The use of pesticides in commercial farms can lead to exposure among various vulnerable groups. This study assessed the distribution, human health risks, and origins of 13 targeted organochlorine pesticides (OCPs) in soil samples from commercial farms in Southern Nigeria. Following a questionnaire survey on pesticide usage, soil samples were subjected to Soxhlet extraction and analyzed using gas chromatography-mass spectrometry. Results indicated that 31.6 % of farmers did not use personal protective equipment, and only 37.6 % had received training on safe pesticide application. While pyrethroids and organophosphates were commonly used, organochlorines were rarely applied. The detected levels of OCPs in the agricultural zones ranged from below detection limit (BDL) to 18.35 ± 13.83 µg/kg and were generally within the minimum risk level (MRL), except for α-HCH and β-HCH in Oron and Etinan zones. The estimated non-carcinogenic risk s from detected OCPs were insignificant at the time of the study, as the calculated Hazard Indexes (HIs) and Hazard Quotients (HQs) for ingestion, dermal absorption, and inhalation were all less than 1, indicating generally low risks. The carcinogenic risk assessment showed that the Incremental Lifetime Cancer Risk (ILCR) values ranged from 10⁻¹⁰ to 10⁻⁴, indicating a very low to low risk level according to the classification by the United States Agency for Toxic Substances and Disease Registry (US ATSDR). Source apportionment suggested that most OCP congeners were of historical origin, with only a few indicating recent use. In conclusion, organochlorine pesticide residues in the studied farms posed minimal health risks, with most originating from historical rather than recent use.

Biochar utilization for environmental remediation applications has become very popular. We investigated the trace metal levels and soil nutrient characteristics of a biochar–humus sediment slurry treatment of a simulated crude oil-contaminated soil in the present work. The results revealed that biochar prepared at moderate pyrolysis temperature (500 °C) could still retain a significantly higher nutrient content than those prepared at high temperatures (700 and 900 °C). Despite the suitability for soil treatment, one-pot treatment studies seem not to be very effective for monitoring trace metal sorption to biochar because trace metals do not biodegrade and remain in the system.

Article Making Global Green Connections: The Importance of Green Chemistry Summer School for Sustainable Development was published on October 1, 2022 in the journal Chemistry International (volume 44, issue 4).

This preface introduces the proceedings of the African Early Career Chemists Workshop & 8th Annual Symposium of the American Chemical Society (ACS), Nigeria International Chapter, which was held both virtually and onsite from June 4th to 8th, 2023. This special issue of Pure and Applied Chemistry (PAC) journal includes 8 manuscripts covering a range of topics from pure to applied chemistry.

This study investigated the antimicrobial activity of the ethanol extract of lemongrass (Cymbopogon citratus) and thyme (Thymus vulgaris) on dental caries-causing bacteria. Standard microbiological techniques were carried out on samples obtained from patients at St. Luke Hospital, Anua, Uyo. The percentage occurrence of five bacterial isolates obtained included: Enterococcus faecalis (20%), Corynebacterium sp (10%), Bacillus sp (5%), Lactobacillus acidophilus (25%) and Streptococcus mutans (40%). The ethanol extract of lemongrass and thyme as well as the phytochemical analysis were determined. The results revealed the presence of flavonoids, alkaloids, tannins, glycosides, steroids and phenols in lemongrass. It also showed the presence of flavonoids, alkaloids, saponins, tannins, glycosides, steroids and terpenoids in thyme. Antimicrobial activity and minimum inhibitory concentration (MIC) of the ethanol extracts of lemongrass and thyme were also determined. The results indicated that at 100% concentration, Bacillus sp (25.5 mm) exhibited more susceptibility; Enterococcus faecalis (19 mm) exhibited the least susceptibility and Corynebacterium sp was resistant to the ethanol extract of lemongrass. Enterococcus faecalis (32 mm) exhibited the highest susceptibility while Streptococcus mutans (14 mm) exhibited the least susceptibility to the ethanol extract of thyme. Bacillus sp and Enterococcus faecalis exhibited the lowest Minimum Inhibitory Concentration (MIC) value which was 6.25 mg/ml. In this study, lemongrass and thyme proved to be potential antimicrobial agents against dental caries-causing bacteria.