The calibration factors of target PCBs were estimated to test the linearity of the GC-ECD within a concentration of 0.025 ng/µL to 0.400 ng/µL. RSD of the calibration factors ranged from 4.6% to 12.3%, indicating a good response. Mean total PCBs in samples increased in the order water < soil < dust < sediment, with average values of 23.0 ng/mL, 27.3 ng/g, 272.6 ng/g, and 510.6 ng/g respectively. One way ANOVA revealed the mean concentrations of PCBs in the four sample types to be statistically different. The study provides a baseline report on the presence of PCBs in environmental samples from an electrical power facility in Lagos, Nigeria.

Concentrations of 7 indicator polychlorinated biphenyls (PCBs) were measured in dust and soil samples from 12 power stations collected over the two major seasons of the Nigerian climate. Median ƩPCB concentrations in soil ranged from 2 ng/g for power station A to 220 ng/g for power station I; while those in dust ranged from 21 ng/g for power station L to 2200 ng/g for power station I. For individual congeners, median PCB concentrations ranged from 3.8 ng/g for PCB 101 to 52 ng/g for PCB 180 in dust, and <0.07 ng/g for PCB 28 to 5.9 ng/g for PCB 153 in soil. The type of power station activity exerted a significant influence on concentrations of ΣPCB in dust and soil (generation > transmission > distribution). Congener patterns in dust and soil samples were compared using principal component analysis (PCA) with those in transformer oil samples from 3 of the power stations studied and with common PCB mixtures (Aroclors). This revealed congener patterns in soil were more closely related to that in the transformer oil than dust. Congener patterns in most samples were similar to Aroclor 1260. Concentrations of PCBs in soil samples close to the transformers significantly exceeded those in soil sampled further away.

Pesticide use is a common practice worldwide, especially in Sub-Saharan African (SSA) countries, where ongoing agriculture intensification and the need for disease vector control make it essential. The population can thus be exposed to variable amounts of pesticides through the diet. Edible insects are a highly regarded food source in SSA. However, they are still mostly harvested from the wild, where chemical applications are not necessarily controlled, representing a major cause of concern for consumers. We investigated residues of legacy (OCPs) and current-use pesticides (CUPs) in selected edible insects commonly consumed in Uganda and Nigeria, and evaluated the eventual health risk for the adult population associated with their consumption. Targeted OCPs were < LOQ in all analysed edible insects, except for hexachlorobenzene (up to 0.87 ng/g dw), while several CUPs were present at notable levels. Cypermethrin showed the highest median concentration (17 ng/g dw), while the Nigerian cricket Brachytrupes membranaceus was the most contaminated sample, with concentrations of aldicarb, propoxur, chlorpyrifos, dichlorvos and paclobutrazol reaching 118 ng/g dw, 327 ng/g dw, 156 ng/g dw, 26 ng/dw, and 14 ng/g dw, respectively. The concentrations of pesticides were generally well below the available maximum residue levels (MRLs), and the dietary risk assessment did not indicate health threats for the adult population. However, we suggest that the monitoring of the chemical safety of edible insects in SSA should be further investigated and insects should be integrated into more extensive dietary studies.

Dioxin‐like polychlorinated biphenyls (dl‐PCBs) are ubiquitous chemicals which mediate toxicity in a way similar to polychlorinated dibenzo‐p‐dioxins and polychlorinated dibenzofurans. In silico modeling was used to predict the absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties of eight dioxin‐like PCBs in soil samples of 12 power stations in Lagos, Nigeria. Concentrations of Σdl‐PCB8 in soil samples ranged from 490 to 61,000 pg g−1, with mean concentrations of 17,000 pg g−1. The corresponding toxic equivalent (TEQ) concentrations of Ʃdl‐PCB8 ranged from 0.01 to 450 pg TEQ g−1, with a mean value of 42 pg TEQ g−1. Mean TEQ concentrations for Ʃdl‐PCB8 in soil samples from all but one of the sites exceeded the Canadian guideline value of 4 pg TEQ g−1 and the US and German guideline values of 5–10 pg TEQ g−1. However, the TEQ concentrations obtained were all below the US action level of 1000 pg TEQ g−1. The ADMET predictions revealed that all studied dl‐PCBs are inhibitors of three major isoforms (1A2, 2C9, and 2C19) of cytochrome P450 enzyme. Acute oral toxicity (median lethal dose) predictions revealed that all target dl‐PCBs were class III compounds. Hepatotoxicity and carcinogenicity were positive, signifying that the studied compounds all have a tendency to elicit these effects. Occupational daily TEQ exposure via soil ingestion was estimated for an average adult worker weighing 70 kg. The maximum exposure obtained was 0.14 pg TEQ kg−1 body weight day−1, which is half of the European Food Safety Authority (EFSA) tolerable daily intake (TDI) for dioxin‐like compounds. This raises concern over the possible exceedance of the EFSA TDI for these workers if other dietary and nondietary exposure pathways and dioxin‐like compounds are considered. Environ Toxicol Chem 2022;41:800–809. © 2021 SETAC