Patrick Onen

Mr. Patrick Onen

Department of Chemistry, University of Kerala, Thiruvananthapuram, Kerala, International
orcid
Department of Chemistry, Kyambogo University

Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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27 September 2022 in Pollutants
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GABSON BAGUMAGABSON BAGUMA
GABSON BAGUMA
AMAndrew Musasizi
Andrew Musasizi
HTHannington Twinomuhwezi
Hannington Twinomuhwezi
Allan GonzagaAllan Gonzaga
Allan Gonzaga
CNCaroline Nakiguli
Caroline Nakiguli
Timothy OmaraTimothy Omara
Timothy Omara
Lake Victoria (L. Victoria) is the largest African tropical and freshwater lake, with one of the highest pollution levels, globally. It is shared among Uganda, Kenya and Tanzania, but it is drained only by the river Nile, the longest river in Africa. Though environmental studies have been conducted in the lake, investigations of the heavy metals (HMs) contamination of sediments from fish landing sites and ports on the Ugandan portion of L. Victoria are limited. In this study, sediments of an urban, industrial and fish landing site (Port Bell) on L. Victoria, Uganda was investigated to establish its HMs pollution levels and potential health risks to humans and ecosystems. Sediment samples were collected in triplicate (n = 9) from three different points of Port Bell, digested and analyzed using atomic absorption spectrometry for the presence of these HMs: copper (Cu), lead (Pb), cadmium (Cd) and chromium (Cr). The average daily dose through dermal contact and hazard quotient (HQ) were calculated to assess the health risk that is associated with dredging works (lake sand mining). Four geochemical enrichment indices: contamination factor (CF), geo-accumulation index (Igeo), pollution load index (PLI) and potential ecological risk (PERI) were used to quantify the contamination of the HMs in the sediments. The results showed that the mean HM content of the samples ranged from: 6.111 ± 0.01 to 7.111 ± 0.002 mg/kg for Cu; from 40.222 ± 0.003 to 44.212 ± 0.002 mg/kg for Pb; from 0.352 ± 0.007 to 0.522 ± 0.010 mg/kg for Cr; from 3.002 ± 0.002 to 3.453 ± 0.003 mg/kg for Cd. Health risk assessments indicated that there are no discernible non-carcinogenic health risks that could arise from the dredging works that are conducted in the study area as the indices were all below one. The contamination factors that were obtained suggest that Cd has reached a state of severe enrichment in the sediments (CF > 6). An assessment using Igeo established that the sediments were not contaminated with regards to Cu and Cr, but they exhibited low-to-median and median contamination with respect to Pb and Cd, respectively. Though the pollution load indices show that the contamination levels raise no serious concerns, the potential ecological risk indices show that there is considerable pollution of the Port Bell sediments, particularly with regard to Cd. Upon examination using multivariate statistical analyses, Cd and Cr showed a strong correlation which alluded to their introduction from anthropogenic sources. Based on the sedimentary HMs concentrations and the environmental indices that are employed in this study, it is recommended that the spatial variations in the concentrations of the HMs in water, sediments and biota should be monitored.

4 December 2023 in Pollutants
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GABSON BAGUMAGABSON BAGUMA
GABSON BAGUMA
GBGadson Bamanya
Gadson Bamanya
Allan GonzagaAllan Gonzaga
Allan Gonzaga
AAAmpaire Ampaire
Ampaire Ampaire
Patrick OnenPatrick Onen
Patrick Onen
Contaminants of concern (CoCs) pose significant threats to Uganda’s ecosystems and public health, particularly in the face of rapid urbanization, industrial expansion, and intensified agriculture. This systematic review comprehensively analyzed Uganda’s CoC landscape, addressing imminent challenges that endanger the country’s ecosystems and public health. CoCs, originating from urban, industrial, and agricultural activities, encompass a wide range of substances, including pharmaceuticals, personal care products, pesticides, industrial chemicals, heavy metals, radionuclides, biotoxins, disinfection byproducts, hydrocarbons, and microplastics. This review identified the major drivers of CoC dispersion, particularly wastewater and improper waste disposal practices. From an initial pool of 887 articles collected from reputable databases such as PubMed, African Journal Online (AJOL), Web of Science, Science Direct, and Google Scholar, 177 pertinent studies were extracted. The literature review pointed to the presence of 57 pharmaceutical residues and personal care products, along with 38 pesticide residues and 12 heavy metals, across various environmental matrices, such as wastewater, groundwater, seawater, rainwater, surface water, drinking water, and pharmaceutical effluents. CoC concentrations displayed significant levels exceeding established regulations, varying based on the specific locations, compounds, and matrices. This review underscores potential ecological and health consequences associated with CoCs, including antibiotic resistance, endocrine disruption, and carcinogenicity. Inefficiencies in traditional wastewater treatment methods, coupled with inadequate sanitation practices in certain areas, exacerbate the contamination of Uganda’s aquatic environments, intensifying environmental and health concerns. To address these challenges, advanced oxidation processes (AOPs) emerge as promising and efficient alternatives for CoC degradation and the prevention of environmental pollution. Notably, no prior studies have explored the management and mitigation of these contaminants through AOP application within various aqueous matrices in Uganda. This review emphasizes the necessity of specific regulations, improved data collection, and public awareness campaigns, offering recommendations for advanced wastewater treatment implementation, the adoption of sustainable agricultural practices, and the enforcement of source control measures. Furthermore, it highlights the significance of further research to bridge knowledge gaps and devise effective policies and interventions. Ultimately, this comprehensive analysis equips readers, policymakers, and regulators with vital knowledge for informed decision-making, policy development, and the protection of public health and the environment.

26 September 2023 in Journal of Xenobiotics
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Patrick OnenPatrick Onen
Patrick Onen
ARAkemkwene Robin
Akemkwene Robin
CNCaroline Kiwanuka Nakiguli
Caroline Kiwanuka Nakiguli
NDNimusiima Daniel
Nimusiima Daniel
Daniel Hendry RumaDaniel Hendry Ruma
Daniel Hendry Ruma
Timothy OmaraTimothy Omara
Timothy Omara
Pollution of water resources is one of the major impediments to the realization of Sustainable Development Goals, especially in developing countries. The aim of this study was to investigate the physicochemical quality and potentially toxic element (lead and cadmium) concentrations in surface water sampled from Pager River, a tributary of the Nile River in Northern Uganda. Water samples (n = 18) were taken from six different points upstream (A, B, and C) and downstream (D, E, and F) of the river and analyzed following standard methods for their physiochemical properties. Atomic absorption spectroscopy was used to quantify lead and cadmium concentrations. Human health risks from ingestion and dermal contact with potentially toxic metal-contaminated water were calculated. The results obtained indicated that the mean temperature (27.7 ± 0.5–29.5 ± 0.8 °C), turbidity (40.7 ± 2.1–50.1 ± 1.1 NTU), lead (0.296 ± 0.030–0.576 ± 0.163 mg/L) and cadmium (0.278 ± 0.040–0.524 ± 0.040 mg/L) occurred at levels that surpassed their permissible limits as per World Health Organization guidelines for drinking water. Human health risk assessment showed that there are potential non-cancer risks from the ingestion of water from Pager River by adults, as the total hazard quotients were greater than one. These results emphasize the urgency to restrict the dumping of wastes into the river to minimize chances of impacting the Nile River, which flows northwards to the Mediterranean Sea. Further studies should perform routine monitoring of the river during both dry and wet seasons to establish the spatiotemporal variations of physicochemical, microbial, and trace metal profiles of the river and the associated health risks.

30 January 2024 in Journal of Xenobiotics
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ENEunice Nuwamanya
Eunice Nuwamanya
DBDenis Byamugisha
Denis Byamugisha
CNCaroline Kiwanuka Nakiguli
Caroline Kiwanuka Nakiguli
Christopher AngiroChristopher Angiro
Christopher Angiro
AKAlice V. Khanakwa
Alice V. Khanakwa
TOTimothy Omara
Timothy Omara
Metal fabrication workshops (MFWs) are common businesses in Ugandan cities, and especially those producing metallic security gates, window and door frames (burglar-proof), and balcony and staircase rails. The objective of this study was to comparatively assess the pollution levels and potential health risks of manganese (Mn), chromium (Cr), cadmium (Cd), lead (Pd) and nickel (Ni) in pooled surface soil samples from four 5-, 7-, 8-, and 10-year-old MFWs (n = 28) and a control site (n = 8) in Mbarara City, Uganda. The concentration of the potentially toxic elements (PTEs) was determined using inductively coupled plasma–optical emission spectrometry. Contamination, ecological, and human health risk assessment indices and models were used to identify any risks that the PTEs could pose to the pristine environment and humans. Our results showed that PTE pollution of soils is occuring in the MFWs than at the control site. The mean concentrations of the PTEs (mg kg−1) in the samples were: Mn (2012.75 ± 0.23–3377.14 ± 0.31), Cr (237.55 ± 0.29–424.93 ± 0.31), Cd (0.73 ± 0.13–1.29 ± 0.02), Pb (107.80 ± 0.23–262.01 ± 0.19), and Ni (74.85 ± 0.25–211.37 ± 0.14). These results indicate that the PTEs could plausibly derive from the fabrication activities in these workshops, which is supported by the high values of contamination factors, index of geoaccumulation, and the overall increase in pollution load indices with the number of years of operation of the MFWs. Human health risk assessment showed that there are non-carcinogenic health risks that could be experienced by children who ingest PTEs in the soils from the 7-, 8- and 10-year-old MFWs. The incremental life cancer risk assessment suggested that there are potential cancerous health effects of Cd and Ni that could be experienced in children (who ingest soils from all the four MFWs) and adults (ingesting soils from the 8- and 10-year-old MFWs). This study underscores the need to implement regulatory guidelines on the operation and location of MFWs in Uganda. Further research should be undertaken to investigate the emission of the PTEs during welding operations in the MFWs.

14 May 2021 in Asian Journal of Applied Chemistry Research
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Patrick OnenPatrick Onen
Patrick Onen
DODaniel Ocira
Daniel Ocira
Timothy OmaraTimothy Omara
Timothy Omara
JNJacob Nyeko
Jacob Nyeko
Augastine OkwirAugastine Okwir
Augastine Okwir
Aim: To perform phytochemical screening of Plumbago zeylanica L. root extracts and assess the claim of its use in traditional management of erectile dysfunction in Uganda through evaluation of the aphrodisiac effect of its aqueous extracts in male Wistar rats. Study Design: This study employed both qualitative and quantitative research designs. Place and Duration of Study: All research work were performed at the Department of Biological Sciences, Gulu University, Gulu, Uganda between August 2019 and December 2019. Methodology: Classical phytochemical screening of aqueous and methanolic extracts of Plumbago zeylanica roots were performed following standard methods. Aqueous extracts were administered to Male Wistar rats and the effect of the extracts on the mounting and intromission frequencies were determined. Results: Glycosides, phenols, saponins, quinones, terpenoids and steroids were present in both methanolic and aqueous extracts. Alkaloids were present in methanolic extracts only while tannins and phlobatannins were only present in aqueous extracts. Flavonoids, coumarins and anthraquinones were not detected in both extracts. Aqueous root extracts of Plumbago zeylanica produced pro-sexual stimulatory effects in male rats when administered at 150, 300 and 450 mg/kg body weight. Conclusion: The results support the use of Plumbago zeylanicaroots by indigenous people in Uganda to increase libido, treat premature ejaculation and erectile dysfunction. The extracts had low sexual enhancement in sexually inexperienced male rats and therefore, further studies using experienced animal models are needed to better apprehend the prosexual effects of P. zeylanica roots. The toxicity of the extracts as well as structural elucidation and pharmacological evaluation of the responsible bioactive compounds merit further studies.

17 August 2022 in Asian Journal of Fisheries and Aquatic Research
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RNRonald Ntuwa
Ronald Ntuwa
Patrick OnenPatrick Onen
Patrick Onen
GBGabson Baguma
Gabson Baguma
ENEric Niringiyimana
Eric Niringiyimana
IBIvan Byaruhanga
Ivan Byaruhanga
DODaniel Ocira
Daniel Ocira
Aims: Access to clean and safe water is a challenge globally. This study assessed the levels of three trace metals (iron, copper and chromium) and chlorine in water samples from municipal water supply points in Makerere University and springs from Bunga, Uganda. Study Design: This research employed a quantitative analytical method. Place and Duration of Study: Samples were collected from five different sites of Makerere University halls and Bunga springs, Kampala. This study was undertaken between May 2021 and October 2021. Methodology: Trace metal content and free chlorine of the water samples were determined and calibrated using multiparameter Palintest 7100 photometer. Results: Analytical results indicated that the average iron, copper and chromium and chlorine content of the tap water samples from the municipal supply system were 0.0125 ± 0.00433 mg/L, 0.155 ± 0.0384 mg/L, 0.0325 ± 0.01479 mg/L and 3.045 ± 0.180623 mg/L, respectively. The corresponding mean values for water samples from Bunga springs were 0.0080 ± 0.0109 mg/L, 0.0124 ± 0.2019 mg/L, 0.056 ± 0.02073 mg/L and 0.00 ± 0.00 mg/L, respectively. These average values were within the maximum permissible limits of 0.3 mg/L, 0.5 mg/L and 0.05 mg/L for iron, copper and chromium in drinking water as recommended by the World Health Organization. However, springs A and B had chromium concentrations above the recommended value of 0.05 mg/L. Conclusion: Trace metal and chlorine content of the sampled water were within compliance limits except for chromium which exceeded at springs A and B in Bunga, Kampala.