Lecturer in Agricultural Protection, School of Agriculture, Charles Sturt University.
Wagga Wagga. NSW 2678
The Australian community is experiencing heightened awareness of environmental and public health issues and this has focused attention on pesticides and their potential hazards. The result has been strong pressure on those involved in farm chemical management to limit the use of these products. At the extreme there are those who wish to ban pesticides completely or at the least impose very harsh legislation to strictly control their use (Kent, 1991).
From an agricultural industry perspective, pesticides are an important component of economic and effective pest control and their continued use is essential. With the benefits of increased knowledge and experience, it is apparent that these products must no longer be used as they were in the past. All farm chemicals must be utilised strategically in the farming system and only be applied with care by competent operators. We all benefit from farm chemicals and therefore we all have a responsibility to ensure that these benefits are maximised, while any adverse effects are minimised.
What are pesticides?
Pesticides (or farm chemicals, agro chemicals or agvet chemicals) are those substances which are used to control, destroy, repel or attract pests in order to minimise their detrimental effects. Pests are those organisms like weeds, insects, bacteria, fungi, viruses and animals which adversely affect our way of life. Pests can reduce the quality and quantity of food produced by lowering production and destroying stored produce; they can harm our animals (like fleas, worms and diseases); they compete with humans for food and affect the health, welfare and way of life of people; they can destroy buildings (termites) and are a major cause of land degradation (noxious weeds, rabbits, feral pigs, etc). Pests are also a major nuisance around our homes (prickles in the lawn, flies,etc). Pest activity greatly increases the costs of farming.
Pesticides therefore are used in many situations such as livestock farming, cropping, horticulture, forestry, home gardening, homes, hospitals, kitchens, roadsides, recreational and industrial areas. They are a vital facet of farming and our everyday life.
Pesticides may be derived from inorganic sources (copper, sulphur), natural organic sources (plants) or be organic compounds synthesised in a laboratory. Many of these synthesised products mimic the activity of natural organic compounds.
While the first recorded use of chemicals to control pests dates back to 2500 BC, it is really only in the last 50 years that chemical control has been widely used (Hock et al., 1991). Many of the earliest pesticides were either inorganic products or derived from plants, for example burning sulphur to control insects and mites. Other early insecticides included hellebore to control body lice, nicotine to control aphids, and pyrithrin to control a wide variety of insects. Lead arsenate was first used in 1892 as an orchard spray while about the same time it was accidentally discovered that a mixture of lime and copper sulphate (Bordeaux mixture) controlled downy mildew, a serious fungal disease of grapes. It is still one of the most widely used fungicides (Hock et al., 1991).
Many of these early chemicals had disadvantages. They were often highly toxic, were very persistent, posing a threat to the environment, or they damaged the crops they were meant to protect.
The modern era of chemical pest control commenced during World War II. For example, the much maligned DDT played a major role in the health and welfare of soldiers who used it to control body lice and mosquitoes which transmitted major illnesses. Further developments of insecticides and herbicides followed. With their relatively low cost, ease of use and effectiveness, they became the primary means of pest control. Protection of crops, produce, animals and humans over extended periods became possible with corresponding increases in food production and improved standards of living (Hock et al., 1991).
Modern pesticides are sophisticated compounds which are very carefully researched to ensure they are effective against target organisms, are safe to the environment and can be used without undue hazards to the operators or consumers. Many of these have been developed to target specific biochemical reactions within the target organism, e.g. an enzyme necessary for photosynthesis within a plant or a hormone required for normal development in an insect. Modern chemicals are much safer, more specific and friendlier to the environment than the older products they have replaced.
Why do we need farm chemicals?
Farm chemicals are important because they enable us to produce sufficient high quality, wholesome food for a growing population. They also allow efficient and economic pest control and often there is no alternative control option.
People who enjoy a healthy lifestyle because they have unrestricted access to an abundance of good, inexpensive food easily overlook the fact that historically starvation has been a major health hazard. Civilization has been combating weeds, insects, diseases and other pests throughout history and there are many examples of how these pests have had a major impact on humans. One of the worst examples is the Black Plaque of Europe in the fourteenth century when millions died from a bacterial disease spread by fleas from rats (Hock et al., 1991). Another example is the infamous Irish potato famine of the nineteenth century in which millions died and many more were forced to emigrate. A fungus also destroyed the entire German potato crop in the early twentieth century resulting in 700,000 deaths from starvation (Anon, 1992a). These disruptions directly influenced Australia's population.
In many countries similar situations continue. Economically advanced countries have plenty of good wholesome food due to a scientific approach to agriculture which includes the use of pesticides.
Without the use of farm chemicals, the production and quality of food would be severely jeopardised with estimates that food supplies would immediately fall to 30 to 40% due to the ravages of pests (Anon, 1990b; Anon, 1992a). While there are mountains of food in Europe and the US, this represents only 45 days food supply for the world. Only part of the problem is distribution and the ability to pay for purchases.
A recent United Nations report (Anon, 1992b) stated that population growth is a major problem facing our planet. In 1900 there were 1.6 billion people on the planet. In 1992 this had risen to 5.25 billion and by the year 2050 it will reach 10 billion. World population is increasing by 97 million per year. By the year 2000, 50% of world population will live in cities (Anon, 1992c) and 75% will live in developing countries. This explosive increase in world population is mostly in developing countries and this is where the need for food is greatest. FAO estimates that 500 million are already undernourished. There is a limit to new areas to cultivate, therefore we must increase agricultural production from the areas available.
At a local level, Australia has a population of around 17 million. Each of us eats approximately 770 kg food each year. We only have 160,000 farmers to provide this food and to earn valuable export dollars. One hundred years ago, each farmer was able to produce enough food to feed 6 other people. By 1960 this had risen to 26 other people, by 1980, 70 people, and now, each farmer is able to feed and clothe more than 80 other Australians plus earn around $12 billion or 25% of total export earnings (Craven, 1992). In the 15 years from 1975 to 1990, the value of farm produce rose from $3.5 to $14.3 billion and even taking inflation into account, this still represents a 36% increase in value. It is estimated (Anon, 1990b) that farm chemicals contribute nearly $4 billion of this to the Australian economy. Every one of us benefits through agriculture's contribution to our standard of living.
While there may be some nervousness about the misuse of pesticides, there would be even more concern if there were no means of combating insects such as plague locusts which can eat up to 100,000 tonnes of green plants in a day. AVCA (Anon, 1990a) calculates that without pesticides, Australia would lose $7000 million per year because, for example, wheat yields would be reduced by up to 70% due to weeds and the loss from sheep blowfly would be $465 million per year. It would also not be economical to grow cotton worth between $300 and $500 million per year in exports.
Australian food is recognised as some of the healthiest, safest and most pest- and disease-free in the world, a status which is valuable for securing export markets. It is essential we maintain this clean status (Stephens and Harris, 1992).
Advantages Of Using Pesticides
Pests are an ecological problem and therefore our control strategies must be ecologically sound.
Basically, there are two approaches to pest control:
cure or removal of the cause.
Modern agriculture is a combination of both and human intervention is necessary, whether it be pulling out weeds by hand, use of pesticides or genetic engineering. Control methods evolve over time as knowledge and techniques improve. This includes the development of chemical means of control which become very important because of a number of advantages. For example:
Cost effectiveness. Farm chemicals are an economical way of controlling pests. They require low labour input and allow large areas to be treated quickly and efficiently. It has been conservatively estimated that for every dollar a farmer spends on farm chemicals he receives $4 return (Anon, 1990a). Production per labour unit has increased while production costs and energy inputs are lower.
Timeliness and flexibility. A suitable farm chemical is available for most pest problems with variations in activity, selectivity and persistence. The best product can be chosen for the situation. This allows more flexibility in management options and better timeliness of pest control.
Quality, quantity and price of produce. Farm chemicals ensure a plentiful supply and variety of high quality, wholesome food at a reasonable price. Modern society demands nutritious food free from harmful organisms and blemishes. Ornamental horticulture also requires unblemished and pest-free plants and flowers. This would be very difficult without farm chemicals.
Prevention of problems. Farm chemicals are frequently used to prevent pest problems from occurring, e.g. preventing weeds in gardens and lawns; treatment of export and import produce to prevent the spread of pests; treatment of stored products to prevent pest attack and destruction during storage.
Protection of pets and humans. Without farm chemicals the treatment of spiders, cockroaches, etc in houses; fleas on pets, etc, would be most difficult.
Protection of the environment. If no farm chemicals were available to control environmental pests like noxious weeds, feral animals, etc, our environment would suffer very badly. Using herbicides to control crop weeds reduces the need for cultivation, thus reducing land degradation.
Farm chemicals are a management tool to aid in the control of pests and their continued use is supported by the conclusions of the Senate Select Committee on Agricultural and Veterinary Chemicals in Australia, and even Dr Kate Short of the Total Environment Centre states: "we do not have a problem with pesticides being used as a management tool in pest control in Australian agriculture" (Colston et al., 1990).
Potential adverse effects of pesticides
Despite their many advantages, there are some potential hazards or risks when using farm chemicals. These risks may be associated with all chemicals whether they be industrial chemicals, pesticides, household products or even natural chemicals found in the environment. Undesirable side effects of farm chemical use usually stem from a lack of understanding of the impact of the chemical on the environment, compounded by indiscriminate and overuse of the product. These side effects do not always occur when farm chemicals are used and damage does not necessarily result. Some of these effects may be:
1. Reduction of beneficial species. Non-target organisms, including predators and parasites of pests, can also be affected by chemical application. The reduction of these beneficial organisms can result in changes in the natural biological balances. Losses of honeybees and other pollinating insects can also be a problem.
2. Drift of sprays and vapour during application can cause severe damage and residue problems in crops, livestock, waterways and the general environment. Care in the methods of application and the weather conditions under which it is carried out can reduce drift. Environmental pollution from careless application and runoff can result in wildlife and fish losses. This should be a concern for all of us.
3. Residues in food for humans and feed for livestock can be a consequence of direct application of a chemical to the food source, by the presence of pollutants in the environment or by transfer and biomagnification of the chemical along a food chain. Not all residues are undesirable although good agricultural practice must be observed to prevent unnecessary and excessive levels of residues.
4. Ground water contamination by leached chemicals can occur in high use areas if persistent products are used.
5. Resistance to the pesticide used can develop in target pests due to overuse and incorrect use of the chemical.
6. Poisoning hazards and other health effects to operators can occur through excessive exposure if safe handling procedures are not followed and protective clothing not worn. Poisoning risks depend on dose, toxicity, duration of exposure and sensitivity.
7. Other possible health effects due to indiscriminate use of farm chemicals also concern many people in the community.
Problems result from misuse, abuse and overuse. Farm chemicals can be used safely and effectively without these undesirable effects although there is always a risk associated with any activity. This risk is relative, as evidenced by smoking or driving a car or a tractor. For example, in May this year, 166 Australians died in motor vehicle accidents while there are very few poisonings from farm chemicals. Many commonly used substances like aspirin or common salt are more toxic than many pesticides.
Despite the relative risks being low, all users of farm chemicals, whether on a large scale or in the home, have a responsibility to use them correctly.
Maximising benefits of farm chemicals
We must aim to maximise the advantages and benefits of farm chemicals while minimising potential problems. This can be achieved in three ways:
(i) by ensuring there are adequate safeguards over the manufacture, sale and use of these products;
(ii) by ensuring farm chemicals are only used with an integrated pest management (IPM) approach;
(iii) by ensuring farm chemicals are used correctly, safely and accurately by well trained and competent applicators.
Each of these will be considered in turn.
In Australia there are very stringent controls and regulations governing all aspects of farm chemicals, including:
- development and testing
- transport, storage and sale
- residues in food
- disposal of waste
- environmental contamination
It is important to understand the development and testing procedures to which modern pesticides are subjected, and the controls placed on their use. A company cannot simply develop a chemical, call it a pesticide and immediately sell it. A long and costly process is involved. Out of every 10,000 compounds developed by chemists, only about one completes the development phase and satisfies the many controls that have to be passed before it can be offered for sale.
Any pesticide must be registered with Federal government authorities before sale. To gain registration all public health, occupational health, environmental and agricultural concerns must be satisfied. This requires rigorous testing by government and independent scientific experts. Data provided includes the fate and effects of the chemical and its breakdown products in the environment and in foodstuffs; possible impact on wildlife; toxicity to all organisms including humans; prolonged exposure tests; effects on reproduction, etc. All tests are conducted to international standards. All agricultural and veterinary chemicals are subject to ongoing review at all times thus ensuring that new scientific information can be taken into account as soon as it becomes available. Should this information indicate a problem with a chemical product then its use may be severely restricted or its registration withdrawn thus making it illegal to sell or use the product. The time scale from synthesis to final marketing takes anything from 8 to 12 years and requires an investment by the company of around $50 million.
As well as stringent controls over the development and sale of pesticides, there is also strict regulation of their use. This regulatory system aims to protect human and environmental safety, ensure product effectiveness thereby avoiding unnecessary chemical use, and to safeguard Australia's export trade by ensuring our produce is free of pests and also free of unwanted chemical residues.
To back up this comprehensive legislation, State and Federal authorities monitor pesticide use through inspectors and continual testing of produce for illegal residues.
With these levels of control, we can be confident that commercial farm chemicals are effective and can be used with minimum adverse effects, and our food is free of undesirable residues provided the chemicals are applied correctly and the directions on the label are adhered to. In my opinion, if substances such as beer, wine, cigarettes and probably even peanut butter were to undergo the same level of testing and control to which pesticides are subjected, they would never be available for sale. In fact, pesticides are tested to the same levels as human medicines (Anon, 1992a).
At this point I must express my concern that many of the home-made "pesticides" and other substances which are substituted for commercial pesticides do not undergo this testing and are not subject to controls. The result is that we have no information on the residues they leave in food or the effect they have on the environment. This is an area the organic farming movement needs to urgently address. Simply substituting one product for another does not constitute organic farming and naturally occurring chemicals are not necessarily better than synthesised ones. They are all chemicals.
(ii) Operator competency
Competency is a combination of knowledge, skills and attitude. Farm chemical users need to know what they are doing and have a sound knowledge of the products they are using. They then need to have the skills to ensure this knowledge is used to best advantage, while the correct caring attitude is necessary to safeguard themselves, their families and the community.
Such competency can best be achieved through training and accreditation.
Industry commitment to training and competency is exemplified by two national industry training programs:
- the Farm Chemical Industry Accreditation Program introduced in 1988 by the Agricultural and Veterinary Chemicals Association of Australia Ltd (AVCA) for the manufacturing, distribution, merchandising and advisory sector;
- the recently launched National Farm Chemical User Training Program introduced by the National Farmers' Federation.
Both of these programs have been introduced by the industry for the industry and they are aimed at ensuring a thorough understanding of legislative requirements, the correct use of farm chemicals and a high level of competency in the industry.
(iii) Correct use of pesticides
It is essential that pesticides are not used as the sole means of pest control. Misuse, overuse and abuse leads to many of the problems previously discussed. Pesticides must be used as part of a planned systematic pest management program utilising as many control techniques as applicable. This is called Integrated Pest Management (IPM). Controls such as biological, physical, cultural, genetic, environmental and mechanical techniques are just as important as pesticides. I believe that our approach should be to use all the techniques of the organic farmers, but to supplement these with the use of pesticides. In other words, using pesticides as part of an organic farming system. The IPM philosophy and approach is in my opinion the only way to economically and ecologically sustainable farming.
When pesticides are used, it is vital they are used correctly. Some of the considerations involved are:
- selection of product
- compatibility with other controls
- safe work practices
- following label directions
- timing of application
- accurate application to the target
- selection, adjustment and calibration of equipment
- application under favourable weather conditions
- keeping good records
By correct, safe and accurate use of these products, better pest control will result, adverse effects will be minimised, and farming will be more profitable.
In our free society there is a place for people to grow and consume organic food, but if all our farmers decided against using farm chemicals, we would soon find ourselves in a grave situation.
Agricultural and veterinary chemicals are vital to our welfare and the protection of the health of our families and pets. Unless, and until, better, more efficient and more cost effective means of pest control are developed, farm chemicals will remain a major weapon in our constant battle against pests. They are an integral component of Australia's agricultural systems, and Australian agriculture as we know it today could not survive without them. Production would drop drastically, and food would be of poorer quality, more expensive and in short supply. Many pets and farm animals would suffer and die needlessly. Australia's economy and our standard of living would rapidly decline.
This dependency brings with it a responsibility. All concerned with the manufacture, distribution and use of farm chemicals must ensure these products are used to maximum advantage. This can be achieved by ensuring farm chemicals are used accurately and correctly. They must be used in conjunction with other pest control techniques as part of an integrated pest management approach. This is the only way agriculture can be environmentally, economically and socially sustainable. Operators must be competent and well trained, and all users must be environmentally aware.
By combining these principles with the long established regulatory safeguards, we can be confident that farm chemicals are effective and can be used safely. We can also be reassured that our food is safe, wholesome and of high quality.
1. Anon (1992a). Scientific agriculture prevents mass starvation. The Herxter. J. of the Agvet Division, Hoechst, Aust. Inc.
2. Anon (1992b). Exploding populations and solutions. Wagga Wagga Daily Advertiser, June 1992.
3. Anon (1992c). A Question of Survival. ABC Television, 1992.
4. Anon (1990a). Submission by the Agricultural and Veterinary Chemicals Association to the Senate Select Committee inquiry into the use of agricultural and veterinary chemicals in Australia.
5. Anon (1990b). Evidence of the Bureau of Rural Resources to the Senate Select Committee inquiry into the use of agricultural and veterinary chemicals in Australia.
6. Colston, M. et al. (1990). Report of the Senate Select Committee. Aust.Govt. Printing Press.
7. Craven, B. (1992). Is Australian agriculture a good investment? The Herxter. J. of the Agvet Division, Hoechst, Aust. Inc.
8. Hock, W. et al. (1991). Farm Chemicals Manual: A Guide to Safe Use and Handling. The Agric. and Vet. Chem. Assoc. Aust. Ltd.
9. Kent, J. (1991). Education and training in farm chemical management. Proc. conf. Agriculture, Education and Information Transfer. Murrumbidgee College of Agriculture, 1991.
10. Stephens, M. and Harris, I. (1992). A broad vision for a preferred Australian agriculture in the year 2020. Agric.Science (5)3, 1992.