Induced-Toxicity of Pesticides on Edible Freshwater Fishes in Pakistan: A Review

Industrial advancements and development of novel technologies are essential to achieve success and comfort in ongoing era, but these are causing deterioration of precious natural water resources on earth (Tahir et al., 2021). Increasing number of industries, modernization and urbanization eventually steered us to the contamination of our environment and left us to face the problem of environmental pollution. These pollutants include domestic wastes, industrial effluents, agro-chemicals, etc. that include different organic and inorganic substances, heavy metals such as cadmium, arsenic, and pesticides. An after effect of urbanization and industrialization is that the pollutants released from industries eventually reach the aquatic bodies where they get dissolved and cause water pollution (Ullah et al., 2014). Environmental pollution is an elaborate phenomenon having multiple aspects with partial or unidentifiable origins (Ullah et al., 2014). International Agencies reported that such chemical substances have high potential and a constant threat to aquatic life including fish and bioaccumulation of these pollutants eventually entre into human food chain and is the main cause of human health hazard (Ullah and Zorriehzahra, 2015).

In view of its consumption by human, industrial production, industrial irrigation and stabilization of biodiversity, fresh water is extremely valuable in terms of preserving life. However, these ecosystems are at risk of suffering biodiversity losses due to being vulnerable to environmental pollutants including pesticides (Geist, 2011; Pisa et al., 2015; El-Murr et al., 2015; Javed and Usmani, 2015).

Pesticides are chemical compounds that are used to get rid of pests including insects, rodents, fungi and unwanted plants, herbs, weeds etc. (Akashe et al., 2018). These chemical compounds are grouped into different classes such as insecticides, herbicides, rodenticides, fungicides etc. According to the chemical nature of pesticides; it is further divided into groups like carbamates, organochlorine, organophosphate, pyrethroids (widely used), and aliphatic fungicides, inorganic rodenticides, amide fungicides, ammonium herbicides. Pesticides are a big source of potential environmental hazards to birds, fish, and other animals as well as humans when they infiltrate food chain (Khan et al., 2012). An increased burden of chemicals can arise in environment due to non-biodegradability of some of these classes of pesticide chemicals (Mahboob et al., 2011). Effluents with pesticides resulted in a marked rise in the mortality rate, growth retardation and tissue damage in fish (Rana et al., 2011). Susceptibility of different fish species to these pesticides is different at different concentration. The changes in different body parts and systems of fish have been observed to be different than each other as well as in response to different pesticides (Ullah and Zorriehzahra, 2015).

Pakistan is an agricultural country with most of its agricultural land irrigated by canal systems from rivers and their tributaries. Main rivers are Indus, Kabul, Chenab, and Ravi. Freshwater ecosystems of Pakistan have rich biodiversity including a large number of edible fish species such as Labeo rohita, Cirrhinus mrigala, Cyprinus carpio, Catla catla. Agriculture run-off, sewage wastes, fall into the rivers causing aquatic pollution and adversely affect fish life, leading to various hematological, biochemical, histopathological changes in fish body which when consumed by human’s results in different types of disorders in body. This review discusses research over past decade regarding toxic effects of pesticides induced in edible freshwater fishes of Pakistan and some future considerations.

(Modified from Yadav and Devi, 2017).

Organochlorines pesticides are organic compound attached with five or more chlorine atoms. Organochlorines (OC) are widely used in health sector and agriculture as insecticides and these are non-biodegradable. These pesticides have a negative effect on insects’ nervous system which cause disruption of the insect nervous system causing convulsions, then paralysis and eventually cause death, slowly and gradually. Most common examples of these pesticides includes: DDT, endosulfan, aldrin, lindane, dieldrin and chlordane. Production of DDT is now prohibited throughout the globe.

Organophosphate pesticides are multi-purpose broad spectrum pesticides, which are derivatives of phosphoric acid used to get rid of different types of pests and act when inhaled, ingested, or penetrate in skin, leading to stomach abnormalities, nervous system impairments in affected organisms. These are biodegradable pesticides, causing little environmental pollution and show delayed pest resistance. They are more toxic to animals as they have cholinesterase-inhibiting properties leads to excess accumulation of acetylcholine neurotransmitter across a synapse. This results in failure of nerve impulses to move across the synapse causing muscular cramps, paralysis and eventually death. Most common OPPs include malathion, diazinon, glyphosate, and parathion.

The carbamates share similar structural makeup with organophosphates(OP), but carbamates are distinct in that they originate from carbamic acid. Carbamates work by interfering with transmission of nerve signals resulting in the death of the pest by poisoning. Under natural conditions, they are easily degraded with little environmental pollution. They are occasionally used as fumigants, contact poisons, and poisons for the stomach. Insecticides that contain carbamates include carbaryl, carbofuran, propoxur, and aminocarb.

Synthetic pyrethroid insecticides are produced from natural pyrethrins. Compared to pyrethrins, they are more stable and have a longer residual impact in environment. These insecticides are only mildly hazardous to mammals and birds, but they are extremely toxic to fish and insects. Majority of synthetic pesticides are non-persistent and quickly break down when exposed to light. Pyrethroids are considered safe to use in food. Cypermethrin and Permethrin are examples of popular synthetic pyrethroid pesticides.

Behavior: Different studies on pesticides over past decade have shown alterations in behavior of various fish species such as sluggish swimming movements, lethargy, faintness, and disruption in swimming ability which renders the fish more prone to predators, affect their feeding, orientation, and territory defense (Prashanth et al., 2011). Interruption in behavior of fish by pesticides makes the fish stressed and immunocompromised, making them susceptible to different kinds of pathogens and infections (Nwani et al., 2013). In freshwater fish Labeo rohita commonly known as Rohu , imidacloprid induced morphological and behavioral changes such as avoidance mechanisms, abrupt and sluggish swimming movement in all directions, occasional jumping and hitting on the walls of tank, rapid scale loss, mucous secretion, change in body color (Qadir and Iqbal, 2016), while organophosphates (profenofos, trizaophos) and carbamates (carbofuran, carbaryl) caused suffocation, lethargy, descending movement, irregular swimming, gulping before death (Mustafa et al., 2014) in the same fish. Also, fipronil resulted in shakings, twitching, dizziness, increased operculum movement, body curving, breathing troubles in Cyprinus carpio (common carp) (Ghaffar et al., 2018). There are many different studies confirming the effects of different pesticides on behavior of different freshwater fishes of Pakistan (Mahboob et al., 2015a; Ghaffar et al., 2020, 2021; Usman et al., 2020; Zulfiqar, 2020; Akram et al., 2022; Wang et al., 2022) mentioned in Table 2.

Hematology: Blood parameters were assessed as physiological indicators of animals exposed to stressful conditions such as the presence of toxic substances, because blood acts as a patho-physiological reflector of the whole body (Velisek et al., 2012). Various pesticides have been extensively studied to trace for hematological changes such as changes in number of RBCs and WBCs, thrombocytes, neutrophils, hemoglobin content, hematocrit values in different freshwater fish species of Pakistan such as in Cirrhinus mrigala (Indian carp) due to diazinon (Rauf and Arain, 2013; Haider and Rauf, 2014), Chlorfenapyr, dimethoate, and acetamiprid (Ghayyur et al., 2021), Labeo rohita (Rohu) exposed to acetamiprid (Alam et al., 2014), triazophos (Ghaffar et al., 2015a), butachlor, a chloroacetanilide herbicide (Ghaffar et al., 2015b), Chlorpyrifos (Ismail et al., 2018), Diafenthiuron (Riaz-ul-Haq et al., 2018), thiamethoxam (Ghaffar et al., 2020; Hussain et al., 2020), fipronil (Ghaffar et al., 2021), pyriproxifen (Naseem et al., 2022; Li et al., 2022), Ctenopharyngodon idella (Grass carp) to endosulfan (Ullah et al., 2017), Cyprinus carpio (Common carp) in response to fipronil and buprofezin (Qureshi et al., 2016), fipronil (Ghaffar et al., 2018),Oreochromis mossambicus (Mozambique tilapia) to Chlorpyrifos (Ghayyur et al., 2019), Tor putitora (Mahaseer) to cypermethrin (Bibi et al., 2014), Oncorhynchus mykiss (Rainbow Trout) to Chlorpyrifos (Ali et al., 2020), Aristichthys nobilis (Bighead Carp) to acetochlor (Mahmood et al., 2022), triclosan (Akram et al., 2022), Hypophthalmichthys nobilis (Bighead carp) to pendimethalin (Wang et al., 2022).

Histopathology: Histopathological changes have been traced in different organs such as brain, gills, liver, kidneys, intestines, blood and muscles of different edible freshwater fish species of Pakistan. Pesticides-induced changes in histopathology of fish include lamellar disorder, lesions, hyperplasia, congestion, epithelial stimulating, micro gliosis, hemorrhages, necrosis, discoloration, neuronal degeneration, karyorrhexis, hepatocellular hypertrophy, and accumulation of pesticides residues in muscles (Khan et al., 2018). The pesticide damage tissue, effect function of Kidney, centers in spleen, edema, and disruption of cardiac myofibers in heart have been reported over past decade from various freshwater fishes. Some of the lethal pesticides are cypermethrin (Khan et al., 2018), mixture of endosulfan and chlorpyrifos (Naz et al., 2019), thiamethoxam (Ghaffar et al., 2020), profenofos and carbofuran to Labeo rohita (Mahboob et al., 2014a), cypermethrin to Tor putitora (Ullah et al., 2015), fipronil plus buprofezin to Cyprinus carpio (Qureshi et al., 2016), DDT and HCHs to Cyprinus carpio, Tor putitora, Glyptothorax punjabensis, Orienus plagiostomus (Aamir et al., 2016), Chlorpyrifos to Oncorhynchus mykiss (Ali et al., 2020), acetachlor to Aristichthys nobilis (Mahmood et al., 2022), pendimethalin to Hypophthalmichthys nobilis (Wang et al., 2022), Lambda-cyhalothrin to Ctenopharyngodon idella (Niaz et al., 2022). Some other researchers have also reported the histopathological changes in edible freshwater fishes of Pakistan (Rana et al., 2011; Nasir et al., 2012; Eqani et al., 2013; Bibi et al., 2014; Mahboob et al., 2015; Jabeen et al., 2015; Ullah et al., 2017; Qadir and Iqbal, 2016; Robinson et al., 2016; Karim et al., 2016a, 2016b; Riaz et al., 2018; Hussain et al., 2020; Ghaffar et al., 2021; Naseem et al., 2022; Li et al., 2022) (Table 2).

Exposure to pesticides induces various biochemical changes in fish body. Chlorpyrifos cause increased activity of antioxidant enzymes in freshwater fish Oncorhynchus mykiss (Ali et al., 2020). Activity of anti-oxidant enzymes such as superoxide dismutase, peroxidase, and glutathione S-transferase increases in liver, gills, kidneys, brain, muscles, and heart of Labeo rohita when treated with mixture of endosulfan and chlorpyrifos (Naz et al., 2019). Rise in quantity of oxidative stress biomarkers and decline in concentration of antioxidant enzymes occur when Labeo rohita is exposed to pyriproxifen (Li et al., 2022), Aristichthys nobilis to acetochlor (Mahmood et al., 2022), Hypophthalmichthys nobilis to pendimethalin (Wang et al., 2022).

Various studies showed the changes in protein content in various tissues such as liver, gills, intestines, blood, and muscles of different edible freshwater fishes of Pakistan when exposed to different pesticides. Total protein content declined in Cyprinus carpio when exposed to Karate i.e. λ-Cyhalothrin, protein value recorded in different tissues, Muscles 20.77±1.21a, Brain 26.01±2.06a and Liver 27.84±1.46a (Bibi et al., 2014), and fipronil and buprofezin (Qureshi et al., 2016). Exposure of Labeo rohita to Diafenthiuron, total serum protein (P = 0.004), cholesterol (P = 0.033) and creatinine (P = 0.002) were significantly reduced (Riaz-ul-Haq et al., 2018). Catla catla (Major Carp) recorded heights protein content range, 18.59±0.04 then used 0.038mg/L profenofos, reduce protein level 12.76±0.04, Labeo rohita (Rohu) protein content 19.18±0.02, used 0.06mg/L profenofos, decreased protein level 12.71±0.04. Cirrhinus mrigala (Mrigal carp) 14.62±0.02 protein value in healthy fish, used 0.041mg/L profenofos, reduced total protein level 8.70±0.01. showed decline in total protein when exposed to profenofos, (Ghazala et al., 2019). Oreochrmois mossambicus (Mozambique tilapia), also showed a decline in total protein content when treated with organophosphates, pyrethroids, and herbicide (Naqvi et al., 2017), and Chlorpyrifos (Ghayyur et al., 2019). Oreochromis niloticus (Nile Tilapia) also show a significant decrease in total protein content when exposed to malathion, Chlorpyrifos, and λ-Cyhalothrin, significant decrease total protein level in different tissue such as in brain (19.33±0.58) and muscle tissues (27.02±0.57) (Amin et al., 2021) and malathion (Zulfiqar, 2020). Exposure of Ctenopharyngodon idella (Grass Carp) to mixture of endosulfan+chlorpyrifos and endosulfan+bifenthrin decrease protein content interval of time reported in different tissues such as Hepatic, control group protein content 3.95±0.56Ba, lowest total protein recorded 1.98±0.21Bc, Muscle highest protein 1.04±0.17Ba and lowest 0.18±0.01Bc, Gills highest protein 2.86±0.33Ba and lowest 1.46±0.15Bc, Cardiac highest protein 0.86±0.12Ba and lowest 0.03±0.01Bc etc. (Usman et al., 2020), Lambda-cyhalothrin (Niaz et al., 2022) and Aristichthys nobilis (Bighead carp), to acetochlor (Mahmood et al., 2022) lead to decline in total protein content in investigated fish tissues followed by different standard procedure for determination of protein contents in different tissues of the different fresh water species.

Acute toxicity may be measured as oral, dermal and inhalational acute toxicity. LC50 is the measure of acute inhalation toxicity. Acute toxicity is expressed by various changes in behavior and physical activities, even death. However, different pesticides have distinct LC50 values in different organisms, determine by using Probit analysis and comparison was done by the APHA method (Mahboob et al., 2015). A list of common pesticides together with their lethal concentrations for different fish spe­cies have been listed in Table 1. For further information, “handbook of acute toxicity of chemicals to fish and other aquatic vertebrates” is also helpful (John­son and Finley, 1980).

Organophosphates and carbamates apparently share the common mechanism of acetylcholinesterase inhibition at nerve endings that results in excess acetylcholine accumulation in the nerve ending overstimulating the effector organ. Studies have shown that acetylcholinesterase inhibition in fish has been associated with exposure of fish to different pesticide. In a study conducted by (Haider and Rauf, 2014), acetylcholinesterase activity was inhibited in Cirrhinus mrigala exposed to diazinon. Oncorhynchus mykiss also showed a decline in AChE activity when exposed to Chlorpyrifos (Ali et al., 2020). Inhibition of AChE activity occurred in Labeo rohita when exposed to profenofos and carbofuran (Mahboob et al., 2014), and Cyprinus carpio when treated with λ-Cyhalothrin (Bibi et al., 2014).

Genotoxicity is a property possessed by some substances that makes them harmful to the genetic information contained in organisms. Heavy metal ions and polycyclic hydrocarbons are the most influencing genotoxicants for fishes. Pesticides-induced genotoxicity has been reported in various freshwater fishes of Pakistan. Genotoxic threats and increased DNA damage have been noticed in Labeo rohita when exposed to triazophos, used standard blood test, staining method, serum enzyme such asALT, AST, ALP and measured by spectrophotometrically (Ghaffar et al., 2015a),endosulfan (Ullah et al., 2017), thiamethoxam (Hussain et al., 2020), and pyriproxifen (Li et al., 2022), Aristichthys nobilis when treated with acetachlor (Mahmood et al., 2022), and triclosan (Akram et al., 2022) and Hypophthalmichthys nobilis to pendimethalin (Wang et al., 2022).

Table 1: List of common pesticides along with their lethal concentrations for different fish species.

Table 2: Effects of pesticide induced toxicity in different edible freshwater fishes of Pakistan studies over past decade.

Profenofos (LC50): Profenofos are new insecticide and neuro toxic molecules. Widely used in in India, Pakistan, Bangladesh for agriculture purpose. The pesticide is highly risk for aquatic organism like fish (Lundebye et al., 1997).

λ-cyhalothrin: The λ-cyhalothrin used for Agriculture purposes such vegitable production and cotton cultivation. It observed in running water in irrigation canal.the toxicity clearly indicates acute and sub-acute toxicity test, toxicity of pesticide with species temperature, and size of the fish (Bibi et al., 2014).

Dichlorodiphenyltrichloroethane (DDT): The Dichlorodiphenyltrichloroethane is used pesticide and kill the Aquatic organism (vertebrates and invertebrates). Causes death in fish hatchery kill fry and effect on fish fecundity (Hopkins et al., 1969).

Pyriproxyfen: Pyriproxyfen is most sensitive pesticide, high concentration detected in Daphnia magna, effected reproductive organ such as, Xiphophorus maculatus, Eurytemora affinis, Leander tenuicornis, Danio rerio (zebrafish) and Capitella sp. (polychaete). highly detected from river water and effected 25.82% species (Moura and Souza-Santos, 2020).

Pendimethalin: Thy known as (N-(1-ethylpropyl)-2, 6-dinitro-3,4-xylidine) belong to dinitroaniline herbicide and commonly used in terrestrial system (Danion et al., 2014). High concentratin detected in river (840 ng/L) at France and effected biotic and abiotic components of ecosystem (Dupuy et al., 2019).

Triclosan: The 5-chloro-2-(2,4-dichlorophenoxy)-phenol commonly used in personal care products such as dental care products, deodorants and textiles (Liang et al., 2013). TCS higher concentration recorded in sediments then water. It has androgenic effects potential, altering swimming of (Oryzias latipes), reproductively effects of (Closterium ehrenbergii) and genotoxic effects on C. ehrenbergii has reported (Liang et al., 2013).

Acetochlor: Acetochlor is well known herbicide, effect the aquatic species including Bighead carp, there are different Scientific names base on divergent branchial row abdominal keel and Length, such as Aristichthys nobilis, Cephalus hypothalamus, Leuciscus nobilis, Hypophthalmichthys mandschuricus, and Hypophthalmichthys simony. Hypophthalmichthys nobilis (Ghaffar et al., 2017).

Hexachlorocyclohexane (HCH): Hexachlorocyclohexane is harmful pesticide mostly used in Pakistan. It cause serious health impact including reproductive, neurological, hematological and immunological disorder on animals (Kalyoncu et al., 2009).

Atrazine: Atrazine (2–18 chloro-4-ethylamino-6-isopropylamino-s-triazine) is toxic herbicide. Effect erythrocyte of Lithobates catesbeianus, Dendrophryniscus minutus, Rhinella, schneideri Anaxyrus americanus, Xenopus laevis, Lithobates pipiens (Khan et al., 2012).

This article concludes that increased and unplanned of pesticides renders great threat to environment, aquatic life, and humans. Pesticides causes different behavioral, hematological, histopathological, genotoxic, endocrine alterations in fish body, which is tolerated by fish only up to a certain level beyond which mortality of fish occurs, resulting in economic losses. On the other hand, these affected fishes cause different hematological and endocrine disorders and some even poses carcinogenic risk to humans when consumed. Regulations and awareness among masses should be developed for responsible utilization of pesticides and to control run-off of these pesticides to aquatic bodies. Furthermore, those fishes should be stocked in water bodies which are least vulnerable to pesticides and chemicals. Further research is needed to study the effects of newly introduced pesticides and to develop biodegradable pesticides that are environment friendly and have least toxicity to non-target organisms.

The authors are thankful to the supporting staff of the Department of Zoology and College of Veterinary Science and Animal Husbandry (CVS & AH), Abdul Wali Khan University Mardan,( KP) for their assistance.

The research and experimental work on the subject title recommends responsible utilization of pesticides and discourage unnecessary use of pesticides in aquatic environment.

Yaseen and Asad Ullah: Designed and prepared the manuscript.

Imad Khan and Maryam Begum: Supervised the write up.

Sumbal Bibi and Umber: Helped in data collection.

Namra and Abbas Khan: Technically assisted at every step.

Shumaila Gul and Raheela Taj: Proof reading.

The authors declared no potential conflicts of interest with respect to research, authorship, and/or publication with the work submitted.