Pesticides, Anthropogenic Activities, and the Health of Our Environment Safety

*Mona Saud AL-Ahmadi* 

### **Abstract**

 Mankind depends on agricultural products for food consumption. Increasing population (more than 7 billion) requires significant growth in crop yield to meet essential demand. This aim was achieved through the use of pesticides to protect crops from diseases. Pesticides are toxic by design for organisms that can threaten food products. Their mode of action is by targeting systems or enzymes in the pests that may be similar to human system and therefore pose risks to human health and the environment as well. The WHO recommended classifying pesticides according to their toxicity and chemicals according to their chronic health and environmental hazards.

 **Keywords:** pesticides, classification of pesticides, pesticide hazards, future of pesticides

### **1. Introduction**

Agriculture is the primary source for human food; it provides different kinds of crop production. Most common crops include wheat, rice, corn, beans, different vegetables, and season fruits.

In 2015, 7.4 billion people call earth their home. Population is projected to reach 9.7 billion by 2050 and 11.2 billion by 2100 [1]. Optimizing crop yields becomes even a more critical factor affecting the availability and affordability of food to meet increasing population demand.

Plant diseases are major factors that affect crop production. Al-Sadi [2] reported that plant diseases can affect plants by interfering with several processes such as the absorbance and translocation of water and nutrients, photosynthesis, and flower and fruit development. Infection of plants by pathogens can have serious consequences on plant health which consequently affect human health. Viruses, bacteria, and fungi that infect plants do not usually cause infection in humans [3]. The ultimate consequences of different plant diseases are reduction in crop production, reducing food availability which may lead starvation in some areas. The famous incident of plant pathology is potato disease caused by *Phytophthora infestans* fungi, which destroyed potatoes that were the main crop in Ireland during 1845–1850, where about 1 million people died and another million immigrated to other countries [4].

This disaster and other similar ones resulted from plant pathogens. Minimizing this risk requires efficient methods and practices to control pests (insects, bacteria, fungi, viruses, etc.). The term "pesticide" indicates any substance or mixture of substance used to kill, "repel," or otherwise control a "pest," including insects, snails, rodents, fungi, bacteria, and weeds [5].

 The early methods used were simple and depended on traditional ways in specific places; however, these traditional practices were insufficient to control pests efficiently. Improvement of pest control gradually started to show satisfactory results for farmers and food manufacturing by the nineteenth century through the introduction of two natural pesticides (pyrethrum and rodent). In 1939 Muller discovered that DDT was a very effective insecticide and quickly became the most widely used pesticide in the world. Not until the 1960s when the harmful side effects of the application of DDT was discovered [6]. Despite the harmful effects of DDT, demand for pesticides continued to increase throughout the world. This is due to the many benefits attributed to pesticides; the most obvious benefits are economic, protection of commodity yield and quality, and the reduction of other costly inputs such as labor and fuel [7]. Pesticides play an essential role in farm profitability, providing reliable supplies of agricultural product, improving the quality of the product [8]. Notwithstanding pesticide benefits, there is plenty of evidence of both direct and indirect dangers involved in the use of these chemical substances both for humans and the environment [8].

For example, the contamination of pesticides may happen in several ways during manufacturing, storing, shipping, application in fields, warehouses, and wrong use by peoples. Several accidents have occurred in different parts of the world: India (1986), Italy (1976), Germany (1953), and Ethiopia (2017) [9]. Maksymiv [10] grouped the side effects of the excessive use of pesticides into diseases of ecospecies such as erosion, loss of soil fertility, pollution of water system, and biological community impact including loss of crop, animal genetic resources, elimination of natural enemies, genetic resistance to pesticides, contamination, and changes to natural control mechanisms.

Due the undesirable side effects of synthetic pesticides, search for safer analogue pesticides of natural origin is one of the most important goals. Potential alternatives to pesticides are available and include specific methods of plant cultivation, use of biological pest control, plant genetic engineering, and methods of interfering with insect breeding [11]. The most common alternative to synthetic pesticide pest control is biopesticides.

Biopesticides are a certain type of pesticides derived from natural material such as animal, plants, bacteria, and certain minerals. As of April 2016, there were 299 registered biopesticide active ingredients and 1401 active biopesticide product registration (US Environmental Protection Agency EPA).

Biopesticide offers a more sustainable solution to pest control than synthetic alternative. Botanical pesticides do not present the residue problems [12]. Microbial pesticides contain a microorganism as the active ingredient; they can control many different kinds of pest, although each separate active ingredient is relatively specific for its target pest(s). Biochemical pesticides are naturally occurring substance that interferes with growth or mating such as plant growth regulators or substances that repel or attract pests, such as pheromone [13]. Even with the satisfactory results of biopesticides on pest management, the efficacy at different geographical conditions and slow pest control makes them less desirable by farmers [14]. The science of biopesticides is still considered to be young and evolving. Some of the biopesticides are under development; this may prove to be excellent alternatives to chemical pesticides. Further research is needed in several areas such as production, formulation, delivery, and commercialization of the products [15].

In recent years, a new technology that provided a sustainable solution is nanotechnology through the development of nanopesticides for conventional agricultural use [16, 17]. Nanopesticides are small engineered structures that provide pesticide properties or formulation of active ingredient of pesticides in nanoform; these nanostructures show slow degradation and controlled release of nanopesticides which make them environmentally safer and less toxic compared to chemical *Pesticides, Anthropogenic Activities, and the Health of Our Environment Safety DOI: http://dx.doi.org/10.5772/intechopen.84161* 

pesticides [14]. The nanosystems have shown great capability of controlled release pattern of active ingredient (AI) making them more efficient for long time period usability that can solve eutrophication and residual pesticide accumulation problem [18]. In spite of the excellent results of this nanotechnology in the agriculture field, further and deep studies should be conducted to ensure application safety.

### **2. Plant pathology and impacts of pesticide usage**

A plant disease is usually defined as abnormal growth and/or dysfunction of a plant resulting from disturbance in normal life process or infections of living organisms (biotic) and nonliving environmental conditions (abiotic) [19].

Plant disease is best managed through an integrated approach, which includes a combination of:


 It has been reported that field losses from pest's average 35% from the world's main food crops. Direct yield losses caused by pathogens, animals, and weeds are altogether responsible for losses ranging between 20 and 40% of global agricultural productivity [20–22].

Although weeds are the major cause of crop loss on a global scale, significant losses are suffered by agricultural crops due to insect damage and plant diseases; estimated worldwide annual production tonnage (%) age loses attributed to pests at the start of the twenty-first century are 18%, due to animal pests, 16% microbial diseases (of which 70–80% caused by fungi), and 34% weeds, totaling 68% average annual loss of crop production tonnage [22].

Oerke [23] reported that the total global potential loss due to pests are estimated at 26–30% for sugar beet, barley, soybean, wheat, and cotton and 35, 39, and 40% for maize, potatoes, and rice. Plant protection in general and protection of crops against plant diseases in particular have an obvious role to play in meeting the growing demand for food quality and quantity [24]. It involves physical, biological, and chemical methods [25].

The only way to reduce crop losses is integrated pest management. Integrated pest management (IPM) is a system approach that combines different crop protection practices with careful monitoring of pest and their natural enemies [26, 27]. The primary IPM method includes synthetic chemical pesticides that are classed by regulators as low-risk compounds and have high levels of selectivity, such as synthetic insect growth regulators.

	- Natural products, such as semichemical or biocidal plant extracts
	- Biological control with natural enemies, including different pathogens of plants
	- Decision support tools to inform when it is economically beneficial to apply pesticides and other controls

Ghandler et al [28] reported that although pesticides act similarly despite their chemical active group. When applied to crops or directly to the soil, for example, systemic insecticides, organophosphates, and carbamates generally persist from only a few hours to several months. However, they have been fatal to large numbers of birds on turf and in agriculture and negatively impacted breeding success in birds [29]. Nanopesticides or nanoplant protection products represent an emerging technological development that, in relation to pesticide use, could offer a range of benefits including increased efficacy, durability, and a reduction in the amount of active ingredients that need to be used [30].

Biopesticides are natural products that can be considered as sufficient alternative of synthetic pesticide in pest management.

### **3. Pesticides in agriculture and their benefits**

The farmers around the world had used different methods and ways to fight the causes that lead to reducing crop yield, most of these methods were simple and traditional, and the result were not satisfactory until the use of pesticide application started.

Pesticides include natural and synthetic substances used to control harmful pests such as insects, plant disease organisms, and weed, as well as many other living organisms that endanger the food supply, health, or comfort [8].

The word "pesticides" is a term for all insecticides, herbicides, fungicides, rodenticides, wood preservatives, garden chemicals, and household disinfectants that may be used to kill some pests [31].

A pesticide controls any pest including vectors of human or animal diseases and unwanted species of plants or animals causing harm or interfering with the production, processing, storage, or marketing of food and agricultural commodities [32].

 Pesticides are a chemical group widely used by humans, both to protect the production from harmful organisms and quality of crops and for control of vectors and pests of public health [33]. In the last decade, pesticide sales have been roughly stable worldwide with an overall budget of \$40 billion, with the US market accounting for 31.6% of the total [34]. In the last decade, the most significant increase in demand for pesticides has occurred in Central and South America (6.7% annual increase from 2004 to 2014). Followed by the Asian market (4% annual increase from 2004 to 2014); the latter is the second largest after North America. Even the small African market, accounting for 3.5% of global pesticide expenditure in 2004, has shown a sharp 6.4% annual increase during the same period. An annual increase has also been observed in Europe [35].

#### *Pesticides, Anthropogenic Activities, and the Health of Our Environment Safety DOI: http://dx.doi.org/10.5772/intechopen.84161*

 The use of pesticides in agriculture has led to significant improvement in crop yield per hectare of land [36]. The economy was boosted, crop yields were tremendously increased, and so were the decreases in fatalities insect-borne diseases [31]. Cooper and Dobson [37] demonstrate the three main effects of pesticides:


The other strategy of protecting crops is to utilize biorational pesticides, such as biopesticides as alternative to synthetic chemicals. As synthetic pesticides are withdrawn owing to resistance problems or because they are no longer commercially viable, biopesticides are used as a replacement especially since they do not feature residue problems, which are a matter of significant concern for consumers. Currently, biopesticides comprise a small share of the total crop protection market globally, with a value of about \$ 3 billion worldwide, accounting for just 5% of the total crop protection market [38, 39].

The most important characteristics that distinguish biopesticides are (a) short RELs (most are 4 hours), (b) zero-day preharvest intervals (PHI), (c) generally safer to plants, (d) low-risk to environmental, (e) quicker to market at lower overall cost—3 years and \$5 million to develop vs. 10 years and \$200 million, (f) complex modes of action [40].

Despite synthetic pesticides' significant effectiveness on pest and crop diseases, their harmful side effects on plants, soil, and the environment require safer products. Biopesticides clearly have a potential role to play in the development of future integrated pest management strategies, and it is very likely that in the future their role will be more significant in agriculture and forestry [41].

 New technology that depends on nanosize of different materials started to spread around the world, because of various and efficient application results. Among nanotechnology sections, pesticides are receiving increasing interest with the development of a range of plant protection products that termed "nanopesticides" [42, 43]. Nanopesticides involve either very small practices of a pesticide active ingredient or other small engineered structures with useful pesticide properties [44]. Dubey et al. [45] reported that there is very limited knowledge about the nanoparticle's long-term adverse effects on soil, plants, and ultimately humans; an intelligent use of nanotechnology may help to achieve food security with the qualitative and sustainable environment.
