**2. Pesticides residues**

The term Pesticide includes all of the following; herbicide, insecticide, nematicides, acaracide, rodenticide, bactericide, fungicide, insect repellent, disinfectant and so on. The most commonly used pesticides are fungicides which account for 80% of all pesticides used. Most pesticides are intended to serve as plant protection products which in general protect plants from weeds, fungi or insects. Target pests can include insects, plant pathogens, weeds, mollusks, birds that destroy crops, cause nuisance or spread diseases. Although pesticides have benefits, most of the pesticides utilized in farm fields or in residential areas to control disease vectors have several drawbacks such as potential toxicity to humans and other organisms.

With the large-scale utilization, they still hold the potential to contaminate our ecosystems, pollute soil, water, air, impact wildlife, beneficial pollinators and

### *Pesticide Residues: Impacts on Fauna and the Environment DOI: http://dx.doi.org/10.5772/intechopen.98379*

human health. Pesticides have physical–chemical properties that will inflate their behavior in the environment. These are the properties of pesticides which after application can cause short-term or long-term effects on the environment and other organisms as well by either persisting at a long period or by drifting to places other than target sites [10].


A number of properties of pesticides can affect their behavior in their environment and can cause multiple numbers of environmental contaminations which include Persistence, Degradation Bio-accumulation, Volatility, Adsorption and Absorption (**Figure 1**) [11]. Sooner or later, pesticides are broken down in the environment by a process called Degradation. Depending upon the nature of pesticide and environmental conditions of a particular area, the process of degradation can be rapid or deliberate. However, microorganisms present in the soil, chemical reactions and sunlight play a key role in the degradation of pesticides. On the other hand, Pesticide molecules can be a food source of microbes while taking the advantage of moist and warm soils; microbes can turn the pesticide molecules into carbon

#### **Figure 1.**

*Factors affecting pesticide and its degree of risk to the environment. (Designed in MS OFFICE POWERPOINT by Muzafar Riyaz).*

#### *Biodegradation Technology of Organic and Inorganic Pollutants*

dioxide and water. Some pesticides such as Chlordane and DDT do not break down quickly, this class of pesticides are called persistent pesticides [12]. Persistence can be greater in heavy clay or organic soil than in sandy soil. Some pesticides after intake through food, water or air may accumulate or build up in body tissues or body fat of humans and animals by a process called Bio-accumulation. These fat-soluble pesticides such as DDT are stores in the body's fat, and when the fatty tissues are used for energy, the compounds are released and cause acute poisoning [13]. If the organism cannot eliminate the pesticides from its body, there is a chance that more pesticide compounds will store in the fat cells, if the organism is exposed to the pesticides routinely. In the 1940s scientists found residues of the man-made chlorinated hydrocarbon pesticide, DDT in human fat which was an alarming issue back then, as many chlorinated hydrocarbon pesticides do not degrade readily and

#### **Figure 2.**

*Drift can cause pesticides to travel away from the target site with vapors or dust particles while application. (Photo Muzafar Riyaz 2021).*

#### *Pesticide Residues: Impacts on Fauna and the Environment DOI: http://dx.doi.org/10.5772/intechopen.98379*

because they accumulate in fat, they move from one organism to another upward in the food chain all the way to humans [14]. Small levels of these types of pesticides in water and soil can magnify into a significant hazard to predators at the top of the food chain. When exposed to air or evaporate, pesticides may change into a vapor by a process called volatility. Once a pesticide evaporates, it is carried for miles simultaneously with the dust particles in the air (**Figure 2**). Pesticides can bind onto soil particles and organic matter by a process called adsorption. In adsorption, A pesticide can bind to the surface of soil particle similarly to that of magnetic attraction. The most adsorptive soils are clay and soils which are having a high concentration of organic matter. Since these pesticides are bound tightly with the soils, there is a very low chance for pesticides to leach with water and therefore they cannot move downward through soil and will less likely to reach groundwater. Water or wind can be the cause of the erosion of pesticides tightly adsorbed to the soil and not be so readily degraded by soil microorganisms. Pesticides can be taken up by the flora and faunal species including insects by a process called absorption. The fate of the pesticides can be determined by a combination of properties and not by a single property. The crusade of pesticides in an environment is very complex as after the application the pesticides can move by some natural processes such as drift, surface runoff, leaching and soil erosion (**Figure 3**) [15].

#### **Figure 3.**

*Movement of pesticide residues in the environment. (Designed in MS OFFICE POWERPOINT by Muzafar Riyaz).*
