North America. Others include fast-growing salmon, disease-resistant cows, and goats that produce antibacterial milk. But before meat and dairy products from these animals move from the barnyard to the dinner table, they need FDA approval. That’s something the agency hasn’t granted yet, but biotech companies are betting big bucks that they will soon. Some environmental and consumer advocate groups, however, worry that there isn’t enough information about the safety of such foodstuffs to bring them to market.

FDA spokesperson Siobhan DeLancey acknowledges that the agency is drafting rules, but she wouldn’t estimate when they’ll be published. “We can't comment on where a particular rule may be in the regulatory process, or provide specifics about what a pending rule may contain.”

Currently, no meat, fish, milk, or dairy products from genetically engineered animals are approved for food or feed use. However, the FDA has given the green light to other biotech-produced foodstuffs. In 1994 the first genetically engineered food, the Flavr Savr tomato, hit the market. And in January 2008, the FDA ruled that cloned animals and their offspring are safe to eat, though there’s been some backlash from consumer advocates about the decision.

Cloning involves taking the nucleus of one somatic (a non-sex cell) cell implanting it into an egg cell whose nucleus has been removed, stimulating the cell to divide, and once an embryo forms, implanting it into the womb of a host mother. Scientists genetically engineer animals by splicing only the genes from another animal into the nucleus of a fertilized egg, and then implanting the embryo into the womb of a host mother.

The FDA keeping mum about how it might regulate genetically engineered animals has some groups concerned that the rules won’t be stringent enough. Critics say modifying animals’ genes could inadvertently bring about harmful changes in the composition of meat or milk, perhaps by turning on a gene that produces a toxin or food allergen. Another worry is that transgenic animals could upset ecosystems if they escaped; wild salmon, for instance, might not be able to find food or mates if they have to compete with fast-growing salmon.

“We don’t know how these genes work in animals, and humans haven’t tried to digest these before, so we don’t know how they’ll work in people, either,” says Jaydee Hanson, policy analyst for the nonprofit Center for Food Safety.

The FDA has proposed regulating transgenic animals under the "new animal drug" provisions of the Federal Food, Drug, and Cosmetic Act. Under its guidelines, the FDA would evaluate the safety of each new transgenic animal on a case-by-case basis, like it assesses each new antibiotic, for instance, to ensure that it’s safe and effective.  

Using the new animal drug standards is the way to go, according to Ronald Stotish, CEO of Aqua Bounty Technologies, a company that has modified Atlantic salmon to grow to market size in half the time of traditional salmon. They’ve engineered the growth spurt by splicing a gene for growth hormone from the Chinook salmon with a genetic on-switch from the ocean pout, an eel-like fish.

Assessing each new transgenic animal on a case-by-case basis would not only address safety concerns, says Stotish, it would also ensure a proprietary niche for the companies or scientists who created the animal.

 “It would mean companies could say our animals are constructed for these specific purposes, and the regulatory review would ensure the animals do what they say they do and are indeed safe,” says Stotish. “It takes the concern out—that question for the consumer, ‘Gee, how do I know that there isn’t some aspect of this technology that isn’t safe, or is less safe?’”

Hanson, too, believes that following the new drug standards would add a necessary safety net, but he worries that the FDA won’t actually use these regulations to evaluate transgenic animals. “That’s what they originally said on cloning, too, but then they invented a new process,” Hanson says. The agency reviewed hundreds of scientific studies, and found meat and milk from cattle, swine, and goat clones to be as safe as that from normal animals. So cloned animals do not have to be approved on an individual basis. “We really saw it as a completely inadequate process,” says Hanson, who points to what he sees as a small number of animals involved in the studies. “If the FDA were to use the new animal drug standards [for regulating transgenic animals], they would have to have bigger sample sizes, they would have to look at issues like allergic reactions, they would have to really overall do a much more thorough job.”

While this regulatory approach would allay public concerns and be good for business, Hanson still views it as potentially problematic. “It makes transgenic animals more easily patented than a traditional animal,” he says. Like genetically engineered crops, transgenic animals can more easily be proven to be ‘inventions’, and therefore patentable, than traditionally bred or crossed plants and animals. “We’ll be introducing into animal breeding what’s happened with crops—ranchers won’t own the next generation, or will owe a royalty.  It might not be Monsanto, but it will be the Monsanto equivalent. At this point, safety should be the main concern, but the next step is these economic issues.

Story by Alisa Opar. This article originally appeared in Plenty in September 2008.

Copyright Environ Press 2008

Beasts of bioengineering
Enviropigs and other genetically modified foods may be coming soon to a market near you. But are they safe?