Ovokeroye Abafe

• PhD Chemistry
• Assistant Professor at Brunel University London

Bacteria’s ability to withstand the detrimental effects of antimicrobials could occur as resistance or tolerance with the minimum inhibitory concentration, the mutant prevention concentration, and the mutant selection window as salient concepts. Thus, this study assessed the impact of exposure to extremely high doses of ampicillin on the level of p...

Most anthropogenically affected environments contain mixtures of pollutants from different sources. The impact of these pollutants is usually the combined effect of the individual polluting constituents. However, how these stressors contribute to the development of antimicrobial resistance in environmental microorganisms is poorly understood. Thus,...

Bacteria’s ability to withstand the detrimental effects of antimicrobials may take the form of resistance or tolerance with the minimum inhibitory concentration (MIC), the mutant prevention concentration (MPC), and the mutant selection window as salient concepts. Isolates exposed for 30 days to different concentrations of selected antibiotics, bioc...

Although the rise in antimicrobial resistance has been attributed mainly to the extensive and indiscriminate use of antimicrobials such as antibiotics and biocides in humans, animals and on plants, studies investigating the impact of this use on water environments in Africa are minimal. This study quantified selected antibiotics, heavy metals, and...

In this study, we optimized and applied an in vitro physiologically based extraction test to investigate the dermal bioaccessibility of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD), incorporated as additives in different types of microplastics (MPs), and assess human dermal exposure to these chemicals. The dermal bioacc...

The use of urine-derived fertilizers has several economic and environmental advantages. However, there is concern that pharmaceutical residues present in urine could enter the food chain after plant uptake and pose potential risks to human and animal health. A pot experiment was conducted to evaluate the uptake of nine target antiretroviral drugs (...

Globally, tea is the second most consumed drink next to water as it is considered healthy with is medicinal properties. A total of 100 tea samples obtained from registered shops within South Africa were extracted using a validated QuEChERS extraction method followed by ultra-high performance liquid chromatography coupled to tandem mass spectrometry...

Aim: The aim of this study was to determine the presence, concentrations, dietary intake, and risk of residues of neonicotinoids (NEO) and insect growth regulators (IGR) in commercially available honey in South Africa. Methods: Sample preparation for honey was based on the “dilute and shoot” principle, followed by analysis using an internally valid...

The presence of micropollutants, such as pharmaceuticals and personal care products, in surface and ground water has escalated globally, leading to adverse effects on aquatic organisms in receiving waters. Untreated or inadequately treated wastewater is the main source of micropollutants entering the environment. In South Africa, the consumption of...

The exposure of infants to per and polyfluoroalkyl substances (PFAS) through breast-feeding is of global concern owing to their numerous detrimental health effects. This study investigated the occurrence of eleven perfluorocarboxylic acids (PFCAs) and four perfluorosulfonates (PFSAs) in breast milk of nursing mothers from South Africa. The concentr...

Analysis of body fluids and tissues of aflatoxin exposed individuals for the presence of aflatoxins and aflatoxin metabolites has emerged as a reliable indicator of exposure and metabolism of aflatoxins. However, current aflatoxin biomarkers are not appropriate for investigating the long-term effects of aflatoxin exposure. In this explorative study...

An ultra-high performance liquid chromatography tandem mass spectrometry method was developed and validated for the sensitive determination and unambiguous confirmation of residues of per and polyfluorinated alkyl substances (PFAS) in breastmilk, retail milk and infant formulas following two sample preparation methods. Sample pre-treatment was carr...

Although the consumption of seafood is a major route of human exposure to perfluoroalkyl substances (PFAS), data on their concentrations in marine shellfish and the exposure of the African population to PFAS through the consumption of shellfish is lacking. In this study, the concentrations of 15 PFAS were measured in four species of farmed marine s...

The occurrence, concentrations and variables associated with tetracycline, polyether ionophore and anthelmintic residues in the livers of chickens sold in the informal market in South Africa were determined. An ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS) was used to simultaneously analyze for four tetracyclin...

Dairy milk and infant formula play important roles in the diet of adolescents, adults and infants, respectively, in the South African population. However, data on the occurrence of legacy and emerging contaminants such as PFAS in these important food sources is lacking. In this study, the concentration of fifteen PFAS were measured in 23 pooled ret...

Organophosphate esters (OPEs) are esters of phosphoric acid that are increasingly used as plasticizers and by the flame-retardants industries as replacement for the regulated polybrominated diphenyl ethers. The most commonly classes of these pollutants are the chlorinated-and non-chlorinated-OPEs. The extent and magnitude of OPEs occurrence in the...

This study report the presence of polybrominated biphenyls (PBBs), polybrominated diphenyl ethers (PBDEs) and novel brominated flame-retardants (NBFRs) in muscle tissues of Labeo capensis (mudfish), Labeo umbratus (moggel), Cyprinus carpio (carp) and Clarias gariepinus (catfish) from Vaal River, South Africa. The concentrations (in ng g⁻¹ wet weigh...

An ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS) based multiclass multi-residue method for the simultaneous analysis of 5 polyether ionophores, 4 tetracycline and 10 sulfonamides in animal and aquaculture fish tissues was developed and validated. Sample extraction and clean-up were based on a modified QuEChERS...

The concentrations of four organophosphate esters (OPEs) were measured in 50 dust samples from homes (n = 10), offices (n = 9), university computer laboratories (n = 12) and cars (n = 19) in Durban, South Africa. The median concentrations Σ n = 4 OPEs were 22940, 26930, 19565 and 49010 ng g⁻ ¹ in homes, offices, university computer laboratories and...

Sediments are known to be the ultimate sink for most pollutants in the aquatic environment. In this study, the concentrations of both legacy polybrominated diphenyl ethers (PBDEs) and alternative halogenated flame retardants (AHFRs) were measured in sediments samples from the Vaal River catchment. The concentrations of Σ7BDE-congeners ranged from 2...

Per- and polyfluoroalkyl substances (PFASs) have since become a major health concern as they have been reportedly found in human tissues, blood and breast milk. The main aim of the study was to review the current data on PFASs in human breast milk, including the challenges of analysis as well as the possible modes of transfer from maternal blood. I...

In the present study, the levels of alkylphenols (APs) and alkylphenol ethoxylates (APEs) in indoor dust of three different microenvironments were measured and daily intake via dust ingestion estimated. Alkylphenols and alkylphenol ethoxylates were extracted with the aid of sonication and analyzed by gas chromatography mass spectrometry after hepta...

South Africa has the largest occurrence of the human immune deficiency virus (HIV) in the world but has also implemented the largest antiretroviral (ARV) treatment programme. It was therefore of interest to determine the presence and concentrations of commonly used antiretroviral drugs (ARVDs) and, also, to determine the capabilities of wastewater...

A simple and accurate ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for the first time as a confirmatory method for the simultaneous determination of stilbenes - hexestrol and diethylstibestrol in serum. Extraction was based on a simple acid denaturation of protein followed by...

The concentration of TBBPA in dust samples from automobiles (n = 14), computer laboratories (n = 8), homes (n = 7), and offices (n = 7), and, also, PBDE concentrations in the indoor dust of 19 personal and previously owned automobiles in Durban, South Africa, were determined. Gas chromatography coupled with mass spectrometry was applied for the sep...

A simple and efficient one-pot method has been developed for the synthesis of benzochromenes (4a-k) using V-CaHAp as a heterogeneous catalyst by the condensation of aldehydes, β-naphthol and malononitrile in ethanol as solvent at room temperature for 20 minutes. The reaction, with this catalyst was carried out under mild reaction conditions with ve...

Workplace exposure to persistent organic pollutants is a concern for human health. This study examined the presence of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in the indoor dust from two major e-waste recycling sites and a university electronic equipment repair workshop in Durban, South Africa, in order to evalua...

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured in indoor dust of three microenvironments in Durban, South Africa. The sum of eight PBDEs and three PCBs were quantified by gas chromatography with mass spectral detection. The mean concentrations of ∑n=8 PBDEs and ∑n=3 PCBs in 10 homes, 11 offices and 13 univ...

Introduction Organophophate esters are used in a variety of applications. The chlorinated alkylphosphates such as tris(1-chloro-2-propyl) phosphate (TCPP), tris(1,3-dichloro-2-propyl) phosphate (TDCPP) and tris(2-chloroethyl) phosphate (TCEP) are used mainly as phosphorus flame retardants (PFRs) in polyurethane foams, 1 electronic equipment, textil...

Introduction Total contaminant concentrations are frequently used in risk assessment of contaminated sites to human health. 1 Such assessment, though advantageous for precautionary measures, may lead to overestimation of the amount of contaminant absorbed by humans. 1 These overestimations have significant implications for cost and sustainability o...

A new series of ethyl 2-(4-substitutedbenzylidene)-5-(3'-(ethoxycarbonyl)biphenyl-4-yl)-7-methyl-3-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyrimidine-6-carboxylate derivatives () were synthesized. The newly synthesized compounds were characterized by , , , and , , analyses. All newly synthesized compounds were screened for their In vitro antioxidant acti...

Artemisinin-based combination therapies (ACTs) are recommended for the treatment of uncomplicated falciparum malaria. Artemisinin derivs. are potent, rapidly acting antimalarias that reduce gametocyte carriage and patient infectivity; the sustained use of artesunate-amodiaquine reduced falciparum malaria transmission and progression of drug resista...

High efficacy of artemisinin-based combinations has been shown over the past few years in areas where malarial is endemic and sulfadoxine-Pyrimethamine has been used extensively worldwide for malaria prophylaxis in areas endemic for chloroquine resistant Plasmodium falciparum malaria. This article describes a routine, simple, precise, economical, a...

The extensive use of some antibiotics for broilers in Nigeria has been a major practice in recent times. The purpose is to enhance the health and productivity of flocks. The use of antimicrobials is strictly restricted by the Food and Drug Administration and USDA to warrant their safety and efficacy. These drugs are retained as residues in tissues...