Organochlorine pesticide levels in Clarias gariepinus from polluted freshwater impoundments in South Africa and associated human health risks

Assessment of organochlorine pesticide contamination in Astyanax altiparanae from the Alagados Dam, Southern Brazil

Organochlorine pesticides (OCPs) are persistent pollutants previously used in agriculture, known for their ability to bioaccumulate and pose health risks. This study analyzed samples of roe, viscera, and muscle from Astyanax altiparanae fish collected from the Alagados reservoir in Paraná, Brazil. Samples were prepared through extraction and purification, then analyzed using gas chromatography with an electron capture detector (GC/ECD), chosen for its sensitivity in detecting OCPs. The method was validated for precision, accuracy, and detection limits. Detected OCPs included Aldrin (17.1 to 50.6 ng/g in roe), α-endosulfan (3.4 to 23.5 ng/g), p, p'-DDE (4.2 to 134.7 ng/g), Dieldrin (84.7 to 183.1 ng/g), β-endosulfan (6.0 to 51.6 ng/g), and p, p'-DDT (56.6 to 286.8 ng/g). In viscera, concentrations ranged from Aldrin (19.8 to 93.3 ng/g) to p, p'-DDT (52.3 to 89.2 ng/g). Muscle samples showed similar trends. Principal component analysis indicated a link between higher OCP concentrations and increased abdominal width of the fish. While OCP levels were below FAO and WHO limits, risk quotient calculations suggest potential health risks from consuming these fish.

The benefit of using in vitro bioassays to screen agricultural samples for oxidative stress: South Africa's case

Applied pesticides end up in non-target environments as complex mixtures. When bioavailable, these chemicals pose a threat to living organisms and can induce oxidative stress (OS). In this article, attention is paid to OS and the physiological role of the antioxidant defense system. South African and international literature was reviewed to provide extensive evidence of pesticide-induced OS in non-target organisms, in vivo and in vitro. Although in vitro approaches are used internationally, South African studies have only used in vivo methods. Considering ethical implications, the authors support the use of in vitro bioassays to screen environmental matrices for their OS potential. Since OS responses are initiated and measurable at lower cellular concentrations compared to other toxicity endpoints, in vitro OS bioassays could be used as an early warning sign for the presence of chemical mixtures in non-target environments. Areas of concern in the country could be identified and prioritized without using animal models. The authors conclude that it will be worthwhile for South Africa to include in vitro OS bioassays as part of a battery of tests to screen environmental matrices for biological effects. This will facilitate the development and implementation of biomonitoring programs to safeguard the South African environment.

Qualitative characterisation and identification of microplastics in a freshwater dam at Gauteng Province, South Africa, using pyrolysis-gas chromatography-time of flight-mass spectrometry (Py-GC-ToF-MS)

Pyrolysis GC-ToF-MS-based analytical study was employed in the identification of microplastics (MPs) in the freshwater of a dam Rietvlei (RTV) located at Gauteng Province, South Africa. These MPs extracted in five locations of the dam were found to contain five different plastic polymeric constituents including PE, PS, PA, PVC and PET along with phthalate esters and fatty acid (amides and esters) derivatives as additives. Based on the fragmented pyrolyzate products, the contribution of plastic polymers and additives was 74% and 26% respectively. Among polymers, PA was dominant with 52% followed by PVC (16%) and others (13%) such as PE, PET and PS in MPs. Scanning electron micrographs of MPs in this aquatic body displayed the rough and fibrous typed patterns. The residual mass of 8-14% was left after the thermal degradation of MPs in RTV samples in the temperature range of 500-550 °C. The results of thermogravimetry (TGA) and energy-dispersive (EDS) analyses are mutually dependent and coherent to each other by way of demonstrating the presence of various inorganic compounds in the form of additives and/or sorbates. The lessened intensities of carbonyl stretching in PA (1625 cm-1) and PET (1725 cm-1) type of MPs attributed the occurrence of degradation and weathering in this aquatic system. The possible causes to the contamination of MPs in this freshwater are the located industries and poor waste management strategies being practised in this densely populated city. Based on the industry, waste management and population perspectives, the increased contamination of MPs is very likely in this freshwater which will drastically affect the ecosystem in the near future. Based on the characterisation results, the presence of various polymers, additives and the metals in MPs is envisaged to deteriorate the aquatic life along with successive risks for the people as a consequence of bio-magnification.

Effect of household culinary processes on organochlorine pesticide residues (OCPs) in the seafood (Penaeus vannamei) and its associated human health risk assessment: Our vision and future scope

Food safety is crucial in today's competitive trading market, as it directly affects human health and promotes seafood exports. The effects of thermal processing (boiling, frying, grilling, and microwave cooking) on pesticide residues (PR) in P. vannamei were assessed. The PR in raw and processed shrimp ranged from 0.007 to 0.703 μg/kg for uncooked/raw, not detected (ND) to 0.917 μg/kg for boiled, ND to 0.506 μg/kg for fried, ND to 0.573 μg/kg for grilled and ND to 0.514 μg/kg for microwave cooked shrimps. The Endrin, endosulfan sulfate, and heptachlor were predominant PR found in the raw and processed shrimp. The PR content in raw and cooked shrimps were below the maximum residue limits (MRL) set by the Codex Alimentarius Commission (2021) and the European Commission (86/363/1986 and 57/2007). The estimated daily intake (EDI) of PR from raw and processed shrimps were below the ADI prescribed by CAC. The hazard quotient (HQ) and hazard ratio (HR) values were <1, indicating no non-carcinogenic or carcinogenic health implications through shrimp consumption. The estimated maximum allowable shrimp consumption rate (CRlim) suggests an adult can eat >100 shrimp meals/month, which is over the USEPA's (2000)recommendation of >16 meals/month without health issues. The Effect of thermal processing was detected in the following order: boiling < grilling < frying < microwave cooking. The processing factor (PF < 0.7), paired t-test (t < 0.05), Tukey post hoc (p < 0.05) test, Bray-Curtis similarity index, and matrix plot exhibited that all the four thermal processing methods have a considerable impact on pesticides in the processed shrimps. But frying (59.4%) and microwave cooking (60.3%) reduced PR far beyond boiling (48.8%) and grilling (51.3%). Hence, we recommend frying and microwave processing are better methods for minimizing PR in seafood than boiling or grilling.

Consumption of Pila globosa (Swainson) collected from organophosphate applied paddy fields: human health risks

Unregulated use of chlorpyrifos (CPF) and monocrotophos (MCP) in agriculture casts adverse effects on non-target freshwater mollusc, Pila globosa and humans. Levels of CPF and MCP were assessed in the paddy field from the edible foot tissue of apple snail (Pila globosa) exposed to low (1.5 ml l^-1 water) and high (2.5 ml l^-1 water) agricultural doses for 48 h to determine human health risk associated with consumption of tissue. CPF and MCP were extracted by liquid-liquid extraction and analysed by QuEChERS method using GC-MS/MS. For low and high concentrations of CPF exposure, the pesticide residue levels in the paddy field water ranged from 4.43 to 1.08 and 5.13 to 1.53 µg l^-1, respectively, whereas, for low and high concentrations of MCP exposure, the residue levels in water ranged from 16.43 to 5.78 and 31.41 to 9. 27 µg l^-1, respectively, for 3-48 h. In the foot tissue, residues ranged from 4.36 to 15.54 µg kg^-1 for low-dose CPF, 7.1 to 18.05 µg kg^-1for high-dose CPF and from 5.28 to 12.3 µg kg^-1 and 8.94 to 18.21 µg kg^-1 for low and high dose of MCP, respectively, during 3 to 48 h of exposure. Pesticides in the tissue were lower than the recommended maximum residue limits. Estimated health risk for adults and children revealed that the estimated daily intake values did not exceed the threshold values of acceptable daily intake. Non-carcinogenic and carcinogenic health effects were less than the safe value of 1.0 and 1 × 10^-6, respectively, suggesting that CPF and MCP residues from ingestion of apple snail posed low risks to both children and adults. This preliminary result suggests regular monitoring of pesticides residues in Pila globosa collected from the paddy field of India.

Hyperbranched polyethylenimine-modified polyethersulfone (HPEI/PES) and nAg@HPEI/PES membranes with enhanced ultrafiltration, antibacterial, and antifouling properties

This study reports a simple fabrication of polyethersulfone (PES)-based membranes, their characterisation, and application. These membranes are modified with hyperbranched polyethyleneimine (HPEI) and -silver (nAg)-decorated HPEI. These were then compared for filtration, organic fouling, antifouling, and antibacterial properties against the neat PES membrane. The fabricated membranes were characterised for their chemistry using attenuated transmission reflectance-equipped Fourier transform infrared spectroscopy (ATR-FTIR) and x-ray photoelectron spectroscopy (XPS). As such, the presence of HPEI interactions between the nAg and HPEI in the membranes was confirmed. An energy-dispersive x-ray detector coupled with a scanning electron microscopy (SEM-EDS) and atomic force microscopy (AFM) were used to study morphological, compositional, topographical, and topological changes to the membrane due to the modifications. A thermogravimetric analyser (TGA) was also utilised to evaluate the effect of modification on thermal stability of the resulting membranes. Optical contact angle (OCA) interrogated the extent of membrane/water interactions which indicated enhanced hydrophilicity due to the modification. Dead-end filtration using these membranes indicated enhanced pure water permeate fluxes and protein rejection (bovine serum albumin, BSA). The results of the BSA rejection for the HPEI/PES membranes were a maximum of 98% while those of the nAg@HPEI/PES ranged between 30-87%. The membranes possessed high flux recoveries, indicating great potential for the membranes for antifouling applications in water treatment. Extensive antibacterial studies were carried out on the membranes to probe bioactivity. Enhanced activity was recorded (except for neat PES) with zone inhibitions of up to 7 mm against five bacterial strains including E. Coli and K. Pneumoniae as found in several wastewater streams. The antibacterial properties of these membranes mean they can prolong membrane operational lifetime by mitigating biofilming during water treatment.

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New flat sheet membranes possessing both organic antifouling and antibacterial properties were fabricated.

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The successive modification of PES with HPEI and nAg resulted in enhanced membrane properties.

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Most of the membranes exhibited good antibacterial activities against the bacterial strains tested.

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Membrane samples with nAg also displayed good antibacterial activities against bacteria E Coli.

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The use of cost friendly HPEI and low levels of modification, and ease of membrane fabrication was achieved.

Pesticides contamination in the Thamirabarani, a perennial river in peninsular India: The first report on ecotoxicological and human health risk assessment

This study evaluates the distribution of pesticides and assesses the ecological and human health risks associated with pesticide residues concentration in the Thamirabarani River, the only perennial river in Tamil Nadu, India. Observed a variation in the pesticide concentration in the water (not detected (ND)-31.69 μg/L), sediments (ND-14.77 μg/kg), and fish (0.02-26.05 μg/kg). Endosulfan, aldrin, and endrin were the predominant organochlorine pesticides present in water, sediments, and fish. The average concentration of pesticides (except endosulfan) in water and sediments was found to be below the acceptable threshold as per the water and sediment quality guidelines, posing no ecological hazard to aquatic organisms. The calculated risk quotient and toxic unit (0.1 > TU/RQ ≤ 1) represent low-to-medium acute and chronic toxicity to the aquatic organisms inhabiting the river basin. The average concentration of pesticides in fish (Labeorohita) was also below the maximum residual limits set by the Codex Alimentarius Commission (CAC). However, the calculated daily intakes of endosulfan, aldrin, and endrin were above the CAC-acceptable daily intake guidelines. The human health risk assessment showed that children and adults exposed to pesticides in water and sediments through ingestion and dermal contact could have higher cancer risks (CR > 10^-4) than inhalation. This study recommends implementing effective and routine pollution management schemes to avoid pesticide threats to aquatic and human health.

Occurrence, distribution, and risk of organochlorine pesticides in food and greenness assessment of method

Organochlorine pesticides (OCPs) have been used globally to boost food production. Although banned, due to their prolonged toxic effects but their residue still impacts the quality of primary and processed agricultural products. This study assesses the levels of residual OCPs (α,β,δ-HCH, heptachlor, heptachlor epoxide, chlordane, methoxychlor, aldrin, dieldrin, endrin, endrin aldehyde, endrin ketone, endosulfan, endosulfan sulfate, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT)) in food commonly consumed in Lagos and Ibadan, Southwest, Nigeria. Health risk associated with human exposure via food intake was evaluated with a statistical predictive model. About 248 composite food samples from 8 categories were analyzed in Lagos and Ibadan. Sample extraction and clean-up were by QueChERS method and extracts injected into GC-μECD. ƩDDT concentration was highest in meat products, aquatic foods, dairy products, edible oils, fruits, and cereals, while ƩHCHs were highest in chicken eggs and vegetables. ƩOCP concentrations (ng/g) in food categories were 6.09±1.6-6.85±0.9 (meat), 5.29±2.0-12.3±14 (aquatic foods), 4.86±1.7-5.89±0.8 (dairy products), 4.53±0.8-6.32±1.1 (edible oils), 3.32±1.3 (eggs), 3.54±1.0-4.80±1.5 (fruits), 4.16±2.7-4.40±0.8 (vegetables), and 6.12±2.0-6.62±0.9 (cereals). The estimated average daily intake of OCPs was 5.91, 12.5, 4.41, 6.40, 1.53, 5.14, 3.95, and 16.7 ng/kg bw/day through the consumption of meat products, aquatic foods, dairy products, edible oils, chicken eggs, fruits, vegetables, and cereals, respectively. The health risk of residual OCPs via ingestion of foods considered in this study was <1, which implied no potential health risk at the current consumption rate. However, regular monitoring of OCPs residues in food is highly recommended. Finally, the method scaled the analytical Eco-Scale evaluation and Green Analytical Chemical Procedure Index as "an acceptable green analysis method."

Electrochemical Detection of Endosulfan Using an AONP-PANI-SWCNT Modified Glassy Carbon Electrode

This report narrates the successful application of a fabricated novel sensor for the trace detection of endosulfan (EDS). The sensor was made by modifying a glassy-carbon electrode (GCE) with polyaniline (PANI), chemically synthesized antimony oxide nanoparticles (AONPs), acid-functionalized, single-walled carbon nanotubes (fSWCNTs), and finally, the AONP-PANI-SWCNT nanocomposite. The electrochemical properties of the modified electrodes regarding endosulfan detection were investigated via cyclic voltammetry (CV) and square-wave voltammetry. The current response of the electrodes to EDS followed the trend GCE-AONP-PANI-SWCNT (-510 µA) > GCE-PANI (-59 µA) > GCE-AONPs (-11.4 µA) > GCE (-5.52 µA) > GCE-fSWCNTs (-0.168 µA). The obtained results indicated that the current response obtained at the AONP-PANI-SWCNT/GCE was higher with relatively low overpotential compared to those from the other electrodes investigated. This demonstrated the superiority of the AONP-PANI-SWCNT-modified GCE. The AONP-PANI-SWCNT/GCE demonstrated good electrocatalytic activities for the electrochemical reduction of EDS. The results obtained in this study are comparable with those in other reports. The sensitivity, limit of detection (LoD), and limit of quantification (LoQ) of AONP-PANI-SWCNT/GCE towards EDS was estimated to be 0.0623 µA/µM, 6.8 µM, and 20.6 µM, respectively. Selectivity, as well as the practical application of the fabricated sensor, were explored, and the results indicated that the EDS-reduction current was reduced by only 2.0% when interfering species were present, whilst average recoveries of EDS in real samples were above 97%.

Agrochemicals in freshwater systems and their potential as endocrine disrupting chemicals: A South African context

South Africa is the largest agrochemical user in sub-Saharan Africa, with over 3000 registered pesticide products. Although they reduce crop losses, these chemicals reach non-target aquatic environments via leaching, spray drift or run-off. In this review, attention is paid to legacy and current-use pesticides reported in literature for the freshwater environment of South Africa and to the extent these are linked to endocrine disruption. Although banned, residues of many legacy organochlorine pesticides (endosulfan and dichlorodiphenyltrichloroethane (DDT)) are still detected in South African watercourses and wildlife. Several current-use pesticides (triazine herbicides, glyphosate-based herbicides, 2,4-dichlorophenoxyacetic acid (2,4-D) and chlorpyrifos) have also been reported. Agrochemicals can interfere with normal hormone function of non-target organism leading to various endocrine disrupting (ED) effects: intersex, reduced spermatogenesis, asymmetric urogenital papillae, testicular lesions and infertile eggs. Although studies investigating the occurrence of agrochemicals and/or ED effects in freshwater aquatic environments in South Africa have increased, few studies determined both the levels of agricultural pesticides present and associated ED effects. The majority of studies conducted are either laboratory-based employing in vitro or in vivo bioassays to determine ED effects of agrochemicals or studies that investigate environmental concentrations of pesticides. However, a combined approach of bioassays and chemical screening will provide a more comprehensive overview of agrochemical pollution of water systems in South Africa and the risks associated with long-term chronic exposure.

Presence and risk assessment of herbicides in the marine environment of Camps Bay (Cape Town, South Africa)

The present study was conducted during a time of drought to assess the concentration of herbicides and their potential for accumulation in marine biota found in the near shore marine environment of an urban setting (Camps Bay, Cape Town, South Africa). The purpose was to establish whether raw sewage containing selected persistent chemicals that are released through a local marine outfall would be sufficiently diluted by the ocean to prevent impact on the near-shore marine environment of the suburb Camps Bay. Samples of seawater, sediment, seaweed, and selected marine organisms present in the near shore environment, such as limpets (Cymbula granatina), mussels (Mytilus galloprovincialis), and sea urchins (Parechinus angulosus), were analysed for five indicator herbicides, namely atrazine, alachlor, simazine, metolachlor, and butachlor, with gas chromatography coupled with a mass spectrometer. The concentration of the compounds detected ranged from below the limit of detection (<LOD) to 4.2 ng/L in seawater, <LOD to 45.3 ng/g dry weight (dw) in sediments, <LOD to 157.8 ng/g dw in marine organisms, and between 12.3 and 87.0 ng/g dw in seaweed. Results of ecological risk assessment for acute and chronic risk, calculated following the US Environmental Protection Agency method, showed a possible threat to the near shore environment from sewage released by the marine outfall, as the herbicide contamination in the biota posed a low to high ecotoxicological risk for marine organisms. The hazard quotients and carcinogenic risk caused by herbicide pollution in Camps Bay seawater were above the acceptable level indicating that these chemicals pose adverse health effects, should an average sized human (70 kg) consume any of the marine species analysed herein on a daily basis (daily consumption of 54 g), over a lifetime period (life expectancy of 70 years). The study also indicated the extensive use of these herbicides for cosmetic and ornamental purposes in gardening, or for weed control in an urban setting, thus, it is apparent that consumers and municipalities need to be educated about their inadvertent use and safe disposal of these compounds. The use of these herbicides to control weeds within the area and discharge of sewage to Camps Bay must be checked through adequate control of the trade, handling of herbicides, and enforcement of appropriate sanctions and development of suitable regulations.

The first report of selected herbicides and fungicides in water and fish from a highly utilized and polluted freshwater urban impoundment

Many of South Africa's freshwater impoundments are compromised by pesticide pollution, and the Roodeplaat Dam, near Pretoria, is no exception. This paper is, to the best of our knowledge, the first report of the herbicides Dacthal, metribuzin, simazine, tebuthiuron, terbuthylazine, and the fungicides azoxystrobin, carbendazim, epoxiconazole, metalaxyl (Ridomil), propiconazole, pyrimethanil and thiabendazole in a South African freshwater impoundment. This short note reports on the screening results of water and muscle tissue samples against a comprehensive library of pesticides, herbicides and fungicides in the polluted Roodeplaat Dam. Muscle samples of Oreochromis mossambicus screened positive for p,p'-DDE and p,p'-DDD and for DCPA (chlorthal-methyl). The muscle tissue of Clarias gariepinus screened positive for p,p'-DDE and p,p'-DDD, chlorpyrifos, trans-chlordane, DCPA and terbuthylazine. The presence of these pesticides, herbicides and fungicides in this impoundment is of great concern as there is substantial evidence of adverse health effects in fish exposed to these chemicals.

Investigating (anti)estrogenic activities within South African wastewater and receiving surface waters: Implication for reliable monitoring

Natural and synthetic steroid hormones and many persistent organic pollutants are of concern for their endocrine-disrupting activities observed in receiving surface waters. Apart from the demonstrated presence of estrogen- and estrogen-mimicking compounds in surface waters, antagonistic (anti-estrogenic) responses originating from wastewater effluent have been reported but are less known. Estrogenicity and anti-estrogenicity were assessed using recombinant yeast estrogen receptor binding assays (YES/YAES) at ten South African wastewater treatment works (WWTWs) and receiving rivers in two separate sampling campaigns during the summer- and winter periods in the area. Four WWTWs were then further investigated to show daily variation in estrogenic endocrine-disrupting activities during the treatment process. Although estrogenicity was notably reduced at most of the WWTWs, some treated effluent and river water samples were shown to be above effect-based trigger values posing an endocrine-disrupting risk for aquatic life and potential health risks for humans. Furthermore, estrogenicity recorded in samples collected upstream from some WWTW discharge points also exceeded some calculated risk trigger values, which highlights the impact of alternative pollution sources contributing towards endocrine disrupting contaminants (EDCs) in the environment. The YAES further showed variable anti-estrogenic activities in treated wastewater. The current study highlights a variety of factors that may affect bioassay outcomes and conclusions drawn from the results for risk decision-making. For example, mismatches were found between estrogenic and anti-estrogenic activity, which suggests a potential masking effect in WWTW effluents and highlights the complexity of environmental samples containing chemical mixtures having variable endocrine-disrupting modes of action. Although the recombinant yeast assay is not without its limitations to show endocrine-disrupting modulation in test water systems, it serves as a cost-effective tier-1 scoping assay for further risk characterisation and intervention.

Occurrence of organochlorine pesticide residues in biological and environmental matrices in Africa: A two-decade review

The widespread use of organochlorine pesticides (OCPs), essentially for the control of insects and the cultivation of food crops, has led to the pollution of ecosystems. Despite being banned several years ago in the developed world, extensive use remains ongoing on the African continent. This review summarizes the occurrence, distributions, sources, and trends of OCPs in seven environmental matrices (atmosphere, water, sediments, soils, biota, human fluids and food products) in Africa. Findings in this review revealed that α-HCH, β-HCH dichlorodiphenyltrichloroethane (DDTs), and endosulfans were the most persistent OCP residues in the African environment, particularly DDTs in breast milk samples occurring in levels above the WHO stipulated limits, thus indicating a call for concern. Also, there was paucity of data available on OCP concentrations in ambient air. Future research efforts should prioritize testing these pollutants in the atmosphere, especially in countries where they are used more frequently. While most POP analysis studies used gas chromatography coupled to electron capture detector or mass spectrometer, it is recommended that further studies should use more sensitive analytical techniques such as gas chromatography with tandem mass spectrometry (GC-MS/MS), or gas chromatography coupled to high-resolution mass spectrometry (GC-HRMS). These instruments allow for the detection of secondary and tertiary metabolites, especially those found in water, biota and food products, which are critical vectors of OCPs to human and animal bodies. Training of farmers and other domestic users on the handling of pesticides is proposed.

Occurrence and risk evaluation of organochlorine contaminants in surface water along the course of Swartkops and Sundays River Estuaries, Eastern Cape Province, South Africa

Organochlorine contaminants were analysed in surface water from Sundays (SDE) and Swartkops Estuaries (SWE), Eastern Cape Province, which is among the largest estuaries in South Africa. The concentration of Σ₁₈OCPs ranged from 16.7 to 249.2 ng/L in autumn, 19.9-81.4 ng/L in winter, 43.6-126.8 ng/L in spring and 68.3-199.9 ng/L in summer for SDE, whereas in SWE, the values varied from 20.9 to 259.7 ng/L in autumn, 58.9-263.9 ng/L in winter, 3.2-183.6 ng/L in spring and 118.0-188.9 ng/L in summer. Among all OCPs, α-HCH, β-HCH, p,p'-DDE, p,p'-DDT, endrin, dieldrin and endrin aldehyde were predominant in surface water samples from SDE and SWE. Furthermore, the mean concentration of polychlorinated biphenyls (PCBs) ranged from 126.7 ng/L in winter to 151.0 ng/L in spring for SDE and 249.0 ng/L in spring to 727.6 ng/L in winter for SWE. Tri- and tetra-PCBs dominated the PCB homologue profile. Hierarchical cluster analysis grouped the study sites into three regions from least polluted to most polluted, indicated that SWE is more polluted compared to SDE, probably due to the influx of agricultural and industrial effluents. Carcinogenic and non-carcinogenic risk assessment revealed that the water from both estuaries is not safe for drinking, although suitable for bathing.

Dietary exposure and risk assessment of organochlorine pesticide residues in rural communities living within catchment areas of iSimangaliso World Heritage Site, South Africa

Dietary intake of contaminated food is a major route of human exposure to organochlorine pesticides (OCPs). Despite the prevalence of OCP usage in southern Africa for several decades, their impact on socioeconomically vulnerable communities remains largely overlooked. We investigated the accumulation of OCPs in crops commonly cultivated by rural communities surrounding iSimangaliso Wetland Park, South Africa. All samples analysed were found to be contaminated, with total OCP concentrations ranging between 190 and 240 ng g^-1 ww. Elevated levels of OCP residues were detected in all products, with the majority of samples exceeding European Commission's maximum residue limits (MRLs). We combine these results with local OCP fish tissue estimates to assess potential dietary risks. Cumulative risk assessment indicated potential non-cancer risks associated with heptachlor epoxide, while a cancer risk as high as 1 in 10 was found to be associated with aldrin and dieldrin. This far exceeds USEPA guidelines and indicates that OCP residues in crops and fish from the study area pose a high risk to human health. The results of this study call for further attention to be given to the health implications of continued OCP use not only within the study area but also in Southern Africa in general.

Environmental contaminants in fish species from a large dam reservoir and their potential risks to human health

The residue levels of antibiotics, metals and organochlorine pesticides (OCPs) were investigated in six fish species from the Karakaya Dam Reservoir, Turkey. Among monitored antibiotics, only enrofloxacin and ofloxacin were detected in muscle of fish species. Enrofloxacin levels in positive samples ranged from 0.0034 to 0.0073 mg/kg. It was detected in four fish species (trout barb, common carp, chub and Euphrates barbell), while ofloxacin was only found in common carp with the concentration of 0.0072 mg/kg. Both enrofloxacin and ofloxacin levels were below the maximum residue levels. No detectable residues of any OCPs were found in fish species. The highest toxic metal (As, Cd and Pb) content was detected in Euphrates barbell (0.103 mg/kg). Arsenic, Cd, Cr, Cu, Pb and Zn levels were well below the maximum permissible limits. The levels of antibiotics and metals found in fish species in the present study were generally lower than or comparable to those reported in other water bodies. According to estimated daily intake and hazard quotient values, antibiotics and metals detected in these wild fish species do not appear to pose a serious risk to public health.

Fish consumption from urban impoundments: What are the health risks associated with DDTs and other organochlorine pesticides in fish to township residents of a major inland city

Organochlorine pesticides (OCPs) in South Africa have for the most part been banned, except dichlorodiphenyltrichloroethane (DDT) which is still used as malaria vector control. The aim of this study was to determine OCP residues in the aquatic fauna of one of South Africa's most populated areas, Soweto. Risk to human health through OCP exposure via fish consumption was investigated. Clarias gariepinus was chosen as bioindicator because it is an apex predator that is in abundance, but is also a valued food source. Dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), and chlordanes (CHLs) were detected in the fish tissue with the DDTs being the most prevalent at all sites. Of the three locations, Fleurhof, Orlando, and Lenasia, the latter location's fish had the highest ΣOCP load, ranging between 81 and 1190ng/gwm. The DDTs were determined to be from historic use, whereas the CHL levels indicated more recent inputs. Although the possibility of illegal use cannot be excluded completely, the presence of OCPs outside of their allowed areas of use indicate that these compounds not only stay in the aquatic systems long term, but may be of concern in areas previously not considered high risk areas. The OCP residues in C. gariepinus from the study area pose an extremely high risk to human health when consumed, and has a cancer risk as high as 1 in 10. This potential problem should be kept in consideration when developing national health and conservation strategies.

Bioaccumulation and risk assessment of organochlorine pesticides in fish from a global biodiversity hotspot: iSimangaliso Wetland Park, South Africa

Organochlorine pesticides (OCPs) have been used extensively in the eastern regions of South Africa for agricultural and malaria control purposes, yet few data exist on the local environmental and social impacts of these compounds. Such issues have become of increasing concern in the iSimangaliso World Heritage Site, where the continued use of OCPs may pose risks to several sensitive and protected species. This study was designed to examine the bioaccumulation of OCPs in two common fish species, Oreochromis mossambicus (Mozambique tilapia) and Clarias gariepinus (African sharptooth catfish) from iSimangaliso Wetland Park. These species are targeted by local subsistence fishermen and sustain substantial bird and crocodile populations. Our findings indicate widespread contamination of the aquatic environment, with ΣOCP fish tissue concentrations in the range of 6907-8740ngg^-1 lw and 2953-5874ngg^-1 lw for C. gariepinus and O. mossambicus, respectively. HCHs (471-1570ngg^-1 lw), DDTs (645-2399ngg^-1 lw), drin-related residues (589-1960ngg^-1 lw), chlor-related residues (455-2162ngg^-1 lw) and endosulfans (457-1495ngg^-1 lw) were detected in all tissue samples. Concentrations detected in the majority of samples exceeded European Commission maximum residue limits and a health risk assessment indicated potential dietary risk associated with exposure to heptachlor, heptachlor epoxide and dieldrin. This study represents the first investigation into OCP bioaccumulation in fish species from iSimangaliso Wetland Park. Our findings highlight the need for more detailed investigations into the bioaccumulation and ecotoxicological effects of these contaminants in the food web and the associated risks to local ecosystems and human health.

CAPSULE

High levels of OCPs detected in two common fish species at iSimangaliso Wetland Park highlight potential human health and ecotoxicological threats to a globally important biodiversity conservation hotspot.

Organochlorine pesticide, antibiotic and heavy metal residues in mussel, crayfish and fish species from a reservoir on the Euphrates River, Turkey

This study investigated the residues of 19 organochlorine pesticides, 37 antibiotics and 5 heavy metals in biota samples (one mussel species, one crayfish species, six wild fish species and one farmed fish species) from the Keban Dam Reservoir on the Euphrates River, Turkey. Among monitored OCPs, only p,p'-DDE was detected in biota samples. It was found only in mussel, fish muscle and fish gill samples. The highest concentration of p,p'-DDE (0.032 mg/kg ww) was determined in the gill of common carp, which was found to be below the maximum residue limit (MRL). Only sulfadimethoxine was detected among antibiotics in biota samples. Its maximum concentration (0.0044 mg/kg ww) did not exceed the MRL of 0.1 mg/kg. Sulfadimethoxine was found only in muscle and gill of common carp collected from site S6, where there are many rainbow trout cage farms. However, no detectable residue of sulfadimethoxine was found in farmed rainbow trout. The highest concentrations of As, Cd and Pb were detected in mussels, while the highest concentrations Cu and Zn were determined in crayfish. Metal concentrations in biota samples did not exceed the maximum permissible levels. According to these results, the consumption of biota samples from the Keban Dam Reservoir is safe for human health.

Status of pesticides pollution in Tanzania - A review

Various studies have been conducted in Tanzania to assess the magnitude of pesticides pollution associated with pesticides application, storage, disposal as well as knowledge of farmers on pesticides handling. The studies analysed samples from different matrices covering vegetation, biota, water, sediments and soil. The objective of this review was to summarise the results of pesticides residues reported in different components of the environment to give a clear picture of pesticides pollution status in the country for law enforcement as well as for taking precaution measures. Gaps which need to be filled in order to establish a comprehensive understanding on pesticides pollution in the country have also been highlighted. Reviewed studies revealed that, most of the samples contained pesticides below permissible limits (WHO, FAO, US-EPA) except for few samples such as water from Kikavu river, Kilimanjaro region and Kilolo district, Iringa region which were detected with some Organochlorine pesticides (OCPs) above WHO permissible limits. Some soil samples from the former storage sites also contained pesticides above FAO permissible limits. Pesticides and their metabolites were also detected both in vegetation, food and biota samples. The prevalent pesticides in the reviewed studies were the organochlorines such as Dichlorodiphenyltrichloroethane (DDT), endosulfan and Hexachlorocyclohexane (HCH). Surveys to assess farmer's knowledge on pesticides handling observed poor understanding of farmers on pesticides storage, application and disposal. Decontamination of former storage areas, continuous monitoring of pesticide applications and training of farmers on proper handling of pesticides are highly recommended.

Influence of Mining Pollution on Metal Bioaccumulation and Biomarker Responses in Cave Dwelling Fish, Clarias gariepinus

Cave ecosystems remain largely unstudied and risk being severely degraded as a result of anthropogenic activities. The Wonderfontein Cave, situated in the extensive gold mining region of the Witwatersrand Basin, is one such system that hosts a population of Clarias gariepinus, which is exposed to the influx of polluted mine water from the Wonderfontein Spruit River. The aim of this study was to investigate the bioaccumulation of metals, as well as relevant biomarkers, in C. gariepinus specimens sampled from the Wonderfontein Cave during high (April 2013) and low (September 2013) flow surveys. Results were also compared to a surface population associated with the Wonderfontein Spruit River. There were temporal differences in metal bioaccumulation patterns and this was attributed to the lack of dilution during the low flow period. Metals associated with acid mine drainage, i.e. Co, Mn and Zn were significantly higher in the Wonderfontein Cave population and were reflected in an increase in oxidative stress biomarkers (catalase, protein carbonyls and superoxide dismutase) and the induction of metallothionein, a biomarker of metal exposure. The surface population was exposed to metals associated with geological weathering processes, i.e. Fe and Al.

Bioaccumulation and human health risk assessment of DDT and other organochlorine pesticides in an apex aquatic predator from a premier conservation area

With the second highest gross domestic product in Africa, South Africa is known to have a high pesticide usage, including the highly persistent and banned group of organochlorine pesticides (OCPs). South Africa is also one of few countries to still actively spray DDT as malaria vector control. The aim of the study was to determine the degree to which aquatic biota in selected rivers of the world renowned Kruger National Park (KNP) are exposed to by use of OCPs in the catchments outside the KNP and how this exposure relates to human health. Tigerfish (Hydrocynus vittatus) are economically important apex predators and was selected as bioindicator for this study. Fish were sampled from the KNP sections of the Luvuvhu, Letaba and Olifants rivers during the high and low flow periods from 2010 to 2011 within the KNP and 19 OCPs were determined in muscle tissue using GC-ECD techniques. Significant flow related and spatial OCP bioaccumulation was observed. Tigerfish from the Luvuvhu River displayed the highest OCP bioaccumulation. Concentrations of the majority of the OCPs including the DDTs were the highest levels ever recorded from South African freshwater systems and in many cases the concentrations were higher than most contaminated areas from around the world. The concentrations found in H. vittatus muscle also exceeded maximum residue levels in edible fat as set by the European Union. The health risk assessment also demonstrated that the levels of OCPs pose very high cancer risks to the local populations consuming tigerfish, as high as 2 in 10 increased risk factor. This is of concern not only when managing the water resources of the conservation area but also for surrounding communities consuming freshwater fish. Contaminants enter the park from outside the borders and pose potential risks to the mandated conservation of aquatic biota within the KNP.

Tissue distribution of HCH and DDT congeners and human health risk associated with consumption of fish collected from Kabul River, Pakistan

Distribution of hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) congeners in tissues of four different fish species and their associated potential health risks to local consumers are presented in this paper. The average ∑(HCHs+DDTs) concentration in Glyptothorax punjabensis (214ngg(-1) wet weight (ww)) (carnivores) was found higher than Tor putitora (155ngg(-1) ww) (herbivores). The distribution of ∑(HCHs+DDTs) in all fish tissues was found in order of liver>muscle>stomach>gills. The profile of congeners (β-HCH/∑HCH from 0.29-0.47) indicated that all selected fish species were contaminated with HCH because of its recent usage in the study area. Furthermore, DDT profile ((DDE+DDD)/∑DDT from 0.61-0.78) showed that fish contamination with DDT originated from past usage and long-time degradation mechanism. The average estimated daily dietary intake of ∑HCHs (15.0ngkg(-1) day(-1)) was higher than ∑DDTs (12.5ngkg(-1) day(-1)) by the local consumers via fish consumption. On the basis of both 50th and 95th percentile exposure levels, the carcinogenic hazard ratios for DDT and its congeners were exceeded one (safe limit) for all fish species, indicating a great potential cancer risk for local consumers with life time consumption of contaminated fish collected from Kabul River.

Risk assessment of agricultural pesticides in water, sediment, and fish from Owan River, Edo State, Nigeria

The distribution of pesticides in water, sediments, Clarias gariepinus, and Tilapia zilli from the Owan River was investigated to evaluate the pollution status and potential hazard in the river system. A total of 16 pesticides were analyzed using gas chromatography (GC) equipped with electron capture detector (ECD). The concentration of pesticide residues ranged from ND to 0.43 μg/l for water samples, 0.82 to 2.14 μg/kg/dw for sediment, 0.04 to 2.34 μg/kg/ww for C. gariepinus, and 0.02 to 1.73 μg/kg/ww for T. zilli. High concentrations of organochlorine pesticides, specifically benzenehexachloride (α-BHC, γ-BHC, and β-BHC) observed in all environmental media, are an indication of the current illegal use of banned pesticides for agricultural activities in the region. Analysis of data showed a strong correlation (r (2) = 0.7) between total organic carbon (TOC) and total pesticide residues in sediment samples. Meanwhile, risk quotient estimates for heptachlor epoxide, dieldrin, endrin, dichlorodiphenyltrichloroethane (4,4'-DDT), endosulfan I, endosulfan II, endosulfan aldehyde, and phosphomethylglycine showed potential risk to aquatic organism under observed mean concentrations (risk quotient (RQ) ≥ 1). Estimated average daily intake (EADI) for organochlorine pesticides (γ-BHC, heptachlor epoxide, aldrin, dieldrin, and endrin) was above their respective acceptable average daily intake (ADI), while hazard quotient for each of these pesticides was above the unity value (1). This indicates that there is a potential cancer risk for the local residents with life time consumption of pesticide-contaminated fish.

Pesticide contaminants in Clarias gariepinus and Tilapia zilli from three rivers in Edo State, Nigeria; implications for human exposure

The concentrations of 16 pesticides residues (alpha BHC, gamma BHC (lindane), beta BHC, Heptachlor, Aldrin, Heptachlor Epoxide, Endosulfan I, Dieldrin, Endrin, Endosulfan II, 4, 4 DDT, Endosulfan Aldehyde, Endosulfan sulfate, Atrazine, Phosphomethylglycine and Carbofuran) in two fish species (Tilapia zilli and Clarias gariepinus) from selected rivers (Illushi, Owan and Ogbesse) in Edo State, Nigeria was investigated and the associated human health risks from the consumption of contaminated fishes was also determined. Fish species were collected for a period of 18 months, and pesticides analyses was carried out using Gas Chromatography (GC) equipped with Electron Capture Detector (GC-ECD). The distribution of pesticide residues was more in the tissues of Clarias gariepinus (5.53-9.98 μg/g wet weight) than Tilapia zilli (3.49- 4.98 μg/g wet weight), while the most dominant pesticide in all the stations and all fish species was the persistent organochlorine; ∑BHC. Furthermore, the estimated dose for alpha BHC, beta BHC, Endosulfan Aldehyde, DDT, Endosulfan I, Endosulfan II, gamma BHC, Heptachlor, Endosulfan sulfate, Atrazine, Phosphomethylglycine and Carbofuran, do not pose direct hazard to human health since values were lower than the reference dose and Hazard quotient (HQ) were lower than toxic threshold of 1. However, estimated dose for, Heptachlor epoxide, Dieldrin, Endrin and Aldrin exceeded the reference dose and were higher than toxic threshold indicating a potential toxicity in humans.