Pesticides in use, their application and risks on human health and ecosystems: A case of Fogera District, Ethiopia

ABSTRACT

The effects of pesticides are largely a function of toxicity, exposure time, dose rate and its persistence in the environment. Previous studies conducted in the study area mainly focused on the knowledge, attitude and practices of farmers against implementation of pesticide safety instructions during application and storing the pesticides. Hence, the objectives of the present study were to assess the pesticides applied on crops per a cropping season; the pesticide application practices of farmers and the health risks of pesticide residues on humans and the ecosystems. Quantitative data were collected using a questionnaire and analyzed using descriptive statistics, and qualitative data were grouped and summarized. The findings of the study confirmed that crops were sprayed with pesticides up to 26 times per a cropping season. A hectare of farmland might be sprayed more than 14 kg and 28 kg of pesticides per a cropping season and per a year. In addition to solid formulations, farmers used more than four liters of pesticides per crop per hectare. Farmers sprayed highly toxic pesticides without following the safety instructions and supplied the sprayed crops without waiting for the post-spray time interval. Most pesticides used in the district are in the lists of highly hazardous pesticides and are highly toxic to aquatic organisms including fish. There were also practices of fishing using pesticides in rivers of Fogera District and symptoms of surface water pollution used for drinking. Hence, pesticide residues might be one of the major health risks for farmworkers, consumers and ecosystems of the District. Therefore, monitoring the pesticide supply chain starting from suppliers to end users, continuous ecosystem assessment and food safety monitoring using GC-MS are needed to minimize the effects of pesticide residues on human health and the ecosystems.

KEYWORDS:

• Pesticide residues
• law enforcement
• fishing
• toxicity
• water pollution
• effects of pesticides

PUBLIC INTEREST STATEMENT

The effects of pesticide residues are becoming a severe problem of human health and ecosystems all over the world. Its effects are mainly a function of toxicity, exposure time, dose rate and persistence in the environment. Farmers in the study area sprayed huge amount of highly toxic pesticides without following the safety instructions and supplied the pesticide-sprayed crops without waiting for the post-spray time interval. There were also practices of fishing using pesticides in rivers and consequently fish population declines in water bodies. There are also higher prevalence of blindness and vision impairment, hypersensitivity and self-suicide, diabetes and cancer among farmworkers in the District. Pesticide residues are one of the top ten health risks in the District for farmworkers and consumers and threat to ecosystems. Thus, everybody should exert his/her effort to protect him/her and the environment from risks of pesticide residues.

1. Introduction

To increase the production and productivity of agriculture, inputs such as pesticides have been the driving forces (Pesticide Action Nexus Association, 2019). Pesticides enable farmers to avoid a 78%, 54% and 32% losses in fruits, vegetables and cereals, respectively (Tudi et al., 2021). Pesticides are relatively easy to apply, cost-effective and sometimes the only option to control pests (Chala, 2022; Helfrich et al., 2009). However, open accesses to all types of pesticides made farmers to use banned and overuse registered pesticides on seeds, vegetables and khat to protect them from pests and weeds (Bureau of Environment Protection, Land Administration and Use (BoEPLAU, 2015b; Mellese, 2016; Mengistie et al., 2016). Moreover, traditional fisheries use a mix of Milletia ferruginea seed powder and Malathion for fishing in tributaries of Lake Tana (BoEPLAU, 2015a). The overuse of registered pesticides and the use of obsolete pesticides including DDT and Endosulfan on food crops are very common practices among farmers in the Central and Eastern part of Ethiopia (Negatu et al., 2016). Previous studies confirmed that the residues of pesticides in contaminated food items and drinking water are becoming a key global human health concern including Ethiopia (Human Rights Council, 2017; Mengistie, 2016; Wumbei et al., 2019; Chaikasem and Roi-et, 2020; Mekonnen et al., 2021). Knowledge about the right types and amount of pesticides, timing of application, method of mixing and application are so important to enhance the efficiency and effectives of a pesticide use, and reduce its risks on human health and the environment (Van et al., 2020). As there are ever-increasing trends in importation and use of pesticides and other chemicals in Ethiopia, the country declared the laws to minimize their negative effects on human health and the ecosystems (FDRE, 2010, 2018).

On the contrary, development projects, including floriculture farms that use huge amounts of pesticides, have been highly encouraged to earn short-term economic benefits without considering their long-term environmental and social effects in Ethiopia (Birkie, 2019; Gubena, 2016). Nearly 30% of the flower farms are established by destructing the swampy areas and 30% of them discharged their liquid waste directly to the water bodies (Fufa, 2018). In the present study area, farmers also use obsolete and persistent pesticides to control crop pests and improve the quality of vegetables and khat (BoEPLAU, 2015b). The pesticides applied to control pests could also affect the non-target plants and animals and might cause species to become extinct regionally or nationally (Darçın & Darçın, 2017; Hashimi et al., 2020; Kassa, 2017; Tassew et al., 2018). Pesticide residues above the maximum limit caused failure of reproduction, loss of tolerance to extreme temperatures and loss of normal growth and development in aquatic biodiversity (Hayes et al., 2011; Helfrich et al., 2009; Landos et al., 2021; UNEP & WHO, 2013; UNEP/AMAP, 2011). The effects of pesticide residues on animals are largely a function of its toxicity, exposure time, dose rate and its persistence in the environment (Helfrich et al., 2009; Maurya et al., 2019).

Different studies were conducted on pesticide use and handling in northwestern Ethiopia, particularly in the Lake Tana watershed (Agmas et al., 2020; Mequanint et al., 2019). The studies mainly focused on the knowledge, attitudes and practices of farmers against instructions of labels of pesticides to minimize its negative effects on farmworkers (Agmas et al., 2020; Ejigu & Mekonnen, 2005). There were no studies on types and amounts of pesticides used per crop type; the time interval between pesticide spraying and crop supplying practices; frequency of pesticide spraying on a cropland per a cropping season; and the factors that expose humans and ecosystems to the effects of pesticide residues. Therefore, the objectives of the present study were to assess the types and amounts of pesticides applied on crops per a cropping season; the pesticide application practices of farmers and the risks of the pesticide residues on human health and the ecosystems.

2. Materials and methods

2.1. Description of the study area

The study was conducted in Fogera District of the South Gondar Administrative Zone, northwestern Ethiopia (fig. 1). Fogera District is one of the ten Districts bordering Lake Tana and it is bordered on the South by Dera District, on the West by Lake Tana, on the North by the Rib River, which separates it from Libo-Kemekem District, on the northeast by Ebenat District and on the East by Farta District (Gebey et al., 2012; Mohammed et al., 2019). Woreta, the capital of the District, is located 625 km northwest of Addis Ababa and 55 km from the regional capital, Bahir Dar (Lema et al., 2017). The District is situated at 11º46’ to 11º59’N latitude and 37º33’ to 37º52’E longitude (Lema et al., 2017) and its altitude ranges from 1774 to 2415 m a.s.l (Mohammed et al., 2019). The study area has an annual total rainfall ranging from 1103 to 1336 mm (Gebey et al., 2012; Lema et al., 2017). Among the 23 999.8 hectares of wetlands in the Lake Tana watershed, 39.14% was in Fogera district (Hunegnaw et al., 2013). The floodplain of Fogera District is waterlogged for more than four months starting from July of each year. Fogera District is one of the leading rice producing Districts in the Amhara Region (Gebey et al., 2012). From the 57,223 hectares of farmland cultivated in the District during the rainy season, 73.12% was used for cereal crop production and 53.35% of the cereal farmland was used for rice production (Fogera District Environment and Forest Protection Office, 2022).

Figure 1. Location map of Fogera District.

(Krauer et al., 0000)

2.2. Data collection methods

To estimate the possible risks of pesticide residues on human health and the ecosystems, both qualitative and quantitative data were gathered using a questionnaire and structured interview. Three rural sub-districts of Fogera District including Shina, Bebekis and Kuhar-Michael, which practice intensive irrigation agriculture, were purposefully selected for data collection. The sampled sub-districts were among the most frequently cultivated areas of the District. It was assumed that an increase in the frequency of cultivation increased the frequency of pesticide use per unit area per a year (Maurya et al., 2019). A cross-sectional survey complemented with Focused Group Discussion (FGD) and field observations were used to gather the necessary data. Data were collected on types and amount of pesticides used, interval between pesticide spraying and crop supplying practices of farmers, pesticide spraying frequencies on croplands per a cropping season and ranks of risk factors that expose humans and the ecosystems to the effects of pesticide residues. Data collection was conducted between January and March 2022. Data on types and amounts of pesticides sprayed on a crop per a cropping season and risks of pesticide residues on human health and the ecosystems were gathered from experts of Fogera District and its sub-districts using FGD in December 2022.

A reconnaissance survey conducted prior to the actual data collection period was used to assess the worst scenario for the types and amount of pesticides used, the frequency of pesticide spraying and its risks on human health and ecosystems. Furthermore, the sites were easily accessible and cost-effective to collect the data required. There are about 2308, 1530 and 1314 household farmers in Shina, Bebekis and Kuhar-Michael Sub-districts, respectively. Among the total of 5152 household farmers in the sampled sub-districts, 2221, 1477 and 793 farmers have been practicing irrigation agriculture in Shina, Bebekis and Kuhar-Michael sub-districts, respectively. Then the lists of the study population who are working on irrigation agriculture were collected from the three sub-districts’ Agriculture Offices and a simplified formula (Yemane, 1967) was used to determine the total sample size from selected rural sub-districts assuming a confidence level of 95 percent (with a margin error of 0.05).

$n=\mathrm{N}/(1+\mathrm{N}{\mathrm{e}}^2)$

Where n= the sample size

             N = the population size and

               e = the level of precision/tolerable sampling error.

The sample size per a sub-district was determined based on the number of farmers working on irrigation agriculture in each sub-district. A total of 380 representative farmers (368 based on the formula given above and 12 additional samples for non-returned questionnaires due to various reasons) were selected from the lists of the study population using simple random sampling technique. To select individual representative farmers, all the names of the target population in the sampled sub-districts were listed on papers and put into carton boxes. Then selection was conducted by randomly drawing each slip of paper.

The questionnaire was prepared in English and translated to the local language, Amharic, for ease of communication. To check the level of clarity, wording and meaning of questions, a pilot test was made by inviting 18 farmers from Woreta Zuria sub-district of the District using convenient sampling methods. Then data for the study were collected from the respondent farmers using a pre-tested and structured questionnaire. The data included the commonest types and amount of pesticides used per a crop type per a cropping season, the frequency of pesticide spraying per crop type and the time interval between pesticide spraying and crop supplying. Moreover, data on the ranks of possible risk factors that expose humans and the ecosystems to effects of pesticide residues were gathered.

Prior to data collection, information about the purpose of the study and the confidentiality of the data gathered were communicated to the respondents and they agreed to be interviewed. The demographic characteristics, including sex, age and educational status of the respondents were also included in the questionnaire. The respondents’ age and education levels were classified into five categories. All rural respondents were farmers working on irrigation agriculture and had more than a year of experience in pesticide application and use.

The required data was collected in a face-to-face mode by the help of six trained extension workers of the sub-districts with close supervision given by the three trained supervisors and the researchers. The close-ended data collected from farmers was complemented by the data gathered from sampled farmers using open-ended questionnaire and FGD. This is to secure in-depth and reliable data about pesticide residues’ effects on human health and ecosystems. A total of 11, 11 and 7 participants were involved in the FGD at Shina, Bebekis and Kuhar-Michael sub-districts, respectively, and the discussions were carried out at the center of each sub-district. In addition to the questionnaire and FGD, data was also collected from repeated field observations supported with photos and videos.

Similarly, data about the ranks of risk factors that expose humans and ecosystems to the effects of pesticide residues were gathered from experts of Fogera District working in the offices of Agriculture, Environmental Protection, Livestock, Cooperative, Water and Energy, and Land Administration and Use. Experts in the offices were selected purposely, assuming that they have had sufficient experience with the effects of pesticide residues on humans and ecosystems in the study area. Furthermore, the respondents were consumers of agricultural products supplied by farmers in the study area. The names of the 151 experts in the offices were listed on a slip of paper and samples were selected using a simple random sampling technique following the same procedure for sample selection of the respondents in the rural sub-districts. Based on a comparative study made among officers of Ethiopia and Hungary, 74%, 82% and 77% of Ethiopian extension officers had knowledge, perception and experience about pesticide toxicity; water, soil and air pollution from pesticide residues; and risks of pesticides to users, respectively (Tessema et al., 2021). From the pilot study using 15 invited experts, 86.67% knew about the risks of pesticides on humans and ecosystems. Hence, the sample size of experts was determined assuming that 86.67% of experts knew about the risks of pesticides on humans and ecosystems with 95% confidence level and 5% margin of error. The sample size was determined using the population proportion formula (Daniel & Cross, 2013; Kathari, 2004; Tessema et al., 2021).

$n=\frac{{\mathrm{z}}^2\mathrm{x}\hspace{0.17em}\mathrm{p}\hspace{0.17em}\mathrm{x}\hspace{0.17em}\mathrm{q}\hspace{0.17em}\mathrm{x}\hspace{0.17em}\mathrm{N}}{e^2\left(N-1\right)\hspace{0.17em}+{\mathrm{z}}^2\mathrm{x}\hspace{0.17em}\mathrm{p}\hspace{0.17em}\mathrm{x}\hspace{0.17em}\mathrm{q}}$

Where

N=Total number of experts in the sector offices

n = Sample size

e = acceptable error(precision) which equals to 0.05

z = The corresponding value to 95% confidence level which is equal to 1.96

p = Proportion of officers with knowledge of pesticide applications(0.8667)

q=Proportion of officers having no knowledge of pesticide application (0.1333)

Based on the formula for n, 82 respondent experts were selected using simple random sampling techniques. In addition to the 82 sampled experts, data was collected from 14 experts of Fogera District sector offices on types and amount of pesticides sprayed per a cropping season and from 46 experts on the ranks of risk factors that exposed humans and the ecosystems to the effects of pesticide residues. The latter group of experts was from the Environmental Protection and Agriculture Office of South Gondar Administrative Zone, Fogera District and selected sub-districts in the District. Secondary data was also gathered from offices reports and from various research findings.

2.3. Data analysis

Data analysis was conducted using descriptive statistics, and mean, frequency and percentage values were calculated to know the amount of pesticides used per a cropping season. The average time interval between pesticide spraying and crop supplying and the ranks of the possible factors that expose humans and the ecosystems to the effects of pesticide residues were also calculated using mean, frequency and percentage values. The mean of the ranks of individual items was calculated to re-rank the possible risk factors from higher to lower. The amounts of pesticides used per crop per a unit area, the ranks of the possible risk factors, the average frequency of pesticide spraying and the average time interval between pesticide spraying and crop supplying practices were computed using SPSS version 26. In addition to quantitative data analysis, the response to open-ended questions was grouped and summarized based on similarities.

3. Results

3.1. Demographic information of respondents

The survey data was gathered from farmers of three rural sub-districts and experts of six sector offices of Fogera District. The demographic information of the respondents is summarized. Among the selected respondents, 97.37% (n = 370) of farmers and 100% (n = 82) of experts responded to the structured interview and questionnaire. Among the 370 farmers, 86.2% were males and 42.7% were in the age ranges of 36–45. Most farmers (73%) were under the general primary school level. Similarly, 81.7% of officers of Fogera District were males and most of them (47.6%) were in the age ranges of 26–35. Among sampled experts, 9.8%, 30.5% and 59.8% had less than 5 years, 6 to 10 years and above 10 years of experience, respectively.

3.2. Types and amounts of pesticide used in the study area

Farmers have been using various types of pesticides to control weeds and pests of crops with different spraying frequencies. The types of pesticides sprayed on khat, cabbage, tomato, pepper and onion were analyzed and are summarized (Table 1). The number of farmers that applied the various types of pesticides per a crop type is also summarized.

Table 1. Types of pesticides sprayed and number of respondent farmers used the pesticides in the district

Tomato		Onion		Cabbage		Khat		Pepper
Pesticides	N	Pesticides	N	Pesticides	N	Pesticides	N	Pesticides	N
Ajanta 72% EC (W/V)	200	Ajanta 72% EC (W/V)	273	Ajanta 72% EC (W/V)	144	Hunter 40 EC	30	Ajanta 72% EC (W/V)	142
Mancozeb with various trade names	96	Ridomil Gold MZ 68 WG	122	Karate 5% EC	85	Agro-Thoate 40% EC	23	Karate 5% EC	69
Ridomil Gold MZ 68 WG	94	Matco	113	tricel 48% EC	37	Alcohol	14	Mancozeb with various trade names	69
Karate 5% EC	90	Mancozeb with various trade names	111	Mancozeb with various trade names	29	Diazinon10%; Diazinon 60%; Diazol 10G	13	Matco	30
Matco	75	Karate 5% EC	93	Ridomil Gold MZ 68 WG	22	Atrazine of various types	10	Nativo SC 300	25
Tricel 48% EC	47	tricel 48% EC	47	Matco	18	Karate 5% EC	8	Ridomil Gold MZ 68 WG	24
Nativo SC 300	21	Omaxim	40	Agro-Lambacin Super 315 EC	17	Malathion of various types	7	tricel48% EC	22
Omaxim	21	Farrate	19	Agro-Thoate 40% EC	17	Radiant 120 SC	4	Omaxim	12
Agro-Lambacin Super 315 EC	16	Profit72% EC	18	Diazinon10%; Diazinon 60%; Diazol 10G	14	Agro-Lambacin Super 315 EC	3	Confidence 350 SC	10
Farrate	12	Launcher	11	Malathion of various types	13	Nativo SC 300	2	Megaban Plus	9
Confidence 350 SC	11	Confidence 350 SC 350 SC	8	Launcher	10	Ridomil Gold MZ 68 WG	2	Commander 35%	7
Launcher	10	Hunter 40 EC	8	Omaxim	8	tricel48% EC	2	Farrate	7
Agro-Thoate 40% EC	7	Agro-Lambacin Super 315 EC	7	Confidence 350 SC	6	Pyriban 48% EC	2	Agro-Lambacin Super 315 EC	6
Malathion with various trade names	6	Comax 72EC	4	Farrate	3	Ajanta 72% EC (W/V)	1	Launcher	6
Diazinon10%; Diazinon 60%; Diazol 10G	5	Diazinon10%; Diazinon 60%; Diazol 10G	4	Commander 35%	2	Farrate	1	deltamethrin with various trade names	5
Commander 35%	5	Agro-Thoate 40% EC	3	Nativo SC 300	2	Lampics 5% EC	1	Guard	4
Best5 EC	4	Nativo SC 300	3	Nimbicidine	2	Profit72% EC	1	Amistar Xtra 280 SC	4
deltamethrin with various trade names	4	Ethiolathion 5% Dust, Ethiolathion 50% EC	2	deltamethrin with various trade names	2	Mancozeb with various trade names	1	Diazinon10%; Diazinon 60%; Diazol 10G	4
Profit 72% EC	4	Commander 35%	2	Selecron 720 EC	1	Megaban Plus	1	Gain 20 SL	3
nimbicidine	3	Alcohol	1	Profit 72% EC	1			Fastac 7.5 g/l ULV	3
Sniper	2	Runner 240 SC	1					Agro-Thoate 40% EC	3
Aim 10% EC	2	Pendico® 33 EC	1					Profit72% EC	2
Amistar Xtra 280 SC	1							Chlortak 48% EC	2
Comax 72EC	1							DDT	2
Dolar 52.5 WDG	1							Sumithion 50% EC	1
Hunter 40 EC	1							Ethiolathion 50%EC	1
Moglamda 5 EC	1							Nimbicidine	1
Orozeb	1
Prior 72 EC	1
Radiant 120 SC	1

N= number of respondent farmers who apply the pesticides in the study area.

Besides, pesticides sprayed on other crops cultivated in the District were annexed at the end of the manuscript (Table 8). Furthermore, the list of the 77 pesticides commonly used in the District was annexed at the end section of the manuscript (Table 9). The frequency of pesticide spraying per type of crops per a cropping season was analyzed and presented (Table 2). The findings of the study confirmed that there were wider differences between the minimum and the maximum frequencies of pesticide spraying on almost all crop types.

Table 8. The most common types of pesticide sprayed on different crops and number of farmers applying

Garlic		Chickpea		Potato		Rice		Maize		Vetch
Names of Pesticides	f	Names of Pesticides	f	Names of Pesticides	f	Names of Pesticides	f	Names of Pesticides	f	Names of Pesticides	f
Ajanta 72% EC (W/V)	182	Karate 5% EC	48	Mancozeb with various trade names	62	2,4-D of various types	224	Karate 5% EC	182	Ajanta 72% EC (W/V)	121
Ridomil Gold MZ 68 WG	89	AgroLambacin Super 315 EC	28	Matco	32	Karate 5% EC	13	AgroLambacin Super 315 EC	115	tricel48% EC	96
Mancozeb with various trade names	74	Diazinon10%; Diazinon 60%; Diazol 10 G	26	Ajanta 72% EC (W/V)	26	Agro-Thoate 40% EC	7	Ajanta 72% EC (W/V)	63	Karate 5% EC	76
Matco	65	Ajanta 72% EC (W/V)	18	Diazinon10%; Diazinon 60%; Diazol 10 G	21	Ridomil Gold MZ 68 WG	5	Diazinon10%; Diazinon 60%; Diazol 10 G	23	Agro-Lambacin Super 315 EC	45
Karate 5% EC 5% EC	60	tricel48% EC	18	Ridomil Gold MZ 68 WG	19	Diazinon10%; Diazinon 60%; Diazol 10 G	4	tricel48% EC	12	Diazinon10%; Diazinon 60%; Diazol 10 G	35
tricel48% EC	26	Atrazine of various types	13	Karate 5% EC	13	tricel48% EC	3	Mancozeb with various trade names	10	Malathion of various types	23
Omaxim	25	Malathion	7	Agro-Thoate 40% EC	11	Tilt 250 EC	3	Farrate	9	Atrazine of various types	11
Launcher	13	Agro-Thoate 40% EC	6	Trust-Sate	4	Matco	2	DDT	8	Matco	11
Farrate	11	DDT	4	Agro-Lambacin Super 315 EC	3	Agro-Lambacin Super 315 EC	2	Aluminum phosphide	8	Ridomil Gold MZ 68 WG	8
Profit72% EC	10	Farrate	4	Agro-Thoate 40% EC	3	Ethiolathion 50% EC	1	launcher	8	Agro-Thoate 40% EC	8
Agro-Thoate 40% EC	8	Lampics 5% EC	3	Ethiolathion	3	Nativo SC 300	1	Ridomil Gold MZ 68 WG	5	Farrate	7
Agro-Lambacin Super 315 EC	6	Aluminum phosphide	3	Triger 5 EC	3			Ethiolathion 50% EC	3	Mancozeb with various trade names	7
Confidence	6	Selecron 720 EC	2	Datozeb 80 WP	2			Matco	3	launcher	7
Diazinon10%; Diazinon 60%; Diazol 10 G	5	Mancozeb with various trade names	2	Farrate	1			2,4-D of various types	3	omaxim	6
Hunter 40 EC	3	Commander 35%	2	rider	1			Bravo 5% EC (W/V)5% EC	2	alcohol	5
Triger 5 EC	3	Hunter 40 EC	2	Sevin 85% WP	1			Jalo 25% EC	2	DDT	3
Comax	2	Aim 10% EC	2	Kenozeb	1			omaxim	2	Commander35%	3
Nativo	2	Tilt 250 EC	2	omaxim	1			prior	1	Lampics 5%EC	3
Malathion	2	Alcohol	1	Orozole 25 EC	1			Hunter 40 EC	1	Profit72% EC	2
Carbaryl	1	Bravo 5% EC (W/V)	1	tricel48% EC	1			Sarin	1	Pyriban 48% EC	2
Ethiothoate 40% E.C	1	Fastac® 100 G/L EC	1	Agro-Laxyl MZ 63.5 WP	1			indoxacarb	1	Aim 10% EC	1
Proven44 EC	1	Ethiothoate 40% E.C	1	Carbenchlor 50% SC	1			Megaban+	1	2,4-D amine	1
deltamethrin with various trade names	1	Ridomil Gold MZ 68 WG	1					Atrazine of various types	1	Decis with various trade names	1
		launcher	1					Vaseline	1	endosulfan	1
		Omaxim	1					Profit72% EC	1	Tilt 250 EC	1
										Hunter 40 EC	1
										prior	1
										Selecron 720 EC	1
										sniper	1
										Vaseline	1

N= number of respondent farmers applying the pesticides.

Table 9. Common pesticides currently used in Fogera district of Amhara region, Ethiopia

S/n	Trade Name	Common Name	S/n	Trade Name	Common Name
1	Karate	lambda-Cyhalothrin	40	Amsac	Indoxacarb
2	Agro-Lambacin Super 315 EC	profenfos 30% + lambda-cyhalothrin 1.5%	41	Comax 72EC	Profenofos
3	Diazinon10%; Diazinon 60%; Diazol 10 G	Diazinon	42	Dolar 52.5 WDG	Famoxadone = Cymoxanil
4	Ajanta 72% EC (W/V)	profenofos	43	Hunter 40 EC	Abamectin + Acetamiprid
5	Tricel 48% EC	Chlorpyrifos	44	Moglamda 5 EC	Lambda Cyhalotrin
6	Lasso/Atrazine 55% SC*	alachlor 35% + atrazine 20%	45	Orozeb	Mancozeb
7	Farrate	lambda—Cyhalothrin	46	Prior 72 EC	profenofos
8	Nativo SC 300	trifloxystrobin 100 gm/lt + tebuconazol 200 gm/lt	47	Radiant 120 SC	Spinetoram
9	Omaxim	Mancozeb + metalaxyl	48	Actellic Gold Dust ®	Primiphos Methyl + Thiamethoxam
10	Mancozeb of Various types	Mancozeb	49	Green Miracle	Fatty alcohol
11	Ridomil Gold MZ 68 WG	Metalaxyl-M	50	Runner 240 SC	Methoxyfenozide
12	Matco	metalaxyl 8% + mancozeb 64%WP	51	Domnator 50% EC	Pendimethalin
13	Confidence 350 SC	Imidacloprid	52	Sevin 85% WP	Carbaryl
14	Commander 35%	Imidachlopride	53	Ethiothoate 40% E.C	Dimethoate
15	Best 5 EC	Lambda Cyhalothrin	54	Malathion various conc.	malathion
16	Decis 0.5 EC/ULV; Decis 0.6 ULV; Decis 2.5 EC	Deltamethrin	55	Proven 44 EC	Profenofos + cypermethrin
17	Profit 72% EC	profenofos	56	Lampics 5% EC	Lambda-Cyhalothrin
18	Agro-Thoate 40% EC	dimethoate 40%	57	Megaban Plus	chlorpyriphos-ethyl 48% w/v
19	Eforia 247 SC	Thiamethoxam + Lambda-Cyhalothrin	58	Sniper	Lambda-Cyhalothrin
20	Ethiolathion 5% Dust,	malathion	59	Triger 5 EC	lambda cyhalothrin
21	Nimbicidine	Neem	60	DDT	DDT
22	Malamar 50% EC (w/v) *	Malathion	61	launcher	Profenophos
23	Aim 10% EC	alpha-cypermethrin	62	Selecron 720 EC	profenofos ‘Q’ 720 g/l
24	Amistar Xtra 280 SC	azoxystrobin 200 gm/lt +cyproconazole 80 gm/lt	63	Pyriban 48% EC	chlorpyrifos
25	Bravo 5% EC (W/V)	lambda-cyhalothrin	64	Chlortak 48% EC	chloropyryfosethyl
26	Ethiotrothion 50% EC	fenitrothion	65	Guard	lambda cyhalothrin
27	Fastac® 100 G/L EC	Alpha- cypermethrin	66	Gain 20 SL	imidacloprid
28	Trust-Sate	Glyphosate	67	Gagazeb	Mancozeb
29	Datozeb 80 WP	metalaxyl + mancozeb	68	Zera insecticide	Fipronil
30	Orozole 25 EC	Propiconazole	69	Ridom 80% WP	Mancozeb
31	Rider 5 EC	Lambdacyhalothrin	70	Sumithion 50%EC	fintrothion
32	Agro-Laxyl MZ 63.5 WP	mancozeb + metalaxyl	71	Thiodan35% or thionex35%	Endosulfan
33	Carbenchlor 50% SC	Carbendazim + Chlorothalonil	72	Zinc phosphide	Zinc phosphide 80% technical
34	Tilt 250 EC	Propiconazole	73	Various types of insecticides	Aluminum phosphide
35	Jalo 25% EC	Propiconazole	74	Sumithion 50% EC	Fenitrothion
36	Sarin	S-Metolachlor + Atrazine	75	Kenozeb	Mancozeb
37	Cupricide 77% WP	Copper hydroxide	76	2,4-D of various types	2,4 D dimethyl-amine salt
38	Natura 250 EW	tebuconazole	77	Tutan 36% SC	Chlorfenapyr
39	megathrin,

Note: the shaded pesticides are included in the list of HHPs at least in either of the references (Pesticide Action Network International PAN, 2016; Pesticide Action Nexus Association, 2019; USAID Ethiopia, 2020).

Table 2. Frequencies of pesticide spraying on different crops per one cropping season

Crop types	N	Frequency of pesticide spraying per a cropping season
		Minimum	Maximum	Mean	Std. deviation
Onion	343	3	26	11.49	4.667
Vetch	308	2	25	8.80	4.255
Tomato	306	1	25	8.07	3.650
Garlic	249	1	20	7.27	3.981
Pepper	230	1	18	6.53	3.182
Cabbage	245	3	24	6.11	2.616
Potato	132	1	10	4.36	1.744
Chickpea	135	1	20	4.34	2.296
Maize	292	1	15	4.23	2.128
Khat	52	1	10	3.67	1.746
Coffee	29	1	16	3.10	2.677
Rice	248	1	5	1.42	0.802

N= number of respondent farmers applying the pesticides.

There were also a wide range of time interval differences between the pesticide spraying and the crop supplying practices of farmers (Table 3). The average time interval between spraying the pesticides on khat, cabbage, tomato, pepper and onion, and supplying these crops to consumers were 5.48, 6.23, 7.24, 7.96 and 16.87 days, respectively.

Table 3. Time interval in days between pesticide spraying and crop supplying practices

Crops	Time interval between pesticide spraying on crops listed and supplying the crops
	N	Min	Max	Mean	Std. Deviation
Khat	56	1	8	5.48	2.000
Cabbage	235	2	12	6.23	1.647
Tomato	299	2	14	7.24	2.721
Pepper	226	1	15	7.96	3.282
Onion	321	3	28	16.87	4.597
Garlic	242	4	35	24.41	5.947
Coffee	29	7	120	35.93	29.780
Vetch	293	1	120	37.78	26.378
Chickpea	128	2	180	39.59	28.930
Potato	130	7	120	57.80	34.892
Maize	289	5	160	65.84	37.757
Rice	230	2	180	102.84	40.098

N= number of respondent farmers applying the pesticides.

The amount of powdered and granular pesticides used on different crop types per a 0.25 hectare of farmland per a cropping reason was analyzed and is presented. The commonest types of pesticides used by farmers in powdered and granular forms were also identified and summarized (Table 4).

Table 4. Amount of pesticides (in k/g) sprayed on crops per one cropping season per a 0.25 hectare

Crops	N	Min	Max	Mean	Std. Deviation	most commonly used pesticides in solid form
Onion	324	0.250	20.000	3.58457	3.803114	Mancozeb, ridomil, matco, Farrate, omaxim
Vetch	298	0.400	21.000	2.84950	3.879043	Agrolambacin, Atrazine, matco
Tomato	270	0.250	7.000	2.13000	1.330004	Mancozeb, agrolambacin, ridomil, Farrate, omaxim, matco
Garlic	199	0.250	10.000	2.07638	1.709582	Mancozeb, ridomil, matco, omaxim
Khat	54	0.400	10.000	2.01574	1.975124	Agrolambacin, novel 25%
Pepper	219	0.250	8.000	1.87352	1.581090	Mancozeb, matco, ridomil, omaxim, confidence, horizon
Chickpea	133	0.250	8.000	1.85376	1.658548	Agrolambacin, atrazine, DDT
Cabbage	235	0.250	6.000	1.65617	1.131406	Mancozeb, ridomil, matco, agrolambacin
Potato	93	0.500	4.200	1.61505	0.983886	Mancozeb, matco, ridomil, dimethoate
Maize	277	0.200	6.000	1.18886	0.804522	Agrolambacin, mancozeb, Farrate
Rice	243	0.125	5.000	0.78591	0.549887	2,4-D, ridomil, dimethoate

N= number of respondent farmers applying the pesticides.

Pesticides in liquid form were also applied on various crop types to protect them from different pests. The amount of pesticides in liquid form used per a crop type per a cropping season per a 0.25 hectare of farmland was analyzed and is summarized (Table 5).

Table 5. Litres of pesticides sprayed on crops per one cropping season per 0.25 hectare

Corps	N	Min	Max	Mean	Std. Dev.	Most commonly used pesticides in liquid form
Vetch	4	0.500	4.500	2.00000	1.779513	Ajanta, tricel, karate, malathion, diazinon
Onion	163	0.250	6.000	1.89337	1.074217	Ajanta, profit, karate, tricel profit, proven
Potato	42	0.250	4.000	1.30000	0.757161	Ajanta, diazinon, karate
Garlic	105	0.200	6.500	1.23881	0.814782	Ajanta, profit, karate, hunter
Khat	12	0.123	3.500	1.23508	1.037357	Hunter, malathion, gain, alcohol, confidence
Tomato	120	0.200	4.000	1.21000	0.687359	Ajanta, karate, Nativo, tricel
Chickpea	3	0.500	2.000	1.16667	0.763763	Karate, Ajanta, diazinon, tricel
Cabbage	25	0.250	6.000	1.15000	1.115702	Karate, Ajanta, tricel, gain, Nativo, malathion
Maize	9	0.250	4.000	1.13889	1.193152	Karate, Ajanta, diazinon, tricel
Pepper	59	0.125	4.000	1.07839	0.738744	Ajanta, Nativo, tricel, karate, confidence, tricel, megaban
Rice	4	0.750	1.250	0.93750	0.239357	Karate, tricel

N= number of respondent farmers applying the pesticides.

Most farmers in the study area used higher amounts of pesticides before harvest to protect the crops from weeds and pests than post-harvest to protect the crops from pests. The divisions of farmers who sprayed pesticides before harvest, post-harvest and before and after harvest were analyzed and presented (Table 6).

Table 6. Farmers applying pesticides before harvest, postharvest, and before and after harvest

		Pesticide spraying time
			Preharvest		Postharvest		Before and after
s/n	Crops	N	N	%	N	%	N	%
1	Onion	342	340	99.4	1	0.3	1	0.3
2	Garlic	252	250	99.2	1	0.4	1	4
3	Cabbage	246	245	99.6	1	0.4
4	Khat	56	39	69.6			17	30.4
5	Vetch	311	242	77.8	1	0.3	68	21.9
6	Chickpea	139	88	63.3			51	36.7
7	Maize	219	182	61.5	8	2.7.	106	35.8
8	Rice	253	222	87.7	2	8	29	11.5
9	Pepper	228	224	98.2			4	1.8
10	Potato	132	131	99.2			1	.8

N= total respondents, n= respondents spray pesticides before, after or before and after harvest.

3.3. Factors that exposed humans and the ecosystems to effects of pesticide residues

Factors that exposed humans and the ecosystems to the effects of pesticide residues were ranked by farmers and experts (Table 7). For farmers, spraying pesticides without selecting the appropriate spraying time, open access of farmers to all types of pesticides, disposal of empty pesticide containers and knowledge gaps on side effects of pesticide residues among pesticide users were the primary factors that exposed humans and the ecosystems to the effects of pesticide residues. However, entry of pesticide residues into water bodies, using highly toxic chemicals, pesticide spraying and crop supplying without waiting for the required time interval and open access to all types of pesticides were the primary factors for experts, which exposed humans and the ecosystems to the effects of pesticide residues.

Table 7. The ranks of risk factors that expose ecosystems and humans to effects of pesticide residues

Variables	Respondent farmers			Respondent experts
	N	M	R	N		M	R
Entry of pesticide residues into water bodies at the time of mixing them near water bodies	370	7.94	11		82	4.37	1
Entry of pesticide residues into water bodies at the time of washing the pesticide spraying equipment near water bodies	370	7.87	9		82	7.39	8
Fishing in the lake tributaries using pesticide poisoning techniques at the time of dry seasons	370	8.28	12		82	7.20	7
Spraying pesticides on harvested food crops and supplying them to consumers	370	7.93	10		82	7.40	9
Supplying pesticide sprayed food crops to consumers without waiting for the required time gaps in between spraying and harvesting.	370	6.61	8		82	5.37	4
Using highly toxic chemicals to control pests of crops	370	6.40	7		82	4.45	2
Open access of farmers to all types of pesticides without any restriction	370	5.08	2		82	4.49	3
Knowledge gaps on side effects of pesticide residues among chemical users	370	5.83	4		82	5.90	6
Awareness gaps among consumers on side effects of pesticide residues in sprayed foodstuff	370	5.95	5		82	5.52	5
Reusing of empty containers for domestic purpose	370	6.31	6		82	8.73	12
Spraying the pesticides without selecting appropriate time	370	4.63	1		82	7.59	10
Disposal of empty containers elsewhere in the environment	370	5.15	3		82	8.05	11

N= number of respondents, M= mean value, R= rank.

3.4. Field observation and Focused Group Discussion (FGD)

The data from field observations showed that farmers sprayed various types of pesticides on their crops per a cropping season repetitively. The FGDs data gathered from farmers indicated that pesticides were sprayed on croplands more than ten times per a cropping season. One of the reasons to spray pesticides on crops repeatedly were the instructions on pesticide containers. Farmers are instructed to spray Omaxim five times per a cropping season with an interval of 7–10 days. In addition to pesticide instructions, releasing the leftover pesticides in ditches and farmlands, buying and applying expired pesticides and failure to control pests in clusters raised the rates and amount of pesticides applied. Farmers participating in the FGD confirmed that they would never stop the current modes of pesticide spraying practices unless effective and efficient substitutes are provided.

With regard to time interval, some farmers supplied the vegetables and khat to consumers starting from the first day after they sprayed the pesticides on them. Furthermore, some farmers sprayed the harvested tomato and khat with pesticides to shine their appearances and supplied them to consumers in the next morning. The pesticide spraying and crop supplying practices of farmers without waiting for the required time interval were the major source of conflict between producers and consumers. Though farmers supplied the newly pesticide-sprayed crops to consumers, consumers of the study area had good experiences of identifying the newly pesticide-sprayed vegetables by smelling and simple observation.

One of the reasons to supply crops to consumers without waiting for the required time interval were knowledge gaps about the negative effects of pesticide residues on consumers. However, knowledge gaps were not the only reason to supply the crops sprayed with pesticides to consumers without waiting for the required time interval in between. Some farmers having sufficient knowledge about the effects of pesticide residues had been spraying the pesticides and supplying the crops without waiting for the required time interval. In addition to health risks from contaminated food crops, there were clear symptoms of water pollution and effects on aquatic organisms in the study area. Data gathered during field observation confirmed that a number of dead organisms were seen in water of a hand dug well near Shesher wetland (Figure 2). The water of the well was used for irrigation, mixing the pesticides and drinking for livestock.

Figure 2. Partial view showing the dead amphibians and insects in a hand dug well at the study area.

Source: Field photo, 2023

Farmers of the study area mixed the toxic pesticides near water bodies without any safety measure to minimize its effects on themselves and the aquatic environment (Figure 3). A farmer was tearing the container of the Bactericide, Cupricide 77%, with his teeth and mixing the four pesticides (Megathrin, Cupricide77%, Natura 250 EC and Tutan 36%SC) at the edge of a water body.

Figure 3. Partial views showing how a farmer breaks the pesticide containers and mixes the pesticides.

Source: Field photo, 2023

In addition to the data gathered on risk factors which expose humans and the ecosystems to the effects of pesticide residues using questionnaire, the risk factors were also ranked by five independent expert groups and re-ranked using the mean value from higher to lower. Thus, the ranks of the risk factors from the questionnaire and the FGD were highly congruent.

4. Discussion and Implications

Crops in the study area were sprayed with pesticides of different persistency and toxicity levels. The mean frequencies of pesticide spraying on crops ranged from 1.42 ± 0.802 for rice to 11.49 ± 4.667 for onion. The instructions of pesticides such as Omaxim directed farmers to spray it repeatedly per a cropping season. In addition to instructions, using expired pesticides, lack of a clustered pest control mechanism among farmers and the re-infestation of the croplands by pests from the adjacent farmlands were the main reasons for the higher frequencies of pesticide spraying. Farmers of the study area spray pesticides 3 to 26 times per a cropping season on onion farmland. A similar study conducted in the Central Refit Valley of Ethiopia confirmed that small holder farmers sprayed the pesticides 8–17 times per a cropping season on their vegetables (Mengistie et al., 2017). There is increasing trends of frequency of pesticide spraying and dosage through time (Mellese, 2016). However, the findings of Agmas et al. (2020) showed that more than 95% of farmers used pesticides 1 to 2 times per year, which was far different from the findings of the present study. Most farmers in the study area focused only on the ability of the pesticides to eradicate pests of crops without concern about their risks on humans and the environment. There are higher prevalence of blindness and vision impairment, hypersensitivity and self-killing/suicide, diabetes and cancer among farmworkers in the District. Previous studies confirmed that the misuse and overuse of pesticides in Ethiopia intensify its negative effects on human health and the environment (Mellese, 2016; Mengistie, 2016). Cancer, infertility, early maturity, hormonal malfunctioning, diabetes and obesity, loss of memory and coordination, reduced visual ability and motor skills, respiratory illness and autism are the known effects of pesticide residues (Hashimi et al., 2020; Human Rights Council, 2017; Pironti et al., 2021). The study confirmed that pesticides are among the top ten human health problems in the District and pesticide-related cases are reported to the Zone and the Regional Health offices monthly. Farmers in Ethiopia including Fogera District did not use protective equipment during pesticide spraying to minimize its negative effects (Hiluf & Ayalew, 2015; Mengistie et al., 2017). Furthermore, all the farmers in the study area mix pesticides either in knapsacks or barrels with their bare hands in a way that poison themselves and contaminate the water sources. A study by Mengistie (2016) confirmed that 94% of farmers mix pesticides with a stick, but with bare hands. Aquatic ecosystems of the study area have been contaminated by pesticide residues through pesticide fishing, runoff and spray drift. There were symptoms of water pollution in the study area such as vomiting and diarrhea immediately after drinking surface and pond water. The pesticide residues in water bodies could pose adverse effects on all life forms including human beings (Gulliya et al., 2020; Mellese et al., 2018). Previous study confirmed that farmers dumped excess pesticides and wash the pesticide spraying equipment in ditches and ponds in the manner that contaminate the water sources (Van et al., 2020). Such contaminated water sources exposed the fish, grazing animals and humans to effects of pesticide residues (Human Rights Council, 2017; Mengistie et al., 2016; Van et al., 2020). In general, water pollution from pesticide residues has become a global health concern for both humans and the aquatic ecosystems (Mengistie, 2016; Human Rights Council, 2017; Wumbei et al., 2019; Chaikasem & Roi-Et Na, 2020; Mekonnen et al., 2021). Unless pesticide users use the pesticides properly, losses to the public health, emergence of pesticide-resistant pests, crop losses due to chemical damage and food scarcity and water contamination are expected consequences (Ejigu & Mekonnen, 2005; Hashimi et al., 2020). Environmental and economic losses from pesticide residues are in billions USD per year per a country (Bourguet & Guillemaud, 2016; Van et al., 2020).

The findings of the present study indicated that Ajanta, Mancozeb, Ridomil, Karate and Matco are the commonest types of pesticides sprayed on tomato, onion, garlic, cabbage, potato and pepper. Hunter, Alcohol, Dimethoate, Diazinon, Atrazine, Karate and Malathion are the most commonly sprayed pesticides on khat crops. Ajanta, Tricel, Karate, Agrolambacin and Diazinon are the most commonly applied pesticides on vetch, chickpea and maize crops. Khat, cabbage, tomato, and pepper were supplied to consumers starting from the first day of spraying the pesticides. In addition to supplying crops without waiting for the post-spray time interval, farmers consumed huge amounts of pesticides per a cropping season. Among crops cultivated in Fogera District, huge amounts of pesticides were applied on onion, vetch, tomato, garlic, khat, and pepper per a cropping season. More than 14 kg, 11 kg, 8.4 kg, 8.2 kg, 8 kg and 7.2 kg of pesticides of various types were used per a hectare of onion, vetch, tomato, garlic, khat and pepper farms per a cropping season, respectively. Similarly, onion, potato, garlic, khat and tomato were the first five crops that farmers used a huge amount of pesticides in liquid form. Except for rice, more than four liters of pesticides in liquid form were sprayed per a hectare of cropland per a cropping season. However, a number of farmers using the pesticides in solid form were much more than those that used in the liquid form or both. The amount of pesticides used per a hectare of onion farmland in the study area was higher than the amount of pesticides used by the leading pesticide user country, China, which used 13.07 kg ha − 1 (Nayak & Solanki, 2021; Sharma et al., 2019). In Fogera District, farmers use more than 14 kg and 4 liters of pesticides per hectare of onion farm per cropping season. Furthermore, most farmers produce three times per year, mainly rice, vetch, and onion starting from July of each year. If rice, vetch and onion crops are cultivated in consecutive order starting from July, the total amount of pesticides sprayed on a hectare of farmland to control the weeds and pests of crops might be more than 28 kg per a year. Accordingly, the amount of pesticides used in the study area was more than the highest pesticide user country in Africa (Mauritius) in the year 2014, which was 27.19 kg ha − 1 (Sharma et al., 2019). Though the farmers used the pesticides throughout the year, November to February were the peak season of the pesticide sprays. Among the sampled farmers, 273 (73%), 224 (60%) and 182 (49%) used Ajanta, 2, 4-D and Karate, respectively. Data obtained from field observation and FGD among experts confirmed that huge amounts of pesticides were sprayed during the peak season, formed fogs in the environment and caused acute poisoning on humans while crossing the farmlands. The acute poisoning effects of the pesticide residues on humans were severer in the morning than the rest hours of the day.

Though the majority of farmers sprayed pesticides before crop harvest, more than 30% of the respondent farmers sprayed pesticides on chickpea, maize and khat after harvest. The post-harvest pesticide spraying practices of farmers were the major health concern of consumers of the study area. Consumers believed that most farmers have kept apart the untreated crops for their own consumption and treated all the rest crops with highly toxic pesticides to store them for longer periods of time. There are about 1011 pesticides registered in Ethiopia (Ministry of Agriculture Plant Health Regulatory Directorate, 2022). More than 77 types of registered and banned pesticides were used in the study area, and most of the registered pesticides are in the lists of Highly Hazardous Pesticides (HHPs) (Pesticide Action Network International PAN, 2016; Pesticide Action Nexus Association, 2019). These HHPs exposed farmers, consumers and ecosystems to the effects of pesticide residues. Previous studies confirmed that some of the registered pesticides used in Ethiopia are banned in other countries (Pesticide Action Nexus Association, 2019; USAID Ethiopia, 2020; Wolde & Abirdew, 2019). The reports of USAID Ethiopia (2020) confirmed that Malathion, Mancozeb, Cypermethrin, Deltamethrin, Diazinon, Aluminum phosphide, Indoxacarb, Omaxim, Matco, Agro-laxyl, Ridomil gold and Zinc phosphide, which are applied in the Fogera District are toxic to extremely toxic to fish and other aquatic organisms. Decis, one of the products of Deltamethrin, is persistent in the soil and is extremely dangerous to fish (Singh et al., 2018). Tricel 48 EC, one of the Chloropyrifos products, is also highly toxic to aquatic species, birds and honey bees (Expert Task Force, 2021; Lewis et al., 2016). Previous studies in different parts of Ethiopia also indicated that the residues of DDT, Endosulfan and Chloropyrifos were beyond the acceptable concentration and could expose the fish species and consumers to health risks (Beyene, 2014; Mellese et al., 2015, Mekonen, 2016; Mitiku & Mitiku, 2022). Though Malathion and Cypermethrin play a key role in controlling pests of crops, they have had significant hepatotoxic and nephrotoxic effects on aquatic organisms including fish species (Farag et al., 2021; Karmakar et al., 2016). Among the farmlands used for cereal production in the District, more than 53% were used for rice production and 60% of the sampled farmers used 2, 4-D to control weeds. The herbicide, 2, 4-D, is the most commonly used pesticide all over the world to control weeds of rice crops (Qurratu & Reehan, 2016). However, it is one of the herbicides that cause hepatotoxic and nephrotoxic effects on organisms including fish species (Abate, 2019). In general, most of the pesticides used in the study area are proven to cause animals to develop both male and female sexual characteristics; reduce the hatching rates of the eggs of fish species, inhibit the growth rates of organisms and reduce the avoidance of offsprings from their predators if their parents are exposed to persistent pesticide residues (Hayes et al., 2011; Helfrich et al., 2009; Landos et al., 2021). Pesticides might also cause change in sex ratio, decrease in body weight and change in the regulation of genes (Lawal et al., 2018; Lyche et al., 2010; Ozkara et al., 2016). Among the pesticides applied on crops of Fogera District, Metalaxyl, Dimethoate and Malathion will persist up to 30 days, and Chloropyrifos, Atrazine, Diazinon and Carbaryl will persist for a range of 30–100 days in the environment (Rahman et al., 2020). However, the pesticides were sprayed on crops and the crops were supplied to consumers starting from the first day after spray. Similar studies in Sudan confirmed that all the farmers cultivated vegetables in greenhouses harvested their vegetables within 2–3 days after pesticide spray (Mohamed et al., 2018). Though Fogera district shares 39.14% of the wetlands of the Lake Tana watershed (Hunegnaw et al., 2013) and is important breeding habitats of fish species (Anteneh et al., 2012; Dejen et al., 2017), they have been exposed to the toxic pesticide residues year round. Fishing by poisoning the feeds of the fish in water bodies might aggravate the negative effects of pesticide residues on aquatic ecosystems of Fogera District. Farmers in the study area chopped the vegetables, put them into pesticides (Malathion) and then dropped the poisoned feed into water to intoxicate and harvest the fish. Previous studies conducted in the Lake Tana watershed showed that farmers used a mix of Malathion and Milletia seed powder to intoxicate and harvest the fish from ponded river waters (BoEPLAU, 2015a, 2015b). Similar study conducted in USA confirmed that Cypermethrin, Deltamethrin and Aluminum phosphide were the primary pesticides used to intoxicate and catch the fish for subsistence use, bait to catch larger fish and sale (Betts et al., 2020). Poisoning the river water to catch fish might damage all aquatic life and cause human diseases including diarrhea, cough, convulsions and miscarriage (Betts et al., 2020; Rahman et al., 2020; Wolde & Abirdew, 2019). The recurrent diarrhea and vomiting incidents soon after drinking surface water of the District might be symptoms of water pollution from pesticide residues (Abate, 2019; Grewal et al., 2017). This water pollution might reduce the availability of forage for fish larvae, reduce the fish larval survival and finally the fish populations (Darçın & Darçın, 2017; Gibbons et al., 2015; Hashimi et al., 2020; Johnson et al., 2013; Kassa, 2017). So the pesticide residues in water bodies might be one of the top reasons for the spread of chronic diseases and the fish production decline in the District (Hayes et al., 2011; Landos et al., 2021; UNEP & WHO, 2013).

The frequency of pesticide spraying, the amount of pesticides sprayed on crops per a cropping season, the nature of pesticides applied on crops and the pesticide spraying and crop supplying practices of farmers are issues that question the sustainability of life in the Lake Tana Biosphere Reserve. The current pesticide application practices of farmers might expose consumers and ecosystems to acute and chronic health risks. A study conducted in the Central Rift Valley of Ethiopia confirmed that the amount of pesticide residues in most samples of surface water including potable water and vegetables were above the maximum residual limits (Loha et al., 2020). Studies on levels of pesticide residues in lakes of Ethiopia indicated that the pesticide residues were at the level of threats to fish species and consumers (Agmas & Adugna, 2022; Beyene et al., 2014; Mellese, 2016; Wodajo, 2020).

There are clear differences between the two groups of respondents in ranking the risk factors that expose humans and the ecosystems to the effects of pesticide residues. However, open access to all types of pesticides and awareness gaps on effects of pesticide residues were among the first five primary risk factors that exposed humans and the ecosystems to the effects of pesticide residues for both groups. Spraying the pesticides without selecting the appropriate spray time, disposal of empty pesticide containers elsewhere in the environment and knowledge gaps on the side effects of pesticides were the foremost risk factors for farmers. Studies confirmed that selecting appropriate time of spray plays key role to effectively control the pests, reduce adverse effects on crops, the environment and human health from pesticide residues (Van et al., 2020). It is also confirmed that disposal of empty pesticide containers on farmlands and mixing the pesticides in sensitive areas expose farmers and the ecosystems to the effects of pesticide residues (Agmas et al., 2020; Negatu et al., 2016). However, farmers underestimated the effects of entry of pesticide residues into water bodies during mixing, spraying the highly toxic pesticides on crops and pesticide spraying and crop supplying practices, which are the primary risk factors for consumers. Using such highly toxic pesticides could result in irreversible negative effects on farmers, consumers and ecosystems to the extent that might alter the physiology of humans and organisms (Helfrich et al., 2009; Human Rights Council, 2017; Maurya et al., 2019; Pironti et al., 2021). Hence, the enforcement of pesticide management laws, awareness raising practices using mass media and continuous monitoring the pesticide residues are highly essential (Chen et al., 2011; Mekonen et al., 2014; Negatu et al., 2021; Ramadan et al., 2020).

5. Conclusions and recommendations

The finding of this study reveals that crops of Fogera District have been sprayed with different types of pesticides up to 26 times per crop per cropping season. Open access of farmers to all types of pesticides, instructions on pesticide containers to spray them repeatedly, lack of clustered pest control measures for any incidence and the use of expired pesticides elevated the spraying frequency and the amount of pesticides applied on a hectare of farmland in the District. Farmers spray pesticides without protective devices and thus expose themselves and the environment to the effects of pesticide residues. A hectare of farmland might be sprayed with more than 14 kg and 28 kg of pesticides per a cropping season and per a year, respectively. Farmers also use more than 4 liters of pesticides per a cropping season per hectare. They sprayed highly toxic pesticides without following the safety instructions and supplied the sprayed crops without waiting for the post-spray time interval. Most pesticides used in the District are in the lists of highly hazardous pesticides. Pesticides used in the study area such as Chloropyrifos, Atrazine, Diazinon, Deltamethrin and Carbaryl are persistent and highly toxic to humans, aquatic life, birds and insects. The crops sprayed with highly toxic pesticides have been supplied to consumers without waiting for the post-spray time interval. In addition to drifting and draining of the pesticide residues into water bodies during mixing and spraying, pesticides have been added to river water for fishing. Fishing practices have been carried out by adding poisoned fish feed into tributaries and rivers of Fogera District. So, pesticide residues are one of the possible factors for fish productivity decline in the District. There are also human health problems from drinking surface water polluted most probably by pesticide residues. Nearly one-third of the farmers have also applied different pesticides on maize, chickpea and khat crops after harvest to protect them from pests in stores and soften the leaves, respectively. Farmers use the untreated crops for their own consumption and treat the rest crops with highly toxic pesticides to sore them for longer periods of time. The effects of pesticide residues are one of the top ten health risks for residents of Fogera District. As the effects of pesticide residues are the primary health risks for farmworkers, consumers and ecosystems, pesticide supply chain monitoring starting from suppliers to the end users, enforcement of laws of pesticides, regular assessment of ecosystems and food safety monitoring using GC-MS are unavoidable actions to minimize the negative effects of pesticide residues on human health and the ecosystems.

Authors’ contribution

Abebaw Abaineh, Dessalegn Ejigu and Minaleshewa Atlabachew participated in field data collection and data analysis. Moreover Abebaw Abaineh contributed in the conception of the study and prepared the first draft of the manuscript. Eshete Dejen helped in the conception of the study and edited the manuscript. Gashaw Tilahun supported during field data collection and data analysis. Dessalegn Ejigu and Minaleshewa Atlabachew contributed in through revision of the manuscript. Abebaw Abaineh contributed in manuscript completion and its submission as a corresponding author to a journal for possible publication. All authors have read and approved the final manuscript. This manuscript was not submitted anywhere else before for publication.

Availability of Data

The data generated and/or analyzed to support the findings of the study is available from the corresponding author, [AA], up on reasonable request.

Consent to Publish

The Author agreed to publish the manuscript in open access journal at no cost to the author or benefit from discounted article publishing charge.

Consent to participate

All participants of the study have been properly informed and agreed to participate without any pressure or coercion.

Disclosure statement

All the authors declared that there was no relevant financial or non-financial interest.

Additional information

Funding

The study was financially supported by Nature and Biodiversity Conservation Union (NABU) project office, Addis Ababa, Ethiopia.

Notes on contributors

Abebaw Abaineh

Abebaw Abaineh Assefa Source: Self-field photo captured during data collection (location: Shina sub district, Fogera district, south Gondar administrative zone of Amhara region, Ethiopia)