1. Department of Chemistry, Tribhuvan University (Birendra Multiple Campus, Bharatpur), Nepal; amritneupane2013@gmail.com

*             Correspondence: amritneupane2013@gmail.com

Keywords: organophosphate insecticide, pesticide, vegetables, Bharatpur

1. INTRODUCTION

It’s unfair to treat a species as a pest that needs a killer to disappear from its habitat on a planet with so much biodiversity. Pests are plants and animals that cause harm to humans and their domestic animals by disrupting their food web, bodies, clothing, or habitation. Pests can also attack domestic animals. The fact of the matter is that non-humans, who are rightly considered to be pests, have been on Earth for a longer period of time than humans. Due to the fact that humans are the masters of the planet, they have the ability to label any other species as a pest, including poor humans. The use of chemical pesticides in agriculture, homes, and institutions results in the death of animals, plants, insects, and other pests. Chemicals and biological substances are known as pesticides. Pesticides are substances that kill or retard pests that cause damage to crops, shrubs, and other types of crops and vegetation. All chemical pesticides are poisons that both harm humans and the environment because they are able to remain in the environment and in the tissues of the body. The majority of pesticides kill harmless or useful life forms [1]. Herbicides, insecticides, fungicides, fumigants, and rodenticides are common pesticides. Since they are toxic and persistent, organochlorine, organophosphate, and carbamate insecticides are of greatest concern. Other developed nations ban organochlorine insecticides for domestic and agricultural use, but Nepal uses them [2]. Rapid population growth worldwide increases food demand. Increased productivity is needed to meet food demand. Research indicates that farmers in various regions use pesticides to boost productivity. Approximately 900 pesticides are used legally or illegally in food, crops, and soil worldwide. From WHO, “Pesticides are the chemical compounds that are used to kill pests including insects, rodents, fungi and unwanted plants (weeds).” Mosquitoes and crop pests are killed by pesticides in public and agriculture [3]. The FAO defines a pesticide as any substance or mixture of substances used to prevent, destroy, control, and mitigate pests, including vectors of human or animal disease, unwanted species of plants or animals that harm or otherwise interfere with food, agricultural commodities, wood and wood products, animal feedstuffs, or substances that can be given to animals [4]. The majority of the 1.8 billion farmers worldwide use pesticides to protect their crops. Numerous people use pesticides for lawn and garden, public health, and commercial applications [5]. Pesticides are sturdy and last for decades, they bio-accumulate and move quickly. In addition to causing health issues in humans and animals, various pesticides that are used in soil and crops also contribute to soil pollution and a loss of soil fertility over the long term. These poisonous pesticides are lethal to both the predatory and the non-predatory species. This toxin is poisonous to the reproductive system, the immune system, and it has the potential to cause cancer. Pesticides can become ingested by humans through the consumption of food, water, or soil. Because of a lack of knowledge about pesticides, farmers in developing countries use pesticides carelessly, which results in a significant number of accidents. The use of pesticides is higher in developing countries. To increase crop yields, farmers in developing countries use pesticides without being aware of the effects that these chemicals have. Pesticides are most commonly used on vegetables, cash crops, and certain food crops that are off-season. Pesticides are used extensively in Nepal because of the country’s growth. Numerous pesticides are utilised by farmers, but organophosphate is utilised excessively. Because organophosphate is readily available and can be applied to a wide variety of pests, its application has increased. The Organophosphorus (OPs) group of pesticides is an important group for controlling insects and pests. A phosphate ester, also known as an organophosphate (OP), is a compound that is derived from phosphoric acid. Organophosphates are utilised in a number of insecticides, herbicides, and therapeutic agents. The term “organophosphates” is typically used to refer to insecticides that interact with acetyl cholinesterase when it is used in communications from the government or the press regarding agriculture, the environment, and the health of humans and animals. About 50% of chemical pesticides contain organophosphates [6]. Agencies allow a certain amount of pesticide residue to remain in or on a harvested crop. Some countries call tolerances maximum residue limits. The status list of active pesticides in the EU market lists over 1100. Multinational and local pesticide manufacturers, formulators, and traders make up the industry. The majority of pesticides are imported as technical materials and blended, diluted, made. Due to their low cost and high pest, weed, and disease control, pesticides are widely used in agriculture. Pesticide production for agricultural and nonagricultural uses pollutes air, soil, ground, and surface water. This poses a serious environmental and health risk due to direct exposure or food and water residues [7].

2. LITERATURE REVIEW

Nepal is diversifying and commercializing its agriculture, which could boost the economy, reduce unemployment, increase agricultural imports, and involve women. However, commercialization has introduced a major threat. Overdose, unsafe, and uncontrolled use of chemical pesticides in commercialization pocket areas has invited dangerous pests whose control is difficult and caused serious health hazards for growers and consumers [8]. Pesticides are not a problem if used in the recommended dose and correct application manner, but their haphazard use in overdose without following any safety measures (even basic), not prioritizing application manner and time, and most importantly, not waiting for the market to dispose of it has harmed the environment and life of grow. Also Pesticide trading in these areas is treated like other supplies [9]. The majority of pesticide sellers in grocery stores, liquor stores, and agro-vets are untrained. Nepalese farmers, like many others, overuse pesticides in crops and soil. Agricultural pesticides are misused and overused, pesticides have been used rapidly for decades to meet rising food and agricultural demand. Pesticides kill animals, plants, insects, and pests in agriculture, homes, and institutions [10]. The most common pesticides are herbicides, insecticides, fungicides, fumigants, and rodenticides. The toxicity and persistence of organochlorine, organophosphate, and carbamate insecticides are major concerns.  Pesticides can last decades before breaking down. Mobile and bio-accumulative, these persistent chemicals are persistent [11]. They circulate globally, and persistent pesticides released in one region can be easily transported to another by evaporation and deposition through the atmosphere. About two million tons of pesticides are used worldwide, with 45% in Europe, 24% in the US, and 25% elsewhere [12]. Nepal consumes 0.142 kg/ha of pesticide, compared to India (0.5 kg/ha), Mexico (0.75 kg/ha), Germany (3 kg/ha), UK (5 kg/ha), USA (7 kg/ha), Netherlands (9.4 kg/ha), Japan (12 kg/ha), China (14 kg/ha), and Taiwan (17 kg/ha). Nepal’s pesticides are mostly fungicides. More than 48% of pesticides in 2011/2012 were fungicides. About 345 thousand kg or liters of pesticide active ingredients were used in 2011/2012, with very little used for public health [13] Esters of phosphoric acid are called organophosphates. Many insecticides, herbicides, and nerve agents use organophosphates. The US Environmental Protection Agency classifies organophosphates as highly toxic to bees, wildlife, and humans [14]. Organic esters of phosphoric, thiophosphoric, and other acids are organophosphates. Organophosphorous compounds, developed by Gerhard Scharder in Germany, are widely used for their broad insecticidal spectrum and short environmental persistence [15]. Environmental damage can result from accidental pesticide use. Most insecticides and herbicides reach non-target species, air, water, bottom sediments, and food (98% and 95%, respectively). Pesticides have many paths after release. Airborne pesticides can land in soil or water. Directly applied pesticides may wash into surface water or percolate into soil and groundwater [16]. Injected soil pesticides may also suffer these outcomes. Pesticides applied directly to water for weed control or indirectly through boat paint, soil runoff, or other routes may build up in water and evaporate, polluting the air [17]. Pesticides may deplete ozone and greenhouse gases, dfferent pesticide groups directly pollute environmental resources, which could cause disaster. POPs inhibit degradation and last for years. Organic compounds that resist chemical, biological, and photolytic degradation are persistent organic pollutants (POPs) [18]. Volatile POPs can go far through the atmosphere and deposit in remote areas. Bio-accumulation, bio-magnification, and bio-concentration can reach 70,000 times their original concentrations. POPs damage non-target organisms and humans by disrupting the endocrine, reproductive, and immune systems. POPs bioaccumulate and harm humans and the environment [19] Aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex, and toxaphene are POPs. The 2001 Stockholm Convention on Persistent Organic Pollutants considered banning or restricting POP production to protect human and environmental health. OP pesticides have saved millions from starvation. They degrade quickly and are eco-friendly bug-killers. OPs are popular and seem to work similarly. Many animals and humans share OP exposure pathways [20]. Crop spraying with OPs can pollute nearby communities. Pesticide runoff into waterways harms aquatic species, terrestrial species that forage around waterways, and nearby residents and recreationists. Long after wildlife spraying, OP-contaminated well water can harm humans. Wild animals can warn of OPs’ health risks. Oxone, other specific inactive metabolites (ME), and dialkylphosphates (DAP) develop from organophosphates. DAPs, the metabolites of all organophosphate pesticides, are environmental biomarkers. In developing countries, organophosphate pesticide poisoning kills many. Many agricultural sectors use OP pesticides [21].Unsafe OP pesticide use can cause short- and long-term health issues. Much of the industry has replaced OP pesticides. Pesticides are easily absorbed through inhalation, skin, ingestion, mucous membranes, and eyes if unprotected. Most sick workers are exposed to OP pesticides for hours or days [22]. Short-term OP exposure causes headaches, excessive sweating, slurred speech, and blurred vision. Acute toxic reactions can cause blurred vision, dizziness, headaches, tremors, respiratory and cardiac issues, and death. Long-term OP exposure can cause weakness, anxiety, and restlessness. Organic phosphates inhibit human acetylcholinesterase. Nervous system that degrades nerve-muscle signaling acetylcholine [23]. Acetylcholinesterase inhibition by organophosphate insecticide may cause exposure. Irritated eyes and skin, nausea, vomiting, abdominal pain, diarrhea, salivation, weakness, fatigue, headache, runny nose, chest tightness, blurry vision, pupil constriction, irregular heartbeat, fasciculation, and difficulty breathing. Organophosphorus (OP) pesticide self-poisoning is a major clinical issue in rural developing nations. Chemicals with carbon-phosphorus bonds are persistent organic pollutants used in pest control [24]. In Nepal, suicides and accidental poisonings occur frequently there due to their accessibility. Many Nepalese women commit suicide from OP compound ingestion [25]. Family stress and financial constraints may be to blame. Accidents from occupational exposure and OP compound inhalation are less deadly than suicide poisoning. To assess hospital-based acute pesticide poisoning incidence, pattern, and mortality for management and prevention. The Chitwan Medical College emergency department reported 88 acute pesticide poisoning cases out of 178, 49.43% [26]. Age-specific acute poisoning rates were 7.95% in 0-14 years, 45.55% in 15-29 years, 30.68% in 30-44 years, 12.50% in 45-59 years, and 3.40% in 60 years and older. Endosulfan poisoning killed the most (28.57%) and organophosphate poisoning 47.73%.30A quantitative hospital survey in four major hospitals found 439 acute pesticide poisoning cases from 12 districts, including Chitwan and neighbouring districts, hospitalised between April 1 and December 31, 2015.Most poisonous pesticides were insecticides (58.0%) and rodenticides (20.8%) [27]. Most used were organophosphates (37.3%) and pyrethroids (36.7%). Hospitalisation was 98.6%, with 41.3% requiring ICU. The admitted case fatality rate was 3.8%.  Pesticide residues in Nepalese food are common, the Central Food Research Laboratory (CFRL) annual bulletins found sampling residues [28]. Organochlorine and organophosphate insecticide residues in cereal grains and vegetables increased from 1981 to 1986 but have decreased. The Kathmandu Food Research Laboratory evaluated 900 samples. The 981–1986 food samples were 94% DDT-contaminated (joshi, 1988). Food Tech and Quality Control survey Pesticides in Nepalese diets are dangerous (Koirala et al., 2009/010) [29]. In 12.1% of food samples, national pesticide surveillance data (1995–2005) found Malathion (3.9%), BHC (3.1%), methyl parathion (2.8%), DDT (1.8%), and parathion (0.3%). Leaf vegetables had 10.9% pesticide residues, while root vegetables had 11.9% (Koirala et al., 2009) [30].

3. MATERIALS AND METHODS

The study was divided into desk, field and lab sections. Desk study examined various papers, books, and literature to understand past pesticide removal methods for food. Field studies were conducted in selected areas to gather pesticide use and safety data. A laboratory study measured organophosphate pesticide residue in vegetable, soil, and water samples. The study covered various Bharatpur metropolitan city areas. Chanauli, Amritnagar, Shukranagar, Dhurba, Bhimnagar, Parbatipur, etc. These areas are Chitwan’s vegetable pocket sites, and their produce is exported and consumed locally. The main reason for choosing this site is to measure organophosphate pesticide use in local vegetables.

Figure 01: Map of Chitwan

Field visit was carried out through questionnaire survey so as to collect information on awareness level of farmers regarding pesticide use, the type and amount of pesticide they were using, their knowledge regarding pesticide the safety measures to be taken during and after pesticide use. A total of N=50 farmers were interviewed. On the basis of these survey different pesticides that they were using in their farm was identified, which were selected for the laboratory analysis of the collected samples to study their residue level.

Figure 02: Collection of different vegetable sample

Figure 03: Farmers spraying insecticides

Different vegetable samples were collected from the interviewed farmers. A list of collected vegetable samples along with their collection places were represented in the table below:

Table 01: Different vegetable sample collected with collection area

No	Product	Place
1	Brinjal	Shukranagar
2	Cauliflower	Bhimnagar
3	Cabbage	Parbatipur
4	Bitter gourd	Shukranagar
5	Bottle gourd	Chanauli
6	Black eyed beans	Chanauli
7	Cucumber	Milan chowk
8	Broccoli I	Bharatpur market
9	Sponge Gourd	Jyotinagar
10	Smooth Luffa Gourd	Parbatipur
11	Squash I	Bharatpur market
12	Capsicum I	Bharatpur market
13	Tomato	Shukranagar

Some of the vegetables samples were purchased from the Bharatpur vegetable market located in Bharatpur Metropolitan City. The vegetable sample collected from vegetable market was labelled as I. Samples of soil were collected from the farms of the interviewed farmers so as to investigate the level of the organophosphate insecticides in that soil. The soil samples were collected from the depth of 10cm. A total of N=5 samples were collected from different places to investigate the level of organophosphate pesticide level. A total of N=5 samples of water were collected from different water bodies which receives water from the irrigated land to investigate the level of organophosphate pesticide level. The collected samples were packed in clean plastic bag and were labelled with sample identification number and sample name. The collected sample were stored in refrigerator at 0oc before further laboratory analysis.

3.1 Apparatus

A Labomed UV-VIS spectrophotometer with 1 cm matched quartz cells was used for spectral measurement. A pH meter for pH measurement, Soxhlet for the extraction of the vegetable sample.

Figure 04: UV-Vis spectrophotometer and Quartz cuvette

3.2 Principle of UV-Vis spectrophotometry

Ultraviolet–visible spectroscopy or ultraviolet–visible spectrophotometry (UV– Vis or UV/Vis) refers to absorption spectroscopy or reflectance spectroscopy in the ultraviolet-visible spectral region. This means it uses light in the visible and adjacent ranges. The absorption or reflectance in the visible range directly affects the perceived color of the chemicals involved. In this region of the electromagnetic spectrum, atoms and molecules undergo electronic transitions. Absorption spectroscopy is complementary to fluorescence spectroscopy, in that fluorescence deals with transitions. From the excited state to the ground state, while absorption measures transitions from the ground state to the excited state. UV spectroscopy obeys the Beer-Lambert law, which states that, “when a beam of monochromatic light is passed through a solution of an absorbing substance, the rate of decrease of intensity of radiation with thickness of the absorbing solution is proportional to the incident radiation as well as the concentration of the solution.”

The expression of Beer-Lambert law is-

A = log (I0/I) = Εcl Where, A = absorbance

I0 = intensity of light incident upon sample cell I = intensity of light leaving sample cell

C = molar concentration of solute L = length of sample cell (cm.)

Ε = molar absorptivity

From the Beer-Lambert law it is clear that greater the number of molecules capable of absorbing light of a given wavelength, the greater the extent of light absorption. This is the basic principle of UV spectroscopy.

Figure 05: Schematic diagram of UV-Vis spectroscopy

3.3 Principle of Soxhlet extraction

Soxhlet extraction is a continuous solid/liquid extraction. A solid which contain material to be extracted is placed in thimble. A thimble is a made out of material which will contain solid but allow liquids to pass through. The thimble containing the material is placed in soxhlet extractor and the solvent is heated to reflux. The solvent vapour travels up a distillation arm, and floods into the chamber housing the thimble of solid. The condenser ensures that any solvent vapour cools, and drips back down into the chamber housing the solid material. The chamber containing the solid material slowly fills with warm solvent. Some of the desired compound dissolves in the warm solvent. When the Soxhlet chamber is almost full, the chamber is emptied by the siphon. The solvent is returned to the distillation flask. The thimbleensures that the rapid motion of the solvent does not transport any solid material to the still pot. This cycle may be allowed to repeat many times, over hours or days. During each cycle, a portion of the non-volatile compound dissolves in the solvent. After many cycles the desired compound is concentrated in the distillation flask. The advantage of this system is that instead of many portions of warm solvent being passed through the sample, just one batch of solvent is recycled. After extraction the solvent is removed, typically by means of a rotary evaporator, yielding the extracted compound. The non-soluble portion of the extracted solid remains in the thimble, and is usually discarded.

3.4 Principle of Column chromatography

Column chromatography is one of the most useful methods for the separation and purification of both solids and liquids. This is a solid – liquid technique in which the stationary phase is a solid & mobile phase is a liquid. The principle of column chromatography is based on differential adsorption of substance by the adsorbent. The usual adsorbents employed in column chromatography are silica, alumina, calcium carbonate, calcium phosphate, magnesia, starch, etc., selection of solvent is based on the nature of both the solvent and the adsorbent. The rate at which the components of a mixture are separated depends on the activity of the adsorbent and polarity of the solvent. The mixture to be separated is dissolved in a suitable solvent and introduced at the top of the column and is allowed to pass through the column. As the mixturemoves down through the column, the components are adsorbed at different regions depending on their abilityfor adsorption. The component with greater adsorption power will be adsorbed at the top and the other will be adsorbed at the bottom. The different components can be desorbed and collected separately by adding more solvent at the top and this process is known as elution.

3.5 Reagent

All reagents used were of analytical grade and distilled water was used throughout the experiment for preparation and dilution of reagents as well as samples. The experiment was performed by using Chloropyrifos (Crystal Pharma, India). For the extraction of the vegetable sample, 100 % pure methanol (Thermo Fisher Scientific, Qualigens, India) was used. All the apparatus was rinsed with distilled water at first and then with Acetone (Thermo Fisher Scientific, Qualigens, India) and then dried. For spectral analysis, N-Bromosuccinimide (NBS) (SDFCL fine chemicals limited, India) and Rhodamine-b (SDFCL fine chemicals limited, India) was used. Stock solution of organophosphorus pesticide was prepared by dissolving 100 mg of insecticide in minimum amount of methanol and then diluted with distilled water. An aqueous solution of 0.01% (w/v) N-Bromosuccinimide (NBS) was freshly prepared in distilled water and stored in amber colored bottle. 0.02% (w/v) Rhodamine B was prepared in distilled water. A 2 mol L-1 aqueous solution of hydrochloric acid (HCl) (Merck, Mumbai, India) was prepared in distilled water.

3.6 Influence of variable

The effects of acid concentration, NBS, Rhodamine-B concentration, mixing time, temperature were studied through a series of controlled experiment. The optimum condition was established by varying one variable and observing its effect on the absorbance of colored product.

Effect of acid concentration

It was found that acidic medium was needed for the better result. As nitric acid and sulphuric acid are oxidizing in nature, hydrochloric acid was tried. From the series of experiment, it was found that 1 ml of 2M HCl gave the better spectral result.

Effect of Rhodamine-B concentration

The effect of rhodamine-b concentration on the intensity of color was carried out in the range of 0.5-1.5 ml and it was found that the optimum concentration to maximum absorbance was obtained with 1 ml of 0.02% of rhodamine-b in the final volume of 35 ml.

Effect of time and temperature

It was found that the sample requires 10 min for the oxidation by NBS and extra 2 min time was sufficient for the completion of reaction between rhodamine-b and NBS. The most suitable temperature for the reaction was found to be 25oC – 30oC. As there was no appreciable increase in absorbance at higher temperature, all the reactions were carried out at that temperature.

Effect of NBS concentration

Theeffect of NBS (oxidant) concentration was studied byadding varyingvolume of 0.01% NBS to a constant volume organophosphate insecticide, 1ml of 2M HCl, 1 ml of 0.02% rhodamine-b at 25oC-30oC temperature and it was found that 2ml of 0.01% of NBS was optimum to bleach rhodamine-b in final volume of 35 ml.

3.7 Procedure

Each vegetable sample was first washed with distilled water, weighted and 40gm of each vegetable sample was taken for extraction process. The vegetable sample was then crushed with the help of mixture and the crushed sample was filled in thimble (Thermo Fisher Scientific, Qualigens, India) for extraction. The thimble was placed in soxhlet and sample was extracted by using 100% pure methanol till 72 hours for complete extraction. The extracted sample from soxhlet was then passed through column packed with silica (Thermo Fisher Scientific, Qualigens, India) for the absorption of the chlorophyll. The extracted sample thus free from chlorophyll was then stored in aconical flask and the entire sample was made equal volume i.e. 400ml either by evaporating or by adding distilled water. Then the spectral properties of the sample were studied.

Figure 06: Soxhlet extraction and column chromatography

Similarly, the soil sample collected from different agricultural field was weighted (40 gm) and then transferred to a reagent vessel. Then methanol was added and made 100 ml by adding distilled water. Then the sample was agitated in magnetic shaker for 30 minutes and filtered. The sample was then made 400 ml by adding distilled water and used for the study of spectral properties. The water sample collected from different irrigated land and nearby rivulets was first filtered from whatmann No. 1 filterpaper, measured (40ml) which is later on diluted to 400 ml by adding distilled water and was used for the spectral analysis. An aliquot of working standards containing 0.028-0.588 µg mL-1 of Chloropyrifos was transferred into a series of 50 mL conical flask and to each flask, 1mL of HCl and 2 mL of NBS were added and the solution in each flask was diluted to 10 mL of water. The solution was kept aside with occasional shaking for about 10 minutes at approximately (~) 25oC in water bath and then 1 mL of rhodamine-B solution was added and diluted to 35 mL with distilled water. The absorbance was measured at 558 nm against a reagent blank. A blank without pesticide (dye and NBS) and dye (devoid of pesticide and NBS) were prepared in similar manner and its absorbance was measured against distilled water. The decrease in absorbance corresponding to consumed oxidant, which reflects the concentration of Chloropyrifos was obtained by subtracting the decrease in the absorbance of test solution (dye minus test) from that of the blank solution (dye minus blank) . Calibration graph was prepared by plotting the decrease in absorbance of the dye against the amount of Chloropyrifos i.e. Organophosphate pesticide present.

Figure 07: Absorbance vs Wavelength curve

3.7.1 Spectral characteristics

The maximum absorbance of rhodamine-B was found to be at 558 nm against distilled water. Beer’s law was obeyed in the concentration range 0.028-0.588 μg mL-1 of Chloropyrifos. The calibration curve was found to be linear with a good correlation coefficient.

Figure 08: Calibration curve, Absorbance vs Concentration

Table 02: Spectral characteristics

Parameter	Chloropyrifos
λmax /nm	558
Beer’s law / µg mL-1	0.028-0.588
Molar absorptivity (L mol-1 cm-1)	0.607*10-4- 0.431*10-4

4. RESULT & DISCUSSION

The present study was carried out in two parts; field study to compile the information from the farmers about the pesticide use, handling and safety while the laboratory study was carried out to investigate the level of organophosphate pesticide in the vegetables, water sample and soil sample.

4.1. Laboratory Study

4.1.1. For Vegetable sample

Table 03: Result for vegetable sample

Figure 09: Amount of pesticide in vegetable sample

4.1.2. For Soil sample

Table 04: Result for soil sample

Figure 10: Amount of pesticide in soil sample

4.1.3. For water sample

Table 05: Result for water sample

Figure 11: Amount of pesticide in water sample

According to European Union Commission Regulation, the MRLs of Organophosphate pesticide in vegetable sample ranges from 0.01 µg/mg to 0.05 µg/mg depending upon the type of vegetable for example for tomato is 0.1 µg/mg, for cucumber is 0.01 µg/mg, for squash is 0.01 µg/mg, for broccoli is 0.01 µg/mg, for cauliflower is 0.05 µg/mg. According to the data generated we can find that all the vegetable sample are contaminated with pesticides. Here maximum amount of pesticide is found in Black eyed beans i.e. 0.095μg/gm followed by Cucumber, Broccoli, cauliflower, brinjal etc. The minimum amount of pesticide is found in smooth luffa gourd and Sponge gourd i.e. 0.036μg/gm and 0.082μg/gm. Similarly for soil sample the MRL of organophosphate ranges from 0.000001-0.0003 μg/gm but the amount of pesticide in soil sample was found to be very much high i.e. ranging from 0.100283575 to 0.087420599 μg/gm Similarly for water sample the MRL of organophosphate is 0.000005μg/ml but the amount of organophosphate in water sample is very high as compared to the MRL value. The unusual high level of organophosphate in water sample may be due to the analytical error or that the water sample have been taken from the area where organophosphate is directly contaminated with water.

4.2 Survey study

A total of 50 farmers were interviewed for the present study from the studied sites. The result of the field survey has been illustrated and described in detail below:

4.2.1 Source of information about pesticide use among farmers

Figure 12: Source of information about pesticide use among farmers

Out of 50 farmers interviewed, 48% got information about pesticide use from friends or other farmers, 40% from shopkeeper, 4% from agricultural department while 8% from own experience. Among the interviewed farmers none of them got information from JTA (junior technical assistance) while very few (only 4%) got information from agricultural

4.2.2 Storage of pesticides

Figure 13: Storage of pesticides

Among the 50 farmers interviewed it was found that only 12% and 24% store pesticide in locked cabinet and locked room respectively while 46% and 8% farmers store pesticide in unlocked room and open space respectively. This negligence in storage of pesticide may lead to many unwanted accidents, especially where there are little children in the family.

4.2.3 Stages of pesticides use by farmers

Figure 14: Stages of pesticides use by farmers

The survey revealed that 32% of farmers use pesticide before presence of any disease for the protection of the crops, 20% use pesticide when there is presence of disease, 10% use pesticide only after the effect of disease is seen while remaining 38% use pesticide in all the three cases. Preharvest application of pesticide is a dangerous practice because it may lead to excessive amount of residue in food crops, especially in vegetables causing adverse health impacts.

4.2.4 Application of pesticides

Figure 15: Application of pesticides

In the study, it was found that 28% of the interviewed farmers (50) applied pesticides in their agricultural field by both male and female while 56% and 16% by male and female respectively. Application of pesticides by female can be more dangerous than that of male because the pesticides in her hands can be easily transferred to other members of family and to the babies through food or through direct contact. So, proper safety measures should be applied before and after the use of pesticides.

4.2.5 Waiting time after pesticide use

Figure 16: Waiting time after pesticide use

The waiting time is different for the different type of insecticides or for different types of vegetables/crops. Waiting time between the pesticide application and harvesting of the crops is very essential things to be known by the farmers as it may lead to pesticide poisoning. But due to illiteracy, carelessness and lack of knowledge some farmers do not wait after pesticide use. It is seen that some of the farmers spray pesticide even in the day of harvesting vegetables. In this study, among 50 farmers, 32% of farmers wait for less than 3 days, 28% of farmers wait less than 1 week, 40% of farmers wait for 1 week, 16% of farmers wait for 2 week and 8% of farmers wait for 1 months. Generally the professional farmer’s do not wait for long period after pesticide use. The application of pesticide close to the harvesting time could be the main reason for the contamination of vegetables in different city of Nepal.

4.2.6 Safety measures adopted during pesticide use

Figure 17: Safety measures adopted during pesticide use

The use of safety measures during the uses of pesticide is one of the important things to be safe from the possible pesticide poisoning. /various kinds of safety measures can be adopted during pesticide use like use of gloves, masks, long sleeve cloth, goggles, boot, etc. The present study showed that among 50 farmers interviewed 24% of farmers do not use any kind of safety measures, 10% use gloves, 30% use masks, 40% use long sleeve cloth and 8% use boots. During the questionnaire survey among the farmers it was found that although they know the possible hazards of pesticide poisoning they hesitate to use the safety measures.

4.2.7 Knowledge about the health impacts of pesticide application

Figure 18: Knowledge about the health impacts of pesticide application

Out of 50 farmers interviewed 78% had knowledge of the health impacts of pesticide while 22% did not have. Although 78% had knowledge about the health impacts of pesticide use very few of them use the safety measures while using pesticides. So, this shows that farmers are careless while using pesticide which may lead to pesticide poisoning and other health problems as well.

4.2.8 Symptoms of health impacts

Figure 19: Symptoms of health impacts

Out of 50 farmers interviewed 32% had the problem of skin irritation after the use of pesticide while 28% had the problem of eye irritation and 24% had the problem of headache. But 16% of the farmers do not have any problems after the pesticide use. The misuse, continuous and unprotective application of pesticide may lead to several healths’ related problems.

5. CONCLUSION & RECOMMENDATION

In the field study, fifty farmers were interviewed, and in the laboratory study, thirteen samples of vegetables, five samples of soil, and three samples of water were collected. For the purpose of achieving a deeper level of comprehension and for the purpose of drawing meaningful conclusions regarding the use of pesticides and their safety among Nepalese farmers, it is recommended that a comprehensive study that encompasses all ecological regions of Nepal be conducted. This is despite the fact that the area of study included only a relatively small amount of land. As indicated by the results of surveys and questionnaires that were filled out by farmers, the level of awareness among farmers regarding the application of pesticides and the safety of these chemicals is extremely low. The field study revealed that some of the farmers, despite being aware of the waiting time that must pass after the application of pesticides, do not adhere to it. This was one of the findings of the study. In addition, it is difficult to change the behaviour that they are currently adopting because of the difficulty involved. It has been found out that some of the farmers are using pesticides that are not allowed to be used in their operations. This is due to the fact that the borders are open. Furthermore, it was found that the pesticides were present in the samples of the vegetables, the soil, and the water during the investigation. Each day, the number of cases of pesticide poisoning continues to rise. After the application of pesticides, it has been discovered that a significant number of farmers experience health-related issues.

From the above findings, following recommendations have to be made so as to improve the present situation of pesticide use in Nepal:

• Education on safety precautions regarding pesticide use to the farmers (male and female) should be made more efficient, covering all regions of Nepal. As long as farmers are not far away from awareness, the problem of pesticide pollution cannot be solved.
• The use of different media like radio, television could be effective in order to spread awareness to the farmers. Also, the local community clubs in association with government could provide training to farmers through public lectures, street theatres in local language etc.
• Farmers should also be well informed of the fact that using pesticide in recommended amount does not result with harmful impacts. It brings hazard only when farmers don’t follow the recommendation and use it haphazardly.
• The activity of pesticide residue monitoring should be made effective and regular by the government. If the government laboratory doesn’t have sufficient technology and manpower, it should work in close collaboration with private or semi-governmental laboratory that has facility (human and technological resource) and resources for pesticide residue monitoring.
• There should be strict regulation that should be implemented for stopping the import of banned chemical pesticides especially from India and China due to open borders.

REFERENCES

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