Adegbenro Peter Daso

Per- and polyfluoroalkyl substances (PFASs) are synthetic chemicals widely used in industrial applications and consumer products due to their thermal stability and resistance to degradation. These properties also contribute to their environmental persistence and potential adverse health effects. Despite increasing global concern regarding PFAS exposure, biomonitoring data from African populations remain limited. This study investigated the serum concentrations of perfluorooctanoic acid (PFOA), perfluorooctanesulfonate (PFOS), and perfluorobutane sulfonate (PFBS), and their association with diabetes mellitus (DM) in a mixed-ancestry population from Bellville South, Cape Town, South Africa. Serum samples (n = 179) were analysed using liquid chromatography–tandem mass spectrometry (LC–MS-8030), and statistical analyses were performed using STATISTICA 13.5 software. All three PFASs were detected in 100% of samples, with PFOA exhibiting the highest mean concentration (9.43 ± 13.16 ng/mL), followed by PFBS and PFOS. PFAS concentrations were generally higher in females than in males, with significantly elevated PFOA levels observed among women (p = 0.0116). No statistically significant associations were identified between PFAS concentrations and glycemic status, obesity, or related metabolic indicators (p > 0.05). However, PFOS showed a modest positive correlation with HbA1c in females, suggesting potential gender-specific interactions. These findings confirm measurable PFAS exposure in the South African population and highlight the need for larger longitudinal studies implications.

The extraction of organic pollutants from environmental samples using green solvents has received a lot of interest recently. Simply said, this is due to their extremely low toxicity and volatility when compared to the common organic solvents. Therefore, many extraction exercises now include ionic solvents, as well as the more current deep eutectic solvents (DES). Hence, the current study reports on 1) the synthesis and characterisation of choline chloride/oxalic acid (1:1) and choline chloride/urea (1:2) deep eutectic solvents and 2) their application in liquid-liquid and solid-liquid assisted extraction of 14 targeted OPFRs from landfill leachate and sediment samples. The densities, refractive indices and melting points of the DES measured were 1.11 ± 0.15 g/mL, 1.14 ± 0.10 g/mL; 1.50 ± 0.12, 1.45 ± 0.20; and 12 ± 0.05°C, 35 ± 0.06–55 ± 0.05°C for choline chloride/urea (1:2) and choline chloride/oxalic acid (1:1) respectively. Choline chloride/urea (1:2) and choline chloride/oxalic acid (1:1) viscosities were 87.0 ± 0.20 kg·m ⁻¹·s ⁻¹ and 13.5 ± 0.14 kg·m ⁻¹·s ⁻¹ respectively. ¹H NMR and FTIR confirmed the structures of the two DES. Recoveries using internal standards dTPP, dTBP, dTPrP and ¹³C₁₈MTPP ranged from 59.9 ± 7.41–103 ± 5.32%; whereas the percent recoveries using CRM ranged from 85.7–117%. In the leachate (510–1433 ng/L) and sediment (725–1224 ng/g dw) samples from each landfill, 14 and 13 targeted OPFRs, respectively, were detected. The high recoveries and extraction of OPFRs demonstrated by the two DES imply that these could replace conventional organic solvents used to extract OPFRs from environmental media.

It has been extensively demonstrated that plants accumulate organic substances emanating from various sources, including soil and water. This fact suggests the potentiality of contamination of certain vital bioresources, such as medicinal plants, by persistent contaminants, such as perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorobutane sulfonate (PFBS). Hence, in this study, the propensity of Tagetes erecta L. (a commonly used medicinal plant) to accumulate PFOA, PFOS, and PFBS was determined using liquid chromatography/tandem mass spectrometry (LC–MS/MS-8030). From the results, PFOA, PFOS, and PFBS were detected in all the plant samples and concentration levels were found to be 94.83 ng/g, 5.03 ng/g, and 1.44 ng/g, respectively, with bioconcentration factor (BCF) ranges of 1.30 to 2.57, 13.67 to 72.33, and 0.16 to 0.31, respectively. Little evidence exists on the bioaccumulative susceptibility of medicinal plants to these persistent organic pollutants (POPs). These results suggest that these medicinal plants (in particular, Tagetes erecta L., used for the management of diabetes) are also potential conduits of PFOA, PFOS, and PFBS into humans.

The presence of 17 pharmaceutical and personal care products (PPCPs) belonging to various therapeutic categories was investigated in two hospital wastewater treatment plants (WWTPs) in North West Province, South Africa. The compounds were extracted from wastewater samples by solid-phase extraction and analysed by liquid chromatography-tandem mass spectrometry. The results showed that ofloxacin, chloramphenicol, and bezafibrate were generally below the limit of quantification (LOQ) in the analysed samples. Acetaminophen and ibuprofen were the dominant pharmaceuticals in the influent streams with corresponding concentrations ranging from 21 to 119 μg/L and 0.3 to 63 μg/L, respectively. Both WWTPs were shown to have the capability to remove some of the target PPCPs, including acetaminophen (76-98%), tetracycline (15-93%), ibuprofen (44-99%), and triclocarban (13-98%). The monitoring of the target PPCPs in both influent and effluent samples of the investigated WWTPs revealed that the discharge of inadequately treated effluents could be contributing to the possible increase in the concentrations of these contaminants in the receiving environmental compartments. Further studies must be focused on the broader characterisation of these matrices in order to assess the potential ecological impacts of this waste disposal practice.

Triclosan and triclocarban are industrial chemicals that are frequently added into consumer and personal care products. Information on the levels on these compounds in water systems in the African continent is still very scarce. In the present study, the occurrence, seasonal variation, and estimated removal of TCS and TCC in six different wastewater treatment plants in Gauteng Province, South Africa, were investigated over a period of two years, together with effluent receiving river water. The instrumental analysis was carried out using Shimadzu LCMS/MS 8030, employing negative electrospray ionization. Both target compounds were ubiquitously detected with influent and raw sludge having elevated concentrations. Generally, TCS concentrations were higher than those of TCC. The concentrations obtained for TCS were (influent, 2.01–17.6 μg/L; effluent, 0.990–13.0 μg/L; river, 0.880–8.72 μg/L; raw sludge, 3.65–15.0 μg/kg; treated sludge, 2.08–7.81 μg/kg and biosolids, 2.16–13.5 μg/kg); while TCC levels were obtained to be (influent, 0.0860–2.84 μg/L; effluent, <LOD - 1.89 μg/L; river, nd - 0.360 μg/L; raw sludge, 3.65–11.8 μg/kg; treated sludge, 1.21–9.19 μg/kg; biosolids, 2.59–8.23 μg/kg). Occurrence of TCS in wastewater was found to be influenced by temporal changes. This was not the case for occurrence of TCS and TCC in sludge samples. Similar to their environmental occurrence, the estimated treatment efficiencies also varied across the wastewater treatments plants, with the highest elimination rates of 63% and 97% for TCS and TCC, respectively