Determination of polycyclic aromatic hydrocarbons in blood plasma of neurology patients

Salt assisted liquid-liquid extraction combined with dispersive liquid-liquid microextraction for the determination of 24 regulated polycyclic aromatic hydrocarbons in human serum

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants of great concern due to their carcinogenicity and mutagenicity. Their determination in human serum, particularly in at-risk populations, is necessary but difficult because they are distributed over a wide range of polarity and are present at trace level. A new method combining salting-out assisted liquid-liquid extraction (SALLE) and dispersive liquid-liquid microextraction with solidification of floating organic drop (DLLME-SFO) adapted to a reduced volume of sample (100 µl) was developed to determine 24 PAHs in human serum. Some key parameters of DLLME-SFO (volume of extraction solvent, ratio of extraction/dispersive solvent volumes, and salt addition) were first studied by applying it to spiked pure water. For its application to serum, a sample treatment step involving SALLE was optimized in terms of nature and content of salts and applied upstream of DLLME-SFO. It was applied to the extraction of 24 regulated PAHs from spiked serum followed by an analysis by liquid chromatography coupled with UV and fluorescence detection. The extraction recoveries ranged from 48.2 and 116.0 % (relative standard deviations: 2.0-14.6 %, n=5-9), leading to limits of quantification of PAHs in human serum from 0.04 to 1.03 µg/L using fluorescence detection and from 10 to 40 µg/L using UV detection. This final method combining SALLE and DLLME-SFO showed numerous advantages such as no evaporation step, high efficiency and low solvent-consumption and will be useful for monitoring PAHs in low volumes of serum.

Comparing the effects of an exposure to a polycyclic aromatic hydrocarbon mixture versus individual polycyclic aromatic hydrocarbons during monocyte to macrophage differentiation: Mixture exposure results in altered immune metrics

Polycyclic aromatic hydrocarbons (PAHs) are generated by the incomplete combustion of carbon. Exposures correlate with systemic immune dysfunction and overall immune suppression. Real-world exposures to PAHs are almost always encountered as mixtures; however, research overwhelmingly centers on isolated exposures to a single PAH, benzo[a]pyrene (B[a]P). Here, a human monocyte line (U937) was exposed to B[a]P, benz[a]anthracene (B[a]A), or a mixture of six PAHs (6-MIX) to assess the differential toxicity on monocytes. Further, monocytes were exposed to PAHs with and without CYP1A1 inhibitors during macrophage differentiation to delineate PAH exposure and PAH metabolism-driven alterations to the immune response. U937 monocytes exposed to B[a]P, B[a]A, or 6-MIX had higher levels of cellular health and growth not observed following equimolar exposures to other individual PAHs. PAH exposures during differentiation did not alter monocyte-derived macrophage (MDM) numbers; however, B[a]A and 6-MIX exposures significantly altered M1/M2 polarization in a CYP1A1-dependent manner. U937-MDM adherence was differentially suppressed by all three PAH treatments with 6-MIX exposed U937-MDM having significantly more adhesion than U937-MDM exposed to either individual PAH. Finally, 6-MIX exposures during differentiation reduced U937-MDM endocytic function significantly less than B[a]A exposed cells. Exposure to a unique PAH mixture during U937-MDM differentiation resulted in mixture-specific alterations of pro-inflammatory markers compared to individual PAH exposures. While subtle, these differences highlight the probability that using a model PAH, B[a]P, may not accurately reflect the effects of PAH mixture exposures. Therefore, future studies should include various PAH mixtures that encompass probable real-world PAH exposures for the endpoints under investigation.

Polycyclic Aromatic Hydrocarbon Levels in Wistar Rats Exposed to Ambient Air of Port Harcourt, Nigeria: An Indicator for Tissue Toxicity

This study investigated the PAH levels in Wistar rats exposed to ambient air of the Port Harcourt metropolis. Twenty Wistar rats imported from a nonpolluted city (Enugu) were exposed to both indoor and outdoor air. Following the IACUC regulation, baseline data were obtained from 4 randomly selected rats, while the remaining 16 rats (8 each for indoor and outdoor) were left till day 90. Blood samples were obtained by cardiac puncture, and the PAH levels were determined using Gas Chromatography Flame-Ionization Detector (GC-FID). GraphPad Prism (version 8.0.2) Sidak's (for multiple data set) and unpaired t-tests (for two data sets) were used to evaluate the differences in group means. Seven of the PAHs found in indoor and outdoor rats were absent in baseline rats. The mean concentrations of PAH in indoor and outdoor animals were higher than those of baseline animals, except for Benzo(a)pyrene, which was found in baseline animals but absent in other animal groups. Additionally, Dibenz(a,h)anthracene, Indeno(1,2,3-c,d)pyrene, Pyrene, 2-methyl, and other carcinogenic PAHs were all significantly higher (p < 0.05) in outdoor groups. The vulnerable groups in Port Harcourt are at the greatest risk of such pollution. Therefore, urgent environmental and public health measures are necessary to mitigate the looming danger.

Exposure and Public Health Effects of Polycyclic Aromatic Hydrocarbon Compounds in Sub-Saharan Africa: A Systematic Review

BACKGROUND AND AIM

In order to achieve improved global health, environmental health risks that could affect this goal have to be reduced as much as possible. This review thus aimed at determining the exposure levels, health risk assessments, and public health effects of polycyclic aromatic hydrocarbons (PAHs) in sub-Saharan Africa (SSA). This review was developed using guidelines provided for Preferred Reporting Items for Systematic Review and Meta-Analysis. Search was done on Google Scholar, Scopus, and PubMed databases. A study was included if it was carried out in SSA from 2000 to 2020 and written in English language. Fifty-two studies were finally retained and used for the review. Extracted data included the concentrations of 8 selected priority PAHs (including the PAHs prioritized for their carcinogenic potentials), their sources and reported outcomes. In SSA, PAHs exposure has been linked to the use of unprocessed biomass fuels for cooking, release of poorly treated petrochemical effluents into water bodies, and so on. Related public health effects included the occurrence of respiratory, cardiovascular abnormalities, and so on. Others included destruction of natural biodiversity in soil, water, and atmospheric environmental media. Health risk assessments also buttressed the occurrence of these public health effects of PAHs. In SSA, the region is exposed to a substantial amount of PAHs pollution which is associated with deleterious environmental and epidemiological effects. The adoption of healthier forms of energy, a change of attitude to one that favors environmental sustainability, and proper enforcement of environmental regulations are, however, necessary for attaining environmental sanity in SSA.