Concentrations and human health risk assessment of organochlorine pesticides in edible fish species from a Rift Valley lake-Lake Ziway, Ethiopia

Level of Heavy Metals in Fish and Associated Human Health Risk From the Omo Delta in Southern Ethiopia: A First-Hand Report

This study was the first to investigate the levels of heavy metals in commercially important fish species (Lates niloticus and Oreochromis niloticus) and the human health risk in Southern Ethiopia. Sixty fish samples were collected from the Omo delta. The target hazard quotient (THQ), hazard index (HI), and target cancer risk (TCR) were used to estimate the human health risks. The mean levels of heavy metals detected in the liver and muscle of Lates niloticus generally occurred in the order of Fe> Zn > Pb > Cu >Mn> Cr > Co > Ni and Fe > Pb > Zn >Mn > Cu > Co > Cr >Ni, respectively. Similarly, the mean levels of iron in the muscle and liver tissues of Oreochromis niloticus were in the order of Fe > Pb > Zn >Mn> Cu > Cr > Co > Ni and Pb > Fe > Zn >Mn> Co > Cu > Ni, respectively. The THQs in the muscle of L. niloticus and O. niloticus decreased in the order Pb > Cr > Cu >Mn> Co > Zn > Fe> Ni and Pb >Mn> Co > Cu > Zn > Ni> Fe respectively. Pb had the highest THQ value in L. niloticus and O. niloticus, which were 0.61 and 0.409, respectively in adult. Similarly, Pb had noted that, L. niloticus and O. niloticus had the highest THQ values, at 0.87 and 0.58, respectively in children. The HI values due to consumption of L. niloticus muscle were 0.668 for adults and 0.942 for children. The mean concentrations of Pb and Cr in the tissues of L. niloticus and O. niloticus were above the FAO/WHO permissible limits. Consequently, investigating heavy metal pollution levels in fish and human health risks from the Omo delta is imperative for addressing environmental and public health concerns.

Strategies for mitigation of pesticides from the environment through alternative approaches: A review of recent developments and future prospects

Chemical-based peticides are having negative impacts on both the healths of human beings and plants as well. The World Health Organisation (WHO), reported that each year, >25 million individuals in poor nations are having acute pesticide poisoning cases along with 20,000 fatal injuries at global level. Normally, only ∼0.1% of the pesticide reaches to the intended targets, and rest amount is expected to come into the food chain/environment for a longer period of time. Therefore, it is crucial to reduce the amounts of pesticides present in the soil. Physical or chemical treatments are either expensive or incapable to do so. Hence, pesticide detoxification can be achieved through bioremediation/biotechnologies, including nano-based methodologies, integrated approaches etc. These are relatively affordable, efficient and environmentally sound methods. Therefore, alternate strategies like as advanced biotechnological tools like as CRISPR Cas system, RNAi and genetic engineering for development of insects and pest resistant plants which are directly involved in the development of disease- and pest-resistant plants and indirectly reduce the use of pesticides. Omics tools and multi omics approaches like metagenomics, genomics, transcriptomics, proteomics, and metabolomics for the efficient functional gene mining and their validation for bioremediation of pesticides also discussed from the literatures. Overall, the review focuses on the most recent advancements in bioremediation methods to lessen the effects of pesticides along with the role of microorganisms in pesticides elimination. Further, pesticide detection is also a big challenge which can be done by using HPLC, GC, SERS, and LSPR ELISA etc. which have also been described in this review.

Factors impacting water quality and quantity in rapidly expanding urban areas based on the DPSIR model: experiences and challenges from Addis Ababa City, Ethiopia

Due to the increasing pressures of global change, such as urbanization, climate change, population growth, and socioeconomic changes, cities around the world are facing significant water challenges, both in terms of supply and quality. This emphasizes the need for concerted effort to manage water supplies effectively for sustainable development. The driver, pressure, state, impact, and response (DPSIR) model was applied in this study to determine the underlying causes of Addis Ababa's water supply and quality issues. Field observations, key informant interviews, and previously published reports were used to identify these variables, impacts, and coping mechanisms. The model suggests that issues with urban water are caused by inadequate waste management, fast urbanization, climate change, sociodemographic shifts, economic challenges, changes in land use and land cover, and institutional pressures. As a result, aquatic ecosystems endure damage and there is also an increase in water-related diseases and unmet water demand. Some of the responses to these effects include using bottled water, digging boreholes, harvesting rainwater, planting trees, and soliciting funds. The study concludes by recommending an integrated approach to managing the risks of declining water quality and shortage. This study will advance the important empirical understanding of how urban water supply and quality are impacted by environmental stresses on a global scale. It will also positively impact the development of sustainable water management policies and practices.

The Ripple Effect of Climate Change: Assessing the Impacts on Water Quality and Hydrology in Addis Ababa City (Akaki Catchment)

This research aimed to evaluate the effects of climate change on the hydrology and water quality in the Akaki catchment, which provides water to Addis Ababa, Ethiopia. This was performed using the soil and water assessment tool (SWAT) model and an ensemble of four global climate models under two Shared Socioeconomic Pathways (SSP) emission scenarios from Coupled Model Intercomparison Project Phase 6 (CMIP6). The climate data were downscaled and bias-corrected using the CMhyd tool and calibrated and validated using the SWAT-CUP software package. Change points and patterns in annual rainfall and temperature were determined using the homogeneity test and Mann-Kendell trend test. Water quality data were obtained from Addis Ababa Water and Sewerage Authority (AAWSA), and more samples were taken and analyzed in accordance with APHA recommended procedures. The SWAT model output was then used to assess the impacts of climate change on hydrological components and water quality. Rainfall increased by 19.39 mm/year under SSP2-4.5 and 12.8 mm/year under SSP8.5. Maximum temperature increased by 0.03°C/yr for SSP2-4.5 and 0.04°C/yr for SSP5-8.5. Minimum temperature increased by 0.03°C/yr under SSP2-4.5 and 0.07°C/yr under SSP5-8.5. This warming will augment the evapotranspiration rate which in turn will have a negative impact on the freshwater availability. Streamflow will increase by 5% under SSP2-4.5 and 9.49% under SSP5-85 which may increase sporadic flooding events. Climate change is expected to contribute to the deterioration of water quality shown by 61%, 36%, 79%, 115%, and 70% increased ammonia, chlorophyll-a, nitrite, nitrate, and phosphorus loadings, respectively, from 2022. The increase in temperature results in increases in nutrient loading and a decrease in dissolved oxygen. Overall, this research demonstrated the vulnerability of the catchment to climate change. The findings of this research can offer vital knowledge to policymakers on possible strategies for the sustainable management of water.

Water quality, human health risk, and pesticides accumulation in African catfish and Nile tilapia from the Kitchener Drain-Egypt

Pesticides are toxic and could negatively impact humans and the ecosystem. The Kitchener Drain is among the longest drains in Egypt and carries a wide range of wastewater from the agriculture sector, which contains pesticides and may pollute the ecosystem. Thus, water quality, human health risk, and pesticide accumulation in African catfish and Nile tilapia from the Kitchener Drain-Egypt. The water and fish samples were collected from Kitchener Drain in Kafr Elsheikh Governorate, Egypt, during the four seasons. The results indicated that heptachlor and diazinon were undetected during the four seasons. However, endosulfan, chlorpyrifos, and dicofol were detected in winter and autumn. Only p,p'-DDT was detected during spring. Endosulfan, heptachlor, and aldrin were detected in Nile tilapia during winter. Only heptachlor and aldrin were detected during spring. Endosulfan, heptachlor, dicofol, p,p'-DDT, chlorpyrifos, and diazinon were detected in the autumn season. In summer, dicofol and p,p'-DDT were detected, while endosulfan, heptachlor p,p'-DDT, aldrin, chlorpyrifos, and diazinon were not detected. In African catfish, endosulfan, heptachlor, dicofol, and p,p'-DDT were detected during winter, while chlorpyrifos, aldrin, and chlorpyrifos, aldrin, and diazinon were not detected. In the spring season, endosulfan, heptachlor, and aldrin were detected. Endosulfan, heptachlor, dicofol, p,p'-DDT, aldrin, chlorpyrifos, and diazinon were detected in the autumn season. Similarly, in the summer season, endosulfan, heptachlor, dicofol, p,p'-DDT, aldrin, chlorpyrifos, and diazinon were detected. The sequence of estimated daily intake (EDI) in Nile tilapia during the four seasons is heptachlor > endosulfan > dicofol > p,p'-DDT > aldrin > diazinon > chlorpyrifos. The sequence of EDI in African catfish during the four seasons is endosulfan > p,p'-DDT > heptachlor > aldrin > dicofol > diazinon > chlorpyrifos. In conclusion, the results confirmed the absence of a hazard index for consuming Nile tilapia and African catfish collected from the Kitchener drain.

Pesticide concentration in three selected fish species and human health risk in the Lake Tana sub-basin, Ethiopia

Pesticide use has increased in the Lake Tana sub-basin due to increased agricultural activity, potentially endangering nontargeted organisms. To assess its potential impact on fish health and fish-consuming human populations, pesticide concentrations in the fillet and liver tissue of three fish species, namely Labeobarbus megastoma, Labeobarbus tsanensis, and Oreochromis niloticus, were investigated in Lake Tana. Fish samples were taken from the lake near the rivers of Ribb and Gumara, which flow through agricultural areas where considerable amounts of pesticides have been applied. A total of 96 fish samples were collected. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) revealed the presence of ten pesticides. Pyrimethanil was frequently detected in 96% of liver and 65% of fillet samples at a median concentration of 33.9 µg kg-1 and 19.7 µg kg-1, respectively. The highest concentration of pyrimethanil was found in L. megastoma (1850.0 µg kg-1). Labeobarbus megastoma also had the highest concentration of oxamyl (507.0 µg kg-1) and flazasulfuron (60.1 µg kg-1) detected in the liver tissue. The highest concentration of carbaryl (56.5 µg kg-1) was found in the liver tissue of O. niloticus. Fish tissue samples from the two study sites contained pyrimethanil, oxamyl, carbaryl, and flazasulfuron. Only pyrimethanil showed a statistically significant difference between the two sites and the species L. megastoma and L. tsanensis. The amounts of pesticides found in the fish species pose no direct risk to the health of fish consumer human population. However, the results show that the lake ecosystem needs immediate attention and regular monitoring of the rising pesticide usage in the lake watershed.

Distribution and ecological risk assessment of herbicide residues in water, sediment and fish from Anyim River, Ebonyi State, Nigeria

The presence of herbicide residues in water, sediment and African catfish (Clarias gariepinus) from Anyim River was investigated bimonthly from November, 2017 to September 2019. The aim of the study was to evaluate the pollution status of the river and the associated health hazard. The herbicides investigated were glyphosate-based and included sarosate, paraquat, clear weed, delsate and roundup. The samples were collected and analyzed accordingly using gas chromatography/mass spectrometry (GC/MS) based method. The concentration of herbicide residues ranged from 0.02 to 0.77 µg/gdw in sediment, 0.01-0.26 µg/gdw in fish and 0.03-0.43 µg/L in water respectively. Risk Quotient (RQ) deterministic method was used to assess the ecological risk of herbicide residue in fish and the result indicated chances of causing adverse effect on fish species in the river (RQ ≥ 1). Human health risk assessment further indicated potential health implications on humans consuming the contaminated fish on long term basis.

Individual Risk Assessment for Population Living on the Territories Long-Term Polluted by Organochlorine Pesticides

The long-term storage of unutilized pesticides raised new problems of long-term environmental contamination. The study presents the results of surveying 151 individuals in 7 villages living close to pesticide-contaminated localities. All individuals have been surveyed concerning their consumption habits and lifestyle characteristics. An assessment of the general exposure risks of the local population was carried out using the analysis of pollutants in food products and the average levels of their consumption in the region. The cohort risk evaluation revealed that the greatest risk was associated with the regular consumption of cucumbers, pears, bell peppers, meat, and milk. The new model to estimate individual risks of long-term pesticide pollution was proposed as a calculation of the combined action of 9 risk factors, including individual genotypes, age, lifestyle, and personal pesticide consumption rates. The analysis of the predictive ability of this model showed that the final score for individual health risks corresponded to the development of chronic diseases. A high level of chromosomal aberrations was evidenced for individual genetic risk manifestations. The combined influence of all risk factors revealed contributions of 24.7% for health status and 14.2% for genetic status, while other impacts go to all unaccounted factors.

Comprehensive GIS based risk surveillance of organochlorine pesticides (OCPs) in edible fish species of River Chenab, Pakistan

The present study was conducted to evaluate Carcinogenic (TR) and non-carcinogenic (THQ) human health risk of organochlorine pesticides (OCPs) in three edible fish species (Labeo boga, Channa marulius and Wallago attu) of River Chenab, Pakistan using USEPA human health risk assessment model. Holistic GIS (Geographic information system) based Geo-Statistical approach has been employed for the first time in River Chenab, Pakistan to categorize contaminated risk zones of OCPs based on single pollution index. The ∑OCPs concentrations in fish species were ranged from 5.09 to 414 ng/g with the prevalence of dieldrin. Results of single pollution index of DDE, aldrin, dieldrin and ∑endosulfan revealed River Chenab as polluted and risk zone area. Distribution pattern assessed significantly higher (p < 0.05) concentrations of OCPs in downstream area suggesting substantial pollution of surrounded industrial region. The human health risk assessment depicted no harmful non-carcinogenic (THQ) risk except for ΣOCPs concentration of C. marulius. Significant carcinogenic (TR) health risk exhibited by all examined OCPs from maximum of the studied sites. Therefore, the high carcinogenic human health risk had highlighted an immediate removal of continuous disposal of OCPs in the River Chenab.

Occurrence, spatio-temporal distribution, and human health risk assessment of pesticides in fish along the Ayuquila-Armería River, Mexico

Pesticide usage has contributed to increasing food production; it has also caused them to be found in ecosystems inducing adverse effects on biota. Fish are the most abundant and diverse vertebrates in the world and are of great importance both economically and ecologically. Some fishes are indicators of the environmental quality of aquatic ecosystems and provide insight as to how pollutants might influence public health. The tilapias species can be considered biomonitors because they present little displacement representing the contamination level of a site. This study aimed at three goals: (1) to determine the concentration of 20 pesticides in tilapia muscle in the Ayuquila-Armería basin, (2) to describe the spatiotemporal variation of analytes and (3) to evaluate the risk of consuming contaminated fish. The presence of 11 pesticides was determined. Ametrine, glyphosate and malathion concentrations showed significant differences by season. The risk assessment showed that the consumption of tilapia muscle from the Ayuquila-Armería basin does not represent a risk for the population. Diazinon concentrations were relatively low compared to the other pesticides concentrations, but its toxic characteristics were the ones that most negatively influenced the risk assessment. The results obtained are relevant from the social and economic points of view.

Organochlorine pesticides residue affinity in fish muscle and their public health risks in North West Ethiopia

Pesticides are the parent compounds, their metabolites, and associated impurities of agricultural and health chemical inputs. If they are found at concentration levels higher than the standard limits, they have potential negative impacts on the ecosystem in general and on fish and humans in particular. This study investigates organochlorine pesticides (OCPs) residue occurrences in fish muscle and assesses their public health potential risks, in North West Ethiopia. The concentration of OCPs residue under gas chromatography with electron capture detector (GC-ECD) was detected in 37.84% of fish muscle samples. The mean amounts detected were Endosalfan I, 341.50 ± 32.19 μg/kg; Endosalfan II, 36.01 ± 2.3 μg/kg; Endosalfan sulfate, 5.43 ± 4.06 μg/kg; 4, 4, DDE (4,4-dichlorodiphenyldichloroethylene), 64.01 ± 9.08 μg /kg; 4,4, DDD (4,4-dichlorodiphenyldichloroethane), 5.65 ± 3.12 μg/kg; and 4, 4, DDT (4,4-dichlorodiphenyltrichloroethane), 1.58 ± 0.30 μg/kg. The mean concentration of Endosalfan I tested in fish muscle samples was higher than that of the permissible limit of different international standards. However, due to the low per capita consumption rate of fish origin food in Ethiopia, the health risk index (HRI) ranges from 0.002 to 0.1275, which shows there is no public health risk. This study highlights the possibility of chemical residue occurrence in fish food products, and hence pesticide use regulations and monitoring concentration levels should be implemented regularly to avoid human and environmental health risks.

Health risk assessment of organochlorine pesticide residues in edible tissue of seafood

Fish is one of the most valuable foods with high-quality animal protein. However, aquaculture, or ingesting contaminated food, allows organochlorine pesticides (OCPs) to enter the fish's body, and therefore, it negatively impacted public health. One-hundred and twenty random samples of Clupea harengus (C. harengus), Mugil cephalus (M. cephalus), Sardinella aurita (S. aurita), Oreochromis niloticus (O. niloticus), Neptunus pelagicus (N. pelagicus) and Sepia savigngi (S. savigngi) (n = 20 each) were collected from local markets in Mansoura city, Egypt. Samples were checked to see whether any residues of OCPs with the application of risk assessment due to their consumption by Mansoura citizens. The findings indicated that summation hexachlorocyclohexane (∑HCH) in examined seafood samples ranged from 0.27 ± 0.13 in N. pelagicus to 61.61 ± 52.03 μg.kg-1 in S. aurita. Also, the γ-HCH isomer was considered the more prominent among isomers. Hexachlorobenzene (HCB) was found in five different species, with mean values of 2.03 ± 1.85, 1.5.7 ± 1.17, 0.94 ± 0.87, 0.35 ± 0.06, and 0.18 ± 0.06 μg.kg-1 in C. harengus, S. aurita, M. cephlaus, O. niloticus, and S. savigngi. Moreover, summation of Heptachlors (∑HPTs) was 10.19 ± 7.63, 1.27 ± 0.26, 2.58 ± 0.11, 0.95 ± 0.12, 0.21 ± 0.11 and 0.32 ± 0.03 μg.kg-1 of wet weight in examined C. harengus, M. cephlaus, S. aurita, O. niloticus, N. pelagicus, and S. savigngi. Aldrin and dieldrin residues were 3.75 ± 1.31 and 4.86 ± 1.33 μg.kg-1 in C. harengu, meanwhile they were 1.61 ± 0.77 and 0.78 ± 0.04 μg.kg-1in M. cephalus. Dichlorodiphenyldichloroethylene (pp-DDE) was dominant in all examined species within different concentrations 5.08 ± 4.12, 0.98 ± 0.10, 3.07 ± 0.91, 0.93 ± 0.27, 0.08 ± 0.01 and 0.35 ± 0.02 μg.kg-1 in C. harengus, M. cephlaus, S. aurita, O. niloticus, N. pelagicus and S. savigngi, respectively. We concluded that all examined seafood samples were lower than the recommended maximum residue limit. Also, the estimated daily intake was less than the permitted daily intake. Non-carcinogenic indices of target hazard quotient and hazard index for OCPs in all examined species were less than 1.

Organochlorine pesticides and polychlorinated biphenyls in carnivorous waterbird and fish species from Lake Hawassa, Ethiopia

Abstract

Agricultural, vector-control and industrial activities around Lake Hawassa pose a risk of organochlorine contamination of the lake biota. To assess organochlorine contamination, we measured levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in 3 species of carnivorous waterbird and 3 species of fish. A total of 50 samples of fish and bird species sampled from Lake Hawassa in 2019. We investigated factors influencing accumulation of OCPs and PCBs. Reproductive risk associated with tissue levels of 4,4’-dichloro-diphenyl-dichloro-ethylene (p,p’-DDE) is also estimated. Results show that dichloro-diphenyl-trichloroethane (DDT) is the dominant contaminant found in both bird and fish species. p,p’-DDE is the dominant DDT metabolite in both bird and fish species. Geometric mean of p,p’-DDE varied from 49.8–375.3 and 2.2–7.7 ng g−1 ww in birds and fish, respectively. Average p,p’-DDE level in birds is 33.3 times higher than in fish. p,p’-DDE constitutes 93.4–95.2% of total DDTs in bird species. Degree of exposure, chemical stability, and resistance to environmental and biological degradation could explain higher levels of p,p’-DDE both in bird and fish species. There is significant variation in p,p’-DDE levels among bird and fish species owing to differences in feeding habits, foraging habitat, and lipid content. An increase in DDT levels with increasing size is observed in both bird and fish species. A significant positive association between log-transformed p,p’-DDE, and stable nitrogen isotope ratio (δ15N) values is found. There is no reproductive health risk in bird species as a result of the current levels of p,p’-DDE.

Article Highlights

Exposure Routes and Health Risks Associated with Pesticide Application

Pesticides play an important role in agricultural development. However, pesticide application can result in both acute and chronic human toxicities, and the adverse effects of pesticides on the environment and human health remain a serious problem. There is therefore a need to discuss the application methods for pesticides, the routes of pesticide exposure, and the health risks posed by pesticide application. The health problems related to pesticide application and exposure in developing countries are of particular concern. The purpose of this paper is to provide scientific information for policymakers in order to allow the development of proper pesticide application technics and methods to minimize pesticide exposure and the adverse health effects on both applicators and communities. Studies indicate that there are four main pesticide application methods, including hydraulic spraying, backpack spraying, basal trunk spraying, and aerial spraying. Pesticide application methods are mainly selected by considering the habits of target pests, the characteristics of target sites, and the properties of pesticides. Humans are directly exposed to pesticides in occupational, agricultural, and household activities and are indirectly exposed to pesticides via environmental media, including air, water, soil, and food. Human exposure to pesticides occurs mainly through dermal, oral, and respiratory routes. People who are directly and/or indirectly exposed to pesticides may contract acute toxicity effects and chronic diseases. Although no segment of the general population is completely protected against exposure to pesticides and their potentially serious health effects, a disproportionate burden is shouldered by people in developing countries. Both deterministic and probabilistic human health risk assessments have their advantages and disadvantages and both types of methods should be comprehensively implemented in research on exposure and human health risk assessment. Equipment for appropriate pesticide application is important for application efficiency to minimize the loss of spray solution as well as reduce pesticide residuals in the environment and adverse human health effects due to over-spraying and residues. Policymakers should implement various useful measures, such as integrated pest management (IPM) laws that prohibit the use of pesticides with high risks and the development of a national implementation plan (NIP) to reduce the adverse effects of pesticides on the environment and on human health.

Levels and Trophic Transfer of Selected Pesticides in the Lake Ziway Ecosystem

The levels of 30 selected pesticides and trophic biomagnification of DDT were investigated in biota samples of the Lake Ziway in the Rift valley region, Ethiopia. Carbon source and trophic position were calculated by using ¹³C and ¹⁵N stable isotopes, individually, and trophic magnification factors (TMFs) were inferred. Only DDT and its metabolites were quantified in all samples analyzed. The most prominent metabolite was p,p'-DDE with mean concentration ranging from the 0.82-33.69 ng g^-1 lipid weight. Moreover, the ratio of DDT/DDD + DDE in all the biota samples was less than 1 signifying historical DDT application. Regression of log [ΣDDT] vs TL (trophic level) among all biota species showed a significant correlation, indicating that DDTs are biomagnifying along with the food web of Lake Ziway with an estimated TMF of 2.75. The concentrations of DDTs and other organochlorine pesticides found in biota from Lake Ziway were, in general, lower than studies found in previous studies carried out in the same lake.

Concentrations and Human Health Risk of Organochlorines in Farmed Freshwater Products: Fish Ponds around Changsha, China

ABSTRACT

The present study was conducted to reveal the concentrations and patterns of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in seven species of freshwater food products (Procambarus clarkii, Ctenopharyngodon idellus, Parabramis pekinensis, Hypophthalmichthys molitrix, Cyprinus carpio, Aristichthys nobilis, and Carassius auratus) collected from aquaculture farms around Changsha, People's Republic of China. The OCPs and PCBs in the muscle tissue of these species were analyzed to assess the health risk associated with dietary intake. The mean concentrations of OCPs and PCBs were 6.38 to 15.90 and 3.18 to 5.12 ng g-1 wet weight, respectively. Heptachlor and δ-HCH were the main OCP contaminants in the tested samples, accounting for >74% of the total OCPs. PCB52 was the main PCB, accounting for >88% of the total PCBs. The bioaccumulation of OCPs and PCBs in these aquatic products depends upon the species. C. idellus had the highest concentrations of OCPs, and H. molitrix had the highest concentrations of PCBs. The mean lipid concentration in these freshwater species was 6.08 to 19.8% (dry weight) and was significantly correlated with the concentrations of OCPs and PCBs. The health risk from consumption of these freshwater species was assessed based on the hazard ratios and hazard quotient, and consumption of these products was determined to pose a carcinogenic risk.

HIGHLIGHTS

Pesticide residue levels in surface water, using a passive sampler and in the sediment along the littoral zone of Lake Ziway at selected sites

Diaion® HP-20 resin passive samplers deployed in water and sediment samples collected from Lake Ziway were analyzed for 30 organochlorine, organophosphorus, carboxamide, and pyrethroid pesticide residues. The samples were collected from purposely selected sampling stations in five sites on Lake Ziway. Levels of selected pesticides were determined by GC–MS/MS in all samples. p,p′DDE and boscalid residues were the only detected pesticides in sediment samples. Similarly, only metalaxyl and boscalid residues were recovered from HP-20 resins. The concentration of p,p′DDE and boscalid in sediment ranged from 0.66–7.23 and 0.1–15.26 ng g−1 dry weight respectively. The presence of p,p′DDE but no other metabolites of DDT in all sediment samples indicated that DDT residues in Ziway Lake were aged and probably originated from the weathered agricultural soils of the surrounding region. The highest level of boscalid was recorded at Site 2 (near the floriculture enterprises) both in sediment and in HP-20 resins with a mean concentration of 11.8 ng g−1 dw and 39.6 ng g−1 disk respectively. However, the concertation of metalaxyl was the highest in the HP-20 resins deployed at Site1 and Site 4 (near the intensive small-scale vegetable farm) with a mean concentration of 54.7 ng g−1 disk and 54.3 ng g−1 disk respectively. Generally, most sampling sites of p,p′DDE were found to have a moderate ecological risk based on levels specified in the sediment quality standards. Moreover, the relatively high boscalid and metalaxyl levels in HP-20 deployed in Lake Ziway would be the result of recent intensive pesticide use by floriculture enterprises and small-scale vegetable farmers in the region. A spatial variation on the accumulation of detected pesticides among the sampling sites depends on the anthropogenic activities, around the lake from the point and non-point sources. Although most of the analyzed pesticides were below the detectable limit, further studies and continued monitoring of currently used pesticide residues in the Lake are highly recommended.

Pesticide residues in Rita rita and Cyprinus carpio from river Ganga, India, and assessment of human health risk

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Accumulation of pesticide residues in fish due to continuous use in agricultural areas along river Ganga basin.

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Residues concentrate in the humans through consumption of food from the river.

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Health impacts like non-carcinogenic (THQ) and carcinogenic (R) risks are never negligible by these residues.

Present study was carried out to determine the concentration and bioaccumulation of pesticide residues in two commonly edible fishes: bagrid fish, Rita rita and common carp, Cyprinus carpio collected from river Ganga at Narora, India. The human health risk via consumption of these fishes was also assessed. The n-hexane extract of the muscle tissues was characterized by gas chromatography coupled to mass spectrometry and quantified by electron capture detector for pesticide residues. Bioaccumulation factor (BAF) in bagrid fish for detected pesticides was found to be higher than those in common carp. Estimated daily intake (EDI) values in our study were insignificantly higher than Average daily intake (ADI) values. Target hazard quotient (THQ) via consumption of selected fishes was found to be lower than the set 1.0, inferring non-carcinogenic risk. With regard to contaminants carcinogenic effects the total risk ratio (R) values of each pesticide was found lower than threshold risk limit except of heptachlor which indicates carcinogenic risk. The results justify pesticide pollution in river Ganga at Narora and thus more attention is required in order to help improve the health status of this ecosystem and reduce contamination of fishes.

Exposure to DDT and HCH congeners and associated potential health risks through khat (Catha edulis) consumption among adults in South Wollo, Ethiopia

Khat (Catha edulis) chewing is widespread in the region of East Africa. Even low levels of organochlorine pesticides (OCPs) in khat could induce public health concern. In a market-based study, from five popular khat varieties, a total of 35 composite khat samples were analyzed for dichlorodiphenyltrichloroethane (DDT) and its main transformation products, and four hexachlorocyclohexane (HCH) isomers. Extraction was carried out by quick, easy, cheap, effective, rugged and safe method (QuEChERS). OCP concentrations were determined by head space solid phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS). Every sample contained β-HCH above the maximum residue limit set by the European Commission. For total DDT, this was the case for 25.7% of the samples. The ratios of (p,p'-DDD + p,p'-DDE) to p,p'-DDT were less than one for 85% of khat samples, demonstrating recent use of DDT in khat farmlands. Conversely, the ratio of β-HCH to total HCH varied from 0.56 to 0.96, implying historical input of technical HCH. Assuming a daily chewable portion of 100 g, dietary intakes of p,p'-DDT, total DDT and total HCH by adults ranged from 3.12 to 57.9, 6.49 to 80.2 and 39.2 to 51.9 ng (kg body weight)^-1 day^-1, respectively. These levels are below acceptable levels suggested by international organizations. Chewing khat showed lower non-cancer health risk, but showed relatively higher cancer risk in terms of OCPs. Because khat is chewed without being subjected to any treatment, uncertainties associated with estimated intakes and health risks should be low. Therefore, this practice is of great concern.

Small-scale Farmer Pesticide Knowledge and Practice and Impacts on the Environment and Human Health in Ethiopia

BACKGROUND

Inappropriate use and application of pesticides in Ethiopia pose a major threat to the health of farmers and the environment.

OBJECTIVE

The present study aimed to assess the level of knowledge, attitudes, and practices of small-scale vegetable farmers towards the use of pesticides in Ethiopia along the Lake Ziway watershed.

METHODS

This was a cross-sectional study involving a total of 210 farmers randomly selected during a period of pesticide application from a purposively selected village located in the immediate vicinity of Lake Ziway, Ethiopia. Data were generated through structured in-depth interviews and on-site observations on farms. A Chi-square test was applied to evaluate whether the collected data and their probable associations were significant.

RESULTS

World Health Organization (WHO) class II pesticides (moderately toxic) were the most frequently used pesticides in the study area. There was no reported use of WHO classes 1a and 1b and banned or restricted pesticides such as dichlorodiphenyltrichloroethane (DDT) and endosulfan. Most (92%) farmers reported indiscriminately disposing of empty containers in the field, while 86.7% applied the leftover pesticides to other crops. More than 90% of small-scale farmers did not use any personal protective equipment (PPE) when handling pesticides. About 95% of farmers had poor knowledge regarding pesticides. A significant association (p < 0.001) was observed between the knowledge of farmers and their practices related to pesticides.

CONCLUSIONS

Generally, the knowledge of small-scale farmers on pesticides was poor. Moreover, the inappropriate disposal of pesticides and pesticide containers poses a risk to the environment. The findings of the present study underline the need to train farmers concerning the safe and proper use of pesticides to mitigate hazards to human health and the environment.

PARTICIPANT CONSENT

Obtained.

ETHICS APPROVAL

The study was granted an exemption from requiring ethics approval from the Hawassa University College of Natural and Computational Science, Research and Review Committee.

COMPETING INTERESTS

The authors declare no competing financial interests.

Activity concentrations of 210Po and 210Pb in fish and mussels in İzmir, Turkey, and the related health risk assessment (dose assessment and pesticide levels) to the consumers

The activity concentrations of natural radionuclides (²¹⁰Po and ²¹⁰Pb) and residual pesticide levels were determined from the fish (red mullet, common sole, anchovy, horse mackerel, gray mullet, and sardine) and mussel samples collected in İzmir Bay seasonally from October 2012 and July 2013. The ²¹⁰Po and ²¹⁰Pb concentrations varied between 5.7 ± 4.0 Bq kg^-1 dry weight (dw) to 353.7 ± 45.0 Bq kg^-1(dw) and 0.7 ± 0.2 Bq kg^-1 (dw) to 4.3 ± 0.8 Bq kg^-1 (dw), respectively. From a public health point of view, the fish and mussel collected from the İzmir Bay are not harmful to consumers.

First evaluation of DDT (dichlorodiphenyltrichloroethane) residues and other Persistence Organic Pollutants in soils of Rwanda: Nyabarongo urban versus rural wetlands

This study was the first to evaluate the occurrence, residue levels, spatial distribution and sources of DDT and other Persistence Organic Pollutants (POPs), which can be found in the Nyabarongo lower catchment (NLC) in Rwanda. These include Aldrin, Dieldrin, Endosulfan, Endrin, Hexachlorocyclohexane (HCH), Heptachlor, Heptachlorepoxide, Hexachlorobenzene (HCB), Isodrin, Methoxychlor, Mirex and Polychlorinated biphenyls (PCBs). A total of 108 soil samples were collected in the wetland area, both extracted and eluted with cyclohexane and analysed by GC-MS. The results indicated that DDT isomers and degradation products were major POPs and were detected in 44 samples (40%). Their detection frequency followed the order of 4,4'-DDE > 4,4' -DDT > 4,4' -DDD > 2,4' -DDT > 2,4' -DDD and 2,4' -DDE. Residues varied from non-detected (nd) to 120 μg kg^-1 dry weight (dw), with a mean value of 3.93 μg kg^-1 dw and a high variation (SD = 10.17 μg kg^-1 dw). The degradation ratios confirmed both the historical and recent application of DDT and Dieldrin (0.53-18 μg kg^-1 dw). Other detected POPs included PCBs in Kigali city which ranged from 0.1 to 0.21 μg kg^-1 dw, confirming that the old contamination drifted from electric transformers. Aldrin (0.38-0.59 μg kg^-1 dw); Heptachlor (0.14-0.19 μg kg^-1 dw) residues probably reached the catchment through rain-washout. This study confirms that even though Rwanda banned the use of DDT and other POPs including pesticides (Aldrine, Chlordane, DDT, Dieldrine, Endrine, Heptachlor, Hexachlorobenzene, Mirex, and Toxaphene); Industrial products (Hexachlorobenzene and Polychlorobiphenyl PCBS) and unintentional sub-products, since 2002, some of above products are still used in random areas (e.g: DDT, Dieldrin). The highest residues were detected close to Lake Muhazi and areas surrounding Kigali city. This study recommends full evaluation of human health and ecological risks from exposure to DDT. Additionally, the National Implementation Plan (NIP) for the Stockholm Convention to eliminate POPs should be reinforcement through strengthening the market control and educational programs.

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.

The correlation study between fatty acids and organochlorine pesticides or δ15N values in fish tissues from Dongting Lake, China

Organochlorine pesticides (OCPs) are ubiquitous environmental contaminants, while their correlations with δ¹⁵N values and fatty acids (FAs) in fish tissues remain largely unexplored. In the present study, six species of fish for daily consumption were collected from Dongting Lake, and they were dissected to tissue samples to analyze the δ¹⁵N values, FAs and OCPs. The results showed that the δ¹⁵N values of fish were ranked in the same order in different fish tissues. The polyunsaturated fatty acids (PUFAs) had a different distribution pattern in fish tissues, while the saturated fatty acid (SFAs) and monounsaturated fatty acids (MUFAs) were not. The composition of HCHs in fish tissues exhibited a tissue-specific and species-specific manner, while such pattern was not detected for DDTs. The correlation analysis indicated that the ratio of DHA/EPA was increased with the increase of δ¹⁵N value in the muscle, liver, gill, skin and intestine, indicating the substance flow in freshwater ecosystem. In addition, there were significant positive correlations between the concentrations of some PUFAs and OCPs in the muscle, suggesting that people should pay attention to co-intake of OCPs when they supplemented the PUFAs needed by the human body through fish.

Determination of Heavy Metal Concentrations and Their Potential Sources in Selected Plants: Xanthium strumarium L. (Asteraceae), Ficus exasperata Vahl (Moraceae), Persicaria attenuata (R.Br) Sojak (Polygonaceae), and Kanahia laniflora (Forssk.) R.Br. (Asclepiadaceae) from Awash River Basin, Ethiopia

The objective of this study was to determine the concentrations, potential sources and evaluate the risks of heavy metals in selected plants from Awash River Basin, Ethiopia. A total of 57 samples were analyzed from four different plant species. Microwave-assisted digestion was applied to digest the samples and the concentration of nine elements namely: Al, Cr, Ni, Cu, Zn, As, Cd, Hg, and Pb were analyzed using Inductively Coupled Plasma-Mass Spectrometry (ICP- MS) (Thermos X SERIES2). The obtained data were analyzed using Statistical Package for Social Sciences (SPSS IBM version 20). The recorded mean concentration of heavy metals in the plants were 1.934, 0.023, 0.023, 0.045, 0.129, ND, 0.025, ND, and 0.009 mg/kg in Xanthium strumarium L.(Asteraceae); 0.834, 0.036, 0.024, 0.021, 0.090, ND, 0.002, 0.001, and 0.006 mg/kg in Ficus exasperata Vahl (Moraceae); 1.603, 0.018, 0.019, 0.025, 0.133, 0.005, 0.006, 0.002, and 0.012 mg/kg in Persicaria attenuata (R.Br) Sojak (Polygonaceae); and 0.557, 0.010, 0.010, 0.024, 0.098, ND, 0.012, 0.020, and 0.004 mg/kg in Kanahia laniflora (Forssk.) R.Br. (Asclepiadaceae) for Al, Cr, Ni, Cu, Zn, As, Cd, Hg, and Pb, respectively. Pearson's correlation analysis indicated that there was a strong positive correlation between Al-Ni (r = 0.927^**) and Zn-Cu (r = 0.764^**) at α = 0.01 significant level. Principal component analysis (PCA) indicated that the sources of heavy metals in the plants were associated with anthropogenic factors. The mean concentrations of all elements except Cd in Xanthium strumarium L. (Asteraceae) and Pb in Ficus exasperata Vahl (Moraceae) were below the permissible limit of FAO/WHO (2001 /2005).

Baseline bio-accumulation concentrations and resulting oxidative stress in Synodontis zambezensis after an acute laboratory exposure to 4,4'-DDT

The use of 1,1'-(2,2,2-Trichloro-1,1-ethanediyl)bis(4-chlorobenzene) (DDT) as a pesticide for the control of insects vectors responsible for the spread of many life threatening diseases was officially banned in 1972 by the United States Environmental Protection Agency (USEPA). It was banned throughout the world, in most developed countries, because of the toxic effects it causes in wildlife, including birds and fish. However, DDT is still used in approximately 43 African countries, including South Africa, to control the spread of malaria. The lipophilic nature of DDT and therefore its persistence in the environment makes it extremely important for laboratory based studies to be conducted in an effort to evaluate the accumulation potential and possible physiological effects of DDT in aquatic organisms under controlled conditions. The aim of this study was to establish baseline bioaccumulation concentrations within Synodontis zambezensis following an acute exposure to 4,4'-DDT. The three metabolites analysed were 4,4'-DDE, 4,4'-DDD and 4,4'-DDT. None of the 2,4'-isomers were analysed in this study since the acute exposure used a solution of 98.7% pure 4,4'-DDT (Sigma-Aldrich PESTANAL®, Analytical Standard, CAS-No 50-29-3, Batch number SZBE057XV) and not a mixture of 4,4'-DDT and 2,4'-DDT as found in technical grade DDT. Soxhlet extraction of tissue samples and liquid/liquid extraction of water samples followed by analysis through Gas-chromatography mass-spectrophotometry was completed. Mean 4,4'-DDE, 4,4'-DDD and 4,4'-DDT concentrations ranged from 15.34 ng/g to 45.34 ng/g, 28.16 ng/g to 63.25 ng/g and 28.64 ng/g to 96.21 ng/g respectively. All of the accumulated concentrations fell within environmentally relevant concentrations with no input through the food web. The accumulated concentrations of 4,4'-DDT and its three metabolites resulted in oxidative stress responses within the gills and the liver tissue of S. zambezensis. Significant differences (p ≤ .05) were observed between malondialdehyde (MDA) and reduced glutathione (GSH) within the liver and in superoxide dismutase (SOD), catalase (CAT) and reduced glutathione (GSH) in the gills.

A review of environmental and health effects of organochlorine pesticide residues in Africa

Organochlorine pesticides (OCPs) are generally categorized as chlorinated cyclodienes, chlorodiphenylethanes, chlorinated benzenes and cyclohexanes. The presence of OCP residues in foodstuffs, water, soil, sediments, blood serum and air has generated a surge of global interest. This is due to their severe environmental and health ill-effects. OCPs are characteristically described as persistent and bio-accumulating substances prone to long-range transportation. The aim of this present study is to assess the environmental and health risks associated with OCP residues. Published works on OCPs in surface water, sediments and fish samples were reviewed. Possible non-carcinogenic (Hazard Quotient, HQ and Hazard Index, HI) and carcinogenic (Cancer Risk, CR) health effects of OCPs were assessed in fish samples. High concentrations of OCP residues were determined in environmental samples from African countries. The non-carcinogenic health assessment of OCPs in most fish samples from Nigeria revealed HI values greater than 1.0 establishing their adverse effects. The CR data of OCPs in fish samples also showed values higher than the permissible standard of 1.0 × 10^-4 indicating possible development of cancer through fish consumption.

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.

Determination of Occurrences, Distribution, Health Impacts of Organochlorine Pesticides in Soils of Central China

Organochlorine pesticides are groups of chemicals applied to prevent pest and insect infestation. This study was aimed at investigating the concentration, potential sources, cancer risk and ecological toxicity of organochlorine pesticides (OCPs) in Huangpi district, Wuhan, China. Eight OCPs in soil samples collected from four land-use types at depths of 0–10 and 10–20 cm were examined. Sample extraction was carried out by solid phase matrix extraction method and analyzed using Agilent gas chromatograph 7890B equipped with electron capture detectors (ECD). The total concentration of OCPs ranged from 0.00–32.7 ng g⁻¹ in the surface and 0.01–100.45 ng g⁻¹ in the subsurface soil layer. Beta hexachlorocyclohexanes (β-HCH) with 2.20 and 7.71 ng g⁻¹ in the surface and subsurface soil layers, respectively, was the dominant compound. The mean concentrations of OCPs in all samples were less than the threshold values for hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethane (DDTs) in China soil. Concentration of OCPs in the four land-use types were in the order of: paddy field > barren land > farmland > plastic greenhouse. Results of composition analysis revealed recent application of lindane as a major and historical use of new technical HCHs as a minor source of HCHs. On the other hand, application of new technical p,p’-DDT is the main source of DDTs in the study area. The estimated lifetime average daily dose, incremental lifetime cancer risks and hazard quotient values revealed that there is less likelihood of carcinogenic and noncarcinogenic health risks on the local residents.

Evaluating polar pesticide pollution with a combined approach: a survey of agricultural practices and POCIS passive samplers in a Tunisian lagoon watershed

A study of pesticides in the Bizerte lagoon watershed on the Mediterranean coast of Tunisia showed that herbicides and fungicides are the most commonly used compounds. A survey was made of selected farmers. Pesticide contamination was monitored in the water column and sediments at four selected sampling sites (lagoon (A) and in three oueds-Chegui (B), Garaa (C), and Tinja (D)). Polar organic chemical integrative samplers (POCIS) were used to assess pesticide contamination. Thirty-two pesticides were investigated; the total concentration of active ingredients ranged from 35.9 ng L^-1 in Tinja oued to 1246 ng L^-1 in Chegui oued. In the lagoon, the total concentration of pesticides was 67.7 ng L^-1. In the sediments, the highest concentration was measured in Chegui oued in the spring (31 ng g^-1 dw). The main compounds found in the analyzed sediments were prosulfocarb and tebuconazole molecules.

Levels of organochlorine pesticide residues in fresh water fishes of three bird sanctuaries in Tamil Nadu, India

Organochlorine pesticide (OCP) residues were determined in nine species of fresh water fishes caught from three bird sanctuaries in Tamil Nadu, India. A total of 302 fishes were analyzed for various types of OCPS. OCPs, namely hexachlorocyclohexane (HCH), dichloro diphenyl trichloroethane (DDT), heptachlor epoxide, endosulfan, and dieldrin were detected among various species of fishes. Among the various OCPs analyzed, HCH was the most frequently detected pesticides. Among the HCH isomers, β HCH contributed more than 50% to the Σ HCH. p,p' DDT, the metabolites of DDT, had high percentage of occurrence. Among the cyclodiene insecticide residues, endosulfan was detected in more than 60% of the fishes. Varying levels of ΣOCPs (a sum of Σ HCH, Σ DDT, Σ endosulfan, heptachlor epoxide, and dieldrin) were detected in various fish species, although it was not significant (p > 0.05). However, significant variations in OCPs were observed among location and between seasons (p < 0.05). However, continuous monitoring is recommended to facilitate the early identification of risks not only to the fishes, but also to fish-eating birds breeding in these sanctuaries.

Investigation of mRNA expression changes associated with field exposure to DDTs in chickens from KwaZulu-Natal, South Africa

The objective of this study was to identify potential mRNA expression changes in chicken livers associated with environmental exposure to dichloro-diphenyl-trichloroethane (DDT) and its metabolites (DDTs). In particular, we focused on genes relating to the immune system and metabolism. We analyzed liver samples from free-ranging chickens in KwaZulu-Natal, South Africa, for contamination by DDTs. This area predominantly uses DDT in its malaria control program, and homes are sprayed annually with the pesticide. Genes relating to the immune system and metabolism were selected as potential genetic biomarkers that could be linked to higher contamination with DDTs. RT-qPCR analysis on 39 samples showed strong correlations between DDTs contamination and mRNA expression for the following genes: AvBD1, AvBD2, AvBD6 and AvBD7 (down-regulated), and CYP17, ELOVL2 and SQLE (up-regulated). This study shows for the first time interesting and significant correlations between genetic material collected from environmentally-exposed chickens and mRNA expression of several genes involved in immunity and metabolism. These findings show the usefulness of analysis on field samples from a region with high levels of environmental contamination in detecting potential biomarkers of exposure. In particular, we observed clear effects from DDT contamination on mRNA expression of genes involved in immune suppression, endocrine-disrupting effects, and lipid dysregulation. These results are of interest in guiding future studies to further elucidate the pathways involved in and clinical importance of toxicity associated with DDT exposure from contaminated environments, to ascertain the health risk to livestock and any subsequent risks to food security for people.

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.

Impacts of nutrients and pesticides from small- and large-scale agriculture on the water quality of Lake Ziway, Ethiopia

The area around Lake Ziway in Ethiopia is going through a major agricultural transformation with both small-scale farmers and large horticultural companies using pesticides and fertilisers at an increased rate. To be able to understand how this influences the water quality of Lake Ziway, water quality data was gathered to study the dynamics of pesticide concentrations and physicochemical parameters for the years from 2009 to 2015. Results indicate that for some physicochemical parameters, including pH, potassium and iron, over 50 % of the values were above the maximum permissible limit of the Ethiopian standard for drinking water. The fungicide spiroxamine poses a high chronic risk when the water is used for drinking water, while the estimated intake of diazinon was approximately 50 % of the acceptable daily intake. Higher-tier risk assessment indicated that the fungicide spiroxamine poses a high acute risk to aquatic organisms, while possible acute risks were indicated for the insecticides deltamethrin and endosulfan. Longer-term monitoring needs to be established to show the water quality changes across time and space, and the current study can be used as a baseline measurement for further research in the area as well as an example for other surface water systems in Ethiopia and Africa.

Persistent organochlorine pesticides in aquatic environments and fishes in Taiwan and their risk assessment

Organochlorine pesticides (OCPs) are ubiquitous contaminants with high bioaccumulation and persistence in the environment; they can have adverse effects in humans and animals. This study examined residual concentrations in water, sediments, and fishes as well as the association between the health risks of OCPs and fish consumption in the Taiwanese population. Various water and sediment samples from Taiwanese aquaculture and fish samples from different sources were collected and analyzed through gas chromatography tandem mass spectrometry to determine the concentrations of 20 OCPs, namely, aldrin; cis-chlordane; trans-chlordane; dieldrin; endrin; alpha-endosulfan; beta-endosulfan; heptachlor; hexachlorobenzene; alpha-hexachlorocyclohexane; beta-hexachlorocyclohexane; lindane; mirex; pentachlorobenzene; o,p'-dichlorodiphenyltrichloroethane (DDT); p,p'-DDT; and DDT metabolites (o,p'-dichlorodiphenyldichloroethane [DDD]; p,p'-DDD; o,p'-dichlorodiphenyldichloroethylene [DDE]; and p,p'-DDE). None of the analyzed samples was positive for OCP contamination, suggesting no new input pollution from the land through washing into Taiwanese aquaculture environments. However, OCP residues were detected in fishes caught along the coast, namely, skipjack tuna and bigeye barracuda, and in imported fishes, such as codfish and salmon. DDT was the predominant pesticide. The contamination pattern of persistent organic pollutants was as follows: dieldrin > cis-chlordane > hexachlorobenzene, with average concentrations ranging from 0.09 to 2.74 ng/g. The risk was assessed in terms of the estimated daily intake (EDI) for potential adverse indices; the EDI of OCP residues was lower than 1% of the acceptable daily intake established by the Food and Agriculture Organization of the United Nations and World Health Organization. The assessed risk was negligible and considered to be at a safe level, suggesting no association between fish consumption and risks to human health in Taiwan. However, a continuous monitoring program for OCP residues in fishes is necessary to further assess the possible effects on human health.

Dietary exposure to HCH and DDT congeners and their associated cancer risk based on Pakistani food consumption

Dietary exposure to organochlorine pesticides such as hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) congeners was assessed using diet study approach, and for this purpose, different food items were collected in August 2014. The levels of ∑(HCHs + DDTs) in different food groups were ranged from 2.57 to 206 ng g^-1, ww, with contamination order of fish > poultry > milk > vegetables > cereals > flour > fruits. In the present study, the ratios of β-HCH/∑HCH (0.19-0.40) were < 0.5, where the ratios of (DDE + DDD)/∑DDT (0.48-6.70 with mean value of 0.61) were > 0.5 demonstrated the recent and past inputs of HCH and DDT, respectively. The major contributing groups (6.3-70.3%) to total dietary intake of HCHs and DDTs were animal origin (fish, poultry, and milk), while the less contributing food groups (2-4.5%) were vegetarian origin (vegetables, cereals, flour, and fruits). Cancer risk was estimated for HCHs and DDTs ingested via local foodstuffs. On the basis of both average and high end (95th percentile) exposure levels, the HRs for HCHs and DDTs were found greater than one (safety limit), indicating a potential cancer risk for Pakistani people from life-time consumption of contaminated food items selected in this study. The congener-specific cancer risk was found in order of α-HCH > β-HCH > ∑DDT > γ-HCH > p,p'-DDE > p,p'-DDT. Graphical abstract ᅟ.

Domestic Cooking of Muscle Foods: Impact on Composition of Nutrients and Contaminants

Meat and fish are muscle foods rich in valuable nutrients, such as high-quality proteins, vitamins, and minerals, and, in the case of fish, also unsaturated fatty acids. The escalation of meat and fish production has increased the occurrence of pesticide and antibiotic residues, as result of pest control on feed crops, and antibiotics used to fight infections in animals. Meat and fish are usually cooked to enrich taste, soften texture, increase safety, and improve nutrient digestibility. However, the impact of cooking on nutritional properties and formation of deleterious compounds must be understood. This review summarizes studies, published in the last decade, that have focused on how domestic cooking affects: (i) composition of nutrients (protein, fatty acids, vitamins, and minerals); (ii) antibiotic and pesticide residue contents; and (iii) the formation of cooking-induced contaminants (heterocyclic aromatic amines, polycyclic aromatic hydrocarbons, and thermal degradation products of antibiotics and pesticides). Cooking affects the nutritional composition of meat and fish; frying is the cooking method that causes the greatest impact. Cooking may reduce the pesticide and antibiotic residues present in contaminated raw meat and fish; however, it may result in the formation of degradation products of unknown identity and toxicity. Control of cooking time and temperature, use of antioxidant-rich marinades, and avoiding the dripping of fat during charcoal grilling can reduce the formation of cooking-induced contaminants.

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.

Assessment of DDT contamination in house rat as a possible bioindicator in DDT-sprayed areas from Ethiopia and South Africa

Ethiopia and South Africa are among the few countries to still implement indoor residual spraying with dichloro-diphenyl-trichloroethane (DDT) for malaria vector control. In this study, we investigated the levels and ecological risks of DDT and its metabolites in liver tissues of house rat, as a sentinel animal, for providing an early warning system for public health and wildlife intervention from Ethiopia and South Africa. The results showed that ΣDDT concentration ranged from 127 to 9155 μg/kg wet weight, and the distribution order of DDT and its metabolites in the analyzed liver samples was p,p'-DDD > p,p'-DDE >> p,p'-DDT, o,p'-DDT, and o,p'-DDD. The risk assessment indicated a potential adverse impact on humans, especially for pregnant women and children, because they spend majority of their time in a DDT-sprayed house. The ecological assessment also showed a concern for birds of prey and amphibians like frogs. This study is the first report on DDT contamination in liver tissues of house rats from Ethiopia and South Africa, and henceforth, the data will serve as a reference data for future studies.

Organochlorine pesticide contamination of foods in Africa: incidence and public health significance

Organochlorine pesticides (OCPs) have been used worldwide, particularly in Africa, for several decades. Although many are banned, several African countries still use OCPs especially for the prevention and control of malaria. OCPs are characterized by their bio-accumulation in the environment, especially in the food chain, where they find their way into the human body. Despite no clear epidemiological studies confirming hazardous effects of these chemicals on human health, many studies have reported positive associations between the use of OCPs and neurological and reproductive disorders, and cancer risk. There is a clear gap in published reports on OCPs in Africa and their potential health hazards. Thus, the aim of this review is to summarize the incidence of OCP contamination in various foods in Africa, to demonstrate the potential transmission of these chemicals to people and to discuss their possible health hazards.

Multiclass pesticide residue analysis in fish muscle and liver on one-step extraction-cleanup strategy coupled with liquid chromatography tandem mass spectrometry

The analysis of pesticide residues in fish samples is challenging due to the low concentrations and large number of analytes that need to be monitored and quantified in a complex matrix. This is the first report providing a novel one-step extraction-cleanup strategy for simultaneous analysis of over 340 pesticides in a fatty fish and liver matrix, coupled with liquid-chromatography tandem mass spectrometry. The samples of fish muscle and liver were prepared according to the modified QuEChERS (quick, easy, cheap, effective, rugged and safe) procedure, wherein the extraction and cleanup protocol were integrated into one step. Among the tested cleanup dispersive solid phase extraction sorbents (C18, primary-secondary amine, Z-Sep), chitin yielded the best results. Spike-in experiments were carried out at three different spiking levels in fish and liver to determine the recovery, precision and limits of detection of the method as well as the matrix effect. The method's detection limits ranged from 0.05 to 1.2μgkg^-1, while recoveries of most pesticides were in the range of 70-120% with associated precision - relative standard deviations below 20%. A linear relationship was observed within the range of 0.005-1mgkg^-1, and the correlation coefficient was R²>0.997. Expanded measurement uncertainty was estimated to be between 7% and 52%, on average. Matrix effects were evaluated and were not significant for the vast majority of pesticides. The validated method was employed in the analysis of 54 real fish and liver samples in which 10 different pesticides with concentrations ranging from 0.005 to 0.047mgkg^-1 were detected.

DDTs and other organochlorine pesticides in tissues of four bird species from the Rift Valley region, Ethiopia

Despite the presence of a wide variety and number of birds, there is exceedingly little data on organochlorine pesticide (OCP) residues in birds inhabiting in Africa. In the present study, concentrations of dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes, drins, cyclodienes, and hexachlorobenzene were measured in liver, kidney, heart and brain of 4 bird species from the Rift Valley region, Ethiopia. Indoor residual spraying of DDT for malaria vector control, and indiscriminate and illegal use of pesticides underline the relevance of this study. Levels of ΣOCPs ranged from 1.87 to 4586ng/g wet weight, and the scavenger bird species Leptoptilos crumeniferus had the highest level in liver. In all tissues, contamination profiles of OCPs within the species were similar, with DDTs≫other OCPs. Among the DDTs, p,p'-DDE was the most abundant compound and had significantly a higher burden in all tissues. The risk characterization demonstrated potential risks to the studied birds associated with DDE exposure. Maximum hepatic levels of p,p'-DDE exceeded the levels reported to trigger adverse effects. The detection of p,p'-DDT in all bird tissues suggests the release of fresh DDT to the environment. This is the first study to assay OCPs in different tissues of birds from the Ethiopian Rift Valley region, and henceforth the data will serve as a reference data for future studies.

Tissue distribution of organochlorine pesticides in largemouth bass (Micropterus salmoides) from laboratory exposure and a contaminated lake

Tissue concentrations of persistent organochlorine pesticides in laboratory-exposed largemouth bass (Micropterus salmoides) and in bass collected from Lake Apopka, FL were determined by both total mass and lipid normalized mass to better understand the bioaccumulation pathways of contaminants. In the laboratory study, male bass were orally administered a single dose of a mixture of two pesticides (p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and dieldrin) and then fed uncontaminated food for 28 days. Gastrointestinal tract, liver, brain, gonad, kidney, spleen, and muscle were collected for chemical analysis. Different profiles were observed by total contaminant mass in tissues compared to lipid normalized mass. On a lipid normalized basis, p,p'-DDE was highest in the gastrointestinal tract followed by the liver, gonad, spleen, muscle, kidney and then brain. Dieldrin, on the other hand, was highest in the gastrointestinal tract and spleen and then followed by the gonad, muscle, liver, kidney, and brain. Distribution of the chemicals among the organs differed by their log KOW values and generally followed the blood flow path after the gastrointestinal tract. The low contaminant levels found in kidney and brain suggest insufficient time for equilibration into these tissues, especially into the brain where the blood-brain barrier may be slow to traverse. In Lake Apopka fish, dichlorodiphenyltrichloroethanes (DDXs, sum of p,p'-DDE, p,p'-DDD, and p,p'-DDT), Drins (sum of aldrin, dieldrin, and endrin), and hexachlorocyclohexanes (HCHs) were found. For DDXs, the lipid normalized concentrations in each tissue were about the same, as predicted from theory. For Drins and HCHs, the lipid normalized concentrations were similar for kidney, spleen, brain, gonad and muscle, but much lower in the gastrointestinal tract and liver, probably because of metabolism occurring in those tissues.

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.