Every second, even as you read this paper, three babies are born each of whom has a right to sufficient food. This means that every day there are approximately 250,000 new mouths to feed, or about 90-100 million a year. By the Year 2000 it is estimated that the world population will stand around 8.5 billion, and around 95% of the increase is expected to be in the developing countries (Bayer, 1992). Experts therefore, predict that in the coming decades all problems that concern us today will be greatly overshadowed by the problem of ensuring sufficient food supplies.

There are nearly six billion people in the world now. Of the six billion, 700 million live below the "poverty line". A hungry man would not think of tomorrow but try to get the maximum out of the accessible resources today. Resulting exhaustive agriculture and resource management lead to environmental degradation, which in turn may cause agriculture to suffer from productivity. (To illustrate, when pesticides are applied continuously to curb the pests in the high yielding varieties, the pesticides become ineffective owing to the development of resistance posed by the insect pests after a certain period of exposure. This would require increased application).

The world does actually produce enough food to feed the present population. So couldn't the entire problem of malnutrition be solved by "more just" distribution of the food resources? This is often repeated, but it is an utopian dream, and will remain so.

In the short term, in acute emergencies, food aid is of undisputed value and is given time and time again. In the long term, however, each country must promote agricultural production itself. It is because past experience has shown that constant assistance from outside paralyses national initiatives, completely undermining all market mechanisms driving the economy.

"Helping countries to help themselves" is therefore the central aim of the international community. In other words, the causes of malnutrition must be attacked at the root and the fundamental nutritional conditions of each country must be improved by stimulating domestic agriculture.

Productivity
The need toincrease agricultural productivity in the developing countries is undisputed. This can be achieved through national programmes to provide the necessary infrastructure, advanced research and impart technical knowledge in the farming sector and also through agricultural training and advisory activity.

This agricultural development package includes the measures needed to increase yields such as the use of high yielding resistant varieties, fertilizers, irrigation and cultivation techniques. It also contains the measures to safeguard the yields such as protection of crops in the fields and during storage after the harvest.

Since in most developing countries the area under cultivation cannot be increased in line with the anticipated population growth, the yield potential will in future not only have to be exploited to the full, but also greatly increase a goal which must be permanently sustainable and which necessitates the use of intensive farming approach.

Role of pesticides in intensive farming
Pesticides are chemicals or natural substances that control pest populations mainly by killing the pest organisms, may be insects, weeds or animals. In 1985 roughly 2,300 million kilograms of pesticides were used world-wide. About 15% of this, including 30% of all insecticides, is used in the Third World. Pesticides use is increasing particularly quickly in developing countries where it is regarded as an easy way to raise production and is often actively promoted and subsidised. It is widely recognised that since the modern synthetic pesticides started to come into the use about 50 years ago, they have made substantial contribution to the agriculture of both developed and developing countries. In the latter, especially they have saved millions of human lives and alleviated distress in great many people, as well as in domestic animals. Although various methods are used to control pests in different pest management systems, pesticides are at present the most important factor in most national programmes, and this will be so for the foreseeable future.

However some disadvantages and dangers of using pesticides are gradually becoming clearer as stated below:

* Yearly, thousands of people are poisoned by pesticides, about half of them in the Third World. For example, in 1983, a total of about 2 million people suffered from pesticide poisoning, and 40,000 of the cases were fatal (Schoubroeck et al, 1990). Because of their toxicity, many types of pesticides, e.g. DDT, has been banned in industrialised countries. However, they are still being used in many developing countries.

* Over time, pest build-up resistance to pesticides, which must then be used in ever higher doses to have effect. Eventually, new pesticides must be developed - a very expensive process. Pest resistance builds up more rapidly in tropical than in temperate climates as biological process are more rapid at higher temperatures. In 1984, resistance to pesticides was known for 447 insects and mites, 100 plant pathogens, 55 kinds of weeds, two kinds of nematodes and five kinds of rodents (Gips, 1987).

* Pesticides kill not only organisms that cause damage to crops but also useful organisms such as natural enemies of pests. The incidence of pest attacks and secondary pest attack may increase after pesticides have killed the natural enemies (resurgence).

* Only a small proportion of the pesticides in fields reaches the organisms that are supposed to be controlled. The major part reaches the air, soil or water, where it has a damaging effect on living organisms. Aquatic organisms are particularly sensitive to pesticides.

* Pesticides that do not breakdown easily are absorbed in the food chain and cause considerable damage to insects, insect consuming animals, prey birds and, ultimately human beings.

The indiscriminate use of pesticides in intensive farming has caused destruction of beneficial organisms, resistance against pesticides, residues in food chains, air and water pollution and health hazards causing environmental imbalances. In order to overcome such adverse effects the current thrust in plant protection is on promoting Integrated Pest Management (IPM), which is ecologically sound, economically viable and socially acceptable for the sustainable development of crop production.

The concept of sustainable agriculture
The production in agriculture could only be sustainable, if the productivity of land, water resources and labour are not allowed to degrade further. The other terms used for sustainable agriculture include natural, ecological, biological, alternative, low input and regenerating agriculture in contrast to high input maximised production systems practised under intensive agriculture.

Sustainable agriculture has been defined as "The integration of sustainable development techniques and traditional farming practices towards environmentally sound, economically viable, socially justifiable and humane agricultural systems. The concept of sustinability has been described by FAO as that which should involve the successful management of resources for agriculture to satisfy changing human needs while maintaining or enhancing the quality of the enviornment and conserving the natural resources". The research branch of Agriculture Canada, defines sustainable agriculture systems as "those that are economically viable and most societies needs for safe and nutrition food, while conserving of enhancing natural resources and the quality of the environment for future generation".

What is Integrated Pest Management?
"Integrated Pest Management means a pest management system that, in the context of the associated enviornment and the population dynamics of the pest species, utilizes all suitable techniques and methods in as compatible a manner as possible and maintains the pest population at levels below those causing economically unacceptable damage or loss".

Integrated Pest Management is a holistic interdisciplinary approach which considers the ecological and socio-economic conditions of a site as one unit, and strives to maintain the productivity of the agro-eco system on a sustainable basis.

It focuses on controlling the losses caused by pests, utilizing natural limiting factors, the selective use of cropping and cultivation techniques and plant breeding measures.

Measures to control pest in festation take into account all the anticipated ecological, toxicological and economic impacts; preference is given to non-chemical methods over the application of chemical pesticides.

Success of IPM
The philosophy and principles of integrated pest management (IPM) have been known for the past 25 years. Although IPM programmes are operational in the developed countries, farmers in the developing countries started adopting IPM practices as a package only very recently. However, farmers in the developing countries used various components of IPM such as cultural pest control practices along with natural botanicals to safeguard their crops from insect pests prior to the introduction of synthetic pesticides. The important success of IPM is achieved through the reduced use of pesticides. For example, since the declaration of the national IPM policy in 1986, Indonesia's annual rice production has increased by more than 15%, its average yield per hectare has exceeded 4.5 tonnes and its use of insecticides in rice has decreased by more than 50% (FAO 1994).

Studies conducted in the Asian region reveals the significant yield increases in the fields where IPM was adopted. Insecticide cost savings were greater than 50% at farm level as shown in experiences in IPM programmes in Bangladesh, China and Vietnam. The number of pesticide applications in the IPM fields of rice and chilli in Sri Lanka were reduced by 25% and 50% respectively compared to farmers practice (Jones, 1996). The reduction of pesticide application has indirectly increased the income in the IPM fields.

The economic benefits from IPM are first recognized by farmers as reduction in cash cost of production. Other benefits from IPM are reduced health risks, increased production of fish and other aquatic foods and pest reduction in other crops by predators conserved in rice.

IPM and sustainable agriculture
The combination of IPM to sustainability is derived from ecological, social and economic factors.

The ecological sustainability of IPM comes from dynamic natural process, which are non-contaminating self-renewing and enviornmentally benign. These include durable crop resistance to pests, the actions of natural enemies and the capabilities of crops to compensate for pest damage.

IPM is socially sustainable because farmers own it. IPM is institutionalised at the level of the farming community and local government. Farmers, as IPM experts, are able to experiment and respond with solutions to changing pest problems.

IPM systems are economically sustainable because IPM programmes reduce farmers' dependence on projects' input of pesticides and Government need to impact or supply them and improve profitability of the crop.

Conclusion
The control of pests is one of most challenging job in tropical and sub-tropical agriculture. In the recent years, the public concern over the pesticide hazard to human health and the environment and squandering of non-renewable natural resources (pesticides are overwhelmingly petroleum derived) are the factors that should hasten the transition of IPM. The development of IPM practices, and the use of selective and relatively safe chemicals, that too only when the economic threshold level have exceeded the prescribed level are the positive steps taken to reduce the pesticide pollution.

Since the first phase of the green revolution has helped in conquering endemic hunger in the world, organic farming will help us in a big way to avoid dumping off of thousands of tonnes of agro-chemicals on the earth every year and give us pesticide residue-free food, safe environment and better living standards.

This has reference to the article titled ''India and Pakistan nuclear tests pose danger to Sri Lanka'' in the Island of 14-7-98 based on an interview given by Dr. Granville Dharma-wardana, Director of the Radioistope Centre and former Chairman of the Atomic Energy Authority (1979-1989). I am writing this to correct the incorrect and misleading statement contained in this article and will be grateful to you to give it the same publicity given to this article. It is regrettable the writer of this article did not consider obtaining the views of the Atomic Energy Authority before publishing it.

The above article implies that nothing had been done to determine whether Sri Lanka was affected by recent testing carried out by India and Pakistan. This is wrong. The Atomic Energy Authority (AEA) in collaboration with the Radioisotope Centre of the University of Colombo, of which Dr. Dharmawardana is the Director, has been routinely monitoring environmental radioactivity over a period of two years. The samples analysed after the Indian and Pakistani testing showed absolutely no increase of radioactivity and as the Chairman of the AFA, I state with full responsibility and utmost confidence that Sri Lanka was not affected at all by the underground testing carried out by India and Pakistan. The Atomic Energy Authority published a press release to this effect on 20th of May, 1998.

Incorrect
It is absolutely incorrect to say that we do not have the necessary monitoring equipment. Both the Atomic Energy Authority and the Radioisotope Centre have equipment and trained personnel to measure radioactivity. The AEA annually analyses about 2500 samples of import and export products for radioactive contamination and imported milk products are released to the market only after it is certified by AEA that they are free of radioactivity.

It is true that in spite of being a scientific organization and employed several highly qualified scientific officers, the AEA (established in 1969) did not have any laboratory facilities of its own during the first 20 years of its existence. Only after 1989, when Dr. Douglas Nethsinghe was appointed as the Chairman a concerted effort was made to obtain laboratory facilities for the AEA. During the past several years the AEA has been able to develop limited laboratory facilities and is in the process of constructing a properly designed laboratory building. The development achieved by the AEA during the last few years is reflected in the income generated by AEA by provision of services, which has gone up from Rs.4000 in 1988 to Rs.4.75 million in 1997.

The statement that three nuclear power plants each with a capacity of 1000 MW have been constructed in South India is wrong. India had been negotiating with the former USSR to construct two 1000 MW plants in South India. The implementation of this project was delayed considerably after the break-up of USSR and although there are plans to construct these plants with the assistance of the Russian Federation the project is yet to commence.

Radiation
The statement that 1 unit of radiation can cause 2200 cancers is wrong. The number of cancers does not only depend on the dose of radiation but also the number of people exposed to radiation. It would be absurd to say there would be 2200 cancers if only one person is exposed to radiation. According to the United Nations Scientific Committee on Effects of Atomic Radiation (UNSCEAR), if a population of 1 million is exposed to an average radiation level of 1 mSv (this is about half the average annual natural background radiation level and maximum annual permissible level of exposure to radiation for general public) there would be 50 additional cancers. This is much less than the incidents of cancer in a population of one million due to other causes. The symptoms mentioned such as diarrhoea and nausea occur in those who are exposed to very high doses of radiation in the range of 1000 mSv (or 1 Sv) as a result of a major accident. The 30 fire fighters who died in the Chernobyl accident were exposed to these levels of radiation.

The article quoting Dr. Dharmawardana also says that the public should have been advised to stay indoors, switch off Air-conditioners, etc. This course of action should have been followed if there has been an increase of radioactive contamination that could lead to doses of radiation exceeding recommended intervention levels. But certainly not in this situation where there was absolutely no radioactive contamination. The suggested course of action would have only caused panic.

No protest
If there was any release of radioactivity in the Indian testing which was carried out very close to the Pakistan border, Pakistan would have been the first country to highlight it and register its protests in international forums. The same can be said about Pakistani testing.

Why ask Sri Lankans to stay in doors when India and Pakistan did not do so.

Treaty
A treaty known as the Partial Test Ban treaty prohibits testing of nuclear weapons in the atmosphere, under water and in outer space and allows only underground testing. The objective of this treaty is to prevent the release of radioactivity to the environment in nuclear testing. The countries that have signed this treaty include India, Pakistan and the nuclear weapons states. Prior to signing this treaty in 1963, USA had carried out 193 atmospheric tests and USSR 142. The increase in the average annual dose in 1963, due to all these atmospheric tests was only 7% of the natural background radiation dose. (Source: Radiation, Doses, Effects and Risks: United Nations Environmental Programme-1985). Could eleven tests carried out underground have affected Sri Lanka?

If the statements attributed to Dr. Dharamawardana in this article are correct it would not be the first occasion for such incorrect and misleading public statements to have been made by him on this issue. Even in the past Dr. Dharmawardana on several occasions has used the media to aim similar baseless criticisms at the AEA. If this is done out of national interests as claimed, then Dr. Dharmawardana who is a former Chairman of the AEA, should have first brought what he perceives as shortcomings, to the notice of the AEA without making public statements criticizing the AEA for not taking any action, even without bothering to find out what the AEA has done.

The writer holds a PhD in Nuclear Engineering from USA and is a Chartered Engineer.