PESTICIDES AND AGRICULTURE

Pesticides have been used to protect foodstuffs, household purposes, livestock, food grain and health

By Dr. S.M. ALAM
Dec 27, 2004 - Jan 02, 2005

A pesticide is any substance or mixture of substances intended for defoliating or desiccating plants, preventing fruit drop, inhibiting sprouting, or for preventing, destroying, repelling, or mitigating any insects, rodents, fungi, bacteria, weeds, or other forms of plant or animal life or viruses, except viruses on or in living man or other animals. Briefly, pesticides include (but are not limited to) herbicides (weed killers), insecticides, fungicides, nematicides, rodenticides, piscicides (fish killers), molluscicides (kill mollusks), algicides, bactericides, insect repellents, insect growth regulators,and some other chemicals. Herbicides are pesticides. Unfortunately, the term "pesticide" is often used interchangeably with "insecticide", and thus we frequently see and hear the phrase "pesticides and herbicides". However, herbicides are pesticides under FIFRA and are regulated as such.

If a company or individual claims a product will control a pest, then that product is a pesticide. A device, instrument or contrivance, subject to US EPA regulation, intended for trapping, destroying, repelling, or mitigating insects or rodents, or mitigating fungi, bacteria or weeds, or such other pests, but not including equipment used for the application of pesticides when sold separately from the device is also considered to be a pesticide.

Some common kinds of pesticides: Algicides control algae in swimming pools, lakes, canals, and water used industrially or stored. Attractants attract pests (for example, lure an insect or rodent to a trap). Pheromones are chemical sex attractants often used to confuse mating behavior of insects. Biocides kill microorganisms. Disinfectants and sanitizers kill or inactivate disease-producing microorganisms (bacteria, viruses, etc.) on inanimate objects. Fungicides kill fungi (many of which can infect and cause diseases in plants, animals, and people; examples of disease-causing fungi: rusts, mildews, blights, and molds). Fumigants produce gas or vapor intended to destroy insects, fungi, bacteria, or rodents, used to disinfest interiors of buildings as well as soil before planting.

Herbicides kill weeds and other plants that grow where they are not wanted. Insecticides kill insects and other "bugs". Miticides also called acaricides, kill mites that feed on plants and animals. Microbials microorganisms that kill, inhibit, or outcompete pests, including insects or other microorganisms. Molluscicides kill snails and slugs. Nematicides kill nematodes (microscopic, wormlike organisms that feed on plant roots). Ovicides kill eggs of insects and mites. Repellents repel pests, including birds and insects (for example, mosquitoes, fleas or ticks). Rodenticides control mice and other rodent pests. The term pesticide also includes related substances: Defoliants Cause leaves or foliage to drop from a plant, usually to facilitate harvest . Desiccants promote drying of living tissues unwanted plant tops or insects, for example, Insect growth regulators disrupt the action of insect hormones controlling molting, maturity from pupal stage to adult, or other life processes . Plant growth regulators Substances (excluding fertilizers or other plant nutrients) that alter the expected growth, flowering, or reproduction rate of plants through hormonal rather than physical action

Around the world, approximately 3 million acute poisonings and 220,000 deaths from pesticides exposure have been reported annually. In UK about 15% of all admissions, to acute medical units are due to pesticide poisoning where mortality rate is about 1% and 80% of all the deaths occurred outside the hospital. About 50,000 calls of acute poisoning per year is received in Greater Cleveland Poisoning Control Centre, USA, where as more than 14,000 deaths occurred each year in the country among which about 6000 deaths are because of suicides and 5000 deaths are due to accidental poisoning by different chemicals. The quite excessive and misuse of pesticides has led to enormous and tremendous hazards to human health and thousands of farm workers are seriously poisoned from their exposure. Pesticides are poison and can become potentially hazardous to environment, if basic common sense rules of their storage, transportation and disposal rules are not followed. The difficult parts or things in the environment, which might be affected by pesticides are: animals, birds, fish, non-target plants, beneficial insects/animals, people, soil, water resources, air, etc.

In order to safeguard agricultural produce from the ravage of pests to comply with the food and fibre demands of escalating population, pesticides were introduced in 1954 in Pakistan. Historically, pesticides use in Pakistan started heavily with the introduction of the Green Revolution Technologies in early sixties. Prior to this, farmers used to control pests through farming practices and through mechanical and biological removal. The high yielding varieties of wheat and rice were cultivated widely in the country, but these proved susceptible to various insects/pests. Pesticide's uses have thus, become the very pest control solution in Pakistan.

The pesticides consumption has risen many folds during the last two decades. The dependency on pesticide is evident from the increasing trend in its consumption from 665 mt in 1980 to 45,680 mt in 1996. Generally, pesticides fall under four chemical groups. These are organo-chlorines, organo-phosphorus, carbonates and pyrethroids. The "cide" in the word "pesticide" means "to kill". Water pollution is also caused by the use of pesticides where source of pollution is very pronounced in this country.

In order to get the potential yields of crops, a large amount of pesticides are used to control the insect pest For example, on an average, 63 per cent pesticides are only used to control cotton pests in the country, followed by 19 per cent on rice, sugarcane and fruits and vegetables. This high dependence on pesticides has disturbed agro-ecosystems, increased health hazards and polluted environment. In the country, nearly 50 per cent of the pesticides used are either extremely hazardous or highly hazardous. Pesticides residues cause dermal and nervous systems toxicity, cause adverse immune functions, peripheral, neuropathies and allergic sensitization reactions particularly of skin. Waters containing pesticides when used for drinking purposes can lead to harmful effects, ranging from mild headaches and skin cancer to cancer of internal organs and even death. Accidental exposure in homes from inappropriate storage of pesticides, poisoning caused due to the use of empty containers of pesticides for carrying water etc. are quite common. The adverse health effects depend upon the degree of toxicity of the pesticide, amount of water intake each day and the individual health. Indiscriminate use of insecticides is a major problem in developing countries and this seems to be responsible for poisoning of small farm animals, human beings and farm ecosystems. Major threat to agriculture comes from pests. Poor planning, faulty management and ineffective control strategies add to the huge crop losses each year.

Pesticides have been used to protect foodstuffs, household purposes, livestock, food grain and health. The development of resistance pest in insects against pesticides poses a severe threat to agricultural productivity of oil seed crops, cereals, cotton, fruits and vegetables. Pakistan being an agricultural country, the financial and the material loss of all the crops suffering to a greater or lesser extent from damage by insects, mites, nematodes, rodents, fungi, bacteria, virus and from competition with weeds is estimated from 40 to 60 per cent annually. When pesticides are applied to different crops, their residue is left in the crop products. This residue enters with in the living system and brings fatal results. A number of complicated diseases have appeared which are also attributed due to the toxic effects of pesticides. As we are trying to grow more food. Despite all these problems and drawbacks insecticides appear to be our best but against pests. We need to use them quite often to boost our food production. And there is no doubt about it that the insecticides are the most powerful tools in our arsenals to fight pest menaces. Nevertheless, there potent poisons need to be used only when necessary and require careful handling. It is essential to encourage the development and marketing of target oriented pesticides in order to avoid damage to our environment.

In Pakistan, among various crops, cotton is recognized as a sink of agro-chemicals. Since 1980, there is almost a linear increase in the use of pesticides in the country. At present, about 86 prominent pesticide companies are registered with the MINFAL in the country. During 1999, the pesticide consumption was 30,212 metric tons. Heavy amounts of this pesticide is used on cotton during four months (June through October), and about 10 per cent is used on vegetables of its growth and other crops. Moreover, cotton is an important cash crop of Pakistan with 60% export earning. Southern Punjab and northern Sindh are major cotton growing areas in the country. This crop suffers about 20-40% losses from insect pests and diseases for the control of which more than 76% of the total consumption of pesticides in the country is used over this crop. Cotton, picking of which is traditionally done by women is pesticide intensive crop and the farm workers are increasingly exposed to the hazards of toxic chemicals. The majority of female pickers are not aware of these hazards and do not take precautionary measure. Studies show that more than 2 million women get sick annually from exposure to pesticides. They are involved in a number of on- farm activities, for example, weeding, hoeing, grass cutting. Picking, cotton-sticks collection, besides separation of seeds from fibre in cotton ginning factories. They also help men to mix and prepare pesticides solution.

Reports say that in the developing countries, a farmer dies every hour from pesticide poisoning. Each year more than ten thousand people die and another four hundred thousand are sicken by pesticide poisoning. The profit margin of growers has eroded and lack of proper education among the farmers about the use of insecticides and their residue has generated tremendous health problems, as treated vegetables can make their way to the market next day.

The following points for mitigating the risks of pesticides measures may help to a great extent in controlling the problems arising due to pesticides use: i) The companies manufacturing the pesticides must be directed to employ trained manpower, who must keep watch on pesticides during field application; ii) Pesticides detoxification medicines must be provided in rural dispensaries so that if there is any emergency that must be tackled immediately and properly; iii) When an area is going to be sprayed it must be demarcated and there must be a continuous watch on it so that an emergency must not happen; iv) Government Act must be strictly obeyed; v) Agency must be given only to qualified persons living the technical know-how of pesticides; vi) The distributors should supply pesticides only to the farmers which have proper prescription from the qualified agriculture officer; vii) Some courses/seminars may be arranged so that the farmers may be aware of good or bad aspects of the pesticides; viii) Dangerous aspects of pesticides and precautions thereof must be broadcast on radio/television; ix) Farmers need to be educated to make them aware of the long term risks of persistent poisons. Farmers need to plan and direct their pest control operations in consultation with people, who can offer expert advice with regard to pest problems; x) The habit of over-eating or over-feeding by the persons must be avoided otherwise along with many other complications, xi) Eating ,drinking or smoking with pesticides contaminated hands should be avoided. After spraying work, the hands should be properly washed with sufficient water. The pesticide may touch its toxic level in the body; selecting pesticides of low toxicity; which are not to be harmful to aquatic organisms (e.g. fish); by taking care to avoid spraying near or over water; through safe storage and transportation of pesticides, as per FAO guidelines and instructions.