Background. Production of foods safe for consumption is an important issue worldwide. Organochlorine pesticides (OCP) are often used to preserve crops. Their use can have serious impacts on human health. Objectives. This research aims at assessing OCP residues in food samples from markets in Lagos in southwestern Nigeria and their risk to human health. Methods. Sixteen food samples were collected from Lagos, Nigeria and analyzed for organochlorine pesticide residues. Extraction was performed using an ultrasonicator, and analysis was carried out using a gas chromatograph-electron capture detector. Risk assessment was carried out by determining the hazard quotient. Results. Results of the OCP residues found in the foods were generally low, with dichlorodiphenyldichloroethylene (p,p'-DDE) having the highest residue concentration. The concentration of p,p'-DDE was as high as 110 ng/g in pulses and 123 ng/g in Cameroon and chili peppers. The risk index was <1 in most cases, with the exception of dichlorodiphen...

This study proposes a new, fast and sensitive multi-residue method for simultaneous screening of different classes of pharmaceuticals in fish using an ultrasonic assisted extraction (UAE) followed by solid phase extraction (SPE) as clean-up step and by ultrahigh-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). The analysis was carried out by spiking ∼1 g wet tissue of sole fish muscle (Solea solea) with internal standards (IS) prior to extraction and quantitative analysis. The approach gave good relative recoveries, precision and accuracy for thirty six out of forty one compounds analysed with most compounds having method detection limits (MDLs) < 3 ng g⁻¹ and method quantification limits (MQLs) < 29 ng g⁻¹. Generally, compounds had relative recoveries between 46–113%, overall precision was 75% for most compounds. The method was applied to determine levels of micropollutants in muscles, gills and eyes of seven fish species from the Lagos lagoon. Only three compounds: tramadol, trimethoprim and fluoxetine were detected in the fish samples. In general, measured concentrations were >MDLs with fluoxetine present in all fish tissues (except tilapia eyes and gills) at concentrations >MQL.

Informal recycling of electronic waste leads to soil contamination that can impact human health. To accurately assess exposure to potentially toxic elements (PTE) in soil it is necessary to consider their bioavailability through ingestion, inhalation and dermal contact. However, bioaccessibility tests that estimate dermal absorption following adhesion of contaminated soil particles to skin are not well established. In this study the concentrations of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn were estimated in the <45 µm particle size fraction of a bulk composite soil from an e-waste recycling site using five different artificial sweat formulations. Extractions were performed at temperatures ranging from 17 to 47 °C to investigate the effect of ambient temperature on bioaccessibility. Results obtained using the different artificial sweats were not consistent with one another. In particular, the NIHS 96-10 formulation solubilized larger amounts of analytes (ranging from 6.3 times the next most effective extractant for Cu to 1700 times the next most effective for Pb). There was a general increase in release of PTE with increasing temperature, except for As. Although trends varied between analytes and formulations, this highlights the need to consider ambient temperature when estimating dermal bioaccessibility of PTE in soil.

Rapid population growth and urbanisation pose risk to the environment and public health. The aim of this study is to undertake a large-scale spatiotemporal chemical profiling of chemicals of emerging concern (CECs) in the rapidly growing megacity of Lagos, Nigeria. A one-week monitoring study was carried out on 63 target compounds at four wastewater treatment plants (WWTPs) and two sewage disposal points (SDPs) which represent different socioeconomic areas in Lagos metropolis. Forty-eight CECs out of 63 monitored were quantified at least once in the influent and effluent samples. Results showed that tramadol and its metabolite O-desmethyltramadol were the highest contributors to the overall CEC concentrations in influent samples. High variability in weekly trends suggests complexity of sample matrix influencing method performance and variability in CECs across sites. High concentrations of target compounds in effluent of WWTP2 and WWTP4 indicate a poor elimination rate. The results from effluent samples from the constructed wetland showed efficient removal of compounds in a natural system. Generally, the concentrations of target analytes in surface water appear to be independent of distance from discharge points. Occurrence of CECs at very high concentrations in effluent samples and the higher concentrations detected upstream of surface water is a cause for concern. The study proposes promoting the use of constructed wetlands in Lagos metropolis for effective removal of CECs and achieves a sustainable and environmentally friendly mode of treatment.