Mechanistic action of pesticides on pests and their consequent effect on fishes and human health with remediation strategies

Extensive use of pesticides for increasing food production simultaneously declined food quality. Even while farmers have a conventional grasp of agriculture, they are vulnerable because they lack a technical understanding of pesticides and their uses (WHO/FAO 2016). In the past decade, the global consumption of pesticides has elevated as a result of a demographic outburst and escalating urbanization (FAOSTAT 2019). Instead of agriculture, many pesticides such as insecticides, herbicides, and fungicides are generally used for household purposes in form of sprays, powders, and liquids for controlling mosquitoes, ticks, cockroaches, and bugs. Pesticides have numerous benefits, but the risk aligned with their use is also high. According to Mahmood et al. (2016) <1% pesticides reached the targeted organism to affect their nervous system, growth, and energy production system. The maximum amount of pesticides gets accumulated in the environment such as soil and water. As deposits of excessive pesticide and their metabolites residue in food and aquatic environment may be detrimental to fishes as well as for human health (Boobis et al. 2008; Zhou et al. 2015). Various reports indicate the risk associated with consuming pesticides with different modes of action; continuous exposure to pesticides causes depression and neurological deficits, diabetes, respiratory diseases such as rhinitis and, in extreme cases, cancer, fetal death, spontaneous abortion, and genetic diseases (Ntzani et al. 2013; Mojiri et al. 2020). In addition to ingestion, it is obvious that exposure to these pesticides, particularly for spray workers, has detrimental health impacts (Tsimbiri et al. 2015).

Residue analysis provides a criterion for assessing the quality of food in order to minimize potential threats to human health and determine the degree and duration of chemical contamination in the natural environment. Fifty nations comply with the maximum residual limits (MRLs) established by the Codex Alimentarius Commission (CAC) (Codex 2011), the European Union (EU) Commission (IIT Roorkee Report 2018), and the Gulf Cooperation Council (GCC). Twenty-three additional nations, including the Food Safety and Standard Authority of India (FSSAI), subscribe to their own MRLs (FSSAI 2011). Pesticides are categorized as either inorganic or organic based on the components that comprise their chemical composition. Synthetic pesticides such as cycloidian, organophosphate (OP), synthetic pyrethroids, organochlorine (OC), nicotinoid, triazole, and carbamate are extensively used in crop production (Grube et al. 2011).

Subsurface drainage, leaching, runoff, and spray drift are all potential entry points for pesticides into water bodies (Cosgrove et al. 2019). Due to the direct effects, interest in the process of eliminating pesticide residues from the environment is increasing. Several chemicals, physical, and biological treatment methods, including adsorption, the advanced oxidation process, and membrane filtration, as well as phytoremediation, bioremediation, and the activated sludge process, have been utilized to effectively remove pesticides from aqueous solutions (Chakraborty et al. 2022; Richards et al. 2022). However, the vast majority of modern cleanup technologies are not only inflexible, but also costly, inefficient, and may even generate secondary poisons (Shamsollahi & Partovinia 2019). Furthermore, it is also challenging to comprehend the global trends in pesticide concentrations in streams, fish, and human beings, as well as the removal methods of pesticides by a range of adsorbents. Therefore, the current review analyzes the level of pesticides in aquatic body and their associated organism at a global scale. The overview data will motivate the hydrobiologist, hydrogeologist, and sustainable development manager to fill the gap. A consortium of river conservation with sustainable practices and cost-effective pragmatic techniques will help in policy formulation to achieve the agenda targets of SDGs within a stipulated time period.

Pesticides have been utilized since antiquity. Now, pesticides are widely used in every region of the globe. It is necessary to understand the mechanisms of pesticide action in order to identify the health risks of non-target organisms, hence facilitating the development of a more comprehensive remedial assessment. Here, three major pesticides will be discussed.

Insecticides are primarily active on three target sites in the nervous system: (1) the acetylcholine receptor, acetylcholinesterase, an enzyme that plays a crucial role in the transmission of nerve impulses (organophosphorus and carbamates) and (2) sodium ion channels crossing the nerve membrane which obstructs the synthesis of chitin as well as ecdysone agonists (Chandler et al. 2011). Additionally, pesticides are divided based on their manner of action (Jayaraj et al. 2016).

(a) Nerve and muscle active site: mode of action of insecticide (Table 1).

(b) Growth and development targets: mode of action (Figure 1).

(c) Energy production targets.

• (i)

  Electron transport inhibition

Electron transport hindrance could cause inhibition of energy supply to the targeted organism. For example, aliphatic type of OC insecticides are electron transport inhibitors.

• (ii) Interruption of oxidative phosphorylation

This is one of the most lethal types of mechanism, in which organotin miticides can block the mitochondrial electron transport chains on the other side pyrroles break electron transport and oxidative phosphorylation. This results in a reduction in ATP release and ultimately death of insects (Jayaraj et al. 2016; Thapa et al. 2017).

Herbicides are chemical agents used to eliminate or control weeds. They are utilized instead of the mechanical method of weed removal. Herbicides deprive plants of the benefits of metabolic pathways such as photosynthesis, plant hormone activity, regulation of cell division, synthesis of amino acids as an antidote, and monooxygenase inhibition by graminicides (De Roos et al. 2005; Pretty 2008; Thrall et al. 2011). Herbicides can be classified according to a variety of parameters, including the site of action, mode of action, chemical composition, length of use, translocation, and selectivity (Varshney et al. 2012; Torrens & Castellano 2014). Herbicides attach themselves to an herb's active site prior to killing it. They are able to affect many sites within plants and in the areas of action. Each herbicide has a unique method of action, which is described in Table 2.

Mode of action of fungicide (Figure 2).

Pesticide contamination in river water emerges as a significant concern. Millions of lives depend on the river for their livelihood such as Ganga, Brahmaputra, etc. The Brahmaputra is a river that flows across borders. In Bangladesh and India's eastern and northeastern states, the Brahmaputra River provides a steady flow of freshwater for agricultural, human, and industrial use (Sarker et al. 2021). A researcher (Chakraborty et al. 2019) collected surface water from various locations along the Brahmaputra River to analyze the presence of organochlorine pesticides (OCPs). This class of insecticides, they claim, is widely used in the areas surrounding the Brahmaputra River. OCPs are detected in the river at elevated intensities ranging from 0.002 to 0.245 g L⁻¹ (0.047–0.067 g L⁻¹). γ-HCH demonstrated the highest level of coverage among hexachlorocyclohexanes (HCHs) that used lindane continuously (γ-HCH). dichlorodiphenyl trichloroethane (DDT) OCPs were also detected with high intensity as ND-0.225 g L⁻¹ (0.030–0.066 g L⁻¹), with o,p′-DDT having the highest concentration and p,p′-dichlorodiphenyldichloroethane (DDD) having the second highest (Chakraborty et al. 2019).

Adversity is not boundary-specific or nation-specific, and pesticide contamination in rivers and sediments becomes a transboundary concern. Five pesticides were detected in the Kabul river of Pakistan, namely, triclosan, carbaryl, chlorpyrifos, carbofuran, and methomyl (Saad et al. 2007). Polluted river water pollutes the sediment also. Just like the Asian river, some major rivers of the world face analogous conditions of pesticide contamination levels. In a study, Ahmed et al. (2008) experimented on the Nile River, Rosetta Branch, Egypt. The study estimated the OCP (total DDTs, total HCHs, heptachlor, dieldrin, aldrin, endrin, endosulfan, and methoxychlor) that were found >0.01 μg/kg and was within safety limits. Ogbeide et al. (2015) reported high concentrations of β-BHC, γ-BHC, and α-BHC contamination in Owan River, Nigeria, with concentrations ranged between 0.82 and 2.14 μg/kg/dw (dry weight) and 0.04–2.34 μg/kg/ww (wet weight) in sediments. Reports have estimated 125–130 K metric tons of pesticide application in Nigeria each year. Specifically, it was used to promote yield, agricultural enhancement, and resist vector diseases (Asogwa & Dongo 2009). The presence of pesticide residue without their metabolites in the Nile River, Cairo, Egypt is self-explanatory about the active utilization of p,p′-DDT and aldrin in this region (Shalaby et al. 2018). The concentration of p,p′-DDT (40.3 ppb) in summer, 73.4 ppb in autumn, and aldrin (31.4 ppb) was reported in the autumn season in Nile river sediment, Egypt (Shalaby et al. 2018). Polluted river water may contaminate the sediment of the river Ganga, and eventually, it bioaccumulates in aquatic biota.

The toxicity of POPs on fishes is very prominent. The seriousness of the problem associated with pesticide exposure in fish was reported by several researchers (Hamilton et al. 2016; Saaristo et al. 2018). According to their study, pesticide exposure can reform fishes physiologically and behaviorally. It also alters their immunity system and predator avoidance sensitivity. An experiment was performed by Akter et al. (2020) to check the potential hazards of Envoy 50 SC on Heteropneutes fossils. The result illustrates LC₅₀ of Envoy ₅₀ SC abruptly altered the tissue structure of their vital organs such as kidney, gill, and liver. In blood cells, modification is reflected in peripheral nuclear erythrocytes, binucleated cells, tear-shaped cells, etc.

The Ganga nourishes more than 140 species of fish both native and exotic (Sarkar et al. 2012). The surface water ecosystem supports fisheries resources and contributes significant financial benefits to the riparian inhabitants and to the national economy. The Ganga is home to diverse and abundant fauna and endangered species, like dolphins (Platanista gangetica); otters (Lutrogaleperspicillata, Lutralutra), and Aonyx cinereus; gharial (Gavialis gangeticus); crocodiles (Crocodylus palustris and Crocodylusporosus); turtles (Batagurkachuga); and fishes (Tor putitora and Tenualosailisha) (Wildlife Institute of India 2018). The addition of organic and inorganic pollutants and the reduced volume of water in river Ganga have deteriorated fish diversity and health (Vaseem & Banerjee 2013) An extensive flow of pesticides and herbicides into Ganga water through various means accumulates in the fish, and it hampers the fish's reproductive system and its metabolism (Wildlife Institute of India 2018).

There are numerous studies reported other than in the Ganga basin on the effects of pesticide contamination on aquatic biota (Yahia & Elsharkawy 2014). According to Yamashita et al. (2000), p′p′-DDE was predominantly found in fish (7.6–67 ng/g wet weight) in the Nile River, Egypt. An experiment was conducted by Shalaby et al. (2018) and found OC, OP pesticides in the sample of Clarias gariepinus, Oreochromis niloticus, and Tilapia zillii. Fish samples were collected from the world's longest river Nile from Egypt. Pesticides such as heptachlor, dicofol, p,p′-DDT, diazinon, chlorpyrifos, endosulfan, and aldrin ranged between 1.7 and 46.0 ppb in Oreochromis niloticus sample (Shalaby et al. 2018). According to Varol & Sünbül (2017) experiment on the Euphrates river's aquatic biota in Turkey, a study reported four out of 34 fish muscle samples presence of p,p′-DDE ranged from 0.010 to 0.019 mg/kg. The maximum concentration of DDE isomers found in the gill sample of fishes was 0.032 mg/kg. In fish samples obtained from several sites along the Ganga, Aktar et al. (2009) have observed five pesticide residues, namely, dimethoate ∑-HCH, malathion ∑-DDT, and ∑-endosulfan. In the majority of the samples, the amounts of ∑-HCH and ∑-DDT were found to be above the MRL.

Previous studies showed massive bioaccumulation of HCH and DDT in fishes residing in the river Ganga, whereas aldrin and endosulfan were moderately less (Kumari et al. 2001a, 2001b; Samanta 2013). A comparative study was done on fishes residing in the river Ganga by Kumari et al. (2001a, 2001b), and according to their study, HCHs concentration (upto 7-folds) and endosulfan (upto 2-folds) were higher than the FAO (Food and Agriculture Organization) tolerance limit (Singh et al. 2008). The tolerance limit (mg kg⁻¹) is HCH (0.25) and Endosulfan (0.2). According to Kumari et al. (2001a, 2001b), numerous OCPs found in the muscles of fishes such as DDT, HCH, aldrin, and endosulfan and their values are in the range of 13.6–1,665.9, 115.8–1,206.8, 3.1–86.1, and 2.9–74.5 ng g⁻¹, respectively. Similar results are also reported by Singh et al. (2008). More than the tolerance limit of HCHs and DDTs were found in fish samples collected from river Ganga and its tributary Gomti. The consequences have been very disruptive to fish reproductive systems (Singh et al. 2008).

Pesticides have a negative impact on all aspects of aquatic ecosystem life, including microbes, invertebrates, plants, and fish (Liess & Ohe 2005; Castillo et al. 2006). These cause a risk to human health when entering the food chain. There are three main trophic levels (algae → aquatic invertebrates → fish) that cover the larger food chain in the aquatic ecosystem. The risk to aquatic species may be quantified via risk ratios, which are then classified into four risk categories: high, medium, low, and insignificant ecological risks, which correspond to RQ (risk quotient) values ≥1, 0.1–1, 0.01–0.1, and <0.01, respectively (Palma et al. 2014; Zhang et al. 2016). Contaminated fish consumption and direct intake of toxicants may pose a severe health risk to humans (Gerber et al. 2016).

Toxicants like pesticides degrade the river water quality of Ganga and tremendously influence human health by direct intake of water or through chain contamination. Fishes and irrigated crops near polluted water are directly exposed to these hazardous contaminants. Ingestion of contaminated fish bioaccumulates and magnifies at every trophic level (Mitra et al. 2012; Sudhakar 2014). Consumption of tainted fish from Ganga water sometimes poses a non-carcinogenic health hazard to humans. Few agencies estimated this hazard risk with the establishment of the reference dose (USEPA 1992, 2017). The reference dose of a chemical is the single daily intake rate that does not appear to be toxic if consumed over a long period of a lifetime (USEPA 1991) (Table 4).

The Hazard Quotient is calculated from the average concentration of an individual group of pesticides in fish. The maximum health risk reported from DDTs is preceded by HCHs whereas the Hazard Quotient for endosulfan group, dimethoate, and malathion was found below 1 (USEPA 2017). OCP contamination in humans may pose a significant impact on human and animal health including neurotoxic, tumorigenic, reproductive, immunological, developmental, and genotoxic effects (Yilmaz et al. 2020). Gerber et al. (2016) studied the effects of OCPs on three rivers of South Africa Olifants, Letaba, and Luvuvhu rivers and the bioaccumulation of pesticides on Tiger fish. The result revealed a high risk of cancer for the local inhabitants because of the consumption of contaminated fish. This result assessment demonstrated that the human health risk was as high as 2 in 10 risk factors.

Downstream of Ganga, the consumption of fish for the subsistence of inhabitants may pose severe health risks. USEPA (2017) established ADI values which take into account the maximum permissible daily intake of hazardous toxicants over a person's life span without substantial risk to the individual's health. The chlorinated persistent pesticide has been spotted in animal tissue, human blood, and adipose tissue via food chain contamination. An increment is observed in several cancer cases in and around the Ganga basin with a significant number of gall bladder cancer patients (Jain et al. 2013; Saini et al. 2015).

The risk estimate value of 10⁻⁶ means the risk of one or more incidences of cancer in a million people. The risk levels lower than 10⁻⁶ are accounted for as slight risk or come to an acceptable risk level of the USEPA range (10⁻⁶–10⁻⁴). A risk level of more than 10⁻⁴ for pesticides indicates a high carcinogenic risk from the consumption of individual toxicants (USEPA 2017). A drastic rise in the number of cancer patients in the river basin could be the result of the composite effect of multiple chemicals and pesticides or the consumption of contaminated fish. This level of risk is calculated using maximum reported values of individual toxicant ranges lie between 10⁻³ and 10⁻² (Dwivedi et al. 2018). The increase in the number of cancer cases could be partially attributed to the ill effects of pesticides and other pollutants.

This section will discuss a few cost effective and highly efficient techniques. Pesticide removal techniques involve Fenton technology, adsorption, bioremediation, phytoremediation, and nanotechnology.

Photo-Fenton process is considered one of the most effective ways of pesticide removal from water. The Photo-Fenton reaction is high-performing and can be carried out at room temperature and normal pressure. The Photo-Fenton process is crucial for the reduction of recalcitrant substances in polluted water. This process has some prerequisites which include the presence of (i) Fe²⁺ and (ii) H₂O₂ (hydrogen peroxide) under ultraviolet radiation, which generates oxidative species such as hydroxyl radicals which react to pollutants like pesticides and at last cause complete mineralization. UV light is the most important part of photo-Fenton reactor design because UV light enhances the efficiency of the reactor by promoting Fe³⁺ → Fe²⁺ and hydroxyl radicals.

We can also use Fenton technology in tertiary treatment before discharging the effluent in the river. After disinfecting the contaminated water Solar photo-Fenton is reported to have the potential to remove the acetamiprid and thiabendazole (Carra et al. 2014). Júnior et al. (2021) evaluated the combination of coagulation–flocculation–settling and photo-Fenton and found that it could help in the removal of ametrine, atrazine, imidacloprid, and tebuthiuron. Photo-Fenton with solar irradiance or black light treatment could reduce the target pesticides by 82–95%.

There are a few limitations of this technique which require a need to explore other alternatives. UV Photo-Fenton technique has a high cost and solar photo-Fenton does not work out at the time of high turbidity and elevated concentration of suspended solid (da Costa et al. 2017). So other methods such as phytoremediation were explored for pesticide remediation.

Adsorption comes under the physical method of removal. According to Netto et al. (2021), experiment concludes the hydro-char has rough small cavities and it expresses a favorable role in atrazine adsorption. Activated carbon (AC) has a significant potential for pesticide removal from wastewater. AC has a 164 mg/g removal capacity of carbofuran (Salman & Abid 2013). Some fungicides such as triazole can be removed up to 99% via the use of AC (Crini et al. 2017). Graphene-based compounds, biochar, bentonite clay, Zeolite, and Chitosan-based adsorbents are also convenient and technically efficient in the amelioration of pesticides (Mojiri et al. 2020). This is an economical technique; we can use it to check the mobility of pesticides in water. Before discharging effluent directly into Ganga, a permeable reactive barrier (PRB) will be introduced. PRB can be prepared with iron-turning waste. A study has been done by Abbas et al. (2021) on the evaluation of long-term PRB column performance with iron-turning waste of dieldrin for removal, lindane, and endrin. Pesticide-releasing industries could use such effective techniques to reduce pesticides up to a remarkable level before the outflux of effluent.

Microalgae and cyanobacteria create microbial groups that live symbiotically in a community-defined consortium when they establish associations with other aerobic or anaerobic microorganisms, such as bacteria. This consortium of algae and bacteria has the potential to work synergistically to break down organic and inorganic contaminants considerably more efficiently than any single microbe. According to Abdel-Razek et al. (2019), a consortium of microalgae can reduce malathion by up to 99% from wastewater. The consortium of algae Scenedesmus quadricuda, Spirulina platensis, and Chlorella vulgaris, was found to be most efficacious in removing pesticides (Abdel-Razek et al. 2019).

Bio-adsorption is a passive process (Ardal 2014). Pesticides and other organic pollutants, such as aromatic chemicals, may be adsorbed by microalgae. According to recent research (Mishaqa 2017), farmed algae eradicated 87–96% of different pesticides (simazine, dimethoate, atrazine, pendimethalin, propanil, metoalcholar, molinate, carbofuran, isoproturn, and pyriproxin) from the aqueous phase through bio-adsorption. All processes including electrostatic interaction, ion exchange, absorption, surface complexation, and precipitation are involved in the bio-adsorption process (Nie et al. 2020). According to Nie et al. (2020), pesticide removal is dependent on two factors: (i) optimal conditions for the biome's survival and activity; (ii) the chemical structure of the pesticide and factors supporting the growth of microalgae such as pH, nutrient, light, contact time, availability of water, aeration, redox potential, surface bonding, and carbon substrate (Rath 2012).

Garcia et al.’s (2020) study affirms that a semi-closed, tubular horizontal photobioreactor (PBR) can reduce pesticides from agricultural runoff. According to their illustration high solar irradiation is the best condition for a PBR. It has reduced Cybutrine, terbuthylazine, Malaoxon, and Fenthion Sulfoxide up to a certain extent. The Indo-Gangetic basin has ideal conditions to establish high-rate algal ponds and tubular horizontal PBRs such as high solar irradiation and temperature. The establishment of open microalgae system in high-rated algal ponds has low O&M cost and energy consumption. These are some initiatives that government should incorporate in the manifesto of ‘Aviral and Nirmal Ganga’ or the Ganga rejuvenation program.

In recent days, numerous natural and cost-effective adsorbents have been working in conjugation for the removal of methyl parathion pesticides, such as waste jute fiber carbon (Senthilkumaar et al. 2010), Rhizopus oryzae biomass, and Typha australis leaf powder (N'diaye et al. 2018). Aquatic macrophytes are mostly used for the purpose of pesticide removal possibly because of requisite characteristics of phytoremediation such as (1) rapid growth; (2) easy spreading; (3) minimal cost; (4) facile harvesting; and (5) innocuous for the environment (Ammeri et al. 2021). Some non-edible plant roots and shoots are very emphatic in removing OCPs and pyrethroid pesticides such as Eichornia crassipes, Pistia strateotes (Riaz et al. 2017). Riaz et al. (2017) performed an experiment on E. crassipes and P. strateotes for the removal of OCPs and pyrethroid. During the experiment, the root of both aquatic macrophytes performed well in removal but P. strateotes (76%) removal efficiency was found much better than Eichornia in pyrethroid removal (Table 5). Numerous other aquatic plants also have the potential to reduce pesticide concentration such as water spinach (Ipomoea aquatica), duckweed (Lemna minor), Hydrilla (Hydrilla verticillata), and water ferns (Azolla caroliniana, Azolla filiculoides, and Azolla pinnata) (Anand et al. 2019).

Mangroves are the exclusive group of plants near the coastlines, and their explicit property encourages contaminant removal from river water and provides good space to nurture the mangrove ecosystem (Murdiyarso et al. 2015). A comparative study performed between mangrove and non-mangrove ecosystems concluded that mangrove forests could alleviate the contaminant level of such OCPs and pyrethroid than non-mangrove systems. Root exudates of mangroves have a wide range of compounds, such as organic acids, amino acids, and other secondary metabolites which play a crucial role in the interception or assimilation of these pollutants (Jia et al. 2016). Root exudates promote the absorption of DDT (Ivorra et al. 2021).

A study evaluated 88% pentachlorophenol removal through the combination of Lemnagibba and Typha angustifolia after the incubation of 9 days (Ammeri et al. 2021). Phytoremediation is a technologically efficient and sustainable way to remove contaminants from water and soil. However, this technique also has certain limitations and requirements like (1) selection of potential plant species for specific pesticide removal, (2) coexisting of other ions and organics, (3) effectiveness in particular soil and pH, and (4) disposal of biomass waste (Jeevanantham et al. 2019).

Numerous kinds of nanomaterials, including nanoparticles, nanotubes, and nanocomposites have resulted from ample research in the field of amelioration (Zhang & Fang 2010). Several advantages of nanoparticles in the amputation of a pesticide are as follows: (1) easy fabrication steps, (2) subtle and quick results, and (3) high efficiency of removal. The specific optical characteristics of AuNPs (gold nanoparticles) enable the removal of aromatic compounds (Gu et al. 2016). Zero-valent iron nanoparticles (ZV-FeNPs) have been used for lindane degradation (Rawtani et al. 2018). The mechanism involved in the reduction of lindane via ZV-FeNPs is to eliminate dichloro and dehydrohalogenation. Chlorobenzene, dichlorobenzene, and benzene were found as the degradation products (San Roman et al. 2013). Nanoscale zero-valent iron (nZVI) could remove profenofos (94.51%) at pH 5.12 and 13.83 g L⁻¹ concentrated catalysts (Mansouriieh & Khosravi 2015) (Table 5).

The application of nanotechnology in wastewater treatment will efficiently reduce the pesticide more than other techniques (Table 5). The previous research (Sharma et al. 2016; Shen et al. 2017) and their impactful results urge pollution control boards to implement nanotechnology in wastewater treatment. It can effectively reduce agrochemicals from a variety of matrices.

The prime goal of divergent remediation attempts for the polluted sites is to reinstate the pristineness and flawlessness of the soil water system. A paradigm shift in technological advancement and vision has been incorporated into remedial actions for the cost-effective treatment of contaminated sites. Apropos this intent, bioremediation has been ascertained as an economical biological method to administer the contaminants, for instance in in situ bioremediation (US$ 50–150), and phytoremediation cost for metal and metalloids is evaluated around US $10–35 (Mahajan et al. 2021). They highlighted proximate feasible European and US markets for phytoremediation to 36–54 US$, with a share of 1.2–1.4 billion US$ for the expulsion of heavy metals from the soil. The global market for remediation was quantified at around US$30–35 billion in 2001 and computation also shows positive feedback in the forthcoming future with the favor of 1.5 billion per annum (Singh et al. 2008), but on the other hand, physicochemical treatments like solidification, soil venting, solvent extraction and incineration show much costlier figures as US$240–340, US$ 20–220, US$360–440, and US$200–1,500, respectively. Notwithstanding, nanotechnology is an emerging field which has begun to compete for the aforesaid established technologies such as soil vapor extraction and thermal desorption for soil, but there is an exigency of comprehensive experimentation in that technology for analyzing intermediaries' pros and cons of the application. Now moving toward biological remediation, for CD remediation, the economic cost is assessed by different valuation approaches including ‘willingness to pay, substitution cost, and hedonic price analysis’. Hedonic price analysis delivers much promising value according to their premise which incorporates internal characteristics and external factor affecting. The hedonic price is approximately 14,600 and 14,850€h⁻¹. However, there are diverse implicit factors like site conditions, climatic conditions, types of contaminants, and production costs for the remediation crop, and after all the suitability should be taken into consideration prior to the selection of a particular method and simulation–optimization tools for target contaminated sites must be employed in order to estimate the cost and moreover for multicriteria decision-making.

Pesticides have multiple uses, including increasing crop output, controlling vector-borne diseases, and eliminating dangerous pests. However, pesticides' negative consequences cannot be concealed. As they cause major harm to both aquatic and terrestrial environments, such as fish and humans, they degrade the quality of water and soil, which contaminates the food chain. Pesticides also have a negative impact on biodiversity, and continuous direct or indirect exposure to pesticides can pose grave health risks to humans. Numerous authorities, such as FAO, WHO, etc., have recommended MRL, ADI, and TMDI values for food and pesticide use in an effort to mitigate the dangers to human health. Various remediation strategies, such as adsorption, bioremediation, advanced oxidation, etc. have been described for the removal of pesticides from contaminated environments. The current review suggests some sustainable remediation techniques for reducing pesticide contamination levels. Review promotes the use of nano and Fenton technology in tertiary treatment methods in sewage treatment plants. However, in the context of cost–benefit analysis according to critical review, adsorption and phytoremediation are the most effective procedures since they are ecologically benign, cost-efficient, and produce less harmful byproducts. Environmental protection organizations, farmers, health officials, makers of pesticides, and governments should collaborate to lower the risk of pesticide poisoning.

To effectively manage pesticides, it is necessary to impose stringent rules and toxicity limits. Pesticides should be manufactured with more precision and accuracy, as well as a safer profile, to reduce their detrimental influence on the environment and individuals. This changing trend in policies will provide creditable results in near future in terms of eradicating pesticides’ ill response.

The outcome of an extensive literature review on decadal change pesticide contamination in river Ganges and their major tributaries, we have noticed the vital gaps as per our present understanding that opens a wide spectrum of future research:

• evaluate the effect of Ganga contamination on human health;

• mechanism of pesticide health hazards caused in plants and humans;

• possible cost–effect and feasible alternative to improve productivity and toxic response on non-targeted organisms; and

• implementation of cost-effective pilot-scale projects for decreasing the pollution loads in rivers.

The authors are thankful to the Dean and Head, DESD (Department of Environment and Sustainable Development) and Director, Institute of Environment and Sustainable Development, Banaras Hindu University, for providing needed facilities. R.P.S. is grateful to the authorities of Banaras Hindu University, Varanasi, for providing support under the Institute of Excellence (IOE) scheme under Dev Scheme No. 6031.

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.