Genetic engineering hazards unveiled

Genetic engineering hazards unveiled

The First Meeting of the Parties to the Cartagena Protocol on Biosafety is tasked with building an international biosafety system, including a liability and redress regime. Lim Li Ching highlights evidence of hazards that can throw light on the way forward.

GENETIC engineering (GE) splices together the genetic material or DNA of different organisms and inserts these into genomes of organisms to make ‘genetically modified organisms’ (GMOs). The process creates completely new genes with new functions, and new combinations of genes, which could interact with the organisms’ own genes in unpredictable ways.

Insertion into the genome is random; depending on where the insert lands, it will have different, unpredictable effects on the host genes and genome. GE allows the transfer of genetic material between species that would never inter-breed in nature. New genes and gene products – many from bacteria, viruses and non-food species – are created which we have never eaten before, nor have they been in our food chain.

There is still no scientific consensus on the safety of GMOs. Despite this, GE crops are already released on a large scale and biomedical applications are increasing. GMOs are also being released for industrial use and environmental remediation, with even less public knowledge. In the last few years there has been increasing evidence of ecological and health hazards and risks, as well as adverse impacts on farmers, some of which are highlighted here.

GE bacteria affect soil biota and cause plant death

Research published in 1999 [1] illustrated how the environmental release of GE microorganisms might cause widespread ecological damage.

When a GE strain of Klebsiella planticola bacteria was added to microcosms with sandy soil and wheat plants, the numbers of bacterial and fungal feeding nematodes increased significantly, and the plants died. When the parental, non-GE strain was added, only bacterial feeding nematodes increased, but the plants did not die. The introduction of either strain to soil without plants did not alter the nematode community.

K. planticola is a common lactose-fermenting soil bacterium. The GE bacteria were engineered to produce increased ethanol concentrations in fermentors that convert agricultural wastes to ethanol. Fermentation residues, including the GE bacteria, were proposed for use as a soil amendment.

The study provided evidence that the GE bacteria could persist under conditions found in some soil ecosystems, and for long enough to stimulate changes in soil biota that could affect plant growth and nutrient cycling processes. While it is unclear to what extent these observations occur in situ, the finding that the GE bacteria cause plant death raised the possibility that this soil amendment could kill crops in the fields if it was used.

GE potatoes adversely affect rats

Research by senior scientists showed that GE potatoes expressing a snowdrop lectin (GNA) – to confer nematode and insect resistance – caused growth factor like effects in the small intestine of rats. Growth factors are proteins that promote cell growth and multiplication that, if uncontrolled, result in cancer.

Part of the research was published in the medical journal Lancet [2], and showed that crypt length in the jejunum (the first part of the bowel) of rats fed with raw GE potatoes was significantly greater than in those fed with parent (non-GE) potatoes or non-GE potatoes supplemented with GNA. This impact was attributed to the transformation of the potato with the GNA gene, since the jejunum was stimulated only by GE potatoes but not by dietary GNA. The scientists proposed that the unexpected proliferative effect was caused by either the expression of other genes in the construct, or by some form of positioning effect in the potato genome caused by the GNA gene insertion.

Other results have not been published yet, but are referred to briefly in a review [3], which together appears to confirm that the GE potatoes acted as a growth factor leading to hyperplasia of the small bowel lining. (Hyperplasia is enlargement of an organ or tissue due to increased reproduction rate of its cells, often as an initial stage in the development of cancer.) In addition to increased crypt length, the number of cells in the crypt and the mitotic rate, i.e. the number of cells actually dividing, had also increased in the jejunum of rats fed with GE potatoes. Furthermore, the number of lymphocytes (white blood cells that produce antibodies) within the epithelium increased significantly in rats fed with GE potatoes, showing an immune effect.

As these changes are attributed to the transgenic process or the transgenic construct, rather than the transgenic product, this may be indicative of a safety concern for all GE foods. Since this study was terminated, there have been some independent studies started on feeding trials.

Bt toxin ‘as potent as cholera toxin’

Bt toxins are a large class of Cry proteins found in the soil bacterium Bacillus thuringiensis (Bt), which have been heavily exploited as ‘biopesticides’ in GE crops, on the untested assumption that they are safe for species other than the target insect pests.

However, researchers from the Center for Genetic Engineering and Biotechnology, Cuba, reported in 1999 that recombinant Cry1Ac protoxin is a powerful immunogen (able to produce an immune response) [4], and when fed to mice, induced antibody responses similar to those obtained with the cholera toxin [5]. In 2000, the Cuban researchers teamed up with scientists from the Autonomous University of Mexico and showed that Cry1Ac actively binds to the inner surface of the mouse small intestine [6], especially to the ‘brush border’ membranes on the side of the cells that line the small intestine. This contests the often-heard argument that Cry proteins don’t affect mammals since they supposedly do not have receptors that bind the truncated toxin in the gut.

StarLink maize contaminates food supply

StarLink maize, developed by Aventis, was approved by the US Environmental Protection Agency (EPA) for animal feed and not for human consumption as it contains the Bt toxin Cry9C, a potential allergen. In September 2000, an independent scientific laboratory found traces of Cry9C in samples of taco shells sold in US supermarkets.

Subsequently, Cry9C was found in maize grain and other maize products in the food supply. More than 300 brands of food products were recalled from supermarkets and restaurants throughout the US. Despite the EPA restrictions, StarLink had found its way into the food supply, probably via mixing with other varieties during harvest, storage, handling and distribution, and cross-pollination of nearby maize.

Some people complained about allergic reactions after eating maize products allegedly containing StarLink. While Aventis claimed that Cry9C protein and DNA are neither toxic nor allergenic and therefore safe for human consumption, the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP), which reviewed scientific information concerning the allergenic potential of Cry9C, concluded in December 2000 [7], and again in July 2001 [8], that there is a “medium likelihood” that the Cry9C protein is a potential allergen.

Aventis voluntarily cancelled their registration for StarLink in October 2000; hence it is no longer authorized for planting. Yet, traces of StarLink remain in the maize supply, with US Department of Agriculture (USDA) records showing it in more than 1% of samples submitted by growers and grain handlers over 2003 [9].

The contamination by StarLink, less than 1% of the 2000 US maize acreage, caused major disruption to domestic and export markets [10], with economic repercussions. USDA and Aventis agreed on a buy-back programme, offering farmers 25 cents a bushel over the market price, to divert contaminated maize into the animal feed and non-food markets. USDA also bought back maize seed from seed companies, at an estimated cost of $13 million. The total cost to Aventis so far is about $1 billion, and the legal consequences continue – Aventis agreed in 2003 to pay $110 million to settle claims from maize growers who didn’t grow StarLink but were hurt by the declining market for US maize because of the contamination.

Lethal GE mousepox virus accidentally created

Australian researchers, by genetically engineering a relatively harmless mousepox virus, accidentally created a killer virus that wiped out all its mouse victims [11].

The researchers had inserted a gene for interleukin-4 (which occurs naturally in the body) into a mousepox virus to boost antibody production, to create a mouse contraceptive vaccine for pest control. Very unexpectedly, the inserted gene totally suppressed the immune system of the mice. Mousepox normally causes only mild symptoms, but with the IL-4 gene added, it killed all the animals in nine days. To make matters worse, the GE virus also appeared unnaturally resistant to vaccination.

The modified mousepox does not affect humans, but it is closely related to smallpox, raising fears that genetic engineering could be used in biological warfare. One of the researchers, commenting on why they decided to publish the results, said, ‘We wanted to warn the general population that this potentially dangerous technology is available,’ and ‘We wanted to make it clear to the scientific community that they should be careful, that it is not too difficult to create severe organisms.’
Other questions arise from the unexpected effects of genetic engineering, such as, could the use of viruses to transport genes into the body in vaccines inadvertently create lethal human viruses?

Monsanto successfully sues farmer for patent infringement

In 1998, biotech giant Monsanto launched a lawsuit against Canadian farmer Percy Schmeiser, accusing him of alleged infringement of their patent on Roundup Ready canola, genetically engineered to be tolerant to glyphosate herbicides, including Roundup.

Monsanto alleged that Schmeiser planted and reproduced canola seeds and plants containing genes and cells claimed in its patent, and sold the harvest, without consent or licence. Schmeiser, a seed developer and seed saver for many years, denies the allegations and claims instead that he merely planted his fields with seed saved from the previous year, and that his crops were contaminated by transgenes.

Judge Andrew MacKay ruled in favour of Monsanto in March 2001 [12], setting a legal precedent that places patent rights above farmers’ rights to save and reuse seed. MacKay said that Schmeiser had in 1998, planted without licence, canola fields with seed saved from the 1997 crop, which ‘he knew, or ought to have known’, was Roundup tolerant. The crop, when tested, did contain the gene and cells claimed under Monsanto’s patent. But the judge said, ‘The source of the Roundup resistant canola… is really not significant for the resolution of the issue of infringement…’

A farmer whose field contains seed or plants originating from seed spilled or blown into them, in swaths from a neighbour’s land or even from germination by pollen carried from elsewhere by insects, birds or wind does not have the right to use the patented gene, or the seed or plant it is in, MacKay said. Even though Schmeiser did not use the patented seed because he didn’t spray the crop with Roundup, and hence could not have benefited, this was ruled immaterial.

The implication is clear; if any plants are contaminated by transgenes (a likely scenario for most and almost inevitable for canola, which has high out-crossing rates and pollen that can travel long distances), then farmers would be infringing patents if they used, saved seed, or sold the crop without a licence. No matter how the proprietary genes got there, the judge held that the farmer, rather than the company, is accountable, and they are obliged to inform Monsanto – or risk Schmeiser’s fate. He was ordered to pay Monsanto its court costs and the profit from his 1998 canola crop, amounting to nearly Canadian $175,000. Schmeiser appealed, but all three Appeal Court judges ruled against him in May 2002. The Supreme Court will now hear his case in January 2004, which is in essence a fight for farmers’ rights and a rejection of patents on living organisms.

Transgenes contaminate farmers’ varieties of Mexican maize

In November 2001, scientists from the University of California, Berkeley, reported finding transgenes in farmers’ varieties or landraces of maize in remote areas of Mexico [13], despite a moratorium on growing GE maize in the country.

The finding, reported in Nature, is of great concern, as Mexico is the centre of origin and diversity for maize. One consequence could be the destabilisation of the landraces’ genomes, and the potential for their extinction, threatening food security. Maize is also central to the cultures of Mexicans, particularly the indigenous peoples.

The research attracted criticisms, leading Nature to subsequently say, ‘the evidence available is not sufficient to justify the publication of the original paper’, unprecedented for a paper not proved wrong or fraudulent. Nonetheless, as the Nature editors themselves point out, the paper has not been retracted, and stands as a citable scientific publication. The critics weren’t contesting that transgenic contamination and introgression into local varieties had occurred. In fact, the researchers presented new data [14] firming up this conclusion, and subsequent research by Mexican government scientists confirmed these findings [15].

The main criticisms were on the researchers’ secondary statement of transgene fragmentation after integration with local maize varieties. Apart from contamination with the cauliflower mosaic virus (CaMV) 35S promoter that is in most GE crops, the researchers reported that the promoter in the landraces’ genomes was linked to various other DNA sequences, not to the original transgenes, as though it had broken off and joined up at random. That may not be unexpected, in view of the ‘recombination hotspot’ – a site prone to break and rejoin – associated with the CaMV 35S promoter [16]. The recombination hotspot suggests that transgenic constructs with the promoter may be structurally unstable and prone to horizontal gene transfer and recombination.

Last October, indigenous and farming communities in Oaxaca, Puebla, Chihuahua and Veracruz, together with civil society groups, released the results of their own studies [17]. Contamination has been found in maize fields of 33 communities in nine Mexican states. The organisations were especially alarmed to find traces of the insecticidal toxin (Cry9C), the engineered trait found in StarLink maize, the GE maize prohibited for human consumption in the US but which had entered the food supply. They reported that some plants had the presence of two, three and four different GE genes.

Horizontal gene transfer of transgenic DNA into human gut bacteria

Horizontal gene transfer is the direct transfer of genetic material to cells or genomes belonging to unrelated species, by processes other than reproduction.

To overcome natural species barriers, genetic engineers make artificial vectors to carry genes, by combining parts of infectious natural vectors – viruses, plasmids (pieces of usually circular genetic material that can be indefinitely maintained in the cell separately from the genome) and transposons (blocks of genetic material that can jump in and out of genomes) – from different sources. Transgenic DNA, designed to cross species barriers and invade genomes, could enhance horizontal gene transfer [18].

Research by Newcastle University scientists in 2002, funded by the UK government, showed that transgenic DNA could transfer to human gut bacteria [19]. Seven human ileostomists (with colostomy bags) were fed one meal containing GE soya. Whilst the amount of transgene that survived passage from the small bowel was highly variable between subjects, it was detected in all seven subjects. In one individual, as much as 3.7% of the transgenic DNA was recovered.

To see if horizontal gene transfer had occurred, microbes in the ileal digesta samples were cultured through broth containing glyphosate. Bacterial samples from three subjects showed up the transgene, which was confirmed by the researchers as having originated from the GE soya.
Transgenic DNA typically contains genetic material from bacteria and viruses, and antibiotic resistance marker genes. Because the transgenic constructs used in genetic engineering are chimerical (comprising a mixture of genetic material), they have sequence homologies (similarities) to DNA from viral pathogens, plasmids and transposons of multiple species, which could facilitate horizontal gene transfer and recombination.

Horizontal gene transfer of transgenic DNA could potentially create new disease-causing viruses and bacteria and spread antibiotic resistance genes to pathogenic bacteria, making infections harder to treat.

Pharmaceuticals in crops threaten contamination of food supply

In November 2002, the US government quarantined 500,000 bushels of soybeans that were contaminated with GE maize engineered to produce a drug not approved for human consumption, in this case, a pig vaccine [20].

The GE maize was being field tested by ProdiGene, a Texan biotech company, in Nebraska in 2001. Ordinary soybeans were planted in the same field in 2002. Maize seeds from the year before sprouted into plants containing the protein. The company failed to remove those plants before they set seed. The GE maize contaminated the soybean harvest, 500 bushels of which were then mixed into 500,000 bushels, compromising the whole lot.

USDA imposed more than $3 million in penalties on ProdiGene’s contaminated soybeans, and fined the company $250,000. ProdiGene had to pay for the 500,000 bushels of contaminated soybeans (valued at $2.8 million), the cost to destroy them and the costs of cleaning the storage facility where the soybeans were held. It was also required to post a $1 million bond to pay for any future problems resulting from its products.

The government also disclosed that ProdiGene was involved in a similar incident in September that same year [21]. Fearing that pollen from similar GE ‘pharm’ maize may have spread to nearby fields of ordinary maize, USDA ordered that 155 acres of maize in Iowa be uprooted and incinerated.

‘Pharm’ crops should be banned from open fields, as they could contaminate the food supply, with adverse consequences. Some contain potentially dangerous genes, e.g. the glycoprotein gene gp120 of the AIDS virus HIV-1 has been incorporated into GE maize by ProdiGene, which is trying to develop an edible AIDS vaccine [22]. Evidence suggests that gp120 can interfere with the immune system, and could recombine with viral and bacterial vectors to generate new pathogens.

Bt cotton performs poorly in India

Bt cotton was commercially planted for the first time in India in 2002. Reports from various sources, including state governments, academic researchers, NGOs and farmers’ organisations indicated that, in many areas, Bt cotton performed poorly, and at times failed completely.

There were reports of failure to germinate, damage in drought conditions, susceptibility to root-rot and leaf curl virus, increase in non-target pests, and attacks by bollworms, to which the Bt cotton was supposed to be resistant. Farmers experienced economic losses due to the higher price of Bt cottonseed, little savings in pesticide use and lower yields.

The Andhra Pradesh state government was quoted as saying that farmers weren’t getting the yields they were promised and that the poor quality of the crop commanded a lower market price [23]. It pledged to compensate farmers. A six-member panel set up by the Gujarat state government under the Joint Director of Agriculture (Oilseeds) to evaluate the performance of Bt cotton said that ‘it is unfit for cultivation and should be banned in the State’ [24]. The Parliamentary Standing Committee on Agriculture is reported to have said: ‘The risk of reducing biodiversity and other environmental hazards does not make the sowing of Bt cotton a sensible proposition’ [24].

UK Farm Scale Evaluations find adverse impacts on biodiversity

The results of three-year Farm Scale Evaluations (FSEs) commissioned by the UK government were published in October 2003 [25]. The FSEs examined spring-sown oilseed rape (canola), beet and maize, documenting the impact of managing these herbicide-tolerant (HT) crops on farmland biodiversity. They were the largest experiments of their kind, involving over 200 plots. The GE beet was tolerant to glyphosate, the GE maize and oilseed rape to glufosinate ammonium. Farmers could spray indiscriminately with the herbicides, killing weeds, but not the crop.

Weeds are, however, important for biodiversity, providing food and habitat for countless animal species, including many soil invertebrates crucial for controlling pests or recycling nutrients. Aerial invertebrates such as bees and butterflies play important roles in pollination and recycling detritus; many depend on flowering weeds for nectar or pollen, or have larvae that feed directly on plants. Birds are also dependent on weed seeds and invertebrates, but farmland bird numbers have declined over the past 30 years, partly due to intensive agricultural practices that suppress weeds.
Overall, the FSEs showed that HT oilseed rape and beet would reduce farmland biodiversity, as the stronger broad-spectrum herbicides used with GE crops control a wider range of weeds more efficiently. There was a decreased abundance and availability of weeds and weed seeds in the fields and field margins, and consequently a reduction of some soil invertebrates, bees and butterflies.

There were fewer herbivores, pollinators and natural enemies, but more detritivores (animals which feed on dead organic material), affecting food webs. The reduction in pollinators may influence seed production of insect-pollinated weeds, amplifying the direct effects of herbicides on weeds.

The effect of growing HT maize seemed positive, with more weeds and invertebrates recorded. However, in commercial use, GE maize is generally sprayed with at least two herbicides to give adequate weed control, but only one was used in the FSEs. And the GE maize was compared with non-GE maize that was largely sprayed with a herbicide (azatrine) since banned by the European Union. The maize FSEs are thus flawed, as they don’t reflect the real conditions under which the crops will be grown.

US experience shows increased pesticide use with GE crops

Recent research concludes that the 550 million acres of GE maize, soybeans and cotton planted in the US since 1996 has increased pesticide use [26].
This is the first comprehensive study of the impact of all major GE crops on pesticide use in the US over the first eight years of commercial use, 1996-2003. Official USDA data on pesticide use were used to calculate the overall impact of herbicide tolerant (HT) maize, soybeans and cotton, and Bt maize and cotton.

While Bt maize and cotton reduced insecticide use by 2-2.5 million pounds annually, the increase in herbicide use on HT crops far exceeds these modest reductions, especially since 2001. Over the last eight years, HT crops have increased pesticide use an estimated 70.2 million pounds, while Bt varieties have reduced pesticide use by about 19.6 million pounds. Thus, total pesticide use has risen by some 50.6 million pounds.

The increase in pesticide use, largely due to increased use in HT crops, especially HT soybean, can be traced to heavy reliance on HT crops and a single herbicide (glyphosate) for weed management. This has led to shifts toward tougher-to-control weeds, and the emergence of genetic resistance in certain weed populations, forcing many farmers to spray more herbicides on GE acres to obtain adequate weed control. Glyphosate-resistant marestail in HT soybeans first appeared in the US in 2000, and has also been identified in HT cotton [27].

Other research has shown that GE crops themselves could become resistant to the herbicides used with them, creating serious problems with volunteers (plants germinated from seeds of a previous crop planted in the same field, which then become weeds) and necessitating further herbicide use. Canadian scientists documented rapid evolution of multiple-herbicide resistant GE canola, which combined the single-herbicide tolerant traits created by different companies, as a result of pollen flow over significant distances [28].

Furthermore, scientists confirmed in 2002 that transgenes could migrate from Bt sunflowers to nearby wild sunflowers, possibly making the resulting hybrids stronger and more resistant to chemicals, as they had 50% more seeds than controls without the gene, and were physically fit, even under drought conditions [29].

Research at the University of North Carolina showed that crosses between Bt canola and a related weed, birdseed rape, produced hybrids that are as insect-resistant, which could make weed control difficult [30].

All these incidents highlight that a precautionary approach and strict biosafety regulations are certainly warranted. The precautionary principle is reaffirmed in the Cartagena Protocol on Biosafety, the major international law governing GMOs. In particular, Article 10(6) asserts that in the absence of scientific certainty, a Party can restrict or ban the import of GMOs in order to avoid or minimise the potential adverse effects on biodiversity and human health.
The history of the Protocol is paved with warnings, the question is, are we listening? u

Lim Li Ching is a researcher with Third World Network and the Institute of Science in Society.


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