RESUMEN
Compulsory integrated pest management poses a number of challenges and issues for debate. Some of are discussed with reference to European Union requirements set out in Annex III of Directive 128/2009. Requirements on the use of plant protection products bring with them problems with dose reduction in the light of a resistance prevention strategy, the lack of threshold levels, the necessity of chemical treatments and the limited availability of effective products of biological origin. Use of preventive measures of pest control faces barriers related to profitability and a lack of knowledge on the part of farmers. Challenges to control the system, as well as the fact that some legally enforced rules are not suitable for all crops, seem also to be an issue. © 2019 Society of Chemical Industry.
Asunto(s)
Unión Europea , Control de Plagas/legislación & jurisprudencia , Control de Plagas/organización & administraciónRESUMEN
Pests and diseases are a continuous challenge in agriculture production. A wide range of control strategies have been and will continue to be developed. New control strategies are in almost all countries around the world assessed prior to approval for use in farmers' fields. This is rightly so to avoid and even reduce negative effects for human health and the environment. Over the past decades the approval processes have become increasingly politicized resulting in an increase in the direct approval costs and the length in approval time without increasing the safety of the final product. This reduces the development of control strategies and often has negative human health and environmental effects. Possibilities exist for improvements. They include reducing approval costs and approval time by streamlining the approval process and substituting approval requirements by strengthening ex-post liability. © 2018 Society of Chemical Industry.
Asunto(s)
Control de Plagas/economía , Control de Plagas/legislación & jurisprudencia , Plaguicidas/economía , Plaguicidas/normas , Agricultura/economía , Agricultura/legislación & jurisprudencia , Animales , Control de Enfermedades Transmisibles/economía , Control de Enfermedades Transmisibles/legislación & jurisprudencia , Unión Europea , Organismos Modificados Genéticamente , Control Biológico de Vectores/economía , Control Biológico de Vectores/legislación & jurisprudencia , PlantasRESUMEN
BACKGROUND: Eradication of invasive alien species supports the recovery of native biodiversity. A new European Union Regulation introduces obligations to eradicate the most harmful invasive species. However, eradications of charismatic mammals may encounter strong opposition. Considering the case study of the eastern grey squirrel (Sciurus carolinensis Gmelin, 1788) in central Italy, we developed a structured decision-making technique based on a Bayesian decision network model and explicitly considering the plurality of environmental values of invasive species management to reduce potential social conflicts. RESULTS: The model identified priority areas for management activities. These areas corresponded to the core of the grey squirrel range, but they also included peripheral zones, where rapid eradication is fundamental to prevent the spread of squirrels. However, when the model was expanded to integrate the attitude of citizens towards the project, the intervention strategy slightly changed. In some areas, the citizens' support was limited, and this resulted in a reduced overall utility of intervention. CONCLUSION: The suggested approach extends the scientific basis for management decisions, evaluated in terms of technical efficiency, feasibility and social impact. Here, the Bayesian decision network model analysed the potential technical and social consequences of management actions, and it responded to the need for transparency in the decision-making process, but it can easily be extended to consider further issues that are common in many mammal eradication programmes. Owing to its flexibility and comprehensiveness, it provides an innovative example of how to plan rapid eradication or control activities, as required by the new EU Regulation. © 2016 Society of Chemical Industry.
Asunto(s)
Toma de Decisiones , Especies Introducidas , Control de Plagas/organización & administración , Sciuridae , Animales , Teorema de Bayes , Ciudades , Conservación de los Recursos Naturales/métodos , Italia , Modelos Teóricos , Control de Plagas/legislación & jurisprudencia , Opinión PúblicaRESUMEN
Invasive alien species constitute an increasing risk to forestry, as indeed to natural systems in general. This study reviews the legislative framework governing invasive species in the EU and Sweden, drawing upon both a legal analysis and interviews with main national level agencies responsible for implementing this framework. The study concludes that EU and Sweden are limited in how well they can act on invasive species, in particular because of the weak interpretation of the precautionary principle in the World Trade Organisation and Sanitary and Phytosanitary agreements. In the Swedish case, this interpretation also conflicts with the stronger interpretation of the precautionary principle under the Swedish Environmental Code, which could in itself provide for stronger possibilities to act on invasive species.
Asunto(s)
Agricultura Forestal/métodos , Bosques , Especies Introducidas/legislación & jurisprudencia , Política Ambiental/legislación & jurisprudencia , Control de Plagas/legislación & jurisprudencia , SueciaRESUMEN
Human-wildlife conflict is a global issue. Attempts to manage this conflict impact upon wild animal welfare, an issue receiving little attention until relatively recently. Where human activities harm animal welfare these effects should be minimised where possible. However, little is known about the welfare impacts of different wildlife management interventions, and opinions on impacts vary widely. Welfare impacts therefore need to be assessed objectively. Our objectives were to: 1) establish whether an existing welfare assessment model could differentiate and rank the impacts of different wildlife management interventions (for decision-making purposes); 2) identify and evaluate any additional benefits of making formal welfare assessments; and 3) illustrate issues raised by application of the model. We applied the welfare assessment model to interventions commonly used with rabbits (Oryctolagus cuniculus), moles (Talpa europaea) and crows (Corvus corone) in the UK. The model ranked interventions for rabbits (least impact first: fencing, head shot, chest shot) and crows (shooting, scaring, live trapping with cervical dislocation). For moles, managing molehills and tunnels scored least impact. Both spring trapping, and live trapping followed by translocation, scored greater impacts, but these could not be compared directly as they scored on different axes of the model. Some rankings appeared counter-intuitive, highlighting the need for objective formal welfare assessments. As well as ranking the humaneness of interventions, the model highlighted future research needs and how Standard Operating Procedures might be improved. The model is a milestone in assessing wildlife management welfare impacts, but our research revealed some limitations of the model and we discuss likely challenges in resolving these. In future, the model might be developed to improve its utility, e.g. by refining the time-scales. It might also be used to reach consensus among stakeholders about relative welfare impacts or to identify ways of improving wildlife management practice in the field.
Asunto(s)
Sacrificio de Animales/métodos , Bienestar del Animal , Cuervos , Topos , Control de Plagas/métodos , Conejos , Sacrificio de Animales/ética , Sacrificio de Animales/legislación & jurisprudencia , Distribución Animal , Bienestar del Animal/ética , Bienestar del Animal/legislación & jurisprudencia , Animales , Conducta Animal , Eutanasia Animal/ética , Eutanasia Animal/métodos , Actividades Humanas , Modelos Teóricos , Control de Plagas/ética , Control de Plagas/legislación & jurisprudencia , Restricción Física/ética , Restricción Física/instrumentación , Restricción Física/métodos , Reino Unido , Heridas y Lesiones/prevención & control , Heridas y Lesiones/veterinaria , Heridas por Arma de Fuego/veterinariaRESUMEN
Plant extracts and byproducts furnish various alternative products for crop protection and are traditionally used by farmers. However, the cost and timeframe for their registration as active substances are prohibitive for small companies and farmers' associations with the new Plant Protection Products (PPP) Regulation (EC) No. 1107/2009. However, there is now a possibility of registering light compounds as 'basic substances', a new category described in Article 23 and in 'Whereas/Recital 18'. We developed a regulatory expertise on the approval of such products within the framework of the PPP regulation. A Draft Assessment Report in one volume was established, later transformed by EC Directorate into a Basic Substance Application Template, and subsequently used by the EC as a matrix for the corresponding Guidelines for applicants (SANCO 10363/2012 rev. 9). Here we provide further tools, consisting of methodological, linguistic and strategic recommendations in order to constitute a Basic Substance Application (BSA) and proceed to its registration. While the use of alternative agents for crop protection is increasing both in organic and conventional agriculture, these usages are still considered as 'minor uses'. Our approach and tools are valuable to non-PPP specialised applicants for simplifying and facilitating their submission of the BSA.
Asunto(s)
Control de Plagas/legislación & jurisprudencia , Plaguicidas/normas , Enfermedades de las Plantas/legislación & jurisprudencia , Agricultura/legislación & jurisprudencia , Agricultura/métodos , Unión Europea , Control de Plagas/métodos , Enfermedades de las Plantas/prevención & controlRESUMEN
Feral swine (wild hogs) are one of the most widely distributed free-ranging mammals in the world. In the United States, feral swine serve as game animals for the sport of hunting in some areas, while they are nuisance species at other locations. Increasing feral swine populations creates negative impacts to growing crops, native plant communities, and wildlife. Feral swine can also serve as reservoirs for a number of bacterial and viral diseases that can infect wild animals, livestock, and humans. The US state governments are adopting statutes and regulations to reduce the growth and dispersal of feral swine populations. An analysis of these provisions suggests that while they seek to control feral swine populations, they are unlikely to provide any significant relief from damages to crops and native ecosystems. More localized reduction plans and a national disease control program are suggested to assuage damages being wrought by these invasive animals.
Asunto(s)
Animales Salvajes , Política Ambiental/legislación & jurisprudencia , Regulación Gubernamental , Control de Plagas/legislación & jurisprudencia , Sus scrofa , Animales , Conservación de los Recursos Naturales/legislación & jurisprudencia , Estados UnidosRESUMEN
The introduction of new food safety regulations in the European Union has resulted in the withdrawal of many synthetic active substances used in plant protection products, in light of their potential or actual harmful effect on human and animal health, as well as on the environment. Alternatives to these compounds are being developed - naturally occurring pesticides, also referred to as biopesticides. The use of biopesticides in crop protection leads to decreased levels of pesticide residues in foods, and as a result to lower risk levels for the consumer. Biologically active agents defined as biopesticides are varied, and therefore application of the same environmental and consumer safety criteria to all of them is impossible. This presents serious complications in the approval of these pesticides as active plant protection products and in their registration. It needs to be stressed that, in the registration procedure of the European Union, biopesticides are subject to the same regulations as synthetic active substances. This situation has resulted in the need to introduce numerous new provisions in the legislation, as well as the preparation of new guidelines facilitating the registration of biopesticides. These activities aim to promote naturally originating pesticides.
Asunto(s)
Seguridad Química , Control Biológico de Vectores , Control de Plagas/legislación & jurisprudencia , Plaguicidas , Unión EuropeaRESUMEN
In order to protect human health against communicable diseases, the German Protection against Infection Act (IfSG) requires the use of officially approved products and methods for officially ordered disinfection, disinfestation (control of arthropods) as well as measures for the management of vertebrate pests that spread pathogens. Official approval is granted by registration in lists published by the responsible federal health authorities and only for products and methods that have been tested and found to be sufficiently effective and do not have an unacceptable impact on health and the environment (§ 18 IfSG). It is not compulsory for manufacturers to have their products and methods listed in accordance with § 18 IfSG. In particular listing is not a prerequisite for access to the German market. Users are free to choose a product as long as no officially ordered measure, i.e. disinfection, disinfestation or measures against vertebrate pests, according to § 18 IfSG applies. However, it is highly recommended to use approved products included in the abovementioned lists even for routine application, as these registered products and methods have been tested, i.e. the efficacy has been proven by means of specific, recognized and quality assured testing procedures or by expert reports which have been confirmed by independent institutions.
Asunto(s)
Control de Enfermedades Transmisibles/legislación & jurisprudencia , Desinfección/legislación & jurisprudencia , Legislación de Medicamentos , Control de Plagas/legislación & jurisprudencia , Plaguicidas , Vertebrados , Animales , Control de Enfermedades Transmisibles/normas , Desinfección/normas , Guías como Asunto , Control de Plagas/normasRESUMEN
According to European biocide legislation, pest control products require assessment and authorization by the responsible national or European authorities. Biocidal products can only be authorized if they have no unacceptable effects on human health. The health risk assessment performed for authorization comprises (a) the derivation of reference values for the active substances and substances of concern contained in the biocidal product and (b) an exposure assessment. These parameters are required for risk characterization. No unacceptable health risks are expected if the determined exposure is less than the relevant reference value. In addition, the toxicological information is used for classification of the biocidal product. The assessment may, where necessary, result in specific conditions for use or other restrictions aimed at minimizing risk. The risk to human health from pest control products is mainly based on the toxicological properties of their active substances. Commonly, the coformulants used in pest control products are of less concern than the active substances (e.g., food ingredients and animal feed products). For example, most rodenticides belong to the group of anticoagulants, which are also effective in humans. Regarding intoxications through insecticides, the group of pyrethroids is of particular importance. Fumigants containing metal phosphides, hydrogen cyanide, or sulfuryl difluoride are particularly toxic. This toxicity is linked to the high acute inhalation toxicity of the gaseous active substances themselves or, in the case of phosphides, of the released gas phosphane. The aim of health risk assessment for the authorization of biocidal products is to ensure their safe application for users and all other persons involved, assuming an adequate and label-compliant use.
Asunto(s)
Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/etiología , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/prevención & control , Monitoreo del Ambiente/legislación & jurisprudencia , Contaminantes Ambientales/envenenamiento , Control de Plagas/legislación & jurisprudencia , Plaguicidas/envenenamiento , Monitoreo del Ambiente/métodos , Alemania , Humanos , Medición de RiesgoRESUMEN
European Community (EC) legislation has limited the availability of pesticide active substances used in effective plant protection products. The Pesticide Authorisation Directive 91/414/EEC introduced the principle of risk assessment for approval of pesticide active substances. This principle was modified by the introduction of Regulation (EC) 1107/2009, which applies hazard, the intrinsic toxicity of the active substance, rather than risk, the potential for hazard to occur, as the approval criterion. Potential impacts of EC pesticide legislation on agriculture in Ireland are summarised. While these will significantly impact on pesticide availability in the medium to long term, regulations associated with water quality (Water Framework Directive 2000/60/EC and Drinking Water Directive 1998/83/EC) have the potential to restrict pesticide use more immediately, as concerns regarding public health and economic costs associated with removing pesticides from water increase. This rationale will further reduce the availability of effective pesticide active substances, directly affecting crop protection and increasing pesticide resistance within pest and disease populations. In addition, water quality requirements may also impact on important active substances used in plant protection in Ireland. The future challenge for agriculture in Ireland is to sustain production and profitability using reduced pesticide inputs within a framework of integrated pest management.
Asunto(s)
Agricultura/legislación & jurisprudencia , Política Ambiental , Plaguicidas/economía , Agricultura/economía , Unión Europea , Irlanda , Irlanda del Norte , Control de Plagas/legislación & jurisprudencia , Control de Plagas/métodos , Plaguicidas/toxicidad , Políticas , Medición de RiesgoRESUMEN
BACKGROUND: This paper discusses U.S. agricultural pesticide use trends from 1964 to 2010 based on estimates developed from USDA surveys, and the influence of economic factors, agricultural policy, and pesticide regulation on aggregate quantities and mix of pesticides used. RESULTS: Synthetic organic pesticide use grew dramatically from the 1960s to the early 1980s, as farmers treated more and more acreage. Use then stabilized, with herbicides applied to about 95% of corn, cotton, and soybean acres, annually. Subsequently, major factors affecting trends were: (1) changes in crop acreage and other economic factors, (2) use of new pesticides that reduced per-acre application rates and/or met more rigorous health and environmental standards, and (3) adoption of genetically engineered insect-resistant and herbicide-tolerant crops. CONCLUSION: The use of pesticides and other control practices responded to economic factors such as input and output markets and agricultural policies. Changing societal values toward pesticide risks and benefits profoundly affected pesticide policy, influencing the pesticides available for use, but only indirectly affecting aggregate quantities used. While the current pesticide regulatory process might have economic inefficiencies, it might be consistent with policy preferences held by much of the public-to reduce pesticide hazards rather than minimize regulatory costs.
Asunto(s)
Agricultura/economía , Agricultura/legislación & jurisprudencia , Control de Plagas/economía , Control de Plagas/legislación & jurisprudencia , Plaguicidas/economía , Políticas , Agricultura/tendencias , Control de Plagas/normas , Control de Plagas/tendencias , Plaguicidas/normas , Estados UnidosRESUMEN
Mycotoxins contamination in some agricultural food commodities seriously impact human and animal health and reduce the commercial value of crops. Mycotoxins are toxic secondary metabolites produced by fungi that contaminate agricultural commodities pre- or postharvest. Africa is one of the continents where environmental, agricultural and storage conditions of food commodities are conducive of Aspergillus fungi infection and aflatoxin biosynthesis. This paper reviews the commodity-wise aetiology and contamination process of aflatoxins and evaluates the potential risk of exposure from common African foods. Possible ways of reducing risk for fungal infection and aflatoxin development that are relevant to the African context. The presented database would be useful as benchmark information for development and prioritization of future research. There is need for more investigations on food quality and safety by making available advanced advanced equipments and analytical methods as well as surveillance and awareness creation in the region.
Asunto(s)
Aflatoxinas/toxicidad , Países en Desarrollo , Contaminación de Alimentos , Enfermedades Transmitidas por los Alimentos/etiología , Aflatoxinas/análisis , Aflatoxinas/metabolismo , África del Sur del Sahara , Agricultura/legislación & jurisprudencia , Agricultura/métodos , Animales , Contaminación de Alimentos/prevención & control , Manipulación de Alimentos/legislación & jurisprudencia , Inspección de Alimentos/legislación & jurisprudencia , Calidad de los Alimentos , Enfermedades Transmitidas por los Alimentos/microbiología , Enfermedades Transmitidas por los Alimentos/prevención & control , Enfermedades Transmitidas por los Alimentos/veterinaria , Hongos/crecimiento & desarrollo , Hongos/metabolismo , Humanos , Legislación Alimentaria , Interacciones Microbianas , Micotoxinas/análisis , Micotoxinas/toxicidad , Control de Plagas/legislación & jurisprudencia , Control de Plagas/métodosRESUMEN
For more than a decade, the U.S. government has promoted integrated pest management (IPM) to advance sustainable agriculture. However, the usefulness of this practice has been questioned because of lagging implementation. There are at least two plausible rationales for the slow implementation: (1) growers are not adopting IPM-for whatever reason-and (2) current assessment methods are inadequate at assessing IPM implementation. Our research addresses the second plausibility. We suggest that the traditional approach to measuring IPM implementation on its own fails to assess the distinct, biologically hierarchical components of IPM, and instead aggregates growers' management practices into an overall adoption score. Knowledge of these distinct components and the extent to which they are implemented can inform government officials as to how they should develop targeted assistance programs to encourage broader IPM use. We address these concerns by assessing the components of IPM adoption and comparing our method to the traditional approach alone. Our results indicate that there are four distinct components of adoption-weed, insect, general, and ecosystem management-and that growers implement the first two components significantly more often than the latter two. These findings suggest that using a more nuanced measure to assess IPM adoption that expands on the traditional approach, allows for a better understanding of the degree of IPM implementation.
Asunto(s)
Agricultura/métodos , Ecosistema , Control de Insectos/métodos , Control de Plagas/métodos , Agricultura/economía , Agricultura/legislación & jurisprudencia , Animales , Toma de Decisiones , Control de Insectos/economía , Control de Insectos/legislación & jurisprudencia , Control de Plagas/economía , Control de Plagas/legislación & jurisprudencia , Formulación de Políticas , Medición de Riesgo/métodosRESUMEN
Drivers behind food security and crop protection issues are discussed in relation to food losses caused by pests. Pests globally consume food estimated to feed an additional one billion people. Key drivers include rapid human population increase, climate change, loss of beneficial on-farm biodiversity, reduction in per capita cropped land, water shortages, and EU pesticide withdrawals under policies relating to 91/414 EEC. IPM (Integrated Pest Management) will be compulsory for all EU agriculture by 2014 and is also being widely adopted globally. IPM offers a 'toolbox' of complementary crop- and region-specific crop protection solutions to address these rising pressures. IPM aims for more sustainable solutions by using complementary technologies. The applied research challenge now is to reduce selection pressure on single solution strategies, by creating additive/synergistic interactions between IPM components. IPM is compatible with organic, conventional, and GM cropping systems and is flexible, allowing regional fine-tuning. It reduces pests below economic thresholds utilizing key 'ecological services', particularly biocontrol. A recent global review demonstrates that IPM can reduce pesticide use and increase yields of most of the major crops studied. Landscape scale 'ecological engineering', together with genetic improvement of new crop varieties, will enhance the durability of pest-resistant cultivars (conventional and GM). IPM will also promote compatibility with semiochemicals, biopesticides, precision pest monitoring tools, and rapid diagnostics. These combined strategies are urgently needed and are best achieved via multi-disciplinary research, including complex spatio-temporal modelling at farm and landscape scales. Integrative and synergistic use of existing and new IPM technologies will help meet future food production needs more sustainably in developed and developing countries, in an era of reduced pesticide availability. Current IPM research gaps are identified and discussed.
Asunto(s)
Agricultura/legislación & jurisprudencia , Ecología/legislación & jurisprudencia , Inocuidad de los Alimentos , Control de Plagas/legislación & jurisprudencia , Plaguicidas , HumanosRESUMEN
America's school children are at risk of developing asthma and other respiratory illnesses as a result of exposure to hazardous pesticides. Integrated pest management (IPM) policies are being implemented in states and school districts across the country; however, the content and regulation of these policies vary. The need for standardization of such policies and a federal IPM law is the only way to ensure that children in America's schools are adequately protected from exposure to hazardous pesticides used to control pests.
Asunto(s)
Exposición a Riesgos Ambientales/prevención & control , Control de Plagas/organización & administración , Plaguicidas , Política Pública , Humanos , Gobierno Local , Exposición Profesional/prevención & control , Política Organizacional , Control de Plagas/legislación & jurisprudencia , Gobierno Estatal , Estados UnidosRESUMEN
Pesticide Risk Indicators (PRIs) are widely used to evaluate and compare the potential health and environmental risks of pesticide use and to guide pest control policies and practices. They are applied to agricultural, landscape and structural pest management by governmental agencies, private institutions and individuals. PRIs typically assess only the potential risks associated with the active ingredients because, with few exceptions, pesticide manufacturers disclose only the identity of the active ingredients which generally comprise only a minor portion of pesticide products. We show that when inert ingredients are identified and assessed by the same process as the active ingredient, the product specific risk can be much greater than that calculated for the active ingredient alone. To maintain transparency in risk assessment, all those who develop and apply PRIs or make decisions based on their output, should clearly disclose and discuss the limitations of the method.
Asunto(s)
Contaminantes Ambientales/química , Contaminantes Ambientales/toxicidad , Control de Plagas , Plaguicidas/química , Plaguicidas/toxicidad , Control de Plagas/legislación & jurisprudencia , Control de Plagas/métodos , Control de Plagas/normas , Medición de Riesgo , Estados UnidosRESUMEN
This manuscript provides an overview of past wildlife contraception efforts and discusses the current state of research. Two fertility control agents, an avian reproductive inhibitor containing the active ingredient nicarbazin and an immunocontraceptive vaccine, have received regulatory approval with the Environmental Protection Agency and are commercially available in the USA. OvoControl G Contraceptive Bait for Canada Geese and Ovo Control for pigeons are delivered as oral baits. An injectable immunocontraceptive vaccine (GonaCon Immunocontraceptive Vaccine) was registered with the Environmental Protection Agency for use in female white-tailed deer in September 2009. An injectable product (GonaCon Immunocontraceptive Vaccine) is registered for use in female white-tailed deer. Both products are labeled for use in urban/suburban areas where these species are overabundant. Several other compounds are currently being tested for use in wildlife in the USA, Europe, Australia and New Zealand that could have promise in the future. The development and use of reproductive inhibitors for resolving human-wildlife conflicts will depend on a number of factors, including meeting the requirements of regulatory agencies for use in the environment and on the biological and economical feasibility of their use. Use will also be dependent on health and safety issues and on public acceptance of the techniques.
Asunto(s)
Anticoncepción Inmunológica/veterinaria , Anticoncepción/veterinaria , Anticonceptivos/normas , Nicarbazina/uso terapéutico , Control de Plagas/métodos , Vacunas Anticonceptivas/uso terapéutico , Animales , Animales Salvajes , Aves , Anticoncepción Inmunológica/métodos , Ciervos , Hormona Liberadora de Gonadotropina/agonistas , Humanos , Nicarbazina/farmacología , América del Norte , Control de Plagas/legislación & jurisprudencia , Control de Plagas/estadística & datos numéricos , Opinión Pública , Vacunas Anticonceptivas/farmacologíaRESUMEN
There remains a lack of a clear overarching policy framework for decision-making in pest control programmes. In comparison, ethical principles have been extensively developed for scientific procedures, such as those underlying the UK's Animals (Scientific Procedures) Act 1986. This paper assesses the extent to which the principles and methodology underlying the act and secondary guidance could be used to provide principles of rodent management. Useful principles include that any programme has a legitimate purpose; that methods are used only if the harms are outweighed by the benefits; that harms are minimised by refinement, replacement and reduction and that there is personal responsibility. The usefulness and implications for pest control of each principle and the overall approach are discussed.