Genetically modified organisms
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A genetically modified organism (GMO) is an organism whose genetic material has been altered using genetic engineering techniques. Genetic engineering essentially involves incorporation of gene(s) from an different species - even across Kingdom - into the host genome. Thus, genes from animals and bacteria may be inserted into a plant genome, to create a novel transgenic plant. Transgenic breeding is thus different from the traditional selective breeding, and therefore novel gene products (like proteins) from the GMO may have some unexpected environmental effects.
Several antibodies and medicines have already been commercially produced by using genetic engineering. For example, mammalian insulin is being produced by recombinant DNA in bacteria. This make the hormone much cheaper than natural insulin derived from conventional biosynthesis. However, when genetic engineering is applied in agriculture for production of crops, there are many uncertainties and risks.
Unlike insulin or other GM drugs and hormones manufactured in the laboratory, GM crops cannot be controlled or revoked, once they are released in nature. In addition to the possible harmful effects on ecosystems (including agro-ecosystems), introduction of the GMOs into the human food chain poses an unprecedented risk to public health. No wonder GMOs has caused considerable controversy since the early 1990s, when it was first introduced.
Genetically modified food has caused considerable controversy since the early 1990s, when it was first introduced. However, this controversy only relates to GM organisms that have been created using the transgenesis method. Cisgenesis has been proven equally safe as regular plant breeding by the EFSA
Advantages of GMO's
- GMO's can increase yields
- GMO's can reduce pesticide use
- GMO's can reduce fertiliser use
- GMO's can improve the nutritional value of some plants
Disadvantages of GMO's
The uncertainty inherent in GMOs entails unprecedented and unintended effects on the environment. The expression of the transgene (the exogenous gene incorporated into the host organism) is uncertain, and gene silencing as well as upregulation of the gene is frequently encountered in GMOs. Owing to differential gene regulation processes, production of completely novel proteins is also likely. Because the inserted gene produces the toxin all the time, the expression of the gene in all tissues and all the time would have unknown consequences on the life forms normally associated with the plant. Not only the pest insects that damage leaves and stems, but also pollinators that consume nectar and pollen are also affected by the toxin. Natural enemies of the crop pest, like predatory insects and higher organisms are also likely to be killed after feeding on the toxin-affected insects. Furthermore, differential expression of genes in different tisses of the same GMO has also been documented (Kranthi et al. 2005). Thus, the bacterial Bt toxin in Bt cotton may express in roots, but not in the flower, with the consequence that cotton bollworm, the target pest insect will remain unharmed, while affecting the soil microbial community.
Indirect deleterious effects of GM crops on biodiversity is also common. Transgenic herbicide tolerant (HT) crops (like Monsanto's Roundup Ready crops) that facilitate repeated application of glyphosate herbicide, cause elimination of all "weeds" including a wide range of broadleaved plants. When the broadleaved plants are eliminated, the pollinators and birds depending on their flowers and fruits are also eliminated. The deleterious effect of transgenic HT crops on avian, floral and insect biodiversity has already been documented (Bohan et al. 2005; Heard et al. 2006). The application of Monsanto's Roundup herbicide, whose application is enhanced by the GM Roundup Ready crops, is known to enhance mortality of both terrestrial and aquatic frogs and other aquatic animals (Relyea 2006; Perez et al. 2007).
There are several research publications that indicate different environmental effects of GM crops (see section below). Risk to human health is also considerable, because a toxin (like Cry A1 toxins) that is harmless to humans when made in bacteria could be modified by the GM plant cells in many ways, some of which might be harmful to humans. Human health effects are particularly difficult to detect by employing short-term studies of anything that goes into human food - whether a pesticide or food coloring agent. With GM food, the chance of detection of a direct link is remote. As Schubert (2002) pointed out: "Prompt toxicity might be rapidly detected once the product entered the marketplace if it caused a unique disease and if the food were labeled for traceability, as were the GM batches of tryptophan. However, cancer or other common diseases with delayed onset would take decades to detect, and might never be traced to their cause.”
There are many publications on the risks of GMOs. One of the most thorough and authoritative account of environmental and health risks from GMOs is Genetic Engineering: Dream or Nightmare? by Mae-Wan Ho. A more technical anthology of risks of GMOs by a group of professional scientists is Biosafety First, edited by Terje Traavik and Lim Li Ching. A popular expositor is Jeffrey M. Smith, whose Seeds of Deception and Genetic Roulette are quite famous, although does not cite many important scientific work. Another popular writer is F. William Engdahl. A recent account of the scientific uncertainties and unpredictable hazards on molecular, organismal and ecological levels, is Debal Deb (2014). A thorough account of how distorted facts, misinformation and hyperboles are spread to promote GM crops is given in Drucker's (2015) Altered Genes, Twisted Truth.
Absence of Evidence?
Biotech corporations tend to perpetuate the myth that "there is no evidence of harmful effect of GM crops". Scientists point out that the "absence of evidence" (as yet) does not warrant an evidence of the absence of effects. The present lack of knowledge of effects should entail rigorous and intensive research into the possible long term effects until the GMOs are proven safe.
There is an active corporate pressure on many researchers to suppress research results that might affect the sale of GM products. First of all, the access to the proprietary GM crops for study is denied to any independent researcher. Secondly, when the access is not denied, there is a contract that compels the researcher to submit her results to the company prior to submission to any journal for publication. In almost every case, the company does not allow publication if the results indicate any adverse effect of the product. As a recent Scientific American (August 2009) report describes, "Only studies that the seed companies have approved ever see the light of a peer-reviewed journal. In a number of cases, experiments that had the implicit go-ahead from the seed company were later blocked from publication because the results were not flattering. It is a matter of selective denials and permissions based on industry perceptions of how ‘friendly’ or ‘hostile’ a particular scientist may be toward seed-enhancement technology.” Finally, "whenever a paper describes problems with biotech crops, several critics spring up, who react quickly, criticize the work in public forums, write rebuttal letters, and send the to policy-makers, funding agencies and journal editors" (Waltz 2009).
Another tactic of biotech corporations is to oppose any scientific publication that purports to reveal any negative effects of GM crops. Thus, when an empirical study, published in Nature, showed pollen transfer from GM corn to traditional corn landraces in Oaxaca, Mexico, the study was blasted for technical inaccuracy and choice of samples. Nature later distanced itself from the paper, on grounds that the evidence was not strong enough to warrant publication. However, Elena Alvarez-Buylla and co-workers (Piñeyro-Nelson et al. 2009a) examined nearly 2000 samples from 100 fields in the region from 2001 and 2004, and found that around 1% of the samples had genes that had jumped from GM varieties. Even this paper was subsequently critiqued as false evidence, as the samples were partly contaminated - a charge the authors refuted (Piñeyro-Nelson, et al. 2009 b).
Similarly, Rosi-Marshall et al. (2007) showed that Bt toxin run-off from Bt corn fields caused significant mortality in certain aquatic organisms. This work, peer reviewed and published in PNAS received a barrage of critical emails, some of which were from ghost authors.
A. Unexpected mortality of non-target Lepidoptera from pollen from Bt crop:
1. Losey, J.E., L.S. Rayor and M.E. Carter 1999. Transgenic pollen harms monarch larvae. Nature 399: 214.
2. Hansen, L and J Obrycki 2000. Field deposition of Bt transgenic corn pollen: lethal effects on the monarch butterfly. Oecologia DOI 10.1007/s004420000502, published online: 19 August 2000.
3. Zangerl, A R, McKenna, D, Wraight, C L, Carroll, M, Ficarello, P, Warner, R and M R Berenbaum 2001. Effects of exposure to event 176 Bacillus thuringiensis corn pollen on monarch and black swallowtail caterpillars under field conditions. Proc. Natl. Acad. Sci. USA 98: 11908-11912.
4. Stanley-Horn, G. P. Dively, R. L. Hellmich, H. R. Mattila, M. K. Sears, R. Rose, L. C. H. Jesse, J. E. Losey, J. J. Obrycki and L. C. Lewis 2001. Assessing the impact of Cry1Ab-expressing corn pollen on monarch butterfly larvae in field studies. Proc. Natl. Acad. Sci. USA 98: 11931–11936.
5. Anderson, P. L., R. L. Hellmich, M. K. Sears, D. V. Sumerford, and L. C. Lewis 2004. Effects of Cry1Ab-Expressing Corn Anthers on Monarch Butterfly Larvae. Environmental Entomology 33: 1109-1115.
6. Dively, G. P., R. Rose, M.K. Sears, R.L. Hellmich, D.E. Stanley-Horn, J.M. Russo, D.D. Calvin and P.L. Anderson 2004. Effects on monarch butterfly larvae (Lepidoptera: Danaidae) after continuous exposure to Cry1Ab-expressing corn during anthesis. Environmental Entomology 33: 1116–1125 (2004).
B. Unexpected high mortality of lacewings and silkworm from Bt crop:
1. Hilbeck, A., M Baumgartner, P M Fried and F Bigler 1998. Effects of transgenic Bacillus thuringiensis corn-fed prey on mortality and development time of immature Chrysoperla carnea. Environmental Entomology 276: 480-487.
2. Wang, Z-H, Shu Q-Y, Cui H-R, Xu M-K, Xie X-B & Y-W Xia 2002. The effect of Bt transgenic rice flour on the development of silkworm larvae and the sub-micro-structure of its midgut. Scientia Agricultura Sinica 35: 714-718.
3. Hilbeck, A and Schmidt 2006. Another view on Bt proteins. Biopesticides International 2 (1): 1-50.
C. Effect of Bt toxin on hoppers and dragonflies
1. Bernal, C C, Aguda, R M and M B Cohen 2002. Effect of rice lines transformed with Bacillus thuringiensis toxin genes on the brown planthopper and its predator Cyrtorhinus lividipennis. Entomological Exp. Appl. 102: 21–28.
2. Ponsard, Sergine, Andrew P. Gutierrez and Nicholas J. Mills 2002. Effect of Bt-toxin (Cry1Ac) in transgenic cotton on the adult longevity of four Heteropteran predators. Environmental Entomology 31: 1197-1205.
D. Additonal mortality of honeybees from Bt crops:
1. Brodsgaard, H F, Brodsgaard C J, Hansen H & Lovei G L 2003. Environmental risk assessment of transgene products using honey bee (Apis mellifera) larvae. Apidologie 34: 139-145.
E. Bt-induced resistance in pest insects:
2. Huang, F., L. Buschman and R Higgins 1999. Inheritance of resistance to Bacillus thuringiensis toxin (Dipel ES) in the European corn borer. Science 284: 965-966.
F. Elimination of pollinators and birds from GM crops:
1. Watkinson, A R, R P Freckleton, R A Robinson and W J Sutherland 2000. Predictions of biodiversity response to genetically modified herbicide-tolerant crops. Science 289: 1554-1557.
G. Impact on soil organisms.
1. Saxena, D, S Flores and G Stozsky 1999. Insecticidal toxin in root exudates from Bt corn. Nature 402: 480.
2. Tapp, H and G Stozsky 1998. Persistence of the insecticidal toxin from Bacillus thuringiensis subsp kurstaki in soil. Soil Biol. Biochem. 30: 471-476.
H. Horizontal gene transfer from GM crop to non-GM varieties.
1. Wheeler, CC, D Gealy and D O TeBeest 2001. Bar gene transfer from transgenic rice (Oryza sativa) to red rice (Oryza sativa). Rice Research: AAES Research Series 485: 33-37.
2. Greene, A E and R F Allison 1994. Recombination between viral RNA and transgenic plant transcripts. FEMS Microbiol. Ecol. 15: 127-135.
3. Serratos-Hernández, J.-A., J.-L. Gómez-Olivares, N. Salinas-Arreortua, E. Buendía-Rodríguez, F. Islas-Gutiérrez and A. de-Ita 2007. Transgenic proteins in maize in the Soil Conservation area of Federal District, Mexico. Frontiers in Ecology and the Environment 5: 247-252.
4. Piñeyro-Nelson, A, J. Van Heerwaarden, H. R. Perales, J. A. Serratos-Hernandez, A. Rangel, M. B. Hufford, P. Gepts, A. Garay-Arroyo, R. Rivera-Bustamante and E. R. Álvarez-Buylla 2009a. Transgenes in Mexican maize: molecular evidence and methodological considerations for GMO detection in landrace populations. Molecular Ecology 18:4: 569-571.
5. Piñeyro-Nelson, A., J. Van Heerwaarden, H.R. Perales, J.A. Serratos-Hernández, A. Rangel, M.B. Hufford, P. Gepts, P., A. Garay-Arroyo, R. Rivera-Bustamante and E.R. Álvarez-Buylla 2009b. Resolution of the Mexican transgene detection controversy: error sources and scientific practice in commercial and ecological contexts. Molecular Ecology, 18: 4145–4150.
6. A. Snow 2009. Unwanted transgenes re-discovered in Oaxacan maize. Molecular Ecology 18: 569-571.
I. Gene silencing in GM crops:
1. Kumpatla, S.P., W. Teng, W.G. Buchholz and T.C. Hall 1998. Gene silencing and reactivation in transgenic rice. Rice Genetics Newsletter 14: 155-159.
J. Persistence of Bt toxin in soil:
2. Stotzky, G. 2004. Persistence and biological activity in soil of the insecticidal proteins from Bacillus thuringiensis, especially from transgenic plants. Plant and Soil 266: 77-89.
3. Sun, X, L. J. Chen, Z. J. Wu, L. K. Zhou and H. Shimizu 2006. Soil persistence of Bacillus thuringiensis (Bt) toxin from transgenic Bt cotton tissues and its effect on soil enzyme activities. Biology and Fertility of Soils 43: 617-620.
K. Toxic root leachate from Bt crop affecting soil insects and microbial activity:
1. Sun, C. Wu, Z., Zhang, Y. & Zhang, L. 2003. Effect of transgenic Bt rice planting on soil enzyme activities. Ying Yong Sgeng Tai Xue Bao 14: 2261-2264.
2. Saxena, D, Stewart, C N, Altosaar, I, Shu, Q & Stotzky, G 2004. Larvicidal Cry proteins from Bacillus thuringiensis are released in root exudates of transgenic B. thuringiensis corn, potato, and rice but not of B. thuringiensis canola, cotton, and tobacco. Plant Physiol. Biochem. 42: 383–387.
3. Wu, W-X., Ye, Q-F, Hang, M, Duan, X-J & Jin, W-M. 2004. Bt-transgenic rice straw affects the culturable microbiota and dehydrogenas and phosphatase activities in a flooded paddy soil. Soil Biol. Biochem. 36: 289-295.
4. Wu, W-X., Ye, Q-F. & Min, H. 2004. Effect of straws from Bt-transgenic rice on selected biological activities in waterflooded soil. European Journal of Soil Biology 40: 15-22.
L. Toxin released from Bt crops fatal to aquatic organisms:
1. Rosi-Marshall, E.J., J.L. Tank, T.V. Royer, M.R. Whiles, M. Evans-White, C. Chambers, N.A. Griffiths, J. Pokelsek & M.L. Stephen 2007. Toxins in transgenic crop byproducts may affect headwater stream ecosystems. Proc. Natl. Acad. Sci. USA 104: 16204–16208.
M. Pathological effects of Bt toxin on rat hematopoetic system, spleen, heart and adrenal glands.
1. de Vendômois, J. S, F. Roullier, D. Cellier, Gilles-Eric Séralini 2009. A Comparison of the Effects of Three GM Corn Varieties on Mammalian Health. Int. Jour. Biol Sci. 5: 706-726. http://www.biolsci.org/v05p0706.htm
N. Threat to organic farming:
1. Paull, J. 2015. GMOs and organic agriculture: Six lessons from Australia. Agriculture & Forestry, 61 (1), pp. 7-14. http://orgprints.org/28525/7/28525.pdf
O. GMOs as invasive species:
1. Paull, J. 2018. Genetically Modified Organisms (GMOs) as Invasive Species. Journal of Environment Protection and Sustainable Development. 4 (3), pp.31–37. http://orgprints.org/28525/7/28525.pdf
As a reviewer commented, “From the accumulating evidence it is clear that the large-scale introduction of GE crops containing entirely novel gene products in new combinations at high frequencies with their associated complex of non-target organisms will have unknown impacts on future agricultural and, ultimately, natural ecosystems” (Velkov et al. 2005).
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- Jeffrey M. Smith, Seeds of Deception: Exposing Industry and Government Lies About the Safety of the Genetically Engineered Foods You're Eating. Yes! Books, 2003. ISBN 0972966587
- Jeffrey M. Smith, Genetic Roulette: The Documented Health Risks of Genetically Engineered Foods. Yes! Books, Fairfield, IA USA 2007. ISBN 9780972966528
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- Kijk magazine 10/2012