GLUFOSINATE AND GENETIC ENGINEERING

ECONOMIC AND ENVIRONMENTAL IMPLICATIONS
OF HERBICIDE RESISTANCE

Prepared for Greenpeace International by Topsy Jewell -
A report of The Pesticides Trust, November 1996

CONTENTS

1. Introduction
2. What is glufosinate
3. Who is Agrevo?

3.1 Background
3.2 Markets
3.3 Strategy

4. Impacts on the Environment

4.1 Genetic Pollution
4.2 Increased Herbicide Use
4.3 Effects on Soil and Water
4.4 Effects on Non-Target Species

5. Impact on Farmers
6. Conclusions
7. References

 

1. INTRODUCTION

In March 1996, the European Union (EU) approved the marketing of Plant Genetic Systems' (PGS) genetically modified oilseed rape for non-food uses. It was the second genetically engineered plant to be approved in the EU (the first was a herbicide resistant tobacco plant). The PGS oilseed rape has been genetically altered to resist the herbicide glufosinate. It has been granted food and feed safety approval in the UK. AgrEvo's glufosinate resistant oilseed rape is already on sale to farmers in Canada. In December 1996, the EU authorised the marketing of a further genetically modified plant, Ciba's transgenic corn borer resistant maize. This is also resistant to the herbicide glufosinate and to the antibiotic, ampicillin.

PGS are now awaiting final approval from the European Commission to extend the use of their first glufosinate resistant oilseed rape to food. PGS have another glufosinate resistant oilseed rape also awaiting final approval. Although several countries opposed their introduction, a qualified majority has approved them. The European Commission has now to make the final decision. Thus oilseed rape and Ciba's maize are the first transgenic crops likely to be grown on a large scale in several EU countries. Oil extracted from oilseed rape is used in products for human consumption.

Glufosinate is produced by the chemical giant AgrEvo. The development of herbicide resistant plants promises the prospect of increasing AgrEvo's sales of this product. AgrEvo has sought further to enhance its competitive position by buying up PGS. The benefits of herbicide resistant crops for farmers, the environment, and consumers are less clear-cut. Herbicide resistance may be transferred to weeds, which may then become a more serious problem. Where herbicide resistant crops remain in the field after cultivation in earlier years ('volunteers'), or where they escape into the wild ('feral crops') they may become much more difficult to control. The associated increases in herbicide use may itself pose a problem. Finally, the long term health risks of genetically altered food are largely unknown.

These are all pressing concerns for regulators, scientists, farmers and consumers. Government and industry documentation tends to place greater emphasis on asserting the benefits of transgenic plants than on assessing the risks. Relatively little attention is given to consideration of alternative farming methods. New systems of weed control which drastically reduce herbicide use are becoming available and yet are not being actively promoted. The establishment of a dependency on herbicide resistant crops would seriously impede the adoption of these non-chemical and more environmentally benign control methods.

2. WHAT IS GLUFOSINATE?

Glufosinate (sometimes called phosphinothricin) is a short name for the ammonium salt, glufosinate-ammonium. It is a broad-spectrum contact herbicide. It is used to control a wide range of weeds after the crop emerges or for total vegetation control on land not used for cultivation. Glufosinate herbicides are also used to desiccate crops (remove leaves) before harvest.

Glufosinate is a compound isolated from two species of Streptomyces fungi. It inhibits the activity of an enzyme, glutamine synthetase, which is necessary for the production of the amino acid glutamine and for ammonia detoxification. The application of glufosinate leads to reduced glutamine and increased ammonia levels in the plant's tissues. This causes photosynthesis to stop and the plant dies within a few days [1]. Glufosinate also inhibits the same enzyme in animals. Ingestion of the herbicide can affect the nervous system and cause convulsions, diarrhoea and irregular respiration [2]. Glufosinate products are toxic to humans. They have been used in suicide attempts and in some cases have resulted in death [16].

Uptake of glufosinate is through the leaves and stem. Damage is restricted to those parts of the plants which are in direct contact with the spray. The active ingredient can move within leaves but cannot move to other parts of the plant such as underground rhizomes or stolons. Long term control of perennial weeds is therefore limited.

Glufosinate is produced by AgrEvo, a joint venture established by the German chemical corporations Hoechst and Schering. It is produced at Hoechst's Frankfurt plant in Germany where work began in 1995 to double production capacity in anticipation of the launch of glufosinate resistant crops [3].

The herbicide was introduced into Japan in 1984 and was registered in the USA in 1993. The product is approved for use in more than forty countries and is marketed under a number of trade names including 'Basta', 'Rely', 'Finale' and 'Challenge'. AgrEvo recently launched 'Liberty', a glufosinate product for use on crops genetically engineered to tolerate glufosinate. In Canada, glufosinate is marketed for transgenic oil seed rape (canola) as the 'Liberty Link' system. Liberty Link soybean and maize are expected to be introduced soon.

3. WHO IS AGREVO?

3.1 Background

In January 1994, the German chemical companies Hoechst and Schering combined their agrochemical interests to establish a joint venture, AgrEvo. In December 1994, the crop protection and environmental health sectors of the Hoechst subsidiary, Roussel Uclaf were transferred to AgrEvo. In 1995, AgrEvo was the fourth largest company in terms of agrochemical sales, with sales of $2,344M [4]. Between them, the top ten companies control nearly eighty percent of the global agrochemical market.

Since it was established, AgrEvo has made a number of acquisitions, the most significant of which was the purchase of Plant Genetics Systems (PGS) in 1996. AgrEvo is reported to have spent between $550 and $730 million against rival bids from other chemical giants [4,5] .

This acquisition signifies a major expansion of AgrEvo's plant genetic engineering operations. PGS is the largest biotechnology company in Europe. Even so, it is a comparatively small company with annual sales of only $5 million. The reason AgrEvo spent up to $730 million to acquire PGS is because the company owns a significant patent portfolio with at least 46 patents or patent applications for herbicide resistance or insect protection. For example, the purchase of PGS, enables AgrEvo to join the battle for control of key maize technologies currently being fought over by two other chemical giants, Monsanto and Dow Elanco[5].

3.2 Markets

Europe is the most important market for AgrEvo. In 1995, the European market represented 46% of AgrEvo's sales, with AgrEvo holding 14% of the European agrochemical market. In the same year, 17% of AgrEvo's sales were in North America, only 4% of the total US pesticide market [4].

Cereal herbicides are AgrEvo's biggest product group. Sugar beet herbicides are also important but sales have been affected as a result of competition. AgrEvo's products are significantly under-represented in maize and soybean herbicide markets. According to AgrEvo, the US market for these two crops alone is valued at $3,000 million per year [3]. The company is therefore currently targeting its R&D to gain access to this market. It is also planning to expand its share of the Canadian oilseed rape market.

3.3 Strategy

AgrEvo aims to increase sales and secure its place in the top five agrochemical corporations. Since 1991, the company has seen its European market contract by 25%. The company aims to stabilise sales in Europe and to rapidly increase sales in North America to achieve 8% of the US agrochemical market by 2000 [4]. An important part of this strategy is the launch of crops genetically engineered to tolerate glufosinate [3]. There are currently no selective, broad-spectrum herbicides for use in key crops such as maize and soybean. The introduction of a tolerance gene to a broad-spectrum non-selective herbicide offers important opportunities to AgrEvo.

AgrEvo expects glufosinate to become its linchpin product by 2000, with an annual turnover of about $680 million by 2001-2 [3,6]. The company has made its gene technology for glufosinate resistance available to seed companies without asking royalties. AgrEvo aims to promote the fast spread of glufosinate resistance into popular crop varieties including oilseed rape, maize, soybean and sugar beet (see table below) and to profit from the consequent sales [1]. Even with Monsanto's glyphosate-resistant soybeans already on sale, AgrEvo believes that glufosinate can compete in this market.

Herbicide tolerance is not the only strategy open to agrochemical companies, but it is an attractive one to companies like AgrEvo that specialise in broad-spectrum herbicides and lack selective herbicide products. The German chemical company, BASF, which is also amongst the top ten agrochemical companies by sales, does not produce a total herbicide. Nor is it looking to develop herbicide resistant varieties. Instead BASF is aiming to expand its specialist product range by buying up competing businesses [7].

Genetically Modified Glufosinate Resistant Crops being Developed by AgrEvo [1].

4. IMPACTS ON THE ENVIRONMENT

4.1 Genetic Pollution

The large scale sowing of genetically modified crops has given rise to a number of serious concerns including the effect on volunteer and feral populations and on wild relatives of the crop. Genetically modified oilseed rape is a particular worry since the crop is a member of the brassica family which has its centre of origin in Europe. This means that Europe is an important centre of diversity and there are many related plants growing in close proximity to cultivated oilseed rape. Natural biodiversity could be placed at special risk if gene flow from genetically modified oilseed rape to wild relatives was to occur.

AgrEvo claims that the risk of cross pollination with wild relatives under natural conditions will be very minimal [1]. Recent research suggests that the risks of cross pollination are significant and are of increasing concern to scientists. Assessments of the risks of gene pollution are based on knowledge concerning pollen dispersal and the spread of transgenes in wild or feral populations.

Pollen Dispersal: Oilseed rape is pollinated by both bees and the wind. Early, small scale field trials suggested that the levels of pollen carried by the wind were too small for the dispersal of the modified genes. More recent research, however, has demonstrated high levels of pollen at significant distances from the margins of large fields. Researchers have concluded that the dispersal of oilseed rape pollen from agricultural fields occurs at greater distances and at higher concentrations than occurs in demonstration plots [8]. In addition, researchers have found that gene flow occurs between fields of spring and autumn sown crops and between field and experimental feral populations. They conclude that significant levels of gene flow will occur from genetically modified oilseed rape fields following their full commercial release [8].

Wild Populations: Of even more concern, are recent studies that show that the release of herbicide resistant oilseed rape can lead to spontaneous hybridisation between the crop and its weedy relatives. Research at INRA in France demonstrates that hybridisation can occur in the field between oilseed rape and wild radish (Raphanus raphanistrum). The progeny of the crop/weed hybrid exhibited characteristics of both parents and the authors of the study recommend further careful research before planting large areas of herbicide resistant crops [9].

Other studies in France have shown that hybridisation occurs between oilseed rape and hoary mustard (Hirschfeldia incana). It was found that, under competitive conditions, the hybrid plants do better than the hoary mustard suggesting that hybridisation may be an important avenue for gene escape for oilseed rape [17]. Danish researchers also observed spontaneous hybridisation between oilseed rape and another weedy relative (Brassica campestris) under field conditions. The hybrid plants were highly fertile and carried a transgene from the oilseed rape. The researchers concluded that there is a possible rapid spread of genes from oilseed rape to the weedy relative B. campestris [18].

Volunteer and Feral Populations: The effects of herbicide resistant crops on volunteer and feral populations is another area of concern. Unharvested and spilled seed can give rise to huge populations of oilseed rape which grows amongst subsequent crops in the rotation, in field margins or roadside verges. Feral populations can establish in both urban and rural locations. The recruitment of herbicide resistant transgenes in these populations by pollen dispersal or spillage of transgenic seeds could reduce the effectiveness of control measures. This may create new weed problems for the farmer and enhance the survival of species outside agriculture [8].

The little work that has been done in the areas described above highlights the magnitude of the uncertainties in current understanding of the consequences of the release of transgenic plants. It also underscores the problems of making generalisations based on the results of small-scale trials.

4.2 Increased Herbicide Use

When the European Commission approved EU-wide marketing of glufosinate resistant transgenic oilseed rape, it did so in spite of concerns raised by Denmark, Austria, and Sweden [15]. Regulators in these countries are concerned about the long term environmental impact of releasing the transgenic plants and the lack of research into these impacts. In Denmark, the Government is concerned that if herbicide resistant plants are used, then the greater volumes and varieties of herbicides required in removing volunteer and feral plants will have impacts on soil and groundwater. Herbicides already contaminate groundwater over large areas of intensive agriculture throughout the EU [10].

In the Netherlands, scientists working for DLO-NL, the Government funded organisation for agricultural research, are concerned that herbicide resistance will intensify chemical dependence in agriculture. DLO-NL are assessing new systems of weed control that do not use genetically modified plants. These methods aim drastically to reduce the level of herbicide used in sugar beet and maize. The scientists are worried that widespread use of herbicide resistant plants will remove the incentives for farmers to adopt these non-chemical, more environmentally benign control systems. They recommend that herbicide resistant crops only be used as a last resort [11].

4.3 Effects on Soil and Water

The US Environment Protection Agency classifies glufosinate as persistent, mobile in soil and highly soluble in water. This reinforces fears that glufosinate is likely to pose a risk of water contamination [2]. The manufacturers claim that glufosinate is unlikely to leach into groundwater. However, if glufosinate resistant crops are cultivated on a large scale, the use of this herbicide could rise dramatically in the next few years, increasing the likelihood of such leaching. Only extensive long term monitoring programmes will establish the true extent of the risk posed to water sources. In the UK, AgrEvo is currently facing restrictions on another of its herbicides, isoproturon, because of residues already found in drinking water following extensive use of the herbicide.

Studies of agricultural and forest soils in Canada have confirmed the persistent nature of glufosinate [2]. One study found that the herbicide reduces beneficial species of fungi, while disease causing fungi appear to be resistant. The researchers concluded that glufosinate use may have important microbiological consequences [12].

4.4 Effects on Non-Target Species

Glufosinate is a broad spectrum herbicide. It is therefore a threat to all plants, including rare and endangered species. Glufosinate is also toxic to a number of aquatic animals including the larvae of clams and oysters, to daphnia and to some freshwater fish species [2].

Glufosinate is also toxic to humans and ingestion of the herbicide can be fatal. In Japan, the Poison Information Centre recorded six fatalities in 34 cases of glufosinate ammonium poisoning [16].Glufosinate affects the nervous system. Evidence of neurotoxicity have been found in most species of laboratory animals exposed to glufosinate. Symptoms include trembling, irregular breathing and convulsions in rats and mice. It was found that these behavioural changes could last for several days in the animals tested [2]. The effects of other nerve toxins on farm workers, most notably organophosphate insecticides used in sheep dips, are now becoming a matter of serious concern.

In Germany, the Robert Koch Institute, the competent authority for authorising the marketing of glufosinate resistant oilseed rape, noted that a metabolite (N-acetyl-L-phosphinothricin) is formed in glufosinate treated transgenic plants which does not appear to degrade, or to only degrade at a very slow rate. Data provided by AgrEvo demonstrates that this metabolite can be reconverted into the active herbicidal form by micro-organisms in the digestive tract of warm blooded animals [19]. The Robert Koch Institute concluded that the use of glufosinate herbicides in genetically modified oilseed crops may result in metabolites whose physiological activity corresponds to that of the herbicide glufosinate. This finding has serious implications for consumers of products made from oilseed rape. Oil extracted from the crop is used in cooking oil, margarine, mayonnaise, dressings and cocoa butter substitutes.

5. IMPACT ON FARMERS

The economic and technical advantages to farmers that AgrEvo claim for transgenic herbicide resistant crops are not proven. If the new technology is to be cost effective, market research shows that the cost of the new transgenic seeds must be no more than 10 per cent higher than for non-transgenic seeds and herbicide costs must be reduced by more than 30 per cent [13]. It is far from certain that these techniques will be able to meet these demanding targets. Even if cost reductions are achieved initially, increased weed problems may seriously detract from any advantage.

Moreover, the market concentration associated with a move to transgenic crops may lead to increasingly monopolistic control of seed prices, with implications for costs to farmers over the longer term. The increasing control of the Farmer's activities by the chemical industry is already apparent in the US. Here farmers using Monsanto's herbicide resistant soybean (the 'Roundup Ready Soybean') have to sign a contract which requires them to use only Monsanto's Roundup brand on the crop and prevents them from using any part of the crop for seed. The contract gives the chemical company the right to visit the farm at any time over the next three years to check that the farmer is abiding by the terms.

Other issues for farmers include the agronomic performance of transgenic seeds compared to non-transgenic seeds; climatic conditions affecting the success of the package (especially if herbicide application timing is important); and herbicide resistance in weedy relatives and volunteers creating new weed problems. These are concerns, not only for farmers, but also for the agrochemical companies which are competing in the herbicide market. For example, Hans Loose, vice-president of BASF's US agricultural business concedes that some weeds are already showing tolerance to broad spectrum herbicides, that application timing can pose a problem for farmers and that controlling tolerant volunteers may be difficult [7].

6. CONCLUSIONS

AgrEvo claims that farmers will be able to control weeds in glufosinate-resistant plants using lower quantities of more environmentally benign herbicide. The company also claims that the risk of the resistant gene escaping into weeds is low and that tolerant volunteers will easily be able to be controlled with other herbicides [1,7,14]. Yet the benefits of transgenic crops for farmers, consumers and the environment remain highly uncertain. There is growing evidence that, while benefiting agrochemical companies' commercial standing in the short term, transgenic crops may in the long term cause irreversible damage to the environment.

As more data is gathered by independent scientists, a picture is emerging of the many risks involved in the commercial growing of genetically modified crops. These include genetic pollution as a result of outcrossing with wild relatives and the establishment of feral and volunteer populations of modified varieties. There is also evidence that harmful effects may be associated with the consumption of the genetically modified crop products. Of equal concern is the fact that herbicide resistant crops will enhance dependency on herbicides. The introduction of these transgenic crops is taking place at a time when many countries are struggling to prevent herbicide contamination of water resources. Alternative farming methods which greatly reduce herbicide use will be irrelevant if herbicide resistant crops are taken up on a wide scale.

References

1. E. Rasche, J. Cremer, G. Donn, J, Zink. 1995. The Development of Glufosinate Ammonium Tolerant Crops into the Market. In Brighton Crop Protection Conference, Weeds, 1995. British Crop Protection Council, Farnham, Surrey.
2. C. Cox, 1996. Herbicide Fact Sheet: Glufosinate. Journal of Pesticide Reform Winter 1996 Vol 16, No. 4. Northwest Coalition for Alternatives to Pesticides (NCAP), Oregon.
3. S. Watkins, 1995. Agrow's Top Twenty Five. Report ref: DS 106, PJB Publications, London.
4. L.G. Copping, Agrow's Top Twenty Five, 1996 edition. Report Ref: DS 126. PJB Publications, London.
5. GRAIN, 1996. The Biotech Battle over the Golden Crop. Seedling October 1996, pp23-32. Genetics Resources Action International (GRAIN) Barcelona.
6. Farmers Weekly, 27 Sept 1996.
7. Farmers Weekly, 18 October 1996.
8. M.J. Wilkinson, A.M. Timmons, Y. Charters, S. Dubbels, A. Robertson, N. Wilson, S. Scott, E. O'Brien, H.M. Lawson, 1995. Problems of Risk Assessment with Genetically Modified Oilseed Rape. In Brighton Crop Protection Conference, Weeds, 1995. British Crop Protection Council, Farnham, Surrey.
9. Darmency, H. A. Fleury and E. Lefol. 1995. Effect of transgenic release on weed biodiversity: oilseed rape and wild radish. In Brighton Crop Protection Conference, Weeds, 1995. British Crop Protection Council, Farnham, Surrey.
10. RIVM/RIZA 1991. Sustainable Use of Groundwater: problems and threats in the European Communities. Report No. 600025001. RIVM/RIZA, Netherlands.
11. ENDS Daily, 20 February 1997.
12. Ahmad, I., J. Bissett, and D. Malloch. 1995. Effect of phosphinothricin on nitrogen metabolism of Trichoderma species and its implications for their control of phytopathogenic fungi. Pest. Biochem. Physiol.53:49-59.
13. Agrow, 15 March 1996 p. 11.
14. Farmers Weekly, 14 June 1996.
15. Agrow, No 251 1 March 1996 p.13.
16. Tanaka, J., Yamashita, M., Yamamoto T., 1995. A comparative-study of direct hemoperfusion and hemodialysis for the removal of glufosinate-ammonium. Journal of Toxicology-Clinical Toxicology. Vol 33, No. 6 Pp 691-694.
17. Lefol E., Danielou, V., Darmency, H., Boucher, F. Maillet, J, Renard, M., 1995. Gene Dispersal from Transgenic crops. I. Growth of interspecific hybrids between oilseed rape and the wild hoary mustard. Journal of Applied Ecology 32: 803-808.
18. Mikkelsen, T.R., Andersen, B. and Jorgensen, R.B., 1996. The risk of crop transgene spread. Nature 380:31.
19. Robert Koch Institute, Notification for the placing on the market under Part C, Article 13 of Directive 90/220/EEC; Notification No. C/DE/96/5: Application for the placing on the market of glufosinate-tolerant, genetically modified rape (Brassica napus): Statement of the competent authority of the Federal Republic of Germany, 25 October 1996.

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