Special Safety Concerns of LMOs

This paper was presented at the Risk Assessment/Risk Management and Information Management on Biosafety Regional Workshop, Limbe, Cameroon, 9-11 August 1999. The workshop was organised by the Ministry of the Environment and Forestry, Cameroon.

by Mae-Wan Ho

Contained use versus release to the environment

For biosafety purposes, it is customary to distinguish between contained uses of LMOs [Living Modified Organisms] and their releases to the environment. Contained uses occur inside a physical facility designed to prevent escape into the open environment. It can be controlled in principle, and made as safe as possible, though the current regulation of contained use is far from adequate.1 Within the past ten years, geneticists have discovered that the genetic material - DNA or RNA - not only persists long after the organism is killed, but is capable of being taken up and incorporated into unrelated organisms. This possibility of horizontal gene transfer puts a whole new complexion on risk assessment and risk management.

Releases of LMOs to the environment consist of all uses that occur outside a physical facility. Apart from commercial releases and open field trials, they should also include caged transgenic organisms placed in open water, gene therapy and vaccinations2 and transgenic wastes disposed into the environment. All of these are capable of spreading transgenic DNA by horizontal gene transfer. Released LMOs and transgenic DNA cannot be controlled nor recalled, which is why great care must be taken in advance of release.

Some examples of contained uses and environmental releases are listed in Tables 1 and 2 respectively. As can be seen, most industrial processes entail both contained

Table 1. Contained uses of LMOs

 Genetically modified micro-organisms to produce pharmaceuticals and enzymes
 Genetically modified livestock to produce pharmaceuticals or industrial chemicals
 Genetically modified livestock destined for environmental release
 Production of new vectors for manipulating and transferring genes
 Transformation of plant tissues to create transgenic plants destined for environmental release
 Production of new vaccines destined for environmental release
 Research in cancer genes (oncogenes)
 Genetically modified cell lines
 Gene cloning, including amplifications with PCR
 Gene therapy research
 Transgenic laboratory animals for research such as mice, fruitflies, fish and flatworms
 Production of transgenic microorganisms, including pathogens, in research
 Production of trangenic viruses, including pathogens, in research
 Biological warfare research

Table 2. Environmental releases

 All commercial plantings
 All marketing of LMOs and products thereof
 All field-trials
 All caged aquatic LMOs (fish, shellfish, etc.) placed in open water
 Gene therapies
 Escapes from contained uses
 Waste products from contained uses (air, water and solids)

use and environmental release (deliberate or otherwise), and the legislation must take that into account. In the rest of my paper, I shall concentrate on environmental releases of transgenic crops, though many of the hazards involved are inherent to the technology and are shared by other uses such as the construction of transgenic animals, transgenic microorganisms, gene therapy, and recombinant DNA vaccines. The most immediate hazards of environmental releases are those associated with transgenic crops, but escapes and wastes from contained uses may pose greater threats to health and biodiversity simply because the LMOs involved are often more dangerous.

Genetic engineering biotechnology is new and raises special safety concerns3

Genetic engineering biotechnology is an industry built on a set of techniques for cutting, joining, modifying, and replicating genes, and, most of all, for transferring genes from one species to another, bypassing reproduction, so genes can be transferred between species that would never interbreed in nature. Thus, human genes are transferred to pig, sheep, cattle, mouse, fish, plants and bacteria. And genes of all species can be recombined, cloned and modified in any and every way.

Genetically engineering organisms is a new departure from conventional techniques such as selective breeding, mutagenesis (induction of gene mutations by chemical or physical means such as X-rays), cell fusion and tissue culture. It raises safety concerns different in kind from those of conventional techniques, and which are inherent to the processes used.

Typically, genes of one or more donor-species are isolated, and spliced into artificially constructed infectious agents, which act as vectors to carry the genes into the cells of recipient species.4 Once inside a cell, the vector carrying the genes will insert into the cell's genome. A transgenic organism is regenerated from each transformed cell (or egg, in the case of animals) which has taken up the foreign genes. And from that organism, a transgenic variety can be bred. So-called 'vectorless' genes transfers are done with physical methods such as 'bioballistic' bombardment of cells with gold or tungsten particles coated with the foreign DNA. The foreign DNA will be in the form of 'expression cassettes' each consisting of a genetic signal for gene expression, a promoter/enhancer, which is linked to the gene to be expressed. Several cassettes are often linked in tandem.

The artificial vectors for transferring genes are made by joining together parts of the genetic material of natural viruses that cause diseases and other genetic parasites, plasmids (pieces of usually circular DNA found in bacteria and yeasts, replicating independently of the chromosome(s)) and transposons (mobile genetic elements, or 'jumping genes' found in all species). The genetic parasites carry genes for antibiotic and drug resistances, as well as genes associated with diseases. Most, if not all of the disease-causing genes will have been removed from the artificial vectors, but antibiotic resistance genes are often left in as 'selectable markers', so those cells which have taken up the foreign genes can be selected with antibiotics. While natural genetic parasites are limited by species barriers to varying degrees, the artificial vectors made by genetic engineers are especially designed to cross species barriers and to overcome mechanisms in the cell that destroy or inactivate foreign DNA. Artificial vectors facilitate horizontal gene transfer and must be strictly contained in laboratories (see Table 3).5

Table 3. Artificial vectors facilitate horizontal gene transfer

 They are derived from elements that mediate horizontal gene transfer most effectively.

 Their chimaeric nature means that they possess sequence homologies to DNA from widely different species and their viral pathogens, plasmids and transposons, thus facilitating successful horizontal transfer and recombination.

 They contain antibiotic resistance marker genes enhancing their successful transfer in the presence of antibiotics, either intentionally applied or present as pollutants in the environment.

 They often have origins of replication and transfer sequences, all of which facilitate horizontal gene transfer and recombination. In this context, the fact that they are 'crippled', so that genes for mobility and/or virulence are removed, is irrelevant. That is because 'helper' functions can be supplied by other viruses, plasmids and mobile genetic elements present in the donor, recipient or a third strain of bacteria. And virulence genes can be regained by recombination.

 It is well-known that chimaeric plasmids and viral vectors are subject to structural instabilities which make them more prone to recombine.6 Vector instability is a continuing problem for genetic engineers and the biotech industry as far as the stability of the transferred genes is concerned. It also increases the probability and scope for unintended, secondary horizontal gene transfer, which has already been directly demonstrated.

 The now routine incorporation of strong promoters and enhancers in vectors to boost expression of transgenes is one main cause of structural instability, which is in addition to the instability arising from the attendant metabolic stress to the organism, that again, may increase unintended horizontal gene transfer.

 Vectors are designed to escape restriction - being broken down by restriction enzymes - thereby also enhancing the probability of successful horizontal gene transfer.

The promoters/enhancers introduced with the foreign genes are generally those that make the genes express at very high levels continuously, effectively placing those genes outside the normal metabolic regulation of the cell, and of the transgenic organism resulting from the transformed cell. The most common promoter used in plants is from the cauliflower mosaic virus (CaMV). Promoters used in animals are from a wide range of animal viruses such as the SV40 from monkeys, Rous Sarcoma Virus from chickens, the mouse Murine Mammary Tumour Virus and Murine Leukemia Virus, and Adenovirus and Cytomegalovirus from humans.7 Thus, the gene constructs are novel, in the sense that they have never existed, and are made in every case by joining a promoter of a pathogenic virus to a gene from an organism.

There are four special safety concerns arising from current technologies:
1. Effects due to the exotic genes and gene products introduced into the transgenic organisms.
2. Unintended, unexpected effects of random gene insertion and interaction between foreign genes and host genes in the transgenic organisms.
3. Effects associated with the nature of the gene-constructs inserted into the transgenic organisms.
4. Effects of gene flow, especially horizontal spread of genes and gene-constructs to unrelated species.

It is important to have biosafety legislation that address all those concerns.

Safety concerns of exotic genes

The exotic genes introduced into transgenic crops are often from bacteria and non-food species, and their expression is greatly amplified by strong viral promoters/enhancers. In practice, that means all species interacting with the crop-plants - from decomposers and earthworms in the soil to insects, small mammals, birds and human beings - will be exposed to large quantities of proteins new to their physiology. Adverse reactions may occur in all species, including immunological or allergic responses. Safety testing is therefore paramount for all transgenic crops, and those used as animal feed or for human consumption must be tested as stringently as new drugs. In addition, impacts on biodiversity must also be assessed. Unfortunately, neither has been done for the transgenic crops that are already on the market; and problems are only now emerging.

Herbicide-tolerant and insecticidal transgenic plants now account for 71% and 28% respectively of all transgenic crops in the world, with the remaining 1% carrying both traits.8 These traits are associated with genes isolated from soil bacteria. The insecticidal bt-toxins, isolated from Bacillus thuringiensis, are often engineered into plants in a pre-activated form, and are already known to be harmful to bees directly, and to lacewings further up the food-chain. Recently, bt-maize pollen was found kill 44% of the larvae of monarch butterflies compared with 0% mortality with non-transgenic pollen.9 Another insecticide, the snowdrop lectin, engineered into potato, was found to be toxic to ladybirds fed on aphids that have eaten the transgenic potato.10

Because the bt-toxin genes are expressed continuously at high levels throughout the growing season, insect pests have already become resistant barely a few years after the transgenic crops were first released, so other pesticides have to be used.11 This also deprived organic farmers of a biological pest control in the form of occasional sprays with suspensions of the soil bacteria producing the bt-toxins.

The safety of genes and gene products introduced into transgenic agriculture must be thoroughly assessed in advance. In particular, current attempts to introduce vaccines and industrial chemicals into agricultural crops, including food crops, should be banned, as they will have devastating effects on wild life and human health.12 An acceptable and feasible alternative is to engineer cultured plant cells for those purposes under contained use conditions.

Safety concerns of random unpredictability

The special safety concerns of unpredictability come both from the random, uncontrollable insertion of foreign genes into the host genome13 and from the unpredictable interaction of exotic genes with host genes. These effects are graphically illustrated by the gross abnormalities in transgenic animals, even among the 'successes'.14Among the first were 'superpigs' engineered with a human growth hormone gene. They turned out to be crippled, arthritic, blind, covered with ulcers and impotent. Equally deformed transgenic calves and sheep are routinely created.

Tranformations with the T-DNA from the Ti-plasmid of Agrobacterium have been the most widely used vector system for plants. The assumption is that only the T-DNA - located between left and right borders in the Ti-plasmid - is inserted into the plant genome. However that has proven not to be the case; unintended transfer of parts outside the borders occurs frequently.15 Furthermore, T-DNA can be inserted in a truncated or rearranged form, in single copies or tandem repeats at one or more sites, reflecting the instability of the gene constructs (see below); and insertion mutagenesis (mutations of host genes due to insertion within the genes) is relatively common.16 The inserted DNA may also influence other genes downstream or up-stream of it. For example, its strong promoter(s)/enhancer(s) may activate or inactivate host genes. Such influences are known to spread very far into the host genome from the site(s) of insertion.17

Interactions between introduced genes and host genes are bound to occur, as no gene functions in isolation, and in particular because the foreign genes are being continuously over-expressed. The transgenic organism is, in effect, under constant metabolic stress, which may have many unintended effects on its physiology and biochemistry, including increase in concentrations of toxins and allergens. Another frequent unintended effect is transgenic instability due to 'gene silencing' - the gene being still in the genome but is chemically modified so it is not longer expressed, or it could be due to secondary mobility of the introduced genes - the inserted genes jumping out of the genome.18

On account of the unpredictabilities and randomness inherent to the technology, every time the same vector system is used to introduce the same genes into the same plant variety, a different transgenic line results. Furthermore, there is no guarantee that the transgenic line retains its identity in subsequent generations, as transgenic organisms typically do not breed true, possibly due to the instability of the unnatural gene constructs in the insert (see below).19

Examples of unexpected, unintended toxicities and allergenicities are already known, even for cases where the organism's own genes are being increased in copy number.20 Monsanto's transgenic soya was approved by the UK Novel Foods Committee for our market since 1996 as 'substantially equivalent' and therefore safe. It was found, nevertheless, to have a 26.7% increase in a major allergen, trypsin-inhibitor, which is also a growth inhibitor.21 Consistent with this result, the growth rate of male rats was found to be inhibited by the transgenic soya.22 This raises the question as to whether the transgenic soya is responsible for the reported recent increase in soya allergy.23

A great deal of heated debate arose from the work of Dr. Arpad Pusztai's group. They were awarded a (Sterling Pound)1.6 million contract by the UK Government to do proper safety testing of transgenic foods, which, up to then, had not been done, even though many transgenic crops and products have already been approved for market. Their results suggest that the major toxicities of two transgenic potatoes lines engineered with snowdrop lectin are due to the transgenic process, and not the lectin.24 The two transgenic lines are different from each other, and from subsequent generations of each line, underscoring the unpredictable, unstable nature of transgenic varieties.

There is no case for regarding transgenic lines constructed with the same methods and involving the same gene constructs and plant varieties as a class, as far as safety assessment is concerned. Each resulting transgenic line is different, with different unexpected, unintended characteristics. Therefore, before each line is authorized for release into the environment, it must be thoroughly characterized with respect to the site(s) of foreign gene insertion. There must be evidence, supported with the appropriate molecular genetic and other scientific data, that the line is stable in gene expression and gene insert(s) under a reasonable range of conditions of growth for at least five generations. There must also be a specified means for identifying the line, and to monitor for the spread of the transgenes, either by cross-pollination or by horizontal gene transfer. These considerations apply all the more to transgenic livestock and fish.

Safety concerns of gene-constructs

Safety concerns have been raised over the high levels of unregulated foreign gene expression by putting a viral promoter next to the gene, and also over the viral promoter itself. One viral promoter used in practically all transgenic plants currently grown commercially or being field tested is from the cauliflower mosaic virus (CaMV), which is closely related to human hepatitis B virus, and also has affinities to retroviruses such as the AIDS virus.25 The CaMV promoter is functional in most plants, in yeast, insects26 and E. coli.27 Two kinds of potential hazards exist within the transgenic plant itself: the reactivation of dormant viruses, and recombination between the CaMV promoter and other viruses, dormant or otherwise, to generate new, super-infectious viruses or viruses with broadened host-range.

The safety of CaMV promoter has never been assessed before it was widely used. As it is active in many species, and as horizontal gene transfer from the transgenic plant to unrelated species is now known to occur (see below), all the genes linked to this promoter will be actively over-expressed in any species to which the gene expression cassettes happen to be transferred. In addition, the reactivation of dormant viruses which are in all genomes, and the generation of new, super-infectious viruses may also occur in those species. Signs suggestive of viral infection in the tissue of rats fed transgenic potatoes have been reported to be among the findings of Pusztai's group.28 Was CaMV promoter involved? This is an urgent question which needs to be addressed.

New findings further indicate that the CaMV promoter contains a 'recombination hotspot' - a site especially prone to break and join up with other DNA.29 Consequently, it will enhance horizontal gene transfer and recombination, even in the absence of other viral genes. The potential ecological damages due to the spread of the cauliflower mosaic viral promoter alone warrants an immediate moratorium on further environmental releases of transgenic crops and products that might contain transgenic DNA. There is urgent need for an independent enquiry and targetted research on the hazards of CaMV and other similar promoters.

Again, the many viral promoters used in transgenic animals and human gene therapies are subject to the same hazards.

Safety concerns from the uncontrollable spread of transgenes and marker genes

Genes can spread from transgenic plants by ordinary cross-pollination to nontransgenic plants of the same species or related species, and also by secondary horizontal gene transfer to unrelated species.

The most obvious effects of cross-pollination already identified are in creating herbicide-tolerant, or insecticidal weeds and superweeds.30 Other hazards are associated with the spread of the novel genes and gene-constructs for over-expression, and the antibiotic resistance marker genes, which are in a high proportion of transgenic plants. These will multiply the unpredictable physiological impacts on the organisms to which the genes and gene-constructs are spread, and hence on the ecosystem.

Horizontal gene transfer is the very process that is exploited for creating the transgenic plants themselves. Secondary horizontal transfer from the transgenic plants will spread the novel genes and gene-constructs and antibiotic resistance marker genes to unrelated species. This can, in principle, occur to all species that interact with the transgenic plants, either directly or indirectly: microbes in the soil and other parts of the plants as well as in other organisms, worms, insects, arthropods, birds, small mammals and human beings.31

Several factors make it more likely for the foreign genes introduced into the transgenic plants to take part in secondary horizontal gene transfer than the plant's own genes (Table 4).32 The same considerations apply to transgenic animals.

Table 4. Transgenic DNA more likely than non-transgenic DNA to spread horizontally

 The mechanisms that enable foreign genes to insert into the genome may enable them to jump out again, to re-insert at another site, or to another genome. For example, the enzyme, integrase, which catalyzes the insertion of viral DNA into the host genome, also functions as a disintegrase catalyzing the reverse reaction. These integrases belong to a superfamily of similar enzymes present in all genomes from viruses and bacteria to higher plants and animals.33

 The integration sites of the most commonly used vector for transgenic plants, the T DNA of Agrobacterium, are very similar to the recombination hotspots found in the CaMV promoter and other sites,34 which means that the whole of the integrated DNA will have an increased propensity for secondary horizontal gene transfer and recombination.

 The unnatural gene constructs tend to be unstable, and hence prone to recombine with other genes.

 The metabolic stress on the host organism due to the continuous over-expression of the foreign genes may contribute to the instability of the insert, as it is well-known that transposons are mobilized to jump out of genomes during conditions of stress, to multiply and/or reinsert randomly at other sites resulting in many insertion-mutations.

 The foreign gene-constructs and the vectors into which they are spliced, are typically mosaics of DNA sequences from many different species and their genetic parasites; these homologies mean that they will be more prone to recombine with, and successfully transfer to, the genomes of many species as well as their genetic parasites.35

 DNA sequence homology is not required for successful horizontal gene transfer,36 otherwise it would have been impossible to create many transgenic organisms in the first place. Recent evidence also shows that recombination associated with 'recombination hotspots' do not require homologies and the insertion borders of vectors are often recombination hotspots.

The potential hazards from secondary horizontal gene transfer to unrelated species are as presented in Table 5.

Table 5. Hazards from secondary horizontal gene transfer

 Creating new viruses by recombination between the viral genes or promoters and viruses in recipient species and in the general environment

 Creating new bacterial pathogens by recombination between the bacterial genes introduced and bacteria in recipient species and in the general environment

 Spreading drug and antibiotic resistance marker genes among pathogens in recipient species and in the general environment

 Random, secondary insertion of genes into cells of recipient species, with harmful position and pleiotopic effects, including cancer

 Reactivation of dormant viruses that cause diseases by the CaMV and other viral promoters in recipient species

 Multiplication of ecological impacts due to all the above.

There is evidence that a herbicide-tolerance gene introduced into Arabidopsis by means of a vector may be up to 30 times more likely to escape and spread than the same gene obtained by mutagenesis.37 One way this could happen is by secondary horizontal gene transfer via insects visiting the plants for pollen and nectar.

Secondary horizontal tranfer of transgenes and antibiotic resistant marker genes from genetically engineered crop-plants into soil bacteria and fungi have been documented in the laboratory.38 Successful transfers of a kanamycin resistance marker gene to the soil bacterium Acinetobacter were obtained using DNA extracted from homogenized plant leaf from a range of transgenic plants: Solanum tuberosum (potato), Nicotiana tabacum (tobacco), Beta vulgaris (sugar beet), Brassica napus (oil-seed rape) and Lycopersicon esculentum (tomato).39 It is estimated that about 2500 copies of the kanamycin resistance genes (from the same number of plant cells) is sufficient to successfully transform one bacterium, despite the fact that there is six million-fold excess of plant DNA present. A single plant with say, 2.5 trillion cells, would be sufficient to transform one billion bacteria. Despite the misleading title in one of the publications,40 a high "optimal" gene transfer frequency of 6.2 x 10-2 was found in the laboratory from transgenic potato to Erwinia chrysanthem, a bacterial pathogen. The authors then proceeded to 'calculate' a frequency of 2.0 x 10-17 under extrapolated "natural conditions". The natural conditions, are of course, largely unknown. There is no ground for assuming that such horizontal gene transfer will not take place under natural conditions. On the contrary, there is now a large body of evidence to suggest it can occur.

The genetic material, DNA, released from dead and live cells, is not readily broken down as previously supposed, but rapidly sticks to clay, sand and humic acid particles where it retains the ability to infect (transform) a range of organisms in the soil.41 That means transgene-constructs and marker genes will be able to spread to bacteria and viruses with the potential of creating new bacterial and viral pathogens and spreading antibiotic resistance genes among the pathogens. The bacteria and viruses in all environments essentially act as a reservoir for the genes and gene-constructs, allowing them to multiply, recombine and further spread to all other species. Horizontal gene transfer among bacteria by transformation (DNA uptake), conjugation (direct cell-to-cell transfer) and transduction (carried by viruses) have been demonstrated in all environments.42 The aquatic environment is particularly favourable for horizontal gene transfer by transduction. Thus, transgenic DNA may well spread to microorganisms from which it may gain access to all other species.

DNA is not broken down rapidly in the gut as previously supposed.43 That means genes can spread from ingested transgenic plant material to bacteria in the gut and also to the cells of all organisms ingesting the material.

Horizontal gene transfer between bacteria in the human gut has been demonstrated since the 1970s and similar transfers in the gut of chicken and mice in the early 1990s.44 This is confirmed in new research showing that antibiotic resistant marker genes from genetically engineered bacteria can be transferred to indigenous bacteria in an artificial gut.45 The transformed bacteria will constitute a reservoir of antibiotic resistance genes that may be passed onto pathogenic bacteria.

Mammalian cells are known to take up foreign DNA by many mechanisms, including conjugation, a process previously thought to occur only between bacteria.46 Studies since the 1970s have documented the ability of bacterial plasmids carrying a mammalian SV40 viral genome to infect cultured cells which then proceeded to make the virus. Similarly, bacterial viruses and baculovirus (of insects) can also be taken up by mammalian cells. Baculovirus is so good at gaining access that it is being engineered as a vector for human gene therapy, at the same time that it is being engineered to control insect pests in agriculture.47 We have called on all projects engineering baculovirus for agricultural use to be banned immediately.48

Viral and plasmid DNA fed to mice have been found to resist digestion in the gut. Large fragments passed into the bloodstream and into white blood cells, spleen and liver cells. In some instances, the viral DNA was found attached to mouse DNA and E. coli DNA, suggesting that it has integrated into the mouse cell genome and the bacterial genome respectively.49 When fed to pregnant mice, large fragments of the DNA are found in the nucleus of cells of the foetus and the newborn.50

Viral DNA is now known to be more infectious than the intact virus, which has a protein coat wrapped around the DNA. For example, intact human polyoma virus injected into rabbits had no effect, whereas, injection of the naked viral DNA gave a full-blown infection.51 Viral DNA is in practically all transgenic plants especially in the form of CaMV. Many promoters from animal viruses are also present in a range of vectors and gene constructs in transgenic DNA released in wastes from contained users. Viral promoter, if integrated into mammalian cells may reactivate dormant viruses, generate new viruses by recombination, and also cause cancer.52

Terje Traavik and I have been independently calling attention to the dangers of horizontal gene transfer for several years. Of course, we were not the first. The pioneers of genetic engineering themselves recognized this danger in 1970s, and called for a moratorium. You will be interested to learn that among the scientific advice given by the UK Ministry of Agriculture, Fisheries and Food (MAFF) to the US Food and Drug Administration (FDA) at the end of last year53 are the following warnings:
 Transgenic DNA can spread to farm workers and food processors via dust and pollen. DNA is not readily degraded during food processing.
 Antibiotic resistance marker genes may spread to bacteria in the mouth, as the mouth contains bacteria that readily takes up foreign DNA. Similar bacteria are present in the respiratory tracts.
 Antibiotic resistance marker genes may spread to bacteria in the environment, which then serves as a reservoir for antibiotic resistance genes.
 Foreign DNA can be delivered into mammalian cells by bacteria that can enter into the cells.
 The ampicillin resistance gene in transgenic maize undergoing 'farm-scale' field-trials in the UK and elsewhere is very mutable, and may compromise treatment for meningitis and other bacterial infections.

There is as yet no direct evidence that latent viruses can be reactivated in transgenic plants by the CaMV promoter, if only because the possibility has not been investigated. However, plants engineered with coat-protein and other genes from viruses to resist virus attack actually show increased propensity to generate new, often super-infectious viruses by horizontal gene transfer and recombination with infecting viruses.54 This suggests that the viral promoters engineered into practically all transgenic plants may also take part in horizontal gene transfer and recombination to generate new viruses.55 Once formed, the new viruses will spread by insects to other plants, unleashing wide-spread disease epidemics.

In the light of the knowledge that 'naked DNA' released from dead or living cells can persist in the environment and remain infectious, the most serious genetic pollution of the environment may be coming from the transgenic wastes of contained users, which include cancer genes from viruses and cells, virulence genes from bacterial and viral pathogens and all kinds of novel constructs. Waste treatment is ineffective and out of date.56 DNA is still regarded as a 'chemical',57 because it is in all organisms, is not thought to be a dangerous chemical. I have been corresponding with the UK MAFF and HSE since 1996, to warn them specifically of the horizontal gene transfer from DNA released into the environment, to no avail. Large amounts of hazardous transgenic DNA may even have been recycled into the ecosystems as 'organic' fertilizers. This area needs the most urgent attention.

It has been argued that 'fluid genome' processes, which include horizontal gene transfer, have always operated in nature, and therefore, transgenic organisms cannot be said to pose a new threat. However, horizontal gene transfer has been relatively rare in our evolutionary past, even though the total number of events over billions of years of life on earth is significant. Natural species barriers have evolved to prevent gene exchange, especially between distant species, and there are mechanisms which inactivate or break down foreign DNA.58 Furthermore, genomic fluidity is increasingly recognized to be part and parcel of the regulatory repertoire that keeps genes and genomes stable under ecologically balanced conditions while allowing rapid changes to take place under stress.59 Genetic engineering biotechnology greatly accelerates the rate of horizontal gene transfer as well as enlarging its scope. It has created highways for gene exchange where previously only tortuous footpaths existed.60

The world is experiencing a public health crisis from the accelerated resurgence of drug and antibiotic resistance diseases over the past 20 years. Many factors are thought to be responsible, among them, environmental destruction, urbanization, the abuse and overuse of antibiotics in medicine and intensive agriculture. One factor which has not been considered is the development of genetic engineering biotechnology on commercial scales over the same period.61 There is overwhelming evidence that the new viral and bacterial pathogens have been created by horizontal gene transfer and subsequent recombination, which also spread drug and antibiotic resistance genes among the pathogens. Many of the horizontal gene transfer events have occurred very recently, as evidenced by the identity or near-identity of the same genes in unrelated species. New, cross-species viral agents, in particular, have been emerging in great numbers in recent years, with a trend towards increasing virulence and infectivity that has not been seen previously.62

The most recent epidemic is in Malaysia, which experienced a national emergency due to a serious outbreak of a mysterious viral disease which may have crossed from race-horses via fruit-bats and pigs to humans.63 The death toll was well over 100 since October 1998, and more than a million pigs have been slaughtered. The disease has continued to spread to pet dogs and cats.

Many scientists have already called for phasing out antibiotic resistance genes in transgenic plants on grounds that they may spread horizontally and compromise treatments for infectious diseases. Since May 1998, strains of at least 5 dangerous bacteria including the one causing tuberculosis are resistant to all diseases and hence untreatable, and unlicensed antibiotics are being used on compassionate grounds.64 Phasing out antibiotic resistance genes is an important step in controlling the spread of antibiotic resistance, but it does not address the emergence of the bacterial pathogens themselves, nor the plagues of new viruses and viral strains. It requires the tight control over environmental releases of GMOs and transgenic DNA from all sources.

Recent findings also reveal that while disease-causing functions in bacteria are due to many genes, those genes are often clustered together in mobile units - pathogenicity islands - that transfer horizontally as a unit. Thus, non-pathogens can be converted into pathogens in a single step.65 These pathogenicity islands are thought to have originated from bacterial viruses which have integrated into bacterial genomes and picked up a range of virulence genes. They are highly mosaic, consisting of parts of plasmids and bacteria, particularly of those parts that might have been assembled into artificial vectors for genetic manipulation. In a report co-authored by seven scientists including myself, we have asked whether genetic engineering may have inadvertently contributed to creating pathogenicity islands. We should remind ourselves that it was precisely the fear of creating new viral and bacterial pathogens by horizontal gene transfer that made the pioneers of genetic engineering call for a moratorium in the Asilomar Declaration.

A scientist from the Center for Complex Infectious Diseases in Rosemead, California, claims to have found more than 50 bacterial genes in a virus isolated from a woman with chronic fatique syndrome.66 He regards this as a new organism and coined the term, "viteria" to describe the hybrid virus-bacteria. The virus most closely resembles a Cytomegalovirus, which is one of the first viruses used as vectors for gene manipulation in animals. And top of the list of bacteria from which the virus has captured genes are E. coli and Bacillus subtilis, two of the most commonly used bacteria in genetic engineering. Is this virus related to the pathogenicity islands? And could genetic manipulation have contributed to its evolution? These are urgent questions which should be addressed.

Some new hazards

Biosafety legislation and biosafety committees should examine new research developments to anticipate possible hazards, and if necessary, discourage such lines of research. I would like to comment on two that are being promoted as more environmentally friendly and more safe than current technologies. The first is the 'Genetic Use Restriction Technologies' (GURT), based on the original 'terminator technologies' that engineer harvested seeds not to germinate.67 One of the claimed benefits is that it prevents the spread of transgenes. A newer version makes seeds dependent on the application of a chemical for germination, or for expressing the desired transgenic trait. It offers no benefit to farmers or consumers. The real purpose of this kind of technologies is to protect corporate patents.

As you have seen, transgenesis is not a precise technology. It is extremely hit or miss, and generates a lot of unexpected effects in plants, including toxins and allergens. The GURT technologies are even worse. They depend on site-specific recombination engineered to be under the control of an external stimulus, such as the application of a chemical. Thus, multiple feats of precise engineering has to be done, and subsequent to that, the regulation has to be very precisely. However, those requirements are beyond the capability of the genetic engineer. The hazards of the transgenic DNA resulting from GURT technologies are much greater, because the imprecisions of inserting multiple gene-constructs are multiplied, and because of the gene-splicing mechanisms deliberately introduced. Recombination creates new combinations of genes and has the potential to scramble genes and genomes when it is imprecise. It is already known that recognition between designated recombination sites and their enzymes (recombinases) are far from exact,68 and many mistakes are anticipated. These genes, once engineered into the plants, will spread by ordinary cross-pollination and by horizontal gene transfer, multiplying the opportunities for scrambling genes and genomes.

The second class of techniques, 'chimaeroplasty', is hailed as a real advance on current crude transgenic technologies, as no foreign genes are actually introduced.69 Instead, little 'hair-pin' loops of 25 bases, are bombarded into cells, which can bind to both the complementary strands of the target gene in order to convert the sequence of the gene to that of the hairpin loop. It depends on imprecise base-pairing of a sequence of 12 bases for each of the complementary strands of the DNA. It can be predicted that many other non-target genes may be 'converted' with unpredictable effects. Furthermore, those hair-pin loops themselves are dangerous if they get into the cells of organisms including human beings.

The precautionary principle and the inverse precautionary principle

When is scientific evidence considered sufficient to indicate that the risk is unacceptable? Risk is technically the extent of damage multiplied by the probability that the damage will occur. People take risk for a number of reasons: because they have to, or because there is overwhelming moral imperative for doing so, or because the likely benefits are compelling despite the potential damage. Not one of these reasons applies in the case of transgenic agriculture. (The medical applications are also questionable, but the issues are more complex.70) On the contrary, the scientific evidence is sufficiently compelling for an immediate halt to the enterprise. That is in accordance with the generally accepted precautionary principle.71

Instead, regulatory committees have been operating on the inverse precautionary principle, which says that unless and until there is certainly of harm, everything must be approved, and 'scientific progress' must not be impeded. The millions who have died from smoking cigarettes, the 8000 babies born with truncated limbs to pregnant mothers who have taken thalidomide, and the increasing number of deaths from new variant Creuzfeld-Jackob's Disease associated with bovine spongiform encephalopathy are just some of the victims of this inverse precautionary principle which has set the standard of corporate behaviour for the past 50 years. Good sound science ought to dissociate itself once and for all from this abysmal history.


Genetic engineering biotechnology is inherently dangerous. The British Medical Association is calling for an indefinite moratorium on transgenic agriculture pending further research on the spread of antibiotic resistance, new allergies and the effects of transgenic DNA.72 The same association ought to be calling for an enquiry into waste treatements and disposal of transgenic wastes from contained users.

Transgenic crops are neither needed nor beneficial. The two main traits introduced, bt-insectides and herbicide tolerance, were supposed to reduce the use of pesticides and herbicides respectively. Their negative impacts on biodiversity and health have already been described. A new study links glyphosate - the world's top selling herbicide used with a range of transgenic crops - with non-Hodgkin's lymphoma.73 At the same time, a survey of 8 200 field-trials of glyphosate-tolerant transgenic soya varieties in US universities reveals that transgenic crops yield on average 6.7% less and require 2 to 5 times more herbicides than non-transgenic soya.74

The myth of feeding the world has never carried much credibility. According to the UN food programme, there is enough food to feed the world one and a half times over. World cereal yields have consistently outstripped world population growth since 1980 (2.2% a year compared with 1.7%). But one billion are hungry.75 It is on account of transnational corporations operating under the globalized economy that the poor are getting poorer and hungrier. Corporations have monopolised food production and distribution, buying cheap and selling dear, or undercutting farmers by subsidized dumping of surpluses. Now, they are monopolising seeds through patenting. Third World farmers, 80% of whom have traditional saved seed for replanting, will no longer be allowed to do so.

Corporate giants already control more than three-quarters of the world trade in cereals.76 Small farmers are being ruined everywhere. In the US, they are receiving below the average cost of production for their produce.77 The current collapse of the transgenic crops market have made things worse. Christian Aid, a major charity working with the Third World, concludes in its report that transgenic crops will create unemployment, exacerbate Third World debt, threaten sustainable farming systems, and damage the environment. It predicts famine for the poorest countries.78

Most of all, transgenic agriculture diverts us from the real solutions to food security. It prevents the implementation of sustainable agriculture which can truly feed the hungry of the world and improve health and nutrition for all. Farming communities in the Third World, marginalized by decades of the export monocultures of the green revolution, have had to regenerate and revitalize degraded agricultural land with many forms of sustainable, organic agriculture, while recovering indigenous varieties adapted to local conditions, that give high yields without artificial fertilizers, do not need irrigation, and are resistant to diseases. Successive studies have higlighted the productivity and sustainability of traditional peasant farming in the third World as well as organic farming in the North. In 20 Third World countries, more than 2 million families are farming sustainably on 4-5 million hectares, with tripled or doubled yields, fully matching if not surpassing intensive agrochemical agriculture.79 And this has happened only within the past 5-10 years. Contracting in to corporate food-production schemes now will set them back once again down the road to escalating debt, poverty and suicide, not to mention the devastation of agricultural land and the environment.

Cuba is demonstrating unequivocably that organic agriculture can work on a large scale, with energetically efficient low inputs and minimal impacts on the environment.80 US economic blockade since the 1960s caused a shortage of agrochemicals. They maintained one-third of the 11 million hectares of agricultural land on agrochemicals, turned another third fully organic, and kept the rest 'transitional' as half agrochemical and half organic. The yields per hectare of the fully organic farms are found to be equal to the fully agrochemical, while the yields of transitional fields are only half as much.

Recent projects in seven industrialised countries of Europe and North America,81 similarly, show that farmers can cut their inputs of pesticides and fertilisers between 20-80% and be financially better off. Yields fall in the beginning, by 10 to 15%, but they soon rise and go on increasing. In the US, the top 25% of farmer practising sustainable agriculture now have higher yields than conventional farmers, as well as a much lower negative impact on the environment.

More and more people are coming around to the view that there is no reductionist solution to food security or healthcare.82 Both are matters of global human ecology: "..the pursuit of world health is inseparable from global economics, preservation of ecosystems, and social justice. The struggle for health is essentialy a struggle for equity and compassion, not just in the provision of health services, but in all sectors and aspects of life."83 The same message is coming from contemporary western science.84

Western scientific findings accumulated over the past twenty years have invalidated every assumption of the discredited ideology of genetic determinism that is driving genetic engineering biotechnology.85 The new genetics is compelling us to an ecological, holistic perspective, especially where genes are concerned. The genes are not constant and unchanging as previously supposed. Instead, genes respond to the physiology of the organism and require a stable, balanced ecology to maintain stability. Organic agriculture is predicated on a balanced ecology, which is sustained by a diverse community of healthy organisms free from agrochemicals. The key to genetic health is precisely the same as physiological health: unpolluted environment, wholesome organic foods free from agrochemicals, and sanitary, aesthetically and socially satisfying living conditions.

Our priorities are in curbing toxic and radioactive discharges as well as releases of genetically engineered organisms, including all kinds of transgenic DNA. Agrochemicals should be phased out and organic agriculture widely introduced. These are the real choices for civil society. Citizens of the UK and elsewhere have taken civil disobedience and other actions to show that they cannot be bullied into accepting this dangerous technology. Already, the biotech industry is in retreat, big corporations are pulling back from agricultural investments.86 One hundred scientists from all over the world have signed a World Scientists' Statement calling for a global moratorium on transgenic agriculture, a ban on patents of life-forms and an independent enquiry on the future of agriculture and food security for all.87


1. Previous submissions to UKHSE and European Commission (1996-1998), available from M.W.Ho; see also Ho, M.W. (1998,1999). Genetic Engineering Dream or Nightmare? The Brave New World of Bad Science and Big Business, Gateway Books, Bath; Ho, M.W., Traavik, T., Olsvik, R., Tappeser, B., Howard, V., von Weizsacker, C. and McGavin, G. (1998b). Gene Technology and Gene Ecology of Infectious Diseases. Microbial Ecology in Health and Disease 10, 33-59; Traavik, T. (1999a). Too early may be too late, Ecological risks associated with the use of naked DNA as a biological tool for research, production and therapy, Research report for Directorate for Nature Management, Norway.

2. Traavik, T. (1999b). An Orphan in Science: Environmental Risks of Genetically Engineered Vaccines, Research report for Directorate for Nature Management, Norway.

3. See Ho, 1998, 1999 (note 1); also Ho, M.W. and Steinbrecher, R. (1998). Fatal Flaws in Food Safety Assessment: Critique of The Joint FAO/WHO Biotechnology and Food Safety Report, Environmental and Nutritional Interactions 2, 51-84; and references therein.

4. See Old,R.W. and Primrose, S.B. (1994). Principles of Gene Manipulation (5th ed.), Blackwell Science, Oxford, or similar texts.

5. From Ho, et al, 1998b (note 1).

6. See Old and Primrose,1994 (note 4).

7. See Ho, et al, 1998b (note 1).

8. See ISAAA Report, 1998.

9. Losey, J.E., Rayor, L.D. and Carter, M.E. (1999). Transgenic pollen harms monarch larvae. Nature 399, 214.

10. See Ho and Steinbrecher, 1998 (note 3) and references therein.

11. Gould, F., Tabashnik, B., Hutchison, W., Ferro, D., Andow, D. and Whalon, M. (1998). Recommendations for developing and implementing resistance management plans for Bt-toxin-producing crops. In Now or Never (M. Mellon and J. Rissler, eds), pp. 13-8, Union of Concerned Scientists, Cambridge, Mass.

12. See Ho and Steinbrecher, 1998 (note 3).

13. Walden, R., Hayashi, H. and Schell, J. (1991). T. DNA as a gene tag. Plant J. 281-8.

14. See O'Brien T. (1998). Farm Animal Genetic Engineering, CWFTrust, Hants.

15. Smith, V. (1998). More T-DNA than meets the eye. Trends in Plant Science 3, 85.

16. Conner, A.J. (1995). Case study: food safety evaluation of transgenic potato. In Application of the Principles of Substantial Equivalence to the Safety Evaluation of Foods or Food Components from Plants Dervied by Modern Biotechnology, pp. 23-35, WHO/FNU/FOS/95.1, World Health Organization, Geneva, Switzerland.

17. Reviewed by Doerfler, W., Schubbert, R., Heller, H., K„mmer, C., Hilger-Eversheim, D., Knoblauch, M. and Remus, R. (1997). Integration of foreign DNA and its consequences in mammalian systems. Tibtech 15, 297-301.

18. See Ho and Steinbrecher, 1998 (note 3).

19. See Ho, 1998, 1999 (note 1); Ho, M.W., Meyer, H. and Cummins, J. (1998a). The biotechnology bubble. The Ecologist 28(3), 146-153, and references therein; Ho, et al , 1998b (note 1).

20. See Ho and Steinbrecher, 1998 (note 3), Ho et al, 1998a (note 1).

21. Padgette, S.R., Taylor, N.B., Nida, D.L., Bailey, M.R., MacDonald, J., Holden, L.R., and Fuchs R.L. (1996). The composition of glyphosate-tolerant soybean seeds is equivalent to that of conventional soybeans. Journal of Nutrition 126, 702-16.

22. Hammond, B.G., Vicini, J.L. Hartnell, G.F., Naylor, M.W., Knight, C.D., Robinson, E.H., Fuchs, R.L. and Padgette, S.R. (1996). The feeding value of soybeans fed to rats, chickens, catfish and dairy cattle is not altered by genetic incorporation of glyphosate tolerance. Journal of Nutrition 1126(3) 717-26.

23. Are vegetables making you ill? Press Release, Food for Thought Food Allergy Testing, 19 March, 1999.

24. Pusztai, A. (1998). SOAEFD flexible Fund Project RO818 Report of Project Coordinator on data produced at the Rowett Research Institute (RRI); see also Goodwin, B.C. (1999). Report on SOAEFD Flexible Fund Project RO818, Jan. 23, 1999.

25. See Cann, A.J. (1997). Principles of Molecular Virology, 2nd ed., Academic Press, London; see also Cummins, J. (1998). A virus promoter used in the majority of genetically engineerd crops. Available from the author at <>.

26. Smerdon, G., Aves, S. and Walton, E. (1995). Production of human gastric lipase in the fission yeast. Gene 165, 313-8; Vlack, J., Scoulten, A., Usmany, M., Belsham, G., KlingeRoode, E., Maule, A., Vanlent, M. and Zuideman, D. (1990). Expression of Cauliflower Mosaic Virus Gene I. Virology 179, 312-20.

27. Assad, F.F. and Signer, E.R. (1990). Cauliflower mosaid virus P35S promoter activity in E. coli. Mol. Gen. Genet. 223, 517-20.

28. See Goodwin, 1999 (note 24).

29. Kohli, A., Griffiths, S., Palacios, N., Twyman, R.M., Vain, P., Laurie, D.A. and Christou, P. (1999). Molecular characterization of transforming plasmid rearrangements in transgenic rice reveals a recombination hotspot in the CaMV 35S promoter and confirms the predominance of microhomology mediated recombination. The Plant Journal 17, 591-601.

30. See, for example, Mellon, M and Rissler, J. (1998).Now or Never , Union of Concerned Scientists, Cambridge, Mass.

31. Traavik, 1999a (note 1).

32. See Ho, 1998, 1999 (note 1); Ho et al, 1998b(note 1); Traavik, 1999a (note 1).

33. Asante-Appiah E. and Skalka, A.M. (1997). Molecular mechanisms in retrovirus DNA integration. Antiviral Researh 36, 139-56.

34. See Kohli, et al, 1999 (note29) and references therein.

35. See Ho et al, 1998b (note 1) and references therein.

36. See Traavik, 1999a (note 1); also Ho, 1998, 1999; Kohli, et al, 1999 (note 29).

37. Bergelson, J., Purrington, C.B. and Wichmann, G. (1998). Promiscuity in transgenic plants. Nature 395, 25.

38. Hoffman, T., Golz, C. & Schieder, O. (1994). Foreign DNA sequences are received by a wild-type strain of Aspergillus niger after co-culture with transgenic higher plants. Current Genetics 27: 70-76; Schluter, K., Futterer, J. & Potrykus, I. (1995). Horizontal gene-transfer from a transgenic potato line to a bacterial pathogen (Erwinia-chrysanthem) occurs, if at all, at an extremely low-frequency. Bio/Techology 13: 1094-1098; Gebhard, F. and Smalla, K. (1998). Transformation of Acinetobacter sp. strain BD413 by transgenic sugar beet DNA. Appl. Environ. Microbiol. 64, 1550-4.

39. De Vries, J. and Wackernagel, W. (1998). Detection of nptII (kanamycin resistance) genes in genomes of transgenic plants by marker-rescue transformation. Mol. Gen. Genet. 257, 606-13; see also Gebhard. and Smalla, 1998 (note 38).

40. Schlutter et al, 1995 ( note 38).

41. Reviewed by Lorenz, M.G. and Wackernagel, W. (1994). Bacterial gene transfer by natural genetic transformation in the environment. Microbiol. Rev. 58, 563-602.

42.  See Ho, et al, 1998b (note 1) and references therein.

43. See Ho, et al, 1998a (note 19) and references therein.

44. See Ho, et al, 1998a (note 19) and references therein.

45. See MacKenzie, D. (1999). Gut reaction. New Scientist, 30 Jan., p.4.

46. See Ho et al, 1998b (note 13).

47. See Ho et al, 1998a (note 3).

48. See Ho and Steinbrecher, 1998 (note 2).

49. Schubbert, R., Lettmann, C. & Doerfler, W. (1994). Ingested foreign (phage M13) DNA survives transiently in the gastrointestinal tract and enters the bloodstream of mice. Mol. Gen. Genet. 242: 495-504; Schubbert, R., Renz, D., Schmitz, B. and Doerfler, W. (1997). Foreign (M13) DNA ingested by mice reaches peripheral leukocytes, spleen and liver via the intestinal wall mucosa and can be covalently linked to mouse DNA. Proc. Natl. Acad. Sci. USA 94, 961-6.

50.  Doerfler, W., Schubbert, R., Heller, H., Hertz, J., Remus, R., Schrier. J., K„mmer, C., Hilger-Eversheim, K., Gerhardt, U., Schmitz, B., Renz, D., Schell, G. (1998)APMIS Suppl. 84, 62-8.

51. See Traavik,, 1999 (note 14).

52. See Ho et al, 1998b (note 13) and references therein.

53. Letter from N. Tomlinson, Joint Food Safety and Standards Group, MAFF, to US FDA, 4 December, 1998.

54.  Vaden V.S. and Melcher, U. (1990). Recombination sites in cauliflower mosaic virus DNAs: implications for mechanisms of recombination. Virology 177, 717-26; Lommel, S.A. and Xiong, Z. (1991). Recombination of a functional red clover necrotic mosaic virus by recombination rescue of the cell-to-cell movement gene expressed in a transgenic plant. J. Cell Biochem. 15A, 151; Greene, A.E. and Allison, R.F. (1994). Recombination between viral RNA and transgenic plant transcripts. Science 263, 1423-5; Wintermantel, W.M. and Schoelz, J.E. (1996). Isolation of recombinant viruses between cauliflower mosaic virus and a viral gene in transgenic plants under conditions of moderate selection pressure. Virology 223, 156-64.

55. This possibility has been suggested by Cummins since 1994 (see Cummins, 1998, note19).

56. See Ho et al, 1998b (note 1) and references therein.

57. This was said to me by a technical expert of the HSE over the telephone, when I asked for details on transgenic waste treatment and disposal on 5 August, 1999.

58. See Ho et al, 1998b (note 1) and references therein.

59. See Shapiro, J. (1997). Genome organization, natural genetic engineering and adaptive mutation. TIG 13, 98-104; also, Ho, 1998, 1999 (note 1).

60. See Ho et al, 1998b (note 1) and references therein.

61. Ho et al, 1998a (see note 1).

62. Mahy, B.W.J. (1997). Emerging virus infection. Viral Immunol. 48, 1-2.

63. Briefing from Third World Network, Penang, Malaysia, March-May, 1999; see also "The pigs must die!". Ian Anderson, New Scientist 3 April, 1999.

64. See "Superbugs are beating at the gates" Zosia Kmietowicz, New Scientist 17 July, 1999.

65. See Ho et al, 1998b (note 1) and references therein.

66. See "Stealing a march. Could viruses be getting a head start by grabbing genes from bacteria? Andy Coghlan, New Scientist 17 July, 1999.

67. Traitor Tech. The Terminator's Wider Implications. RAFI Communique, Janurary/February, 1999.

68 See Kohli, et al, 1999 (note29) and references therein.

69. "Look, no new gene" A. Coghlan, New Scientist 31 July, p. 4, 1999.

70. See Ho, M.W. (1999). Sense and Sensuality, Gateway Books, Chapter 13, for a more detailed discussion.

71. See Traavik, 1999a (note 1).

72. Interim Report on GMOs, May 1999, British Medical Association, London.

73. Hardell, L. and Eriksson, M. (1999). A case-control study of non-Hodgkin lymphoma and exposure to pesticides. Cancer 85(6).

74. Benbrook, C. (1999). Evidence of the magnitude and consequences of th Roundup Ready soybean yield drag from university-based varietal trials in 1998. Ag BioTech Technical Paper Number 1.

75. See Watkins, K. (1999). Free trade and farm fallacies. Third World Resurgence 100/101 33-37.

76. Watkins, 1999 (note 74).

77. See Griffin, D. (1999). Agricultural globalization. A threat to food security? Third World Resurgence 100/101, 38-40.

78.  Simms, A. (1999). Selling Suicide, farming, false promises and genetic engineering in developing countries, Christian Aid, London.

79. Pretty, J. (1995). Regenerating Agriculture: Policies and Practice for Sustainability and Self-Reliance, Earthscan, London.

80. Vasquez Vega, 1998; and personal communication.

81. Pretty, J. (1998). The Living Land - Agriculture, Food and Community Regeneration in Rural Europe, Earthscan, London.

82. See Ho, 1998, 1999; also Ho, 1999 (note 70).

83. Werner, D. (1999). Health and equity: Need for a people's perspective in the quest for world health. Third World Resurgence 100/101, 9-10.

84. See Ho, 1999 (note 69).

85. See Ho, 1998,1999 (note1).

86. The Guardian, 5 August, 1999.

87. World Scientists' Statement, Institute of Science in Society <>

Institute of Science in Society

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Dr Mae-Wan Ho Biology Department, Open University Walton Hall, Milton Keynes, MK7 6AA t:44-01908 653113 f:44-1908-654167 e-mail: