Lab technician preparing cultures

Source: Science Photo Library


INTRODUCTION

This chapter considers the pressures on the environment and potential risks arising from the use and marketing of chemical substances and the development, production, field testing, and release through placing on the market of living, genetically modified organisms. Such substances or organisms may not necessarily be released directly into the environment, but may eventually end up there either during their production and use, or at the end of the product's useful lifetime.

CHEMICALS AND CHEMICAL PRODUCTS

Natural processes are continually transforming chemicals and redistributing them in the environment. Background ('natural') concentrations can be described by media or location, but there are large variations. Many natural chemical compounds are, at specific concentrations, necessary for sustaining life, and most have existed for billions of years. Human activities are increasingly changing the way in which chemicals are distributed in the environment and, with the introduction of new compounds (xenobiotics), are causing new pressures on the environment, both actual and potential.

Technology has provided new materials, methods and processes which have given rise to a whole range of novel industries making use of the ever-increasing number of new compounds in the manufacture of new products. In the service of this need the production of chemicals has increased enormously over the past few decades. It is estimated that more than 13 million synthetic chemical compounds have been produced in laboratories. These either reproduce the structure of compounds found in nature or are made of completely new structures. They can be organic or inorganic, chemically active or inert, and are used in different sectors of the economy. According to EINECS (the European Inventory of Existing (commercial) Chemical Substances), about 100 000 chemicals are marketed in the EU (Box 17A) and it is commonly understood that the chemicals industry markets 200 to 300 new chemicals each year.

The speed and complexity of the development and use of chemical products over the past few decades has not allowed knowledge of environmental effects to keep pace with development. This has already led to a number of unexpected environmental impacts. The state of knowledge of the toxicity and ecotoxicity of chemicals in use and circulation, particularly about their potential impacts on humans and the environment, is in fact very unsatisfactory (see Box 17A). This state of affairs is one of the main reasons why, so often, unexpected, undesirable effects on human health and the environment occur. Rather than just reacting to problems as they arise, more strategic, pro-active approaches are being developed with the aim to control chemical risk (see Chapter 38). The backlog of work to be done testing the numerous existing marketed chemicals, about which little is known concerning their health and environmental impacts, is such that a great deal of time and resources will be necessary to complete the work. The EC Existing Chemicals Directive (93/793/EEC) and notification scheme designed to address this problem and improve basic knowledge about chemicals is already being implemented.

The control of chemical risk, including the goals and strategies being taken to tackle this problem, is considered in Chapter 38.

Impacts of chemicals

Chemical substances vary greatly in their potential to cause undesirable impacts on the environment. Over the last three decades, many chemical substances have been shown to induce severe impacts on natural processes, and organisms including humans. In particular, the release of highly toxic chemicals causes serious problems. A series of events, in the 1950s and 1960s, provided clear evidence that some manufactured chemicals could be a threat to the environment and to human health (Chapter 11) and many questions arose concerning the properties of new chemicals and the risks they pose.

The main sources of risks from chemicals arise from the regular accumulation of contaminants in environmental compartments, leading to long-term exposure, and from accidents. Worldwide, over the period 1977­87, accidents involving chemicals caused about 5000 deaths (not including poisoning by pesticides), 100 000 injuries and evacuation of 620 000 persons. The most serious accident remains that at Bhopal in India in 1984, causing about half of the total number of casualties reported above. Accidents as a cause of environmental pressure are discussed fully in Chapter 18.

Toxic chemicals can be found in air, water, soil and biota (see Chapters 4 to 11), and, as a consequence, they can also be present in food for human consumption. Thus, humans and other living species can be exposed to such compounds through the air they breathe, the food they eat, the water they drink, or by direct contact.

Chemicals display many different properties. They can be highly reactive, flammable, explosive and corrosive. Toxic chemicals that reach sensitive tissues in the human body can cause discomfort and injuries, loss of function and change of structure, and can lead to disease and mortality. Health impacts can include acute poisoning, carcinogenicity and genetic effects (mutations) in humans and other organisms (see Chapter 11). Chemicals can also affect reproduction and the nervous and immune systems, and can cause sensitisation. Other less serious but still highly bothersome effects are also possible, such as irritability and allergic reactions. Impacts can be restricted to isolated individuals, or can affect a whole population in a large area or even future generations.

Toxic chemicals may also have ecological impacts by affecting the biochemical reactions of organisms, altering the balance of processes and their equilibria, as well as having direct effects on fauna and flora. Many unforeseen impacts of chemicals on wildlife have been reported. Chemicals may be lethal to some species, reduce the survival ability of others, or accumulate in the food-chain until toxic levels are reached. The determination of causes and effects in wildlife is usually even more complex than examples in the human health sector.

Certain chemicals can also cause global physico-chemical effects, eg: CFCs and the depletion of the stratospheric ozone layer; NOx in their role of increasing tropospheric ozone; and the contribution of increased levels of carbon dioxide and methane in the atmosphere to the greenhouse effect (see Chapters 27, 28 and 32).

The extent to which a chemical is dangerous is dependent on its physico-chemical properties, its toxicity and ecotoxicity, the use to which it is put, the manner in which it is used and, most importantly, the quantities employed. Unexpected impacts of chemicals usually arise from lack of knowledge related, for example, to the toxicity or degradability of the substances, or to the presence of contaminants. Furthermore, human behaviour can affect chemical concentrations in different compartments of the environment, greatly influencing their environmental impacts (see for example Chapters 22 and 26).

Despite the increasing number of chemical compounds being produced, exposure of the general population and non-human targets is restricted mainly to a low number of so-called high-volume chemicals. Dangerous practices and problematic uses of chemicals can nevertheless lead to exposures to compounds used in lesser amounts (see also Chapter 18). A greater awareness in the use and effects of chemicals is clearly required. In tandem, this needs the assessment of total intake or exposure, based on biological modelling or on environmental monitoring, a knowledge of dose­effect relationships, and innovative approaches to the control of risks associated with new products being put on the market. In order to produce a hazard assessment for a potentially harmful chemical, information is needed about its emission patterns, physico-chemical characteristics, distribution in environmental compartments, bioaccumulation, effects on living organisms, persistence and mobility (Vighi and Calamari, 1992). Predictive instruments such as the so-called QSAR models (Quantitative Structure-Activity Relationships), have been developed for the evaluation of chemicals, and of their environmental distribution and fate (evaluative models) (Karcher and Devillers, 1991). Although these techniques are promising, the complete set of data needed to apply the models is only rarely available for the substance of interest although the physico-chemical properties of most substances are well known. Once obtained this information can be used to calculate the environmental distribution of the substance and to predict its concentration in the different non-living compartments: air, water and soil. Effects on living organisms, bioaccumulation and environmental persistence are much more difficult to deal with due mainly to lack of experimental evidence.

The sources of chemicals

The chemicals industry is well developed throughout Europe. In the EU and EFTA total production was equivalent to about 250 million tonnes for all chemicals, and 15 per cent of the total was exported outside Western Europe. Here, the chemicals industry grew by an average of 2.2 per cent in 1992 and sales totalled ECU 332.9 billion in 1991. In the EU chemicals represent 20 per cent of all exports in financial terms (CEFIC, 1993). In countries of the former USSR the heavy chemicals sector, comprising organic and inorganic chemicals, fertilisers and rubber, is relatively well established. In 1991 production declined by nearly 8 per cent, due, among other reasons, to reduced access to energy supplies from the Russian Federation, the loss of the former CMEA (Council for Mutual Economic Aid) partners, and local military conflicts (CEFIC, 1993). In Central and Eastern Europe, declines in the production of chemicals were recorded in almost all of the former CMEA countries in 1992. Only in Poland did production rise (by 3 per cent) (CEFIC, 1993). (See Chapter 20 for further relevant details of the chemicals industry in Europe.)

In EU and EFTA countries, the main volumes of chemicals produced are basic chemicals, pesticides and pharmaceuticals (see Table 17.1). In the EU, the markets where most chemicals go are consumer goods, service (hospital, research etc) and agriculture (see Table 17.2).

The release of chemical substances to the environment is an everyday occurrence. How chemicals are employed in agriculture, in industry or in households greatly affects what enters the environment. Cultural influences, social behaviour and economic reasons strongly affect the extent and manner of use, particularly those compounds in the hands of the normal consumer. Releases can occur at household level as well as on the larger industrial scale. They can come about as the result of routine actions (the general use and discarding of products or the emission of gaseous and liquid effluents), by the more formal disposal of waste, or as a consequence of accidents (see Chapters 14, 15 and 18). In heavily populated areas, chemicals are often released into waterbodies in exceptionally large volumes through industrial discharge pipes and municipal sewage.

Selected chemicals of concern

A comprehensive discussion of the different types of chemical substances which adversely affect the environment and human health is beyond the scope of this report. A number of chemical substances have attracted a great deal of attention over the past few decades and for these environmental monitoring is carried out.

Some of the chemicals given the most treatment, by, among others, WHO and OECD, are discussed below. These include in particular: eutrophying compounds (phosphorus from washing powders, and nitrates), heavy metals and metalloids, polychlorinated biphenyls (PCBs), dioxins, benzene, polyaromatic hydrocarbons, polyvinylchloride (PVC), chlorofluorocarbons (CFCs) and asbestos. According to WHO, chemicals which are creating most concern for human health are arsenic, mercury, cadmium, lead, nickel, nitrate, benzene, polycyclic hydrocarbons and PCBs. Many other compounds, however, are of potential concern. For example, recent effort is being put into assessing (mainly in conditions of occupational exposure) the carcinogenicity of styrene, the possible infertility effects of glycol ethers, chronic neurotoxicity effects of solvents, respiratory allergens, the effect of polypropylenes, perchlorethylene, polyalkylene glycols, acrylates and metacrylates (ECETOC, 1992). Recently the occurrence of pesticides and their residues in groundwater has caused great concern in several countries. Unless otherwise stated the following discussion is based on information from: Axenfeld et al (1992), CEC (1992), CEFIC (1993), UNEP (1992a, b) and WHO (1990).

Eutrophying substances (nitrogen and phosphorus)

The survival of all living organisms is dependent on a certain level of essential chemical elements in their surroundings. Exceedance of this level can lead to a series of undesirable environmental effects called eutrophication. The process of eutrophication is caused by nutrient imbalances which can disturb the natural biochemical balance of ecosystems. In particular, eutrophication restricts the intentional uses of waterbodies over large areas (see Chapters 5 and 6). The nutrients of particular concern for the environment are nitrogen (from ammonia and nitrate) and phosphorus. These originate from a wide range of uses of which agriculture dominates nitrogen emissions, and the major parts of phosphorus emissions come from domestic (eg, washing powders, see below) and industrial sources (see Chapter 14). The widespread and serious groundwater contamination with nitrates and its health aspects is an area of particular concern (see Chapter 11).

Heavy metals and metalloids

Heavy metals and metalloids of particular environmental concern are lead, mercury, cadmium, arsenic and nickel. They have a wide field of use and are often found as contaminants in other high-volume chemicals and in emissions. The problems related to copper and zinc contamination of inland waters are discussed in Chapter 5.

Lead is a potentially toxic substance with no known biological function. The world production from mining in 1989 was 2.7 million tonnes and from secondary production (recycling) 2.1 million tonnes. Consumption in the EU in 1992 was about 1.5 million tonnes out of a world total of about 5 million tonnes. Lead is used as an additive in petrol and paints, and can be found in some children's toys. Alkyl-lead used as a petrol additive is highly toxic. Because of the introduction of lead-free petrol, lead consumption is decreasing. There is also concern over lead in drinking water. Exposure leads to increased concentrations in blood. One of the most worrying effects of lead is the decline of cognitive ability in children, which occurs at very low blood concentrations.

Mercury has no known biological function. The world production in 1986 was 7000 tonnes. The consumption in the EU in 1986 was about 3100 tonnes and the recovery rate 1500 tonnes. Mercury is used primarily in chloralkali plants, electrical and paint industries and fungicides. Mercury is also present in dental amalgams and in measuring instruments, and is used as a catalyst. It is also emitted during the combustion of fossil fuels, especially coal. Its most toxic derivative is methylmercury, which affects the nervous system and can enter the food-chain. The worst disaster caused by this derivative occurred in Japan in the late 1950s (the Minamata disease), causing the death of more than 200 people and serious illness to many more.

Cadmium is used mostly in electroplating and as a stabiliser in plastics. It is also employed in nickel-cadmium batteries. Cadmium is a natural contaminant in phosphate fertilisers. Because cadmium is strongly adsorbed to soil particles, long-term fertiliser application may lead to enrichment in topsoil. In 1992, EU consumption was about 5400 tonnes out of a world total of about 19 000 tonnes. Cadmium is a category 1 carcinogen (IARC), and a correlation has been noted between cadmium concentration in the human body (especially in the kidneys) and renal damage (WHO, 1990). This element also has undesirable effects on the microbial flora and invertebrates of aquatic ecosystems and soils (see Chapters 5 and 7).

Arsenic is used mainly in pesticides, plant desiccants and wood preservatives. Arsenic emissions come from metal smelters and through the combustion of coal. World production in 1986 was about 5600 tonnes. Inorganic arsenic is an established human carcinogen. Ecotoxicologically, arsenic is a phytotoxic agent, which is especially accumulated in aquatic organisms. A current concern is its content in drinking water as a result of groundwater contamination.

Nickel is used for alloys, man-made fibres, glass, ceramics, electronics and in the fashion jewellery industry. Emissions additionally come from the burning of heating fuels and vehicle exhaust. World production in 1986 was 800 000 tonnes. Consumption in the EU (in 1992) was about 210 000 tonnes, and in the world about 780 000 tonnes. Nickel can cause allergic skin reactions and cancer.

Polychlorinated biphenyls (PCBs)

PCBs are a group of completely artificial compounds; 209 are theoretically possible and 60 have been identified. They have been used in closed, semi-enclosed and open systems and in this way become released to the environment. The desirability of these compounds stemmed from their great stability under different conditions. Up to the end of the 1980s a total amount of about 1.1 million tonnes had been produced worldwide. Main fields of use have included capacitors, transformers, hydraulic and heat exchange systems and pumps, as well as in plasticisers, surface coatings, paints and adhesives. Because of their stability (and non-degradability) PCBs have now found their way into all parts of the environment including the Arctic and Antarctic. The potential primary routes of human exposure are ingestion, inhalation and skin contact. The toxicity of PCBs has been recognised in two major accidents in Japan which led to the Yusho (oil) disease and Yu-cheng disease (WHO, 1990). There is also evidence for carcinogenic properties of PCBs. Restrictions on the use of PCBs and limits to concentrations in food have been established in many countries. Although PCBs are known to accumulate in the food-chain, acute ecotoxicological effects are unknown, but there are effects on reproduction in some mammalian species (UNEP, 1992b).

Dioxins

Dioxin compounds (75 different chemicals or 210 including furans) form a dangerous group of contaminants (not produced for their own sake). Dioxins have recently been extensively reported on and discussed, raising serious public concern. Their main environmental pathways are shown in Figure 17.1.

Dioxins caused serious health and environmental effects after the Seveso accident in 1976 (see Chapter 18). The pesticide 2,4,5-T, for instance, contains small amounts of dioxins (mainly 2,3,7,8-tetrachlorodibenzo-p-dioxin) after synthesis. This impurity has a high acute toxicity to some animals but less to others. For example, for male rats the LD50 (a given dosage necessary to kill 50 per cent of a group of test animals) is as low as 0.022 mg/kg body weight, whereas this dioxin is 200-fold less toxic to a related organism ­ the hamster ­ with an LD50 of 5 mg/kg body weight. Because 2,4,5-T is a widespread herbicide, dioxin-like compounds are found in soils, sediments and biota throughout the world. Dioxins are possible carcinogens according to IARC.

Oil

Of total world oil production of approximately 3.2 billion tonnes per year, an estimated one thousandth of this (3.2 million tonnes) entered the marine environment in 1981 from all sources. This amount decreased to 2.35 million tonnes in 1990 (GESAMP, 1993) but shows large variations between years depending on number and size of shipping accidents (Chapter 18) as well as the effects of war. Seepage of oil from natural sources is estimated to account for at least 15 per cent of the total entering the environment. The environmental effects of oil spills are more conspicuous in shallow coastal waters with poor circulation and long residence times than in open marine areas, in particular, because coastal waters offer spawning ground for many marine animals (fish species and their prey) and because young animals are generally more sensitive than adults to oil pollution. For marine mammals, sea-birds and turtles the physical effect of oil pollution (oiling) is of greater concern than the toxic effect of dissolved hydrocarbons. A detailed discussion of oil-related pollution problems in Europe's seas is contained in Chapters 6 and 18.

Benzene is a natural component of crude oil which is found in petrol and is emitted by motor vehicles and by the chemicals industry. The world production in 1989 was about 15 million tonnes of which the EU had a share of about 5.5 million tonnes. Acute exposure to benzene depresses the central nervous system, and benzene is also a well-known human carcinogen.

Polyaromatic hydrocarbons (PAHs)

The major sources for PAHs are incomplete combustion of organic compounds, industrial solvents and wood stoves. Several hundred compounds exist, the best known of which is benzo(a)pyrene (BaP), which represents around 5 per cent of all the emitted PAHs. BaP, in particular, is considered to be a probable human carcinogen by IARC.

Polyvinylchloride (PVC)

PVC is used for a great range of purposes (eg, for pipes, films, bottles, cable installations, floors, walls). World production in 1991 was 18 million tonnes, with 29 per cent from EU and EFTA countries. Among plastics PVC has attracted attention because it contains chlorine, and the monomer vinylchloride can cause cancer. Burning PVC produces chlorine gas which, with water, forms hydrochloric acid, contributing to the acidification problem (see Chapter 31). Burning PVC can also lead to the formation of dioxins and related substances.

Chlorofluorocarbons (CFCs) and halons

When CFCs became available to the general public, at the beginning of the 1930s, they were considered excellent substitutes for ammonia in refrigeration appliances due to their inert properties. This view was sustained until the 1970s when they were the first substances suspected of depleting ozone at high elevations in the atmosphere (see Chapter 28). Their very stability at low elevations, where CFCs and halons are still considered to be basically inert gases, allowed them over time to reach high into the atmosphere where exposure to UV-B radiation breaks them down into chemically active components.

CFCs are especially used as propellants in aerosols, solvents, for foam blowing, refrigeration and air conditioning. Halons are used primarily as fire extinguishers. The EU production of CFCs in 1990 was 284 000 tonnes and of halons 11 600 tonnes. Due to their stratospheric ozone depleting properties, they may be responsible for increased UV-B radiation reaching the Earth's surface, with potential health and ecological effects. CFCs and halons are now being phased out and substituted by other less harmful products. (eg, HCFCs ­ see Chapter 28).

Asbestos

The term asbestos includes several fibrous silicate minerals which occur naturally as serpentines and amphiboles. It is a widely used material (over 1000 uses are described) which can be woven into incombustible fabric, used as asbestos cement, roof sheets, wall boards and pipes. It is also used as a filler for plastics, as a heat insulant, and in vehicles in brake and clutch linings. World production in 1986 was 4 million tonnes. Major health effects of concern involve the respiratory system, lung cancer and mesothelioma. Exposure to the general population may occur where asbestos is used in buildings. Mesothelioma, whose only known cause is asbestos exposure, has, among other things, been related to the deterioration of insulation in office buildings (Stein et al, 1989).

The Directive on the prevention and reduction of environmental pollution by asbestos (87/217/EEC) has been in force since 1991 and lays down stringent measures and provisions for the working of products containing asbestos, the demolition of buildings as well as the transport and disposal of waste containing asbestos fibres. The aim is to encourage the replacement of asbestos fibres by other materials less harmful to human health. EU countries may go beyond these standards (asbestos has thus been banned in Germany) or may set up more detailed provisions if environmental conditions require it.

Washing powders and detergents

The world production of washing powders and detergents is approximately 15 million tonnes per year. They are used in washing and dyeing of textiles and fabrics, degreasing and tanning of leather, degreasing of metals, floatating processes in ore beneficiation, additives and anti-corrosives, etc. Laundry powders, which represent the largest quantity of detergents, are formulated from five different groups of substances: surfactants, builders, bleaching agents, additives and fillers. The major constituents are phosphates (mainly sodium tripolyphosphate), sodium carbonate, sodium silicate and zeolites. Phosphate is a problematic ingredient because of its eutrophying effect on aquatic ecosystems (see eutrophying substances, above). Zeolites are thought to have undesirable effects as they may release strongly bound heavy metals from organometal complexes.

Pesticides

According to WHO up to 20 000 fatalities per year at world level may result from acute poisoning by pesticides. UNEP (1992b) reports that 3 million tonnes of pesticides are produced worldwide; 30 per cent of this is used in the EU.

A wide range of different chemical compounds are currently in use as insecticides, fungicides and herbicides. About 600 single, active compounds are in use in the EU. Insecticides include, among others, organochlorines, organophosphates, carbamates and pyrethroids. Fungicides include dithiocarbamates, organomercury compounds, organochlorines, phthalimides and a series of other compounds. Herbicides include chlorophenoxy acids, carbamates, urones, sulphonylureas, triazines and many other compounds, eg, glyphosate.

In addition to the danger to workers and users who handle pesticides, these compounds have a direct or indirect impact on flora and fauna, and they may pollute groundwater, rivers and lakes (see Chapter 5). Some pesticides may remain in soils for prolonged periods due to their high persistency. Because most pesticides are applied directly in the environment, direct lethal impact on non-target organisms (eg, honey bees and other pollinators) in agricultural areas has been observed. The major threat to the biodiversity of arable land by pesticide application is the reduction of the amount and quality of food and habitats for the fauna, and the reduction of the seed pool. (See also Chapters 7, 9 and 22.)

To prevent rotting and insect attacks, wood is treated with a wide range of compounds: creosote, mineral oil, arsenic, copper, zinc, boron, mercury and chromium salts, chlorophenols and other insecticides and fungicides. Many of these chemicals can cause cancer (eg, chlorophenol, chromium salts, naphthenates, arsenic), or are highly toxic (eg, mercury salts, organomercury compounds) or can cause allergic reactions.

Conclusions

The manufacture and use of chemical products results in a wide variety of chemical compounds being released to the environment. Once in the environment these compounds can have undesirable impacts on human health and welfare and ecosystems. This can lead to loss of biodiversity and detriment to human health and welfare from loss of living space by contamination, sickness, and change of human behaviour.

The total exposure of an individual to a particular chemical is affected by social factors covering industrial development, lifestyle, cultural habits and personal activities. To estimate the total uptake from all media and the target tissue dose, environmental measurements of chemicals at point locations in individual media are needed with detailed information on individual exposure patterns and toxicity. Much of this information, however, is not available for the many chemicals in use and circulating in Europe today. In particular, insufficient information is available on the toxicity, ecotoxicity and exposure to chemicals concerning environment and health impacts.

Although international initiatives are beginning to improve the situation through increased research, monitoring and notification procedures, much still has to be done before unexpected effects of those chemicals already in circulation and present in the environment are minimised. Environmental auditing, legislation, education and research can contribute to an improvement of risk assessment and risk management procedures required to avoid dangerous and unexpected effects.

The importance of problems related to chemicals and the way in which they potentially affect all parts of the environment and human activities are the reasons for including the issue of chemical risk as one of the prominent environmental problems of concern to the whole of Europe (Chapter 38).

GENETICALLY MODIFIED ORGANISMS

In recent years, the development and use of new techniques of genetic engineering have profoundly changed the traditional methods and scope of biotechnology. These sophisticated techniques enable the identification of many genes which confer desirable characteristics, and the transfer of these genes to organisms which did not possess them before. The bacteria, fungi, viruses, plants, insects, fish and mammals which are designer-made in this way are referred to as genetically modified organisms (GMOs), and can be defined as organisms in which the genetic material has been altered in a way that does not occur naturally by mating and/or natural recombination.

Traditional selection and breeding techniques have been used for a long time in industry and agriculture to produce organisms with more desirable characteristics. However, the new, more powerful tools of molecular biology allow biological barriers to be bypassed and novel organisms with new or enhanced properties to be created. For example, a gene from a microbe responsible for expressing a certain natural toxin against insects can be introduced into the genetic material (DNA) of crop plants, which can then protect themselves from insect attack without the need for application of pesticides. In principle, genes from any species could be inserted into any other species.

The development of a growing number and range of GMOs has opened up significant potential for many useful applications in agriculture and food-processing, pharmaceuticals and diagnostics, environmental clean-up, chemicals production and the development of new materials and energy sources. At the same time, however, there are some concerns about the potential risks to human health and the environment associated with the use and the release of these novel organisms into the environment, and in particular in relation to longer-term effects which are very difficult to predict. The need to undertake environmental risk assessments and to implement risk management measures as required has been recognised by the EU, and also by the USA and the other industrialised countries who are members of the OECD. Many non-OECD countries are also realising the need to take a preventative approach, especially as a result of the discussions at the UNCED in Rio de Janeiro in 1992 and the implications for biotechnology of the UN Biological Diversity Convention.

Uses and applications

The potential for application of the techniques of molecular biology to products and processes has increased dramatically in the last few years. Advances in transformation techniques have resulted in a greater number of different GMOs being developed for a broad range of applications.

By far the most extensive use of GMOs at present is the use of microorganisms in laboratories and production facilities (contained use). Many products can be made by fermentation processes using modified microorganisms with novel characteristics. For instance, human genes encoding for the expression of substances such as insulin, growth hormone or the blood clotting factor have been successfully transferred into the DNA of microorganisms. This allows large-scale production of these substances for medical use.

However, in recent years, new applications, in particular in agriculture, require that new organisms are created for release to the environment. The development and field testing of modified organisms, and plants in particular, has been a major growth area in terms of research, but only now is there a gradual movement to place GMOs on the market as products.

Plants are being genetically modified and released with resistance to herbicides, viruses, fungi and insects, for improved storage of protein, yield or ripening characteristics, and for differentiated flower colour. More basic research is being carried out to develop plants producing pharmaceutical substances or petroleum product substitutes.

Genetically modified viruses are being released as biopesticides (eg, modified Baculovirus) or as live viral animal vaccines (eg, anti-rabies vaccine for foxes and raccoons). Nitrogen-fixing bacteria (Rhizobium) have been modified to improve incorporation of atmospheric nitrogen into plants, while other bacteria have been released as bio-pesticides (Bt-toxin containing Pseudomonas).

Other interesting applications for genetically modified bacteria will be forthcoming, as research progresses in the development of bacteria with the ability to degrade toxic chemicals, to leach metals from low grade ore deposits, to enhance the flavour and the characteristics of processed or fermented food products.

Fish (eg, rainbow trout, Salmo gairdneri) are being modified to alter their growth characteristics, tolerance to temperature changes and resistance to disease. Larger mammals (eg, pigs, sheep, goats, cattle) are being modified to enable them to produce specific chemicals or to alter their growth characteristics, while smaller mammals (eg, mice) are being modified to make them more suitable indicators for certain types of testing (eg, carcinogenicity).

Potential undesirable effects

Concerns have been expressed that the release into the environment of novel organisms which are not a result of natural selection may entail potential risks related to human health and the environment. Examples of such concerns are that organisms with novel properties could cause adverse effects in the environment if they survive and establish themselves, out-competing existing species or transferring their novel traits to other organisms. The introduction of co-competition could have evolutionary effects.

The migration of inserted genes (in particular resistance genes) from cultivated plants to wild species could cause weediness, while an artificially created selection pressure could lead to a dominance of GMOs. Once a GMO is released into the environment, it could be impossible to recall or prevent its spread and therefore adverse effects must be avoided as they might be irreversible.

While the potential environmental risks are more wide-ranging where the release of genetically modified microorganisms to the environment is involved, concern is also expressed with relation to the contained use of genetically modified microorganisms (GMMs), since organisms which are intended to be kept under containment could affect human health or the environment if they are released. Modified pathogenic or potentially pathogenic organisms can be used for certain contained operations, and organisms not designed and approved for release to the environment may find their way there.

Risk assessment and risk management

The introduction and use of GMOs is a recent development, where any associated risks are potential, but also where any longer-term effects are not known. Appropriate risk assessment and risk management are necessary to avoid upsetting the natural ecological processes and, if possible, to avoid undesirable evolutionary effects.

Potential adverse effects to the environment depend not only on the characteristics of the new organism, but also on the interaction with the environment and with the different organisms present in a certain ecosystem. Effective risk management means that a careful assessment must be made of each case, and the necessary measures taken, in relation to the potential risks posed.

The EU has taken a clear preventative approach in adopting legislation to establish a common set of environmental risk assessment requirements and safety measures. This is intended to protect the health of citizens and the environment, as well as ensuring a single unified market for biotechnology.

The EC Directive (90/219/EEC) on the contained use of genetically modified microorganisms covers all activities with GMMs, whether in research facilities or industrial installations. It provides for an appropriate system of risk management, recognising that not all GMMs, and their uses, entail the same risk.

The EC Directive (90/220/EEC) on the deliberate release of genetically modified organisms to the environment covers the environmental assessment and release approval of all GMOs through all the stages of release to the environment. Both small-scale and large-scale experimental introductions, as well as releases through product marketing, fall within the scope of this legislation. The focus of the Directive is risk management. As with other technologies, potential risks associated with the release of GMOs need to be identified and assessed and the appropriate measures taken. Risk management is about the effective assessment and control of any potential adverse consequences that could occur as a result of releasing new GMOs to the environment. The Directive introduces an approach of risk management based on the concept of step-by-step development and testing of novel organisms, whose risks and impacts are analysed on a case-by-case basis.

The Directive on GMO releases contains provisions for circulation of information on notifications for deliberate release of GMOs for research purposes between the EU Member States. The Directive also contains provisions for a common EU marketing approval procedure for GMOs placed on the market as products.

The provisions for circulation of information on notifications provides the EU Member States with a unique opportunity to follow the development of deliberate release of GMOs. Table 17.3 and Figure 17.2 give information on the release notifications sent to the European Commission from 23 October 1991 until 1 July 1994. The figure shows that most of the EU countries have had notifications for approval of releases. However, the number of releases varies greatly between countries.

Of the 292 notifications received so far only 18 have been for releases of genetically modified microorganisms. The rest have been for releases of genetically modified plants, as no notifications for releases of genetically modified animals have yet been circulated. Of the 16 different plant species released in the EU, the most frequently field tested are rape (Brassica napus ssp napus), maize (Zea mays), potato (Solanum tuberosum) and sugar beet (Beta vulgaris ssp vulgaris).

The trait which has been inserted in most organisms is herbicide resistance, and it has been introduced in over 50 per cent of the notified releases. In some cases herbicide resistance is inserted together with other main traits, as for instance male sterility or fertility restoration.

Notifications for the placing on the market of GMOs are now also being submitted for approval. Two vaccine products have been given environmental clearance and a bromoxmynil resistant tobacco has been approved. Herbicide (Basta) resistant rape seed is currently being evaluated.

CONCLUSIONS

Genetic engineering ­ the ability to transfer genetic material in new ways and radically alter the intricate genetic structure of individual living cells ­ has developed rapidly since it first became feasible in the mid-1970s, and promises to have enormous impacts on many sectors of the economy. These new techniques will, within a few years, result in many GMOs being placed on the market as products. This involves the use of new medical diagnostic tests, treatments and vaccines, improved foods, and agricultural and industrial products. However, the use of GMOs needs to be assessed and managed, in order to ensure that damage to human health and the environment is avoided. An environmentally sound management of biotechnology is a prerequisite for its safe and sustainable development.