Even as agribusiness prepares to market genetically engineered animals, there has been minimal public discussion of the many human health dangers that could be introduced by these novel creations. Perhaps most troubling is the engineering of animals containing antibiotic-resistant “markers,” designed to help producers confirm that the new genetic material has been transferred into the host animal. Introducing these marker genes into the food supply via GE animal meat and milk products could further exacerbate antibiotic resistance, rendering many important antibiotics useless in fighting human diseases.
Genetically engineering animals to be “healthier” for humans to consume is a reported goal of some of the transgenic animal research. Geneticists and cloning scientists at the University of Missouri have mixed DNA from the roundworm (Caenorhabditis elegans) and pigs to produce swine with significant amounts of omega-3 fatty acids, the kind believed to stave off heart disease (1). The researchers cloned a dead pig that had the gene in the right location, and that clone later produced five “successful” transgenic piglets that the researchers intended to breed. So far, no companies have announced that they plan to use this technology for pork products. In 2002, Smithfield’s Foods funded cloning research for ProLinia (since purchased by Viagen ), but in 2008 Smithfield and Hormel, two of the top U.S. producers of pork products, announced they would not use cloned animals in their products. Since all GE animals are clones or progeny of clones, this would extend to the use of GE animals. Still, any company that wanted to use the University of Missouri pigs would have to get approval for their marketing from the U.S. Food and Drug Administration (FDA), where these pigs would be evaluated as animals containing a new drug, in this case the modified worm gene.
There is also serious concern that producing pharmaceuticals in GE animals (as well as the practice of genetically engineering animals to obtain organs for transplants) could increase the risk of spreading animal viruses to humans. From human immunodeficiency virus (HIV), avian and swine flu viruses, to the microscopic prions that transmit mad cow disease to humans, numerous animal pathogens—often barely detectable—can create human diseases and even pandemics. Yet biotech companies seeking to commercialize pharmaceuticals and organs from transgenic animals currently have no means for identifying or eliminating pathogens that might be spread to humans. This hazard would seem to be a significant barrier to large-scale commercialization of medical products from GE farm animals.
The experiments conducted to create GE animals also pose potential new virus threats. Researchers deploy viral vectors that invade the cells of animals and deposit new genetic materials; but these vectors can then recombine with viruses in animals to create new diseases in livestock and humans (3). If these GE animals are consumed, these viruses could enter the human food supply.
1 Liangxue Lai, Jing X. Kang, Rongfen, Li, Jingdong Wang, William T. Witt, Hwan Yul Yong, Yanhong Hao, et al., “ Generation of Cloned Transgenic Pigs Rich in Omega-3 Fatty Acids,” Nature Biotechnology 24 (April 1, 2006): 435-36.
2 ViaGen, “ViaGen Aquires Livestock Pioneer ProLinia: Deal Gives Genetics Company Patent Rights, Contract with World’s Largest Hog Producer and New Scientific Talent,” press release, June 30, 2003.
3 Andrew Pollack, “Cancer Risk Exceeds Outlook in Gene Therapy, Studies Find,” New York Times, June 13, 2003.