Science in Society Archive

Transgenic Animals for Food Not Proven Safe

FDA’s guidelines on commercial release of transgenic animals ignore known hazards of GMOs and totally inadequate to protect the public from genetic and epigenetic damages that may result from transgenic foods. Prof. Joe Cummins and Dr. Mae-Wan Ho

This report was submitted to the United States Food and Drugs Administration on behalf of I-SIS

The Food and Drug Administration (FDA) announced a draft guidance document (GFI187) entitled [1] “Regulation of Genetically Engineered Animals Containing Heritable rDNA Constructs.” This draft guidance is intended to clarify FDA's requirements and recommendations for producers and developers of genetically engineered (GE) animals and their products. It describes how the new animal drug provisions of the Federal Food, Drug, and Cosmetic Act (the act) apply with respect to GE animals, including FDA's intent to “exercise enforcement discretion regarding requirements for certain GE animals.” The current Draft Guidance deal with GE animals that provide food or drugs; FDA decided to include all GE animals in this guidance and indicated that another guidance would be prepared to deal with GE animals used in gene therapy and vaccination.

In 2006, the Institute of Science in Society commented to the Codex Alimentarius on foods derived from transgenic animals that included both animals engineered for gene therapy or vaccines [2] ( GM Food Animals Coming , SiS 32) . In 2007, we commented on cloned transgenic animals to the FDA [3] ( Is FDA Promoting or Regulating Cloned Meat and Milk? , SiS 33) . The comments below will deal with studies on transgenic animals published since in the past two years and their implications for the FDA Guidance.

Transgenic animals as pharmaceutical bioreactors

Transgenic animals have grown in importance as ‘bioreactors' (factories) producing pharmaceutical proteins for disease treatment and for vaccines. A recent review [4] compared the advantages of producing pharmaceuticals in transgenic animals with bacteria, yeast, insect or vertebrate cells, and transgenic plants. Transgenic animals appear to avoid the glycosylation patterns provoking immune responses that complicate pharmaceutical protein production in plants and microbes. For the most part, the animal products are isolated from milk, but may be recovered from urine, semen, blood or eggs. A number of the transgenic animal pharmaceutical are in preclinical development while others are in clinical and advanced clinical development; and a few may soon be approved for the market [4]. A fuller list of the transgenic animal pharmaceuticals in clinical or preclinical development was published earlier [5]. Transgenic animal bioreactors were proposed as a new line of defence against chemical weapons by producing enzymes that destroy the chemical weapon after being injected into the bloodstream [6].

A wide range of animals have been exploited to produce pharmaceuticals. Transgenic chickens expressing parathyroid hormone is being developed as a treatment for osteoporosis. The chickens were engineered using a Moloney murine leukemia virus as a vector for delivering the human gene to the chicken genome [7]. Human erythropoietin (stimulating red blood cell production) was produced in chicken using a retrovirus vector derived from the Woodchuck hepatitis virus [8]. A cattle mammary bioreactor was created by transforming bovine fibroblast cells with the human lactoferrin gene. Nuclei from the transformed cells were cloned to produce calves making elevated levels of the anti-bacterial protein [9]. A human vitamin K dependent blood clotting factor was recovered from the milk of transgenic pigs [10]. Human lysozyme (an antibacterial enzyme) was produced in transgenic goats. Pasteurized milk from the transgenic goats was found to influence gastrointestinal morphology in young pigs [11]. Transgenic goats expressing recombinant human butyrl-cholinesterase in its milk were found to produce high levels of the human enzyme at the expense of milk production. Butylcholinesterase could be used to treat pesticide or war gas poisoning [12]. One salient point is that the FDA Guideline document did not lay out details of any scheme to deal with accidental or purposeful entrance of the transgenic bioreactor animals into the human or animal food chain .


Xenotransplantation is the transplant of animal organs and cells into humans. Transplant of transgenic humanized pig organs to humans has been promoted for over a decade. The major concern that has delayed the widespread transplantation of soft tissue organs from pigs to humans is not graft rejection. Hyper acute rejection of the pig organ has been prevented by transgenic modification of pigs to resemble human in their immune signature. In addition, transplant recipients require severe immune suppression of both B and T cells. Using that strategy , lo ng term survival of transgenic pig kidney and heart has been observed in non-human primates [13, 14]. One main remaining hurdle to xenotransplantation i s po rcine endogenous retrovirus (PERV ) i ncorporated into the pig genome. Pig cells when exposed to human cells causes the PERV to be activated and potentially able to invade and infect humans with a new and dangerous virus disease New strategies such as the use of small inhibitory RNA molecules are being implemented to prevent activation of PERV on transplantation or the development of anti-PERV vaccines may prevent the spread of a PERV disease [15]. Until an effective anti-PERV defense is found, xenotransplantation should not be undertaken. The Institute of Science in Society has pointed out that PERV provides a major obstacle to xenotransplantation since 2000 [16] ( Xenotransplantation - How Bad Science and Big Business Put the World at Risk from Viral Pandemics , I-SIS Report)and continues to highlight the fact that the danger of releasing a virus that crosses the species barrier has not yet bee n solved [17] ( Xenotransplant Fails All-round , ISIS News 7/8) . ‘Humanising' transgenic pigs to address immune rejection will also enhance the potential for PERV to cross species barriers [16].

Problems with transgenic farm animals

Dairy products from cloned cattle derived from somatic cells and cloned transgenic cattle derived from modified somatic cell lines were compared with control cattle from the same area. The clon ed transgenic cattle were modified with additional gene copies for the milk proteins b- and k - casein and previously shown to express the transgenes at high levels. Based on gross composition, fatty acid and amino acid profiles and mineral and vitamin contents, milk produced by clones and conventional cattle were deemed e ssentially similar and consistent with reference values from dairy cows farmed in the same region under similar conditions. Whereas c olostrum produced by transgenic cows with additional casein genes had similar IgG secretion levels and kinetics to control cows, milk from the transgenic cows had a distinct yellow appearance, in contrast to the white colour of milk from control cows. Processing of the m ilk into cheese resulted in differences in the gross composition and amino acid profiles; ‘transgenic' cheese had lower fat and higher salt contents and small but characteristic differences in the amino acid profile compared to control cheese [18]. The cloned transgenic cows were certainly not substantially equivalent to cloned cattle or control animals .

In many instances, transgenic animals have been allowed to be destroyed by composting rather than incineration. Transgenic pigs modified with the Escherichia coli appA gene, which codes for phytase to reduce phosphate elimination in manure, were composted, and it was claimed that composting satisfactorily eliminated the transgenic pig remains. There were a number of significant differences between transgenic and control pig carcasses in organic matter, ash, organic carbon and a number of inorganic chemicals [19]. The significant differences recorded were not discussed, but certainly require a fuller comment.

The interaction between cloning and inserted transgenes in farm animals requires fuller investigation. Cloned and cloned transgenic animals are not substantially equivalent to control animals [20] (see Cloned BSE-Free Cows, Not Safe Nor Proper Science , SiS 33) .

Transgenic Salmon

Transgenic salmon appears to be the most advanced transgenic fish preparing for commercial release. The Aqua Bounty company has developed hybrid transgenic salmon with four linked copies of a salmon growth hormone. The transgenes were inserted at one site in four head to tail complete repeats along with two partial copies of the gene. The insertion site caused a 587 base pair deletion of Coho DNA and an insertion of 19 base pairs of unknown DNA upstream and a 14 base pair direct duplication of a sequence downstream. The growth hormone insertion was adjacent to a pseudogene for a membrane protein of a salmon parasite acquired by horizontal gene transfer [21]. The chromosomal DNA insertion site for the transgene adjacent to a site already modified by horizontal gene transfer suggests that the transgene may be an unstable mobile insert capable of horizontal transfer to natural salmon stocks and other organisms.

Horizontal transfer of transgenic DNA has been ignored or denied by regulatory regimes and is a matter of major concern for biosafety [22] ( Horizontal Gene Transfer from GMOs Does Happen , SiS 38). In addition to the health and ecological hazards arising from the spread of transgenes, transgene instability compromises safety assessment and quality control of the transgenic line released. Transgene instability is well documented in genetically engineered plants, which also makes nonsense of patent protection [23] ( Transgenic Lines Unstable hence Illegal and Ineligible for Protection , SiS 38).

There is also concern that the large fast growing transgenic salmon would escape to the natural environment, threatening natural fis h populations and over consume resources. The reply of the producers of transgenic salmon was [24] “ When reared under standard hatchery conditions, the transgenic fish grew almost three times longer than wild conspecifics and had (under simulated natural conditions) stronger predation effects on prey than wild genotypes (even after compensation for size differences). In contrast, when fish were reared under naturalized stream conditions, transgenic fish were only 20 % longer than the wild fish, and the magnitude of difference in relative predation effects was much reduced.” The predation effects of transgenic salmon were reduced under natural conditions but not eliminated.

The glutathione antioxidant system was enhanced (up-regulated) in the transgenic Coho salmon, to combat reactive oxygen production from the increased metabolic rate [25]. The transgenic Coho salmon had altered hepatic gene expression related to iron-metabolism, innate im munity, reproduction and growth [26]. In wild salmon, food intake is reduced during the short days of winter but this was not the case for the tra nsgenic Coho salmon. The transgenic salmon had higher levels of hormone regulating food intake [27], and were unable to cope with low oxygen levels. The inability to cope with low oxygen levels may represent a general constraint on the evolution of rapid growth in natural salmon [28].

Genetic and epigenetic changes resulting from transgenesis need to be characterized

Transgenesis is associated with major rearrangements and mutations in the host genome. This was comprehensively reviewed in 2003 ( Living with the Fluid Genome , I SIS publication [29]), and confirmed by numerous publications since [30].

In addition, transgenesis is expected to affect the epigenome extensively, altering the expression states of many genes, and this has yet to be properly investigated. Epigenetics – the study of heritable changes in gene expression that do not involve alterations in DNA sequence – is a maturing discipline with growing applications in toxicology, cancer, nutrition, and brain and behavioural sciences [31-34].

There is already evidence of serious health impacts from transgenic food and feed (see GM is Dangerous and Futile , SiS 40 [35] for the most recent summary). Within the past week, a comprehensive study commissioned by the Austrian government showed that transgenic corn fed to mice significantly reduced their fertility over three to four breeding cycles within one generation. In the course of three generations fed on the transgenic corn,

significant changes in gene expression were detected with DNA microarray analyses. More than 400 genes were either up or down regulated [36].

Introducing a change to the human diet as far-reaching and fundamental as transgenic foods demands a thorough investigation of both the genetic and epigenetic effects resulting from transgenesis. Genomic and post-genomic technologies such as DNA microarrays, proteomics, and metabolic profiling are now routinely used in laboratory and field studies. They must be included in safety assessment of transgenic food and feed, along with multi-generational and other long-term feeding studies.

The FDA Guidance Document highly inadequate

FDA's Guidance Document provides little or no substantive information on the introduction of transgenic animals, particularly those used as bioreactors, into the environment in general and into the human food supply to be specific. FDA seems to take a passive stance on the matter. Environmental assessment is mandated by FDA but no guidance was provided on the substance of the assessment. It does not call for any health impact assessment that is urgently needed. It does not even call for labelling of the food products of transgenic animals, which is a prerequisite for health monitoring. There is also no provision to prevent surplus bioreactor animals from being released to the food supply. Our successive reviews of the literature on transgenic animals have left us in no doubt that transgenic animals are different from conventional animals and they must be clearly labelled if they are eventually to be sold as food, which we most strenuously oppose. We hope that FDA would protect the public, but the Guidance Document suggests that FDA is more interested in promoting the use of transgenic animals.

Article first published 17/11/08


  1. Food and Drug Administration [Docket No. FDA-2008-D-0394, Guidance for Industry Regulation of Genetically Engineered Animals Containing Heritable rDNA Constructs, Draft Guidance 09/19/2008,
  2. Cummins J and Ho MW. GM food animals coming. Science in Society 32 , 24-25, 2006.
  3. Ho MW and Cummins J. Is FDA promoting or regulating cloned meat and milk ? Science in Society 33 , 24-27, 2007.
  4. Houdebine L. Production of pharmaceutical proteins by transgenic animals. Comp Immunol Microbiol Infect Dis . 2008, Feb 1. [Epub ahead of print]doi:10.1016/j.cimid.2007.11.005
  5. Dunn DA, Pinkert CA, Kooyman DL. Foundation Review: Transgenic animals and their impact on the drug discovery industry. Drug Discov Today . 2005, 10(11), 757-67.
  6. Yang X, Carter MG. Transgenic animal bioreactors: a new line of defense against chemical weapons? Proc Natl Acad Sci U S A . 2007, 104(35),13859-60.
  7. Lee SH, Gupta MK, Han DW, Han SY, Uhm SJ, Kim T, Lee HT. Development of transgenic chickens expressing human parathormone under the control of a ubiquitous promoter by using a retrovirus vector system. Poult Sci. 2007, 86(10). 2221-7.
  8. Kodama D, Nishimiya D, Iwata K, Yamaguchi K, Yoshida K, Kawabe Y, Motono M, Watanabe H, Yamashita T, Nishijima K, Kamihira M, Iijima S. Production of human erythropoietin by chimeric chickens. Biochem Biophys Res Commun. 2008; 367(4), 834-9.
  9. Yang P, Wang J, Gong G, Sun X, Zhang R, Du Z, Liu Y, Li R, Ding F, Tang B, Dai Y, Li N. Cattle mammary bioreactor generated by a novel procedure of transgenic cloning for large-scale production of functional human lactoferrin. PLoS ONE . 2008; 3(10):e3453.
  10. Gil GC, Velander WH, Van Cott KE. Analysis of the N-glycans of recombinant human Factor IX purified from transgenic pig milk. Glycobiology 2008, 18(7), 526-39.
  11. Brundige DR , Maga EA, Klasing KC, Murray JD. Lysozyme transgenic goats' milk influences gastrointestinal morphology in young pigs. J Nutr. 2008;138(5), 921-6.
  12. Baldassarre H, Hockley DK, Doré M, Brochu E, Hakier B, Zhao X, Bordignon V. Lactation performance of transgenic goats expressing recombinant human butyryl-cholinesterase in the milk. Transgenic Res. 2008, 17(1),:73-84.
  13. Sprangers B, Waer M, Billiau A. Xenotransplantation: where are we in 2008? Kidney Int. 2008, 74(1), 14-21.
  14. d'Apice AJ, Cowan PJ.Xenotransplantation: The next generation of engineered animals. Transpl Immunol. 2008 Oct 28. [Epub ahead of print] doi:10.1016/j.trim.2008.10.003
  15. Denner J. Is porcine endogenous retrovirus (PERV) transmission still relevant? Transplant Proc. 2008, 40(2),:587-9.
  16. Ho MW and Cummins J. Xenotransplantation How Bad Science and Big Business Put the World at Risk from Viral Pandemics I-SIS Sustainable Science Audit #2, 2000
  17. Ho MW. Xenotransplant fails all-round. I-SIS news 7/8 2001
  18. Laible G, Brophy B, Knighton D, Wells DN. Compositional analysis of dairy products derived from clones and cloned transgenic cattle. Theriogenology . 2007, 67(1), 166-77.
  19. Murray D, Meidinger RG, Golovan SP, Phillips JP, O'Halloran IP, Fan MZ, Hacker RR, Forsberg CW. Transgene and mitochondrial DNA are indicators of efficient composting of transgenic pig carcasses. Bioresour Technol. 2007, 98(9), 1795-804
  20. Ho MW and Cummins J. Cloned BSE-free cows not safe nor proper science. Science in Society 33 , 28-31, 2007.
  21. Uh M, Khattra J, Devlin RH.Transgene constructs in coho salmon (Oncorhynchus kisutch) are repeated in a head-to-tail fashion and can be integrated adjacent to horizontally-transmitted parasite DNA. Transgenic Res. 2006, 15(6), 711-27.
  22. Ho MW and Cummins J. Horizontal gene transfer from GMOs does happen. Science in Society 38 , 22-24, 2008.
  23. Ho MW. Transgenic lines unstable hence illegal and ineligible for protection. Science in Society 38 , 28-29, 2008.
  24. Sundström LF, Lõhmus M, Tymchuk WE, Devlin RH. Gene-environment interactions influence ecological consequences of transgenic animals. Proc Natl Acad Sci U S A. 2007, 104(10), 3889-94.
  25. Leggatt RA, Brauner CJ, Iwama GK, Devlin RH. The glutathione antioxidant system is enhanced in growth hormone transgenic coho salmon (Oncorhynchus kisutch). J Comp Physiol [B]. 2007, 177(4), :413-22.
  26. Mori T, Hiraka I, Kurata Y, Kawachi H, Mano N, Devlin RH, Nagoya H, Araki K. hanges in hepatic gene expression related to innate immunity, growth and iron metabolism in GH-transgenic amago salmon (Oncorhynchus masou) by cDNA subtraction and microarray analysis, and serum lysozyme activity. Gen Comp Endocrinol. 2007, 151(1), 42-54.
  27. Lõhmus M, Raven PA, Sundström LF, Devlin RH. Disruption of seasonality in growth hormone-transgenic Coho salmon (Oncorhynchus kisutch) and the role of cholecystokinin in seasonal feeding behavior. Horm Behav . 2008, 54(4), 506-13.
  28. Sundt-Hansen L, Sundström LF, Einum S, Hindar K, Fleming IA, Devlin RH. Genetically enhanced growth causes increased mortality in hypoxic environments. Biol Lett. 2007, 3(2), 165-8.
  29. Ho MW. Living with the Fluid Genome, ISIS/TWN, London/Penang, 2003.
  30. Wilson AK, Latham JR and Steinbrecher RA. Transformation-induced mutations in transgenic plants. Analysis and biosafety implications. Biotechnology & genetic engineering reviews 2006, 209-237.
  31. Newbold RR, Padilla-Banks E and Jefferson WN. Adverse effects of the model environmental estrogen diethylstilbestrol are transmitted to subsequent generations. Endocrinology 2006, 147, S11-S17.
  32. Reamon-Buettner SM, Mutschler V and Borlak J. The next innovation cycle in toxicogenomics: environmental epigenetics. Mutation Res 2008, 639, 158-65.
  33. Weidman JR, Dolinoy DC , Murphy SK and Jirtle RL. Cancer susceptibility: epigenetic manifestation of environmental exposures. Cancer J 2007, 13, 9-16.
  34. McGowan PO, Meaney MJ and Szyf M. Diet and the epigenetic (re)programming of phenotypic differences in behaviour. Brain Research 2008, 1237, 12-24.
  35. Ho MW. GM is dangerous and futile. Science in Society 40.
  36. Velimirov A, Binter C and Zenteck J. Biological effects of transgenic maize NK603xMON810 fed in long term reproduction studies in mice. Report, Forschungsberichte der Sektion IV, Band 3. Institut für Ernährung, and Forschungsinttitut für biologishen Landbau, Vienna , Austria , November 2008.

Got something to say about this page? Comment

Comment on this article

Comments may be published. All comments are moderated. Name and email details are required.

Email address:
Your comments:
Anti spam question:
How many legs on a spider?