**2. Traditional pesticides**

#### **2.1 What is a pesticide?**

As FAO defined, pesticide is any substance or mixture of substances intended for preventing, destroying, repelling or mitigating any pest, including vectors of human or animal disease, unwanted species of plants or animals causing harm during or otherwise interfering with the production, processing, storage, transport or marketing of food, agricultural commodities, wood and wood products or animal feedstuffs, or substances which may be administered to animals for the control of insects, arachnids or other pests in or on their bodies. The term includes substances intended for use as a plant growth regulator, defoliant, desiccant or agent for thinning fruit or preventing the premature fall of fruit, and substances applied to crops either before or after harvest to protect the commodity from deterioration during storage and transport. A pesticide may be a chemical substance, biological agent (such as a virus or bacterium), antimicrobial, disinfectant or device used against any pest. We use pesticides to cover a wide range of chemicals used to control insect pests, plant diseases, weeds, rats or other unwanted organisms. Currently, more than 800 pesticide active ingredients in a wide range of commercial products are registered for use in agriculture to meet food supply demands (Stoytcheva, 2011; Food and Agriculture Organization of the United Nations, 2002).

Pesticides can be classified by target organism, chemical structure, and physical state (Council on Scientific Affairs, American Medical Association, 1997). Pesticides can also be classed as inorganic, synthetic, or biologicals (biopesticides) which include microbial pesticides and biochemical pesticides. Plant-derived pesticides (botanicals), which have been developing quickly, include pyrethroids, rotenoids, nicotinoids, and a fourth group that includes strychnine and scilliroside (Kamrin, 1997). In addition, Pesticides can be classified based upon their biological mechanism function or application method. Basically, agricultural pesticides are divided into five categories, depending on the target pest (WWW. Humpath.com):


4 Pesticides in the Modern World - Risks and Benefits

While the first recorded use of chemicals to control pests 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 (i.e. burning sulphur to control insects and mites). Other early insecticides included hellebore to control body lice, nicotine to control aphids, and pyrethrin to control a wide variety of insects. Some heavy metals like 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

Pesticides are an undeniable part of modern life, used to protect everything from flower gardens to agricultural crops from specific pests. Pesticides have contributed significantly to improving quality of life and safeguarding the environment. Although often taken for granted, without these important products, food production would decline, many fruits and vegetables would be in short supply and prices would rise. Some 20 to 40 percent of the world's potential crop production is already lost annually because of the effects of weeds, pests and diseases (according to the FAO reports) (WWW.CropLife America.mht). These crop losses would be doubled if existing pesticide uses were abandoned, significantly raising food prices. Even after harvest, crops are subject to attack by pests or diseases. Bugs, rodents or moulds can harm grains. In addition to increasing crop yields, crop protection products used in stored products can also prolong the viable life of products, prevent huge

On the other hand, although pesticides are now commonplace, concerns still exist about their safety and proper use. Pesticides can be used safely and effectively. But if proper care is not taken, pesticides can harm the environment by contaminating soil, surface and ground water, and ultimately kill wildlife. Also, the modern human is constantly exposed to a variety of toxic chemicals primarily due to changes in life style. The food we eat, the water we drink, the air we breathe, and the environment we live in are contaminated with toxic xenobiotics. Humans are exposed to such chemicals while still in the womb of the mother (Lederman, 1996; Rathinam et al., 2004). Therefore, human life would be threatened not only

However, the chapter tries to discuss about necessity of pesticides use in modern agriculture for supplying human food. Actually, traditional chemical pesticides have environmental inconvenience and disadvantages for human health; thus, the problems along with the benefits of pesticides in improvement of quality of agricultural products and food production and storage are mentioned. According to world's food demands and health hazards caused by traditional pesticides, modern and new generation of pesticides and/or alternative methods to chemicals are modified to one of the most essential needs for modern

As FAO defined, pesticide is any substance or mixture of substances intended for preventing, destroying, repelling or mitigating any pest, including vectors of human or animal disease, unwanted species of plants or animals causing harm during or otherwise interfering with the production, processing, storage, transport or marketing of food, agricultural commodities, wood and wood products or animal feedstuffs, or substances

post-harvest losses from pests and diseases, and protect food safety for eating.

directly by pesticides in environment, but indirectly by contaminated food chain.

agriculture in the present age. Some of the methods are titled in this chapter.

**2. Traditional pesticides 2.1 What is a pesticide?** 

one of the most widely used fungicides (Hock et al., 1991).


All pesticides are toxic to some plant or rodent species; at higher doses, they can also be toxic to farm animals, pets, and humans. In general, prominent insecticide families include organochlorines, organophosphates, and carbamates. Acute toxicity of insecticides for mammals ranges from low to high. Herbicides used to control weeds have low acute toxicity for mammals; and fungicides are characterized as moderately toxic (Shokrzadeh & Saeedi Saravi, 2009).

#### **2.2 Advantages of using pesticides**

A plentiful supply of fresh products is vital for a healthy population. Numerous scientific studies demonstrate the health benefits of regularly eating a variety of fresh fruit and vegetables; and consumers are increasingly aware of these benefits. Agricultural productivity is a key to ensuring that this demand can be met at an affordable price; and crop protection products help increase productivity and usable crop yields.

The crop protection industry's primary aim is to enable farmers to grow an abundant supply of food in a safe manner and prevent costs from increasing. Food production processes benefit from continual advancements in agricultural technologies and practices; in fact, a population now nearly twice as large has more food available per capita than 40 years ago. Tools such as herbicides, insecticides, and fungicides reduce crop losses both before and after harvest, and increase crop yields.

The major benefits of pesticides and their role in food production are listed below (WWW.CropLife America.mht):

Role of Pesticides in Human Life in the Modern Age: A Review 7

species (Miller, 2004). It also happens that some of the pest adapt to the pesticide and don't die. What is called pesticide resistance, to eliminate the offspring of this pest, will be needed a new pesticide or an increase the dose of pesticide. This will cause a worsening of the

There is a growing concern that environmental chemicals, both natural and manmade, can




On the other hand, the human population is exposed to these chemicals primarily through the consumption of pesticide contaminated farm products, leading to long term health

Pesticides may induce oxidative stress leading to the generation of free radicals and alteration in antioxidant or oxygen free radical scavenging enzymes such as superoxide dismutase, catalase, glutothione peroxidase, glutathione reductase and glutothione

Pesticide toxicity can result from ingestion, inhalation or dermal absorption. Also, many evidences show that pesticides are persistent in fish tissues, adipose tissue and other organs including brain cells, nervous system and endocrine glands, and even breast milk, etc (Shokrzadeh et al., 2009). Thus, continued exposure to these chemicals for a long period may






Between specific age ranges, infants and children are at great risk from the effects of pesticides. Several studies suggest that children may be particularly sensitive to the


adrenal gland exhaustions and early menopause (Xavier et al., 2004);

sarcoma), and colorectal and testes carcinomas (Xavier et al., 2004);

and subject to malnutrition (Xavier et al., 2004);

ambient pollution problem.



cause:

chain;

generations;

honeybees.

transferase (Ahmed et al., 2000).

Xavier et al., 2004);

1998; Zahm et al., 1997);


2002);

result in various diseases listed below:

hazards.


#### **2.3 Disadvantages of using pesticides**

Food is the basic necessity of life and food contaminated with toxic pesticides is associated with severe effects on the human health. Hence it is pertinent to explore strategies that address this situation of food safety especially for the developing countries where pesticide contamination is widespread due to indiscriminate usage and a major part of population lives below poverty line.

The four main groups of pesticides such as the organochlorine, organophosphate, carbamate, and pyrethroid insecticides (Smith & Gangolli, 2002; Ahmed et al., 2000) are of particular concern because of their toxicity and persistence in the environment; however several of the banned pesticides are still used on a large scale in developing countries and continue to pose severe health and environmental problems. Pesticide use raises a number of environmental concerns, and human and animal health hazards. Over 98% of sprayed insecticides and 95% of herbicides reach a destination other than their target species, including non-target species, air, water and soil (Miller, 2004). Pesticides are one of the causes of water pollution, and some pesticides are persistent organic pollutants and contribute to soil contamination. As a result, we are closely exposed to pesticides in the food and water we consume and in the air we breathe. Unfortunately these chemicals are non biodegradable, persistent and get accumulated in the environment and thus into the human food chain. Despite regulatory measures, these compounds continue to be detected in measurable amounts in the ecosystem including marine life (Smith & Gangolli, 2002).

In addition, pesticide use reduces biodiversity, reduces nitrogen fixation (Rockets, 2007), contributes to pollinator decline (Hackenberg, 2007; Haefeker, 2000; Wells, 2007; Zeissloff, 2001), destroys habitat (especially for birds) (Palmer et al., 2007), and threatens endangered species (Miller, 2004). It also happens that some of the pest adapt to the pesticide and don't die. What is called pesticide resistance, to eliminate the offspring of this pest, will be needed a new pesticide or an increase the dose of pesticide. This will cause a worsening of the ambient pollution problem.

There is a growing concern that environmental chemicals, both natural and manmade, can cause:


6 Pesticides in the Modern World - Risks and Benefits




Food is the basic necessity of life and food contaminated with toxic pesticides is associated with severe effects on the human health. Hence it is pertinent to explore strategies that address this situation of food safety especially for the developing countries where pesticide contamination is widespread due to indiscriminate usage and a major part of population

The four main groups of pesticides such as the organochlorine, organophosphate, carbamate, and pyrethroid insecticides (Smith & Gangolli, 2002; Ahmed et al., 2000) are of particular concern because of their toxicity and persistence in the environment; however several of the banned pesticides are still used on a large scale in developing countries and continue to pose severe health and environmental problems. Pesticide use raises a number of environmental concerns, and human and animal health hazards. Over 98% of sprayed insecticides and 95% of herbicides reach a destination other than their target species, including non-target species, air, water and soil (Miller, 2004). Pesticides are one of the causes of water pollution, and some pesticides are persistent organic pollutants and contribute to soil contamination. As a result, we are closely exposed to pesticides in the food and water we consume and in the air we breathe. Unfortunately these chemicals are non biodegradable, persistent and get accumulated in the environment and thus into the human food chain. Despite regulatory measures, these compounds continue to be detected in measurable amounts in the ecosystem including marine life (Smith & Gangolli, 2002). In addition, pesticide use reduces biodiversity, reduces nitrogen fixation (Rockets, 2007), contributes to pollinator decline (Hackenberg, 2007; Haefeker, 2000; Wells, 2007; Zeissloff, 2001), destroys habitat (especially for birds) (Palmer et al., 2007), and threatens endangered

high-quality products free of insect fragments.

large benefit of pesticides.

**2.3 Disadvantages of using pesticides** 

degradation.

lives below poverty line.


On the other hand, the human population is exposed to these chemicals primarily through the consumption of pesticide contaminated farm products, leading to long term health hazards.

Pesticides may induce oxidative stress leading to the generation of free radicals and alteration in antioxidant or oxygen free radical scavenging enzymes such as superoxide dismutase, catalase, glutothione peroxidase, glutathione reductase and glutothione transferase (Ahmed et al., 2000).

Pesticide toxicity can result from ingestion, inhalation or dermal absorption. Also, many evidences show that pesticides are persistent in fish tissues, adipose tissue and other organs including brain cells, nervous system and endocrine glands, and even breast milk, etc (Shokrzadeh et al., 2009). Thus, continued exposure to these chemicals for a long period may result in various diseases listed below:


Between specific age ranges, infants and children are at great risk from the effects of pesticides. Several studies suggest that children may be particularly sensitive to the

Role of Pesticides in Human Life in the Modern Age: A Review 9

In the last 10 years, one line of research has been in the area of natural pesticides. This typically means that certain botanical plant oils have been processed, combined, or concentrated into pesticides. These plant oils have a unique action that targets a key neurotransmitter receptor called octopamine which is found in all invertebrates (i.e. insects),

Alternatives to pesticides are available and include methods of cultivation, use of biological pest controls (such as pheromones and microbial pesticides), plant genetic engineering, and methods of interfering with insect breeding (Miller, 2004). Application of composted yard waste has also been used as a way of controlling pests (McSorley & Gallaher, 1996). These methods are becoming increasingly popular and often are safer than traditional chemical pesticides. In addition, EPA is registering reduced-risk conventional pesticides in increasing

Cultivation practices include polyculture (growing multiple types of plants), crop rotation, planting crops in areas where the pests that damage them do not live, timing planting according to when pests will be least problematic, and use of trap crops that attract pests away from the real crop. In the U.S., farmers have had success controlling insects by spraying with hot water at a cost that is about the same as pesticide spraying (Miller, 2004). Release of other organisms that fight the pest is another example of an alternative to pesticide use. These organisms can include natural predators or parasites of the pests. Biological pesticides based on entomopathogenic fungi, bacteria and viruses cause disease

Interfering with insects' reproduction can be accomplished by sterilizing males of the target species and releasing them, so that they mate with females but do not produce offspring (Miller, 2004). This technique was first used on the screwworm fly in 1958 and has since been used with the medfly, the tsetse fly, and the gypsy moth. However, this can be a costly,

Another alternative to pesticides is the thermal treatment of soil through steam. Soil

Some evidence shows that alternatives to pesticides can be equally effective as the use of chemicals. The experiences resulted from some countries used alternatives emphasize that reduction of pesticide use, application of composted yard waste with high carbon to nitrogen ratio to agricultural fields, etc were highly effective at r increasing crop yield. As a result, today's pesticides and alternative methods are safer and more effective in controlling

As agricultural modernization progressed, the ecology-farming linkage was often broken as ecological principles were ignored and/or overridden. In fact, several agricultural scientists have arrived at a general consensus that modern agriculture confronts an environmental crisis. A growing number of people have become concerned about the long-term

time consuming approach that only works on some types of insects (Miller, 2004).

vi. Cultivation practices,

ix. Soil steaming, etc.

but not in mammals.

numbers.

vii. Release of organisms that fight the pests, viii. Interfering with insects' reproduction,

in the pest species can also be used (Miller, 2004).

steaming kills pest and increases soil health.

pests than ever before in our history.

**3.2 Problems of modern pesticide systems** 

**3.1 Effectiveness of alternatives to traditional pesticides** 

carcinogenic effect of pesticides. There is a potential to prevent at least some childhood cancer by reducing or eliminating pesticide exposure (Zahm & Ward, 1998).
