Organochlorine pesticide residues in water and Silver Catfish (Bagrus bajad Fabricius, 1775) from a tropical man-made lake, Northwestern, Nigeria

The present study was conducted to assess the levels of selected organochlorine pesticide (OCP) residues in water, sediments and Nile tilapia, as well as the potential health risks to humans who consume the fish of Lake Nakuru. Nine composite water and nine sediment samples, as well as 30 fish specimens, were collected from five representative sampling sites within Lake Nakuru. The OCPs targeted in the present study included p,p′‐Dichlorodiphenyl dichloroethane (p,p′‐DDD), p,p′‐dichlorodiphenyldichloroethylene (p,p′‐DDE), p,p′‐dichlorodiphenyltrichloroethane (p,p′‐DDT), heptachlor, heptachlor epoxide, α endosulfan (1), β endosulfan (2), endosulfan sulphate, endrin, lindane, aldrin, dieldrin, methoxychlor and hexachlorocyclohexanes (alpha; beta; gamma; delta). Except for aldrin, all 16 OCPs targeted in the present study were detected. The OCP residue levels ranged from below detection limit (BDL) to 7.44 ± 0.66 μg/L, BDL to 6.39 ± 1.10 μg/kg ww and BDL to 319.74 ± 66.94 μg/kg ww in water, sediment and fish samples respectively. Some OCP concentrations exhibited significant differences across the sampling sites (p < .05). The residue level of endosulfan was above the European Union standard, whereas the target hazard quotient of heptachlor epoxide was above 1, therefore being unsafe for human consumption. The present study results indicate that most of organochlorine pesticides though banned in Kenya are still detected in the environment, posing potential long‐term health hazards to humans. Accordingly, environmental monitoring programme and mitigation strategies of reducing pollutant inputs into the lake is recommended, as well as an immediate ban on harvesting and consumption of fish from Lake Nakuru.

This study had been carried out between May 2002 and August 2003 in Meriç Delta, Turkey which is located at a site where the Meriç River falls to the Agean Sea. Residues of organochlorine pesticides (OC) in surface water, sediment, and fish (Cyprinus carpio) samples from Meriç Delta were analysed by gas chromatography. The results of the study showed that all analysed 20 organochlorine pesticides and their residues have been widespread throughout the study area. According to the results, it was found that the concentrations of these selected organochlorine pesticides in fish (Cyprinus carpio) samples were higher than in water and sediment samples. Because of the low water solubility of the organochlorine compounds, it is expected that any organochlorine pesticides present in the study area, will be preferably adsorbed to sediment or bioaccumulated in fish. The α- and β-HCH were the predominant HCH isomers in all analysed fish samples and ranged between 319.5 and 968.15 ng g−1 and between 397.5 and 876.4 ng g−1, respectively. The concentration levels of p,p′-DDT (ranging from 2.68 to 52.45 ng g−1) in all analysed fish samples were consistently higher than its metabolite p,p′-DDE, indicating a recent use of this organochlorine pesticide in the area. We have analysed the distribution characteristics of individual organochlorine pesticide and found that α-, β-HCH, p,p′-DDT p,p′-DDE, β-endosulphan, heptachlore epoxide, and endrin ketone were the most common organochlorine pesticides contaminants in the study area.

This study considered the levels of 15 organochlorine pesticide (OCPs) residues (α-BHC, β- BHC, ϒ-BHC, lindane, chlorothalonil, heptachlor, aldrin, heptachlor epoxide, endosulfan I, endosulfan II, endrin, dieldrin, p, p'-DDD, p, p'-DDT and endosulfan sulphate in water, sediments and fish species from Ogbese river in Ekiti State, Southwestern Nigeria. Samples were extracted and cleaned-up on silica gel adsorbent. The OCPs concentrations were determined using Gas chromatograph (GC) equipped with Electron Capture Detector. The OCPs concentration in water and sediments ranged from below detection limit (BDL): BDL – 13.6 µg/L and 0.52 –450 µg/kg whilst the mean OCPs in the fish ranged from 2.64 – 66.0 µg/kg, respectively. The results indicated that all the analysed fish samples were contaminated with the studied pesticides. Endosulfan I was found to be above EU and FAO/WHO maximum residue limits (MRL) in Clarias gariepinus fish samples. The sediments and fish samples showed evidence of organochlorine pesticides enrichment and bioaccumulation. Chi-square at α = 0.05 showed there were significant differences in the levels of organochlorine pesticide residues in sediments and fish samples except α-BHC.

The levels of organochlorine pesticide residues in water and fish from some rivers in Edo State were determined. The water samples were extracted with 15% diethyl ether in hexane, the extracts were treated with copper tunings for the elimination of sulphur interference and analyzed using a gas chromatograph fitted with an electron capture detector. In all the water samples analyzed, the organochlorine pesticide residues determined (Lindane, Aldrin, pp-DDE, op-DDD, pp-DDD, op-DDT, and pp-DDT) were present, except in Ikoro River, where the water samples exhibited non-detectable levels of pp-DDE and pp-DDT. The level of pp-DDT, (0.7442 ppb) was highest in Ogba River, followed by Lindane (0.7130 ppb), Aldrin (0.5985ppb). Lindane (0.7928 and 0.5912ppb) was found to be highest in river Ovia and Ikoro respectively followed by Aldrin (0.7731 and 0.4867 ppb). The other organochlorine pesticides were present in varied levels from 0.3097 - 0.4860 ppb in Ogba River; ND-0.3100 ppb in Ikoro River and 0.3019 - 0.5557 ppb in Ovia River. The pesticides residues in fish samples were extracted by Soxhlet extraction process using a mixture of hexane and acetone, the extracts cleaned and analyzed using a gas chromatograph fitted with an electron capture detector. The organochlorine pesticide residues detected in water were also present in the fishes but at higher concentrations. This can be due to OCPs being lipophilic. The concentrations of these OCP residues were more in the bottom to middle feeders (Cts) than in the top to middle feeders (Tzs). Lindane levels (0.063 mg/g); 0.054 and 0.039 mg/g were detected in fish from Ovia, Ogba and Ikoro rivers respectively. While Aldrin was found present in 0.059 and 0.027 mg/g in the bottom and top feeders from Ovia river. However these levels were quite high when compared with the allowable Federal Environmental Protection Agency (FEPA) now Federal Ministry of Environment limits and can be harmful if the trend is not checked. Key words: Organochlorine, pesticide residues, rivers, fishes, safety, water, seafood.

The concentrations of some organochlorine, organophosphorus and pyrethroid pesticide residues in water and sediment samples from river Challawa were investigated using High Performance liquid Chromatography (HPLC) with UV/visible Detector. The concentrations of organochlorine and organophosphorus pesticide residues were significantly higher in the sediment samples when compared to water samples. According to the concentrations and detection frequency dieldrin and aldrin were the most dominant compounds among the organochlorine pesticide residues, while chlorpyrifos and dichlovos; permethrin and deltamethrin were the dominant compound among the organophosphorus and pyrethroid pesticides respectively. The result also indicates that the water and sediment samples within the study area were contaminated by dichlovos, diazinon, chlorpyrifos, fenitrothion, dieldrin, aldrin, DDT, DDE and DDDs. The results also show that there is still exists a variety of the studied pesticide in the water and sediment from river Challawa. Despite bans and restrictions on the usage of some of these pesticides in Nigeria, the observed concentrations of the studied Organochlorine and organophosphorus and pyrethroid pesticidesin the eight sample points could explain either their persistence in the environment or continued use in the study area.

Levels of organochlorine (OC) and organophosphorus (OP) pesticide residues in fish, sediments and water and their health risk associated with the consumption of the fish from the Tono Reservoir, Ghana were evaluated. The analytical methods included solvent extraction of the pesticide residues using ultrasound sonication and soxhlet extraction and their subsequent quantification using GC equipped with electron capture detector and pulse flame photometric detector after clean-up on activated silica gel/anhydrous sodium sulphate. A total of 29 pesticides comprising 16 OCs and 13 OPs were analyzed, out of which aldrin, p,p′-DDE and p,p′-DDD were detected in fish and sediment samples. The results showed that all the residues in water had their concentrations below the detection limit. Mean concentrations of organochlorine pesticide (OCP) residues in fish ranged from 0.017 to 0.17, 0.043 to 0.30, 0.027 to 0.243 and 0.097 to 0.263 µg/g in Sarotherodon galilaeus, Clarias anguillaris, Schilbe intermedius and Marcusenius senegalensis respectively. Mean concentrations of organophosphates pesticides ranged from 0.080 to 0.090, 0.080 to 0.087 and 0.050 to 0.063 µg/g in C. anguillaris, S. intermedius and M. senegalensis respectively. The level of chlorpyrifos in S. galilaeus was 0.160 µg/g. Mean concentrations of OCP residue in sediments ranged from 0.047 to 0.090 µg/g. Aldrin recorded the highest level while p,p′-DDD recorded the lowest level. The mean concentrations for all the detected residues were below the WHO/FAO maximum residue limits. Health risk estimation revealed that aldrin in M. senegalensis had great potential for systemic toxicity to consumers.

The misuse of organochlorine pesticides (OCPs) and the lack of adequate regulations have led to contamination of rivers and lakes. In this study, we determined the concentrations of OCPs that have either been banned or restricted for use in the Kibos-Nyamasaria River during two seasons: wet (April-May) and dry (February-March). OCPs were analyzed using GC–MS. Nineteen pesticide residues were detected in the river (water) and sediments. In water, aldrin had the highest concentration of 8.33 ± 0.58 μg/L, dieldrin (8.67 ± 0.5 μg/L), endosulfan sulphate (0.23 ± 0.00 μg/L), α-endosulfan (0.19 ± 0.00 μg/L), methoxychlor (4.57 ± 0.03 μg/L) and α-HCH (3.47 ± 0.00 μg/L) during the wet season, while dieldrin (6.03 ± 5.1 μg/L), methoxychlor (3.43 ± 0.06 μg/L), and α-HCH (8.27 ± 0.06 μg/L) were above 0.1 μg/L detection limit during the dry season. In sediments, aldrin, methoxychlor, and δ-HCH were not detected in either season; however, dieldrin and β-endosulfan were detected only during the dry season. Additionally, OCPs were above 0.2 μg/kg (maximum residue level (MRLs). The concentration of OCPs increased downstream as the river approached Lake Victoria. Because some pesticides were present at levels beyond the recommended limits, strategies must be developed to reduce them and identify potential sources of banned pesticides.

Solid-phase extraction (SPE) of organochlorine pesticide residues from environmental water samples was evaluated using octadecyl (C18)-bonded porous silica. The efficiency of SPE of these pesticide residues from reagent water samples at 1-5 micrograms dm-3 levels was compared with those obtained by solvent extraction with hexane and Freon TF (trichlorotrifluoroethane). Average recoveries exceeding 80% for these organochlorine pesticides were obtained via the SPE method using small cartridges containing 100 mg of 40 microns C18-bonded porous silica. The average recovery by solvent extraction with hexane and Freon TF exceeded 90% in both instances. It was concluded that the recoveries and precision for the SPE of organochlorine pesticides were poorer than those for the solvent extraction method. Organochlorine pesticide residue levels in environmental water samples from two major rivers flowing through predominantly rice-growing areas were monitored by gas chromatography using the solvent extraction method with hexane. Exceptionally high levels of organochlorine pesticide residues such as BHC, DDT, heptachlor, endosulfan and dieldrin were found in these water samples.

A systematic study has been performed for determination of a range of organochlorine pesticides in the water, sediments and fish samples in the Macedonian part of the Lake Ohrid and its larger tributaries. The obtained results give an overview of the contamination levels of these problematic compounds (i) at their potential sources in the river mouths, (ii) in the potentially affected, species-rich littoral section of the lake, and (iii) in the muscle tissue of one selected fish species Barbus peloponnesius, Valenciennes, collected near the rivers’ deltas. The organochlorine pesticides measured in all three matrixes were: γ-HCH, ΣHCH (sum of α-isomer, β-isomer and δ-isomer), endosulfan (total of α and β endosulfan), DDT metabolites (p,p’-DDE, p,p’-DDD and p,p’-DDT). The range of the observed concentrations for p,p’-DDT was between 0.006 μg l–1 in the water samples from Daljan and St. Naum and 0.036 μg l–1 in the water from the Koselska River. The values for p,p’-DDT measured in dry sediment ranged from 0.121 μg kg–1 in the sample from St. Naum to 1.8 μg kg–1 in the dry sediment from the Velgoška River and between 0.553 μg kg–1 for total endosulfan and 5.982 μg kg–1 for p,p’-DDE of wet fish biomass. The most abundant of the detected organochlorine pesticides was the sum of DDT metabolic forms, i.e. p,p’-DDT, p,p’-DDE and p,p’-DDD. The detected concentrations are clearly below toxic thresholds and consequently severe effects on the endemic species of Lake Ohrid are not very likely.

Currently, pesticide production and use are on the rise globally. This trend is certain to continue in the coming decades with residues posing risks to the environment and human health even at low levels. Although various aspects of pesticides and their possible implications have widely been studied, such studies have mostly been carried out in developed countries leaving the rest of the world with little scientific information. We present here the results of a study on the occurrences, concentrations, and ecological risks of 30 pesticide residues (PRs) in water and sediment samples from a tropical freshwater Lake Hawassa in the Ethiopian Rift Valley. A total of 54 composite samples of water and sediment were collected from three sampling sites on three occasions. The samples were prepared by quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique, and analyzed using GC-MS at Bless Agri Food Laboratory Service located in Addis Ababa, Ethiopia. The study applied the risk quotient (RQ) method to scrutinize the risks posed to aquatic biota by the detected PRs. The results showed occurrences of 18 and 20 PRs in the water and sediment samples, respectively. The majority, 78 and 75% of the detected PRs in water and sediment samples, respectively represent the organochlorine chemical class. Concentrations of heptachlor epoxide were significantly (p ≤ 0.001) higher than those of the remaining pesticides in both matrices. Of the pesticides detected, 77% were present in water and 83% in sediment samples and pose a serious risk (RQ ≥ 1) to the Lake Hawassa biota. This calls for further research to investigate the risks to human health posed by the PRs. The findings of this study can contribute to the development of global protocols, as they support the concerns raised about the ecological and public health impacts of PRs on a global level.

Assessment of Organochlorine Pesticide Residues in Water, Sediments and Fish from Lake Tashk, Iran

This study reports the concentration levels and distribution pattern of the persistent organochlorine pesticide (OCPs) residues in the water and bed-sediments of the Gomti River collected seasonally over a period of 2 years. The water and bed-sediment samples were collected from eight different sites and analyzed for aldrin, dieldrin, endrin, HCB, HCH isomers, DDT isomers/metabolites, endosulfan isomers (alpha and beta), endosulfan sulfate, heptachlor and its metabolites, alpha-chlordane, gamma-chlordane and methoxychlor. In the river water and sediments SigmaOCPs residues ranged between 2.16 and 567.49 ng l(-1) and 0.92 and 813.59 ng g(-1), respectively. The results, further, suggested that source of DDT contamination is from the aged and weathered agricultural soils with signature of recently used DDT in the river catchments. To assess any adverse effect of OCPs contamination on river's biological component, the threshold effect level (TEL) was used. The results revealed that bed-sediments of the Gomti River are contaminated with lindane, endrin, heptachlor epoxides and DDT, particularly at site-4 and may contribute to sediment toxicity in the freshwater ecosystem of the river.

Organochlorine pesticides (OCPs) have been of great concern around the world owing to their chronic toxicity, persistence and bio-accumulation in aquatic organisms. The OCP concentrations were measured in water, sediment and shell fishes (Panaeus monodon and Callinectes pallidus) in Lagos State (Lagos lagoon and Badagry creek), between November 2018 and June 2019. The samples were analyzed for Alpha (HCH), Beta (HCH), Gamma (HCH), Delta (HCH), Heptachlor, Aldrin, Heptachlor epoxide, Gamma chlordane, Endosulfan1 Alpha chlordane, Dieldrin, DDE, DDD, DDT, Endrin, Endosulfan II, Endrin Aldehyde, Endosulfan sulfate, Endrin ketone and Methoxychlor. The detection and determination of the pesticide residues were carried out by Gas chromatography with electron capture detector. The mean concentration of OCPs in water samples ranged from 0.150 ± 0.012µg/l (Alpha HCH) to 147.60 ± 10.810 µg/l (Endosufan II). The level of OCPs in sediment ranged from 0.150 ± 0.012 µg/kg (Alpha HCH) in Lagos lagoon to 243.500 ± 138.000 µg/kg (ppDDT) in Badagry creek. The highest mean concentration of OCPs in water and sediments were recorded in Lagos lagoon. The Concentration for shell fish ranged from 0.250 ± 0.009 µg/kg (Alpha HCH) in Lagos lagoon to 67.380 ± 22.860 µg/kg (Endosulfan II) in Badagry creek for Callinectes pallidus and from 1.310 ± 0.210 µg/kg (alpha HCH) to 143.500 ± 71.892 µg/kg (Eldrin Aldehyde) in Badagry creek for Penaeus monodon. Methoxychlor, Lindane and Aldrin were the commonly detected compounds in all the samples from both water bodies. The results showed that OCP levels in all shellfish samples analyzed were above the maximum acceptable limits of 0.01ppm (10 µg/kg) set by EU and Federal Ministry of Environment for aquatic life protection. The highest value was recorded in Penaeus monodon in Badagry creek. Indicating an urgent need for the monitoring of these pesticide residues in water, commercially important food species and the environment, as this will go a long way towards preventing various environmental and public health hazards.

This study examined residual concentrations and associated ecological risks of the organochlorine pesticides (OCPs) hexa- chlorocyclohexane (HCH) and dichloro-diphenyl-trichloroethane (DDT) in water, sediment, and fish of the Songhua River in Zhaoyuan County, China. In June 2012, 10 water, 10 sediment, and 20 fish samples were collected. Residual concentrations of ΣHCH and ΣDDT ranged from 10.0–35.59 ng L−1 (mean 28.03 ± 11.66 ng L−1) and 5.12–39.66 ng L−1 (mean 32.36 ± 11.58 ng L−1) for water. Residual concentrations of ΣHCH and ΣDDT ranged from 0.52–3.00 ng g−1 (mean 2.04 ± 0.73 ng g−1) and 0.34–3.41 ng g−1 (mean 2.38 ± 0.92 ng g−1) for sediment. The ratios of α-HCH/γ-HCH were close to 1 at the majority of sampling points, indicating considerable new pollution from the use of lindane. The ratios of p,p′-DDE + p,p′-DDD/ΣDDT were less than 0.5, indicating recent inputs from DDT impurities in dicofol. All HCH and DDT isomers except for p,p′-DDD were detected in fish tissue samples, but the associated ecological risks were estimated to be below levels of concern. The study revealed a historical usage of OCPs in the Zhaoyuan section of the Songhua River and new OCP from the use of lindane and dicofol.

The levels of 19 organochlorine pesticides (OCPs) in surface water and under water sedimentsfrom tanks located nearby the prime agricultural areas of Kanyakumari district, Tamil Nadu, India wereinvestigated to evaluate their pollution risks. A total of 36 surface water samples at 9 sampling sites and27 sediment samples at 9 sampling stations were collected from tanks, which were the water sources forcultivation. The total OCPs concentration in surface water and sediments were 5.68–25.12 ng/L and 17.7–58.59 ng/g dry weight (dw), respectively. Among the OCPs, hexachlorocyclohexanes (HCHs),dichlorodiphenyltrichloroethane (DDTs) and heptachlor epoxide were the most dominant compounds inthe sediment as well as surface water. The dominant OCPs in sediment and water were β-HCH in HCHs,p,p′-DDD in DDTs and heptachlor epoxide in other OCPs. Distribution of HCHs, DDTs and other OCPswere different indicating their different sources. Composition analysis in sediments indicated a recent usage of lindane.