Relevance: Increasing long-term health and environmental concerns regarding the use of standard agrochemicals (pesticides and fertilizers) is leading to increased controls and limitations on their use. This underscores the need to explore alternatives, including the use of biotechnology, and to weigh up options in a risk-assessment structure.
Agrochemicals play a major role in meeting yield requirements in world food production cost-effectively. However, concern has arisen out of findings relating them to human health and environmental problems. Some pesticides contain active ingredients that have been shown to act as hormone disruptors in acute and chronic toxicity studies, possibly causing loss of fertility, carcinogenesis and mutagenesis. Widespread application to most cash crops means pesticides are present in the ecosystems, aquifers and water systems of the EU’s main agricultural areas. In the long-term, this could have repercussions for both the natural environment and human health.
These health concerns have led to a tightening of EU regulations on pesticide residues entering the food chain. One example is the new directive on baby food, passed this October, requiring that pesticide residues be kept below detection limits. In the same vein, the EU is studying the feasibility of taxing pesticides in an attempt to reduce their application. This situation raises an important economic question: if the use of pesticides is restricted and taxed, will productivity be affected and food prices increase?
Agricultural biotechnology offers a possible alternative, permitting yield levels to be maintained without the intensive use of agrochemicals. However, biotechnology is still at an early stage of development, and further research is needed into its impact on human beings and the environment.
Health risks related to pesticides
The most common way for pesticides to enter the food chain is as chemical traces on crops they have been used to treat. Nevertheless, they can also enter the food chain via contaminated drinking water or dietary animal fats and fish.
Over the past few decades many pesticides have been banned or otherwise restricted because of concern over their carcinogenic potential or other risk to human health or the environment. Hazard assessment and epidemiological studies of pesticides show that many, if not all, are potentially toxic to humans. At lower doses they possibly pose a risk of cancer, neurological damage and loss of fertility, although these effects have yet to be fully quantified.
It has become increasingly clear that cancer arises as a result of genetic alterations. These may be inherited or a result of the mutation of somatic cells. To be more explicit, agents that cause DNA damage or cell replication in certain cell populations will increase cancer risk. This effect is called genotoxicity. Although the genotoxicity of pesticides remains poorly defined, some substances present in pesticide formulations may be genotoxic or may cause indirectly damage to DNA by promoting the formation of oxygen free radicals.
Apart from carcinogenesis, recent scientific studies have suggested that some synthetic compounds found in pesticides can act as hormone disrupters. There is now evidence that, in some cases, wildlife has suffered adverse effects from exposure to environmental chemicals that interact with the endocrine system and therefore with hormone function. In many instances the specific hormones involved in both animals and humans are chemically identical. This profound similarity suggests that although few human studies have been done, endocrine-related effects first observed in animals may also be manifested in human populations.
At least four major categories of adverse biological effects may be linked to exposure to endocrine-disrupting chemicals (EDCs): cancer, reproductive and developmental alterations, neurological and immunological effects.
Suspected hormone disrupters include persistent organohalogens, synthetic pesticides, phthalates and heavy metals. Synthetic pesticides suspected of having reproductive and endocrine-disrupting effects include insecticides, herbicides, fungicides and nematicides. Many of these pesticides enter the food chain in the form of chemical traces from pesticide-treated crops. A major question to be addressed is whether low concentrations of pesticides residues in the food chain (chemical traces) exert any endocrine disrupting effect in humans.
The seriousness of the endocrine disrupter hypothesis has led the European Parliament to pass a non-binding resolution calling for hormone-mimicking substances to be phased out. It states that, with little scientific evidence about the possible dangers to human and animal fertility and other health effects, the precautionary principle requires the substances to be removed from the market.
Over the last few decades agriculture has grown increasingly chemical-dependent. Pesticides have come to play an important role in meeting world food needs. Beyond yield improvements, the reliance on chemicals has underemphasized crop protection. The chemical dependency of agriculture leads many to think that there is no alternative to pesticides in the short term.
However, a new trend is opening the way towards the reduction of the reliance on chemicals: the use of biotechnology and the incorporation of crop protection strategies within plant breeding programmes. This trend is being propelled by new knowledge of molecular biology and the associated biotechnology techniques. These include recombinant DNA technologies which are a pool of techniques that allow DNA from any source to be isolated and transferred between different organisms.
The two main biotechnology techniques involved in recent developments are genetic selection, which uses biotechnology to enhance traditional selective breeding techniques, and genetic modification, which actually changes the organism’s DNA so as to introduce new traits in a much more targeted way. This allows desired traits to be expressed in a useful plant variety without losing the plant’s valuable characteristics.
The application of biotechnology to agriculture therefore makes available a series of valuable tools with which to fight pests and disease, although their use may require prior research on the organism’s vital processes. Also, before attempting the genetic improvement of crop plants, a large body of research in plant genetics is needed (e.g. the Arabidopsis genome project). The outcome of this research will be a better understanding of genetic mechanisms and a greater knowledge of gene function.
Health and environmental concerns of agricultural biotechnology
The idea of releasing genetically modified plants, animals or microorganisms (generically called 'genetically modified organisms' or GMOs) into the environment is currently a matter of debate. The most important health and environmental concerns are direct toxicity (including allergies), transfer of undesirable genetic information across the species barrier and increased resistance to antibiotics. Nevertheless, much of the public anxiety stems from a lack of understanding of the basic science involved and confusion with other food-borne diseases.
There are a number of reasons why these fears are exaggerated:
The human gut naturally hosts enormous populations of microorganisms and has evolved to cope with foreign nucleic acids and proteins, such that there is no risk of genetic transfer from ingested matter.
Crossing the species barrier
A major issue associated with the use of this technology is that it allows genetic information to cross the species barrier. DNA already crosses species barriers in nature. It is transferred both within and between species, for example from viruses to bacteria, or viruses to humans. So far, however, the spontaneous transfer of DNA from plants to microbial or animal species has never been observed.
Gene transfer by normal means in pollen
Gene transfer may pose a threat to the environment by disturbing the existing balance between organisms. However, it is important to realize that any genetic balance is a dynamic one, with gene mutations and rearrangements occurring frequently as normal events in all living organisms. Nevertheless, solutions potentially able to reduce or suppress gene transfer have been developed. These are the use of male sterile clones (when the seeds are not the required product), the use of hybrids to suppress gene transfer by pollen, and transformation of mitochondria and chloroplasts (exploiting the fact that unlike the nuclear genome, the chloroplast or the mitochondria genome is not normally transferred by pollen).
Most gene transfer methods rely on a second gene, known as a marker gene, to enable the selection of transgenic plants. In the majority of cases to date, this marker gene has been the neomycin phosphotransferase (NPTII) gene. NPTII inactivates and provides resistance to the antibiotics kanamycin and neomycin. Methods have been devised to eliminate these marker genes from the crop plant if necessary. It might also be worth considering that as increasingly desirable traits become available for transformation, this may become almost essential. Use of a marker gene in one transformation precludes its use for subsequent modifications. Thus unless markers are removed, new markers will continually be required for each new trait to be inserted. The issue is being addressed at several labs (private and public) and in the long run no markers will be needed.
Biotechnology risk assessment aims to evaluate hazards to human health and the environment resulting from the application of biotechnology techniques. One of the most important tasks concerning safety of transgenic organisms is to assess long-term effects. This includes overseeing the mobility of the inserted genes and assessing the continuous expression of resistant genes, as these may affect non-targeted organisms and may disrupt or interrupt the evolution of other natural resistance mechanisms.
The development of risk assessment procedures should include a risk/benefit comparison of current agrochemicals and agricultural biotechnology so as to quantify and compare the impact that both chemical and biological technologies have on human health and the environment. This comparison should seek to evaluate the broad pros and cons of the various alternatives, and to allow citizens and policy-makers to make educated choices based on the estimated risks and benefits.
Scientific findings relating pesticides in the food chain to human diseases is encouraging policy-makers to establish regulatory maximum residue limits for pesticides in foodstuffs. At the same time, an increasingly indiscriminate use of the precautionary principle is hindering the development of the best alternative to pesticides: biotechnology.
The challenge today is to develop a European policy simultaneously protecting the public and the environment, promoting research and fostering the competitiveness of the agriculture and of the biotechnology industry. Today, the regulatory framework on agricultural biotechnology is made of a few European Directives and Regulations. The main ones are:
Directive on the Deliberate Release into the Environment of Genetically Modified Organisms (GMOs): The European Commission recently presented a proposal (COM/98/0085) for amending the Directive so as to harmonize European approaches to the issue. Several Member States have refused to approve the commercialization of GMOs approved in other Member States in their territories and others have called for a moratorium. The European Parliament’s Committee on the Environment, Public Health and Consumers proposed a Europe-wide moratorium on all transgenic crops awaiting authorization to be placed in the market. The monitoring and regulatory system laid down by this Directive is already stricter than those applied to almost any other area of human activity including new drug discovery.
Council Regulation (EC) No 1139/98 of 26 May 1998 Concerning the Compulsory Indication of the Labelling of Certain Foodstuff Produced from Genetically Modified Organisms: part of the scientific community thinks that one of the main reasons for opposition to GMOs in Europe is the lack of enforcement of this regulation. The labelling of GMOs has taken European food-control bodies by surprise and they are having some difficulty implementing this regulation, e.g. the lack of reliable identification techniques. In this context, the JRC (Joint Research Centre of the European Commission) has recently validated a screening method that permits detection of GMOs in foodstuff.
Directive on the Legal Protection of Biotechnological Inventions (98/44/EEC) concerning intellectual property: IP appears to be a very delicate issue. On the one hand, it allows effort and invention to be rewarded. Indeed, this is important as many SMEs or public groups working specifically on identifying resistance genes are beginning to look like DNA-boutiques for large companies. On the other hand, given the high costs of producing GMOs -including patent applications and fulfilling regulations- together with the monopolistic dominance of a few groups in agricultural biotechnology, it may discourage smaller organizations from producing their own selected or engineered organisms. It also may lead to alienating producers and consumers from a few products.
Today, most of the world seed business is in the hand of 5-6 large companies. These companies, such as Hoechst or Monsanto, were traditionally large chemical companies that appear to have adopted a long-term strategy to move into life sciences. This could indicate a strong shift away from massive use of agro-chemicals. These companies are working on alternative, biotechnology based strategies coupled to the selective use of chemicals. Transgenic plants expressing herbicide-resistance and insect-resistance genes are already on the market. Ironically though, some of the new genetically engineered plant varieties such as herbicide resistance crops depend on the application of specific types and amounts of chemicals to reach their improved yields, possibly compounding public concerns.
At the same time, there is an obvious lack of interest by these same large companies in biological control, perhaps because biocontrol products are limited to small niche markets. R&D in these areas is mainly led by small companies and research groups from scientific institutions. Most of this research is financed by public funds. This has led to the creation of a strong scientific base but few practical technologies or economically viable results. In the US an increasing number of SMEs, research institutes and universities are developing and producing biocontrol products, while in the EU the initiatives from the private sector in this field are scarce. One reason for this situation may be that registration procedures and approval for marketing genetically selected microorganisms or derived-products are not affordable to SMEs.
The regulatory trend towards the restriction of pesticide use could significantly increase the yield losses due to plant diseases and pests if no alternative is found soon. Although these restrictions are being imposed on the grounds of better food quality and environmental protection, agrochemicals remain the main form of crop protection worldwide.
In order to make progress towards weaning agriculture off chemicals it is essential that the emerging contributions from biotechnology be better understood by both the public and policy-makers.
Biotechnology undoubtedly has the potential to make major contributions to the development of sustainable agriculture. The main advantage of agricultural biotechnology is to allow farmers to reduce their reliance on agrochemicals (both pesticides and fertilizers) to achieve the desired yields. If properly done, this will deliver the combined benefits of health improvements for the consumer, decreased environmental impacts and increased competitiveness.
While it is essential to insist on obtaining an ever safer use of biotechnology, if society is to fully benefit from its potential its introduction should not be exclusively based on its intrinsic safety profile but also on its safety relative to the chemicals-based agriculture it aims to replace. The precautionary principle must be applied but should in no circumstance become a barrier for innovation nor bar our society from gaining access to significant long-term environmental and public health improvements.
Updated regulations and better communication to the public are essential if Europe is to avoid falling behind in the international development of biotechnology for an environmentally safe agriculture.