Genetic pollution is undesirable gene flow into wild populations. The term is usually associated with the gene flow from a genetically engineered (GE) organism (or genetically modifed organism - GMO) to a non GE organism;^[1][2] however, conservation biologists sometimes use it to describe gene flow from a domestic, feral, non-native or invasive species to a wild population.^[3][4] Use of the term is however controversial, many scientists saying that it is a meaningless concept.

Genetic engineering

The term genetic pollution was popularized by environmentalist Jeremy Rifkin in his 1998 book The Biotech Century.^[5] While intentional crossbreeding between two genetically distinct varieties is described as hybridization with the subsequent introgression of genes, Rifkin used genetic pollution to describe the risks that might occur due the unintentional process of genetically modified organisms (GMOs) dispersing their genes into the natural environment by breeding with wild plants or animals.^[1][6][7]

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.?^[8]

In a 10 years study of four different crops, none of the genetically modified plants were found to be more invasive or more persistent than their conventional counterparts.^[9] An often cited 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, ^[10] has since been discredited on methodological grounds. ^[11] The scientific journal that originally published the study concluded that "the evidence available is not sufficient to justify the publication of the original paper." ^[12] More recent attempts to replicate the original studies have concluded that genetically modified corn is absent from southern Mexico in 2003 and 2004. ^[13]

A 2004 study performed near a 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.^[14] 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".^[15]

Invasive species

While in the field of agriculture, agroforestry and animal husbandry genetic pollution is being used to describe the undesirable gene flow between GE species and wild relatives;^[1] some conservationists are using the term to describe the undesirable gene flow from domestic, feral, non-native and invasive species into indigenous species.^[3][4] For example, TRAFFIC is the international wildlife trade monitoring network which works to ensure that trade in wild plants and animals is not a threat to the conservation of nature. They promote the awareness of the harmful effects of introduced invasive species that may "hybridize with native species, causing genetic pollution".^[16] 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 harmful 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.?^[17]

?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.?

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. Hymer 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". ^[18]

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". ^[18]

Even environmentalists such as Patrick Moore, an ex-member and cofounder of Greenpeace, questions if the term genetic pollution is more political than scientific. 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."^[19]

See also

• Biodiversity
• Conservation biology
• Eugenics
• Gene pool
• Genetic erosion

References