Genetic pollution

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Genetic pollution is a controversial[1][2] term for uncontrolled[3][4] gene flow into wild populations. This gene flow is undesirable according to some environmentalists and conservationists, including groups such as Greenpeace, TRAFFIC, and GeneWatch UK.[5][6][7][8][9][10][1]

The Food and Agriculture Organization of the United Nations defines genetic pollution as:

"Uncontrolled spread of genetic information (frequently referring to transgenes) into the genomes of organisms in which such genes are not present in nature."[11]

Some conservation biologists and conservationists have used genetic pollution for a number of years as a term to describe gene flow from a domestic, feral, non-native or invasive subspecies to a wild indigenous population.[3][9][12] The term is of late being associated with the gene flow from a genetically engineered (GE) organism to a non GE organism,[13] frequently by those who consider such gene flow detrimental.[5]


Whether the term 'genetic pollution' and similar phrases such as genetic deterioration, genetic swamping, genetic takeover, and genetic aggression, are an appropriate scientific description of the biology of invasive species is debated. Rhymer and Simberloff argue that these types of terms:

...imply either that hybrids are less fit than the parentals, which need not be the case, or that there is an inherent value in "pure" gene pools.[1]

They recommend that gene flow from invasive species be termed genetic mixing since:

"Mixing" need not be value-laden, and we use it here to denote mixing of gene pools whether or not associated with a decline in fitness.[1]

Environmentalists such as Patrick Moore, an ex-member and cofounder of Greenpeace, questions if the term genetic pollution is more political than scientific. The term is considered to arouse emotional feelings towards the subject matter.[8] In an interview he comments:

If you take a term used quite frequently these days, the term "genetic pollution," otherwise referred to as genetic contamination, it is a propaganda term, not a technical or scientific term. Pollution and contamination are both value judgments. By using the word "genetic" it gives the public the impression that they are talking about something scientific or technical--as if there were such a thing as genes that amount to pollution.[2]

Potential sources[edit]

Genetic pollution may come from invasive species, genetically modified organisms, deliberately introduced species, and mutated organisms.

Invasive species[edit]

Conservation biologists and conservationists have, for a number of years, used the term to describe gene flow from domestic, feral, and non-native species into wild indigenous species, which they consider undesirable.[3][9][12] For example, TRAFFIC is the international wildlife trade monitoring network that works to limit trade in wild plants and animals so that it is not a threat to conservationist goals. They promote awareness of the effects of introduced invasive species that may "hybridize with native species, causing genetic pollution".[10] Furthermore, the Joint Nature Conservation Committee, the statutory adviser to the UK government, has stated that invasive species "will alter the genetic pool (a process called genetic pollution), which is an irreversible change."[14] Invasive species can invade both large and small native populations and have a profound effect. Upon invasion, invasive species interbreed with native species to form sterile or more evolutionarily fit hybrids that can outcompete the native populations. Invasive species can cause extinctions of small populations on islands that are particularly vulnerable due to their smaller amounts of genetic diversity. In these populations, local adaptations can be disrupted by the introduction of new genes that may not be as suitable for the small island environments. For example, the Cercocarpus traskiae of the Catalina Island off the coast of California has faced near extinction with only a single population remaining due to the hybridization of its offspring with Cercocarpus betuloides.[15]

Genetic engineering[edit]

In the fields of agriculture, agroforestry and animal husbandry, genetic pollution is being used to describe gene flows between GE species and wild relatives.[13] An early use of the term "genetic pollution" in this later sense appears in a wide-ranging review of the potential ecological effects of genetic engineering in The Ecologist magazine in July 1989. It was also popularized by environmentalist Jeremy Rifkin in his 1998 book The Biotech Century.[16] While intentional crossbreeding between two genetically distinct varieties is described as hybridization with the subsequent introgression of genes, Rifkin, who had played a leading role in the ethical debate for over a decade before, used genetic pollution to describe what he considered to be problems that might occur due the unintentional process of (modernly) genetically modified organisms (GMOs) dispersing their genes into the natural environment by breeding with wild plants or animals.[13][17][18]

Preventative measures[edit]

Since 2005 there has existed a GM Contamination Register, launched for GeneWatch UK and Greenpeace International that records all incidents of intentional or accidental[6][19] release of organisms genetically modified using modern techniques.[7]


Not all genetically engineered organisms cause genetic pollution. Genetic engineering has a variety of uses and is specifically defined as a direct manipulation of the genome of an organism. Genetic pollution can occur in response to the introduction of a species that is not native to a particular environment, and genetically engineered organisms are examples of individuals that could cause genetic pollution following introduction. Due to these risks, studies have been done in order to assess the risks of genetic pollution associated with organisms that have been genetically engineered:

  1. Genetic In a 10-year study of four different crops, none of the genetically engineered plants were found to be more invasive or more persistent than their conventional counterparts.[20] An often cited claimed example of genetic pollution is the reputed discovery of transgenes from GE maize in landraces of maize in Oaxaca, Mexico. The report from Quist and Chapela,[21] has since been discredited on methodological grounds.[22] The scientific journal that originally published the study concluded that "the evidence available is not sufficient to justify the publication of the original paper." [23] More recent attempts to replicate the original studies have concluded that genetically modified corn is absent from southern Mexico in 2003 and 2004.[24]
  2. A 2009 study verified the original findings of the controversial 2001 study, by finding transgenes in about 1% of 2000 samples of wild maize in Oaxaca, Mexico, despite Nature retracting the 2001 study and a second study failing to back up the findings of the initial study. The study found that the transgenes are common in some fields, but non-existent in others, hence explaining why a previous study failed to find them. Furthermore, not every laboratory method managed to find the transgenes.[25]
  3. A 2004 study performed near an Oregon field trial for a genetically modified variety of creeping bentgrass (Agrostis stolonifera) revealed that the transgene and its associate trait (resistance to the glyphosate herbicide) could be transmitted by wind pollination to resident plants of different Agrostis species, up to 14 km from the test field.[26] In 2007, the Scotts Company, producer of the genetically modified bentgrass, agreed to pay a civil penalty of $500,000 to the United States Department of Agriculture (USDA). The USDA alleged that Scotts "failed to conduct a 2003 Oregon field trial in a manner which ensured that neither glyphosate-tolerant creeping bentgrass nor its offspring would persist in the environment".[27]

Introduced species[edit]

Introduced species are species living outside its native range due to the introduction by human beings. The introduction may or may not be intentional. The impact of introduced species is variable and has the potential to cause harm to the native species of its new habitat.

Mutated organisms[edit]

Mutations within organisms can be executed through the process of exposing the organism to chemicals or radiation in order to generate mutations. This has been done in plants in order to create mutants that have a desired trait. These mutants can then be bred with other mutants or individuals that are not mutated in order to maintain the mutant trait. However, similar to the risks associated with introducing individuals to a certain environment, the variation created by mutated individuals could have a negative impact on native populations as well.

See also[edit]


  1. ^ a b c d Rhymer JM and Simberloff, D. (1996) Extinction by Hybridization and Introgression. Annual Review of Ecology and Systematics 27: 83-109 doi:10.1146/annurev.ecolsys.27.1.83
  2. ^ a b What's Wrong with the Environmental Movement: an interview with Patrick Moore By: Competitive Enterprise Institute staff, Environment News 2004 published by The Heartland Institute.[dead link]
  3. ^ a b c ITALY'S WILD DOGS WINNING DARWINIAN BATTLE, By PHILIP M. BOFFEY, Published: December 13, 1983, THE NEW YORK TIMES. Accessed 27 November 2009: "Although wolves and dogs have always lived in close contact in Italy and have presumably mated in the past, the newly worrisome element, in Dr. Boitani's opinion, is the increasing disparity in numbers, which suggests that interbreeding will become fairly common. As a result, genetic pollution of the wolf gene pool might reach irreversible levels, he warned. By hybridization, dogs can easily absorb the wolf genes and destroy the wolf, as it is, he said. The wolf might survive as a more doglike animal, better adapted to living close to people, he said, but it would not be what we today call a wolf."
  4. ^ Norman C. Ellstrand, 2001. "When Transgenes Wander, Should We Worry?" Plant Physiol, Vol.125, pp.1543-1545
  5. ^ a b GE agriculture and genetic pollution web article hosted by
  6. ^ a b "Archived copy". Archived from the original on 2011-06-22. Retrieved 2010-07-08.  ILLEGAL GENETICALLY ENGINEERED CORN FROM MONSANTO DETECTED IN ARGENTINA
  7. ^ a b GM Contamination Register
  8. ^ a b Greenpeace, "Say no to genetic pollution" (n.d.)
  9. ^ a b c Butler D. (1994). Bid to protect wolves from genetic pollution. Nature 370: 497 doi:10.1038/370497a0
  10. ^ a b When is wildlife trade a problem? Archived 2007-12-24 at the Wayback Machine. hosted by, the wildlife trade monitoring network, a joint programme of WWF and IUCN - The World Conservation Union. Accessed on November 25, 2007
    "Invasive species have been a major cause of extinction throughout the world in the past few hundred years. Some of them prey on native wildlife, compete with it for resources, or spread disease, while others may hybridize with native species, causing "genetic pollution". In these ways, invasive species are as big a threat to the balance of nature as the direct overexploitation by humans of some species."
  11. ^ A. Zaid, H.G. Hughes, E. Porceddu, F. Nicholas (2001) Glossary of Biotechnology for Food and Agriculture - A Revised and Augmented Edition of the Glossary of Biotechnology and Genetic Engineering. A FAO Research and Technology Paper, available in 9 languages. ISSN 1020-0541. Food and Agriculture Organization of the United Nations. ISBN 92-5-104683-2. Accessed on October 7, 2011 Archived October 26, 2007, at the Wayback Machine.
  12. ^ a b Potts B. M., Barbour R. C., Hingston A. B., Vaillancourt R. E. (2003) Corrigendum to: TURNER REVIEW No. 6 Genetic pollution of native eucalypt gene pools—identifying the risks. Australian Journal of Botany 51, 333–333. doi:10.1071/BT02035_CO
  13. ^ a b c Gene flow from GM to non-GM populations in the crop, forestry, animal and fishery sectors, Background document to Conference 7: May 31 - July 6, 2002; Electronic Forum on Biotechnology in Food and Agriculture, Food and Agriculture Organization of the United Nations (FAO)
  14. ^ Effects of the introduction of invasive/non-native species - Joint Nature Conservation Committee (JNCC), a statutory adviser to Government on UK and international nature conservation. Accessed on November 25, 2007.
    "Occasionally non-native species can reproduce with native species and produce hybrids, which will alter the genetic pool (a process called genetic pollution), which is an irreversible change."
  15. ^ Levin, Donald A.; Francisco-Ortega, Javier; Jansen, Robert K. (1996-02-01). "Hybridization and the Extinction of Rare Plant Species". Conservation Biology. 10 (1): 10–16. doi:10.1046/j.1523-1739.1996.10010010.x. ISSN 1523-1739. 
  16. ^ Jeremy Rifkin (1998) The Biotech Century: Harnessing the Gene and Remaking the World, published by J P Tarcher, ISBN 0-87477-909-X
  17. ^ Michael Quinion "Genetic Pollution" – World Wide Words
  18. ^ Amy Otchet (1998) Jeremy Rifkin: fears of a brave new world an interview hosted by The United Nations Educational, Scientific and Cultural Organization (UNESCO)
    Will wars be fought for the control of genes in the 21st century? Jeremy Rifkin fears the worst and explains why
  19. ^ Brazil – Illegal Roundup Ready cotton grown on 16,000 hectares
  20. ^ M. J. Crawley et al., Nature 409 682-3 2001
  21. ^ Quist, David; Chapela, IH (2001). "Transgenic DNA introgressed into traditional maize landraces in Oaxaca, Mexico". Nature. 414 (6863): 541–543. doi:10.1038/35107068. PMID 11734853. 
  22. ^ Christou, Paul (2002). "No Credible Scientific Evidence is Presented to Support Claims that Transgenic DNA was Introgressed into Traditional Maize Landraces in Oaxaca, Mexico". Transgenic Research. 11 (1): 3–5. doi:10.1023/A:1013903300469. 
  23. ^ Metz, Matthew; Fütterer, J (2002). "Biodiversity (Communications arising): Suspect evidence of transgenic contamination". Nature. 416 (6881): 600–601. doi:10.1038/nature738. PMID 11935144. Archived from the original (– Scholar search) on October 31, 2008. 
  24. ^ S. Ortiz-Garcı´a et al. 2005, Absence of detectable transgenes in local landraces of maize in Oaxaca, Mexico (2003–2004) Proceedings of the National Academy of Sciences 102:p12338-12343 [1]
  25. ^
  26. ^ L. Watrud et al. 2004, "Evidence for landscape-level, pollen-mediated gene flow from genetically modified creeping bentgrass with CP4 EPSPS as a marker", Proceedings of the National Academy of Sciences 101, p.14533.
  27. ^ "USDA Concludes Genetically Engineered Creeping Bentgrass Investigation".