NRU :: Browsing by Author "Wasswa, John"

Browsing by Author "Wasswa, John"

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Agricultural expansion as risk to endangered wildlife: Pesticide exposure in wild chimpanzees and baboons displaying facial dysplasia
(Science of the Total Environment, 2017) Krief, Sabrina; Berny, Philippe; Gumisiriza, Francis; Gross, Régine; Demeneix, Barbara; Baptiste Fini, Jean; Chapman, Colin A.; Chapman, Lauren J.; Seguya, Andrew; Wasswa, John
Prenatal exposure to environmental endocrine disruptors can affect development and induce irreversible abnormalities in both humans and wildlife. The northern part of Kibale National Park, a mid-altitude rainforest in western Uganda, is largely surrounded by industrial tea plantations and wildlife using this area (Sebitoli) must cope with proximity to human populations and their activities. The chimpanzees and baboons in this area raid crops (primarily maize) in neighboring gardens. Sixteen young individuals of the 66 chimpanzeesmonitored (25%) exhibit abnormalities including reduced nostrils, cleft lip, limb deformities, reproductive problems and hypopigmentation. Each pathology could have a congenital component, potentially exacerbated by environmental factors. In addition, at least six of 35 photographed baboons from a Sebitoli troop (17%) have similar severe nasal deformities. Our inquiries in villages and tea factories near Sebitoli revealed use of eight pesticides (glyphosate, cypermethrin, profenofos, mancozeb, metalaxyl, dimethoate, chlorpyrifos and 2,4-D amine). Chemical analysis of samples collected from 2014 to 2016 showed that mean levels of pesticides in fresh maize stems and seeds, soils, and river sediments in the vicinity of the chimpanzee territory exceed recommended limits. Notably, excess levels were found for total DDT and its metabolite pp′-DDE and for chlorpyrifos in fresh maize seeds and in fish from Sebitoli. Imidacloprid was detected in coated maize seeds planted at the edge the forest and in fish samples from the Sebitoli area, while no pesticides were detected in fish from central park areas. Since some of these pesticides are thyroid hormone disruptors, we postulate that excessive pesticide use in the Sebitoli area may contribute to facial dysplasia in chimpanzees and baboons through this endocrine pathway. Chimpanzees are considered as endangered by IUCN and besides their intrinsic value and status as closely related to humans, they have major economic value in Uganda via ecotourism. Identifying and limiting potential threats to their survival such be a conservation priority.
Analysis for Organochlorine Pesticide Residues in Honey from Kabale District, South-Western Uganda
(American Journal of Analytical Chemistry, 2019) Ntirushize, Benon; Wasswa, John; Ntambi, Emmanuel; Adaku, Christopher
This study was motivated by the reported accumulation of Organochlorine Pesticides (OCPs) residues in the various environmental matrices within Uganda, resulting from their use in agriculture and health sectors. This raised a concern of the likelihood of the accumulation of the OCPs residues in the honey produced within the country which would affect its purity as well as quality and consequently its competition on the world market. Sixty representative honey samples were collected from selected local beekeepers from four sampling stations in Muko sub-county, Kabale, and extracted for OCPs using a solid-phase procedure followed by a florisil column packed clean-up method and Gas Chromatography-Electron Capture Detector (GC-ECD) analysis. Confirmation of the selected samples was done using an Agilent (6890N, USA) gas chromatograph combined with a mass spectrometer. Recoveries of spiked samples ranged from 71% to 96%, except for pp-DDE (54%), with relative standard deviations from 2% to 14% in terms of repeatability, and from 4% to 17% in terms of reproducibility. Limits of quantification were from 0.003 to 0.1 mg∙kg−1. Endosulfan sulfate was the most frequently detected in 38% of the samples, followed by HexaChloroBenzene (Lindane) in 21% of the samples. Residues of DDT and their metabolites were detected in 17% of the samples. Mean concentrations of the pesticide residues detected range from ND (not detected) to 1.53 μg/Kg. The acceptable Maximum residual limits (MLRs) are 200 - 300 μg∙kg−1 fresh weight for dieldrin, 500 μg∙kg−1 for DDT and break down products, and 50 μg∙kg−1 wet weight for Lindane (WHO/FAO 2011). Results indicate that the levels of OCP residues detected in honey from the country’s South Western District of Kabale were within the acceptable limits, and hence this honey was safe for human consumption.
Assessment of Seasonal Variation in Water Quality in River Rwizi Using Multivariate Statistical Techniques, Mbarara Municipality, Uganda
(Journal of Water Resource and Protection, 2017) Ojok, Walter; Wasswa, John; Ntambi, Emmanuel
Assessment of seasonal variations in surface water quality characteristics is an essential aspect for evaluating water pollution due to both natural and anthropogenic influences on water resources. In this study, temporal variations of water quality in river Rwizi section within Mbarara municipality, Uganda, were assessed using multivariate statistical methods. This river section is a major source of water for the inhabitants of Mbarara municipality. Water samples from five sites were analyzed for physicochemical parameters such as pH, EC, turbidity, temperature, TSS, TDS, alkalinity, salinity, colour, NH3-N, 24 SO − , total hardness, BOD, COD, DO, Ca, Mg, Fe, and Mn. About 50% of sites recorded colour above 800 Pt Co, 60% of sites recorded turbidity above maximum permissible limit of 100 mg/l, attributable to erosion and mineral matter. pH for dry season ranged between 6.5 and 8.5 whereas for rainy season was below 6.0. All study sites recorded total Fe above 0.3 mg/l and Mn below 0.5 mg/l, attributable to chemical weathering of host rock materials as well as from industrial effluent. About 60% of sites recorded COD above 100 mg/l, 40% and 80% of study sites showed BOD above 50 mg/l in dry and rainy seasons respectively. Hardness ranged between 50 and 100 mg/l indicating that the water is moderately soft. Colour, turbidity, alkalinity, TSS, TDS, salinity, pH, hardness, Fe, Mn, NH3-N, BOD, COD, and DO were higher in rainy season, as a result of erosion, discharge of domestic and industrial waste. Mg, Ca, and 2 4 SO − were higher during dry season due to high evaporation of water from the river. PCA/FA determined that 81.2% of the total variance was explained by the first factor for the dry season and 69.2% for rain season. These results revealed that water pollution resulted primarily from domestic waste water, agricultural runoff and industrial effluents.
Characterization and Hydrocarbon Identification of Liquid Fuel from Mixed Waste Plastics at Different Heating Time Intervals
(International Journal of Scientific & Engineering Research, 2016) Kigozi, Moses; Wasswa, John; Ntale, Muhammad; Nkedi-Kizza, Peter
Mixed waste plastics which included High Density Polyethylene ((HDPE), Low Density Polyethyline (LDPE),Polystyrene (PS), Polypropylene (PP), Polyethylene Terephthalate (PET) were investigated for production, characterization and hydrocarbon identification of fuel obtained from the plastics by catalytic pyrolysis. Silica-alumina was used as the catalyst. The mixed waste plastics were heatedfor one hour and two hours of contact time. The operation temperatures ranged between 250oC to 370oC giving a yellowish liquid after condensing the vapors with a chiller at 5oC. The reactor was connected to a fractionating column of one meter long and then to the condenser. The production ranged between 58 to 73% liquid, 18 to 34% cake and the rest was estimated as gas. The samples were investigated with different parameters based on diesel standards due to the wide range of hydrocarbon content. The parameters showed acceptable average ranges; cloud point 4oC, flash point 79.4 oC, kinematic viscosity 2.18 mm2/s, sulfated ash 4.7x10-5%, copper strip corrosion 1a, cetane number 63, acid number 72.9 μg and densities of 0.785 g/cm3. The identification of the hydrocarbons showed that the fuel falls into four classes of fuel which include diesel, aviation, naphtha and oil due to the range of hydrocarbons from C8 to C28 when analyzed with GC/MS and named from GC library
Concentrations and sources apportionment of polycyclic aromatic hydrocarbons in 1 sediments from the 2 Uganda side of Lake Victoria
(Environmental Science: Processes & Impacts, 2017) Kerebba, Nasifu; Ssebugere, Patrick; Kwetegyeka, Justus; Arinaitwe, Kenneth; Wasswa, John
This paper presents the levels and possible sources of selected polycyclic aromatic hydrocarbons (PAHs) in surface sediments from Napoleon Gulf and Murchison Bay of Lake Victoria. Sediment samples were extracted and cleaned up for PAHs using UNEP, 1992 and EPA method 3630C protocols, respectively. The analysis of sample extracts was done using a gas chromatograph coupled to a mass spectrometer. Fifteen congeners, mostly the high molecular weight PAHs (HPAHs) (4-6 rings) were detected. Total (Σ) concentrations varied from 44.2 to 80.2 ng g-1 dry weight (d.w.) at Napoleon Gulf while those at the Murchison Bay ranged from 17.0 to 55.0 ng g-1 d.w. Statistical analysis showed no significant difference in the concentrations of PAHs among sites (p <0.05, ANOVA). It was noted that the concentrations for most sampling sites were far below the lowest effect levels based on the Sediment Quality Guidelines except for one station at the Napoleon Gulf. Principal component analysis and diagonistic ratios indicated that PAHs of combustion and petroleum origin were dominant and brought mainly by atmospheric deposition.
Contamination by heavy metals in silver fish (Rastreneobola argentea) caught from Lakes Kyoga and Victoria, Uganda
(International Journal of Environmental Studies, 2010) Mbabazi, Jolocam; Wasswa, John
Little information exists on heavy metal contamination in silver fish (Rastreneobola argentea) caught from Lake Victoria. A large number of Ugandans consume the species. Sun-dried silver fish were collected from 10 landing sites on Lake Victoria, and from five control sites along Lake Kyoga. The finely ground fish was digested with analytical reagent grade nitric acid. Analyses were performed by atomic absorption spectrophotometry. The specimens were found to contain significantly higher levels (p ≤ 0.05) of zinc, Zn (86.1%), copper, Cu (99.1%), cadmium, Cd (99.3%) and lead, Pb (94.6%) compared with those from the control sites. The fish contamination was attributed to discharge into Lake Victoria of untreated industrial and anthropogenic effluent. Although mean Zn, Cu and Pb concentrations were still below, those of Cd were higher than the maximum permissible levels recommended by the World Health Organization (WHO). Overconsumption of the silver fish could pose Cd-related health risks.
Contamination by heavy metals in silver fish (Rastreneobola argentea) caught from Lakes Kyoga and Victoria, Uganda
(International Journal of Environmental Studies, 2010-08-25) Mbabazi , Jolocam; Wasswa, John
Little information exists on heavy metal contamination in silver fish (Rastreneobola argentea) caught from Lake Victoria. A large number of Ugandans consume the species. Sun‐dried silver fish were collected from 10 landing sites on Lake Victoria, and from five control sites along Lake Kyoga. The finely ground fish was digested with analytical reagent grade nitric acid. Analyses were performed by atomic absorption spectrophotometry. The specimens were found to contain significantly higher levels (p ≤ 0.05) of zinc, Zn (86.1%), copper, Cu (99.1%), cadmium, Cd (99.3%) and lead, Pb (94.6%) compared with those from the control sites. The fish contamination was attributed to discharge into Lake Victoria of untreated industrial and anthropogenic effluent. Although mean Zn, Cu and Pb concentrations were still below, those of Cd were higher than the maximum permissible levels recommended by the World Health Organization (WHO). Overconsumption of the silver fish could pose Cd‐related health risks.
Equilibrium and Kinetic Studies of the Stannate(Iv)-Polyol Reaction
(Chemical Society of Ethiopia, 2010) Mbabazi, Jolocam; Wasswa, John; Ntale, Muhammad
The stability constants of 1:1 stannate(IV)-polyol complexes in aqueous media have been determined using a conductimetric technique. The constants are fairly large, and lie in the range 5.3-123.0 for the ten ligands investigated. These values were subsequently used in conjunction with kinetic data to postulate a mechanism involving the species Sn(OH)5 as intermediate in the formation of the chelates. The stannate(IV)- polyol reaction, though taking place at higher pH values, is acid-catalysed and follows first-order kinetics in the oxyanion, but at large ligand-oxyanion mole ratios the reaction exhibits zero-order rate dependence on the polyol. These features taken together are consistent with a unimolecular nucleophilic substitution on the oxyanion.
Essential oil and composition of Tagetes minuta from Uganda.Larvicidal activity on Anopheles gambiae
(Industrial Crops and Products, 2014) Mugumya Kyarimpa, Christine; Böhmdorfer, Stefan; Wasswa, John; Kiremire, Benard T.; Omolo Ndiege, Isaiah; Kabasa, John David
As the search for alternatives to synthetic medicine goes on, several plants have been identified as possible natural insecticides, among which is Tagetes minuta. In this study essential oil from T. minuta was obtained by hydrodistillation. It was tested against the 3rd and 4th instar Anopheles gambiae to determine the larvicidal activity. Six different concentrations of this essential oil were studied and compared with thatof methyl parathion, a synthetic organophosphorus insecticide for 24 h. GC–MS results indicated the presence trans-ocimene 15.90%, I-verbenone 15% of limonene 8.02%, tegetone 3.56%, and 2-pinen-4-one7.84% as the major compounds in the essential oil. The LC50 was 2.9 mg/l while the LC90 was 3.29 mg/l after 2 h of exposure. After 6 h of exposure, the LC50 and LC90 were 2.31 mg/l and 2.68 mg/l, respectively,while after 12 h, it was 1.49 and 1.82 mg/l, respectively. After 24 h, the LC50 and LC90 were not determined because the mortality was 100%. Therefore effectiveness of essential oil from T. minuta is comparable to that of synthetic insecticides and can be studied further in lieu of becoming a possible alternative.
Evaluation of the Cooking Cultures and Practices in Rural Uganda
(Journal of Sustainable Bioenergy Systems, 2021) Kisiki Nsamba, Hussein; Ssali, Robert; Ssali, Sarah N.; Matovu, Fahad; Wasswa, John; Kivumbi Balimunsi, Hussein
Many communities across the globe still practice poor cooking cultures as part of their well-being to prepare food and other heating activities. Such bad cooking practices are not environmentally friendly, are wasteful and have adverse health effects. This work presents the results of the survey that was conducted to establish the existing cooking practices commonly used in Uganda, identify the commonly used fuel during cooking, identify perceptions on improved cooking stoves (ICS), perceived preferences during cooking as well as identify whether users are aware of the health challenges due to poor cooking and describe community opinions of ICS for rural communities in Uganda. The interviews were conducted on household levels across all the regions covering Uganda’s major rural regions. It was observed that the largest population of rural Ugandans still use the 3 stone stove fire for cooking with a percentage of 53.5%, Charcoal stove, 27.3%, Improved cooking stove, 16.9%, Electric cookers,1.2%, LPG 0.7% and biogas 0.5% for the preparation of their various types of cooked foods while forest firewood is the commonly used biomass fuel for cooking with a percentage of 66.8% compared to Charcoal, Briquettes, Saw dust and others with a percentage of 27.1%, 0.7%, 0.7%, 1.1% respectively. This reveals the great majority of users whose life is at risk as 3 stone stoves are characterized by low efficiency and high smoke production which increases the health risks of the users as well as increase the risk of deforestation rates. Household cooks showed great willingness to pay for a novel stove type in all the 4 regions but from the survey data, it was indicated that the preferences varied from one region to another with a great majority preferring minimal smoke production with increased heat retention capacity.
Hydrochemistry and fluoride contamination in Ndali-Kasenda crater lakes, Albertine Graben: Assessment based on multivariate statistical approach and human health risk
(Groundwater for Sustainable Development, 2021) Ojok, Walter; Wanasolo, William; Wasswa, John; Bolender, James; Ntambi, Emmanuel
Hydrochemistry of crater lakes (n = 15) in the Ndali-Kasenda cluster was deciphered using standard methods of the American Public Health Association to understand the major ion chemistry; spatial distribution, occurrence, and non-carcinogenic health risks due to exposure to fluoride levels in the lakes in Ndali- Kasenda cluster, Albertine Graben. Numerous economic activities take place in and around the crater lakes which serve as major sources of domestic water whose origin of potential contaminants is ambiguous. In this study, WHO (2017) regulatory limit exceedance included F􀀀 , pH, Ca2+, Fe2+, Mn2+, and TDS. A strong positive correlation was observed between F􀀀 and TDS; F􀀀 and pH; F􀀀 and EC; F􀀀 and HCO3􀀀 . However, concerning hydrogeochemical signature, the lakes are mainly of Ca–HCO3 type and low in Na–K–HCO3 type due to rock water interaction in the geology of the area. Principal component analysis (PCA) performed on Ndali-Kasenda hydrogeochemical data resulted in six principal components (PCs) explaining 88.6% of the total variance. The PCs represented the primary processes that control the crater lake hydrogeochemistry in the Ndali-Kasenda area which include; weathering of rocks reactions, ion exchange, and evaporation processes. The hazard quotient (HQ) for noncarcinogenic health risks associated with exposure to Ndali- Kasenda fluoride levels via ingestion revealed that HQ for infants surpassed the acceptable HQ limit for all the lakes studied, while 86.67 % of the sampled lakes exceeded the HQ value for children via ingestion. Based on the hydrogeochemical parameters analyzed, aside from L. Murigamire and L. Wankenzi, water from the other studied lakes is chemically not acceptable for drinking purposes. An urgent need to take ameliorative action in this area to protect the inhabitants from exposure to excess fluoride in drinking water was recommended.
Mobility of Chromium, Copper and Arsenic in Amended Chromated Copper Arsenate Contaminated Soils
(Asian Journal of Applied Chemistry Research, 2020) Kiwanuka Nakiguli, Caroline; Ojok, Walter; Omara, Timothy; Wasswa, John; Ntambi, Emmanuel
The use of copper-based preservatives such as chromated copper arsenate (CCA) and creosote to prolong the life of lumber present environmental concerns because they contain heavy metals and polycyclic aromatic hydrocarbons which are toxic to humans. The aim of this study was to investigate the effects of sewage sludge biosolid amendment on the distribution and mobility of chromium, copper and arsenic in chromated copper arsenate contaminated soils subjected to phytoremediation using maize (Zea mays L.). Place and Duration of the Study: Random composite soil samples from Kitetika wood factory, Wakiso, Uganda and sewage sludge biosolid from National Water and Sewerage Corporation plant in Bugolobi, Kampala, Uganda were collected and prepared. Maize grains were obtained from FICA Seeds Limited (Uganda). The pot experiments and analysis of samples were done at Mbarara University of Science and Technology (Mbarara) and Directorate of Government Analytical Laboratory, Kampala (Uganda), respectively. Methodology: The fresh CCA contaminated soils and sewage sludge biosolid were analyzed for physicochemical parameters and heavy metals (chromium, copper and arsenic). Sewage sludge biosolid was added to 1 kg of the contaminated soils at 5-25% (w/w) in 2 L plastic containers, watered and maintained at 25 ℃ for 14 days to stabilize. Controls were set up with unamended soils. Thereafter, maize was planted in the potted soils for 40 days. The concentrations of the trace metals in the soils were determined after 20 and 40 days of maize growth by atomic absorption spectroscopy. Results: The concentrations of chromium, copper and arsenic in fresh CCA contaminated soils were 365.8 ± 6.18 mg/kg, 109.72 ± 14.04 mg/kg and 28.22 ± 3.8 mg/kg, respectively. Basing on mobility factor, bioavailability of the trace metals followed the chemical sequence copper (8.9%) < chromium (17.1%) < arsenic (30.2%). Conclusion: The maize variety experimented could be used to phytoextract or phytostabilize the trace metals in the CCA contaminated soils without or with 5-25% amendment. Amendment with sewage sludge biosolid improved the phytoremediation potential of maize. Arsenic was the most mobile and bioavailable metal in CCA contaminated soils. Further studies should use other local maize varieties such as Longe series.
Modified Activation Process for Supercapacitor Electrode Materials from African Maize Cob
(Materials, 2020) Kigozi, Moses; Kali, Ravi; Bello, Abdulhakeem; Padya, Balaji; Kalu-Uka, Godwin Mong; Wasswa, John; Kumar Jain, Pawan; Azikiwe Onwualu, Peter; Dzade, Nelson Yaw
In this work, African maize cobs (AMC) were used as a rich biomass precursor to synthesize carbon material through a chemical activation process for application in electrochemical energy storage devices. The carbonization and activation were carried out with concentrated Sulphuric acid at three di erent temperatures of 600, 700 and 800 C, respectively. The activated carbon exhibited excellent microporous and mesoporous structure with a specific surface area that ranges between 30 and 254m2 g􀀀1 as measured by BET analysis. The morphology and structure of the produced materials are analyzed through Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Di raction (XRD), Boehm titration, X-ray Photoelectron Spectroscopy (XPS) and Raman Spectroscopy. X-ray photoelectron spectroscopy indicates that a considerable amount of oxygen is present in the materials. The functional groups in the activated carbon enhanced the electrochemical performance and improved the material’s double-layer capacitance. The carbonized composite activated at 700 C exhibited excellent capacitance of 456 F g􀀀1 at a specific current of 0.25 A g􀀀1 in 6MKOH electrolyte and showed excellent stability after 10,000 cycles. Besides being a low cost, the produced materials o er good stability and electrochemical properties, making them suitable for supercapacitor applications.
Occurrence, distribution, and ecotoxicological risk assessment of selected pharmaceutical compounds in water from Lake Victoria, Uganda
(Chemosphere, 2020) Nantaba, Florence; Wasswa, John; Kylin, Henrik; Palm, Wolf-Ulrich; Bouwman, Hindrik; Kümmerer, Klaus
The occurrence of 24 pharmaceuticals (including; 15 antibiotics, three analgesic/anti-inflammatory drugs, three anti-epileptic/ antidepressant drugs, two beta blockers, and one lipid regulator) was investigated in 75 water samples collected from four bays in the Ugandan part of Lake Victoria. In addition, the potential environmental risk of the target pharmaceutical compounds to aquatic organisms in the aquatic ecosystem of Lake Victoria was assessed. Water samples were extracted using solid phase extraction and analyzed for pharmaceuticals using high- performance liquid chromatography coupled with triple quadrupole mass spectrometry (LC/MS/MS). Eighteen of the 24 pharmaceuticals occurred at quantifiable concentrations. Sulfamethoxazole (1-5600 ng L-1), trimethoprim (1-89 ng L-1), tetracycline (3-70 ng L-1), sulfacetamide (1-13 ng L-1), and ibuprofen (6-780 ng L-1) occurred at quantifiable concentrations in all water samples. Sulfamethazine (2-50 ng L-1), erythromycin (10-66 ng L-1), diclofenac (2-160 ng L-1), and carbamazepine (5-72 ng L-1) were only quantifiable in water samples from Murchison Bay. The highest concentrations of pharmaceuticals were found in Murchison Bay, the main recipient of sewage effluents, industrial and municipal waste from Kampala city via the Nakivubo channel. Ecotoxicological risk assessment showed that sulfamethoxazole, oxytetracycline, erythromycin, and diclofenac pose a high toxic risk to aquatic organisms in the lake, while ciprofloxacin, norfloxacin, and ibuprofen pose a medium risk. This study is the first of its kind to report the levels and ecotoxic risks of pharmaceutical compounds in Lake Victoria waters, of Uganda, and East Africa as a whole.
Organochlorine pesticide residues in sediments from the Uganda side of Lake Victoria
(Chemosphere, 2011) Wasswa, John; Kiremire, Bernard T.; Nkedi-Kizza, Peter; Mbabazi, Jolocam; Ssebugere, Patrick
Organochlorine (OC) residues were analysed in 117 sediment samples collected from four bays of the Uganda side of Lake Victoria. The sediments were collected with a corer at a depth of 0–20 cm, and extracted for OC residues using a solid dispersion method. The extracts were cleaned using gel permeation chromatography and analysed for pesticide residues using a gas chromatograph (GC) equipped with an electron capture detector. The results were confirmed using a GC equipped with a mass spectrometer (MS). A total of 16 OC residues, most of them persistent organic pollutants (POPs) were identified and quantified. The OC residue levels were expressed on an oven dry weight (d.w.) basis. Endosulphan sulphate, in the range of 0.82–5.62 lg kg 1 d.w., was the most frequently detected residue. Aldrin and dieldrin were in the ranges of 0.22–15.96 and 0.94–7.18 lg kg 1 d.w., respectively. DDT and its metabolites lay between 0.11–3.59 for p,p0-DDE, 0.38–4.02 for p,p0-DDD, 0.04–1.46 for p,p0-DDT, 0.07–2.72 for o,p0-DDE and 0.01–1.63 lg kg 1 d.w. for o,p0-DDT. The levels of c-HCH varied from 0.05 to 5.48 lg kg 1 d.w. Heptachlor was detected only once at a level of 0.81 lg kg 1 d.w., while its photo-oxidation product, heptachlor epoxide, ranged between non-detectable (ND) to 3.19 lg kg 1 d.w. Chlordane ranged from ND to 0.76 lg kg 1 d.w. Based on the threshold effect concentration (TEC) for fresh water ecosystems, aldrin and dieldrin were the only OCs that seemed to be a threat to the lake environment.
Organochlorine pesticide residues in skin, flesh and whole carrots (Daucus carota) from markets around Lake Victoria basin, Uganda
(International journal of environmental studies, 2013) Nannyonga, Stella; Kiremire, Bernard T.; Ogwok, Patrick; Nyanzi, Steven A.; Sserunjogi, Mohammed L.; Wasswa, John
Residual concentrations of organochlorine pesticides in vegetables cause concern because of their adverse health effects. Pesticides have been applied in agricultural production and vector control in Uganda. Vegetables may absorb high residual levels of cyclodienes necessitating regular monitoring. Carrots are commonly consumed in Uganda as raw salads or components of different dishes. A gas chromatograph with electron capture detector was used to quantify organochlorine pesticides. Pesticide residues were confirmed by gas chromatography with a mass spectrometer. Trace amounts of 4,4′-dichlorodiphenyltrichloroethane (DDT), 2,4′-DDT, 2,4′-dichlorodiphenylchloroethane (DDE), α- endosulphan, β-endosulphan, α-lindane, γ-lindane and dieldrin were detected in carrots. Levels of organochlorine residues in carrots were below the maximum residue limits considered safe for human consumption by Codex Alimentarius and the European Union Commission.
Organochlorine pesticides and their markers of exposure in serum and urine of children from a nodding syndrome hotspot in northern Uganda, east Africa
(Elsevier Ltd, 2024-08-28) Odongo, Silver; Ssebugere, Patrick; Spencer, Peter S.; Palmer, Valerie S; Angues, Raquel Valdes; Mwaka, Amos Deogratius; Wasswa, John
Nodding syndrome (NS) is a neurologic disorder of unknown etiology characterized by vertical head nodding that has affected children aged 5-18 years in East Africa. Previous studies have examined relationships with biological agents (e.g., nematodes, measles, and fungi), but there is limited data on the possible contributions of neurotoxic environmental chemicals frequently used as pesticides/insecticides to the development and progression of this disorder. We examined the levels of persistent organochlorine pesticides (OCPs) in children (5-18 years old) from Kitgum District, Northern Uganda. These children previously lived in internally displaced people's (IDP) camps, where they were exposed to various health risks, including contaminated food and water. Exposure to OCPs through contaminated food and water is postulated here as a potential contributor to NS etiology. We analyzed serum (n = 75) and urine (n = 150) samples from children diagnosed with NS, and from seizure-free household controls (HC), and community controls (CC). Samples were extracted using solid-phase extraction (SPE) and extracts were analyzed for OCPs using gas chromatography with a triple quadrupole mass spectrometry (GC-MS/MS). Mean levels of total (∑) ∑OCPs in serum samples from NS, HC and CC subjects were 23.3 ± 2.82, 21.1 ± 3.40 and 20.9 ± 4.24 ng/mL, respectively, while in urine samples were 1.86 ± 1.03, 2.83 ± 1.42, and 2.14 ± 0.94 ng/mL, respectively. Correlation and linear regression analysis indicated that potential markers for ∑hexachlorocyclohexanes (HCHs), ∑chlordane compounds (CHLs), ∑endosulfan and ∑dichlorodiphenyltrichloroethanes (DDTs) were γ-HCH, heptachlor-exo-epoxide, endosulfan-α and p,p'-DDD in NS cases while in controls were α -HCH, heptachlor, endosulfan-α and p,p'-DDE, respectively. Since, in some instances, higher OCP levels were found in controls vs. NS cases, we conclude that exposure to organochlorine pesticides is unlikely to be associated with the etiology of NS.Nodding syndrome (NS) is a neurologic disorder of unknown etiology characterized by vertical head nodding that has affected children aged 5-18 years in East Africa. Previous studies have examined relationships with biological agents (e.g., nematodes, measles, and fungi), but there is limited data on the possible contributions of neurotoxic environmental chemicals frequently used as pesticides/insecticides to the development and progression of this disorder. We examined the levels of persistent organochlorine pesticides (OCPs) in children (5-18 years old) from Kitgum District, Northern Uganda. These children previously lived in internally displaced people's (IDP) camps, where they were exposed to various health risks, including contaminated food and water. Exposure to OCPs through contaminated food and water is postulated here as a potential contributor to NS etiology. We analyzed serum (n = 75) and urine (n = 150) samples from children diagnosed with NS, and from seizure-free household controls (HC), and community controls (CC). Samples were extracted using solid-phase extraction (SPE) and extracts were analyzed for OCPs using gas chromatography with a triple quadrupole mass spectrometry (GC-MS/MS). Mean levels of total (∑) ∑OCPs in serum samples from NS, HC and CC subjects were 23.3 ± 2.82, 21.1 ± 3.40 and 20.9 ± 4.24 ng/mL, respectively, while in urine samples were 1.86 ± 1.03, 2.83 ± 1.42, and 2.14 ± 0.94 ng/mL, respectively. Correlation and linear regression analysis indicated that potential markers for ∑hexachlorocyclohexanes (HCHs), ∑chlordane compounds (CHLs), ∑endosulfan and ∑dichlorodiphenyltrichloroethanes (DDTs) were γ-HCH, heptachlor-exo-epoxide, endosulfan-α and p,p'-DDD in NS cases while in controls were α -HCH, heptachlor, endosulfan-α and p,p'-DDE, respectively. Since, in some instances, higher OCP levels were found in controls vs. NS cases, we conclude that exposure to organochlorine pesticides is unlikely to be associated with the etiology of NS. MEDLINE - Academic
Organochlorine pesticides in soils from south-western Uganda
(Chemosphere, 2010) Ssebugere, Patrick; Wasswa, John; Mbabazi, Jolocam; Nyanzi, Steven A.; Kiremire, Bernard T.; Marco, John A.M.
Organochlorine (OC) residues were analysed in soil samples collected from Kihiihi sub-county, Kanungu District, which is located in south-western Uganda. Mabira Central Forest Reserve which is located in central Uganda was used as a reference site in this study. The samples were collected at 15–20 cm depths below the soil surface and extracted with organic solvents. The extracts were cleaned using florisil, and were analysed using a gas chromatograph (GC) equipped with an electron capture detector (ECD). The results were confirmed using a GC equipped with a mass spectrometer (MS). The levels of the OC residues in soil from Kihiihi sub-county varied from non-detectable (ND) to 59 μg kg−1 dry weight. The frequencies of detection for p,p′-DDT, p,p′-DDE and p,p′-DDD in the total soil samples were 47%, 24% and 11%, respectively. The o,p′compounds were detected in the following frequencies: o,p′-DDT (23%), o,p′-DDE (19%) and o,p′-DDD (8%). The low p,p′-DDE/p,p′-DDT residue ratios (0.2–0.9) in Kihiihi samples suggest recent inputs of DDT in Kihiihi sub-county. The detection frequencies for dieldrin, endosulfan-α, -β and -sulphate in the soil samples were 21%, 26%, 31% and 19%, respectively. Mabira Forest Reserve soils showed detection frequencies of p,p′-DDT (5%) and p,p′-DDE (9% of the soil samples), varying from ND to 9 μg kg−1. Although the use of OCPs has been banned, our results show that they can still be detected in the environment. Their presence may be attributed to adulteration of pesticides which are not banned and also atmospheric deposition.
PCDD/Fs and dioxin-like PCBs in fish species from Lake Victoria, East Africa
(Chemosphere, 2013) Ssebugere, Patrick; Kiremire, Bernard T.; Henkelmann, Bernhard; Bernhöft, Silke; Kasozi, Gabriel N.; Wasswa, John; Schramm, Karl-Werner
Two commercially important fish species, Nile perch (Lates niloticus) and Nile tilapia (Oreochromis niloticus) belonging to different trophic levels were collected from the Napoleon Gulf and Thurston Bay in Lake Victoria. Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxinlike polychlorinated biphenyls (dl-PCBs) were extracted from the fish muscles and livers using the 13C isotope dilution method, followed by multiple column chromatography clean-up. Analysis was achieved by a high resolution gas chromatography coupled with a high resolution mass spectrometer. The concentrations of analytes ranged from 0.07 to 0.59 pg g 1 fresh weight (fw) and 0.3–19.0 pg g 1 in L. niloticus and 0.06–0.18 and 0.2–15.7 pg g 1 in O. niloticus, for PPCDD/Fs and Pdl-PCBs, respectively. Differences in congener concentrations were observed between the two fish species and study sites, and this was attributed to differences in feeding habits and trophic levels. World Health Organization-toxic equivalents (WHO-TEQs) were in the range 0.01–0.16 pg TEQ g 1 for the PCDD/Fs and 0.001–0.74 pg TEQ g 1 for the dl-PCBs. The TEQ values in the present study were lower compared to those of most fish samples reported in literature and were within permissible levels recommended by the European Union, implying that the fish was fit for human consumption.
PCDD/Fs and dioxin-like PCBs in surface sediments from Lake Victoria, East Africa
(Science of the total environment, 2013) Ssebugere, Patrick; Kiremire, Bernard T.; Henkelmann, Bernhard; Bernhöft, Silke; Wasswa, John; Kasozi, Gabriel N.; Schramm, Karl-Werner
Surface sediments (b60 cm) from the Napoleon Gulf and Thurston Bay on the northern shore of Lake Victoria were analyzed for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs). Fifteen PCDD/Fs and eleven dl-PCBs were found in 75.5% of the samples. The maximum concentrations of PCDD/Fs and dl-PCBs were 44.1 and 136 pg g−1 dry weight (dw), respectively. Octachlorodibenzo-p-dioxin was the predominant PCDD/F congener at the Napoleon Gulf and Thurston Bay area. Regarding the dl-PCBs, a variation in levels was observed between the mono-ortho PCBs and non-ortho PCBs, with the former having higher levels than the latter. The PCDD/F and dl-PCB levels, in the sediments of Napoleon Gulf, which is near urban centers and industrial areas were markedly higher (α ≤ 0.05) than those from the Thurston Bay, which is offshore, suggesting that human activities could be sources of the pollutants to the surrounding water resources. World Health Organization-toxic equivalency quotients (WHO-TEQs) lay in the range of 0.07–5.53 pg g−1 dw for PCDD/Fs and 0.01–0.23 pg g−1 dw for dl-PCBs. 23.1% of samples from the Napoleon Gulf had their results above the set WHOPCDD/Fs-TEQ value.

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