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]


Invasive species

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][11] 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] The Joint Nature Conservation Committee (JNCC) is the statutory adviser to the Government of United Kingdom and international nature conservation. Its work contributes to maintaining and enriching biological diversity and educating about the effects of the introduction of invasive/non-native species. In this context they have advised that invasive species:

"will alter the genetic pool (a process called genetic pollution), which is an irreversible change."[13]

A classic example of an introduced species creating issues revolving around genetic pollution is the Mallard (A. Platyrhyncos), which is able to breed with other duck species and create fertile hybrids, introducing unwanted genes into the populations of other wild ducks.

Genetic engineering

In the fields of agriculture, agroforestry and animal husbandry, genetic pollution is being used to describe gene flows between GE species and wild relatives.[12] 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.[14] 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.[12][15][16]

The usage of genetic pollution by the Food and Agriculture Organization of the United Nations (FAO) is currently defined as:

"Uncontrolled spread of genetic information (frequently referring to transgenes) into the genomes of organisms in which such genes are not present in nature."[17]

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][18] release of organisms genetically modified using modern techniques.[7]

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.[19] 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,[20] has since been discredited on methodological grounds.[21] The scientific journal that originally published the study concluded that "the evidence available is not sufficient to justify the publication of the original paper." [22] More recent attempts to replicate the original studies have concluded that genetically modified corn is absent from southern Mexico in 2003 and 2004.[23]

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.[24]

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.[25] 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".[26]

Controversial term

Whether genetic pollution or similar terms, 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]

See also


  1. 1.0 1.1 1.2 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. 2.0 2.1 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. 3.0 3.1 3.2 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. 5.0 5.1 GE agriculture and genetic pollution web article hosted by
  7. 7.0 7.1 GM Contamination Register
  8. 8.0 8.1 Greenpeace, "Say no to genetic pollution" (n.d.)
  9. 9.0 9.1 9.2 Butler D. (1994). Bid to protect wolves from genetic pollution. Nature 370: 497 doi:10.1038/370497a0
  10. 10.0 10.1 When is wildlife trade a problem? 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. 11.0 11.1 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
  12. 12.0 12.1 12.2 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)
  13. 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."
  14. Jeremy Rifkin (1998) The Biotech Century: Harnessing the Gene and Remaking the World, published by J P Tarcher, ISBN 0-87477-909-X
  15. Michael Quinion "Genetic Pollution" – World Wide Words
  16. 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
  17. 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
  18. Brazil – Illegal Roundup Ready cotton grown on 16,000 hectares
  19. M. J. Crawley et al., Nature 409 682-3 2001
  20. 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.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  21. 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.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  22. 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 24, 2006. Unknown parameter |deadurl= ignored (help)<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  23. 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. 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.
  26. "USDA Concludes Genetically Engineered Creeping Bentgrass Investigation".<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>