Unveiling distribution and health risks of polycyclic aromatic hydrocarbons (PAHs) bound to PM2.5 in indoor and outdoor environments of urban primary schools

Comparative Assessment of Polycyclic Aromatic Hydrocarbon Levels in Indoor and Outdoor Air and Associated Inhalation Health Risks in Akpajo, Alesa and Aleto Communities, Eleme, Rivers State, Nigeria

Polycyclic aromatic hydrocarbons (PAHs) are persistent semi-volatile organic contaminants generated mainly during the incomplete combustion of organic materials and petroleum-derived fuels. This study assessed PAH levels in indoor and outdoor air and estimated the associated inhalation health risks in Akpajo, Alesa and Aleto communities of Eleme Local Government Area, Rivers State, Nigeria, an industrially and traffic-influenced area of the Niger Delta. Twelve 24-hour integrated air-sampling conditions were evaluated across three communities, two seasons (dry and wet) and two microenvironments (indoor and outdoor). Airborne particulate-bound PAHs were collected using a high-volume air-sampling approach, solvent-extracted with dichloromethane:n-hexane (1:1, v/v), concentrated and quantified by gas chromatography-mass spectrometry. Method quality control included internal-standard calibration, field and method blanks, duplicate checks, surrogate recovery assessment, blank correction, and limits of detection and quantification. Statistical analysis was based on descriptive statistics, including range, arithmetic mean, pooled congener totals, community means, seasonal means and indoor-outdoor means. Total PAH concentrations ranged from 7.40 µg/m³ in Alesa wet-season indoor air to 30.55 µg/m³ in Aleto dry-season outdoor air. The mean total PAH concentration was highest in Aleto (21.41 µg/m³), followed by Akpajo (11.80 µg/m³) and Alesa (10.39 µg/m³). Dry-season air had a higher mean total PAH concentration (18.18 µg/m³) than wet-season air (10.88 µg/m³), while outdoor air (15.75 µg/m³) exceeded indoor air (13.32 µg/m³). Anthracene, pyrene, benzo(k)fluoranthene, naphthalene, fluorene and phenanthrene were the dominant contributors to the pooled PAH burden. Non-detected high-molecular-weight PAHs were reported as below the method detection limit rather than as true zero values. Screening-level risk assessment showed that children had higher estimated lifetime average daily dose and incremental lifetime carcinogenic risk than adults under the same sampling conditions. The highest child ILCR occurred in Aleto dry-season outdoor air (4.12E-04), while several child-risk estimates exceeded 1.00E-04, indicating potential concern under the assumptions used. The findings indicate measurable PAH contamination, higher dry-season burden and greater screening-level risk estimates for children. Routine monitoring, emission reduction, dust control and targeted public-health communication are recommended.

Rising Carcinogenic Risk from Polycyclic Aromatic Hydrocarbon Exposure Through Indoor Settled Dust: First Comprehensive Residential Dust Assessment from India

Per- and polyfluoroalkyl substances (PFAS) in Portuguese primary schools: Occurrence in air and implications for children's inhalation exposure.

BACKGROUND Per- and polyfluoroalkyl substances (PFAS) are persistent environmental pollutants increasingly detected in indoor environments, yet information on PFAS in school settings remains scarce. OBJECTIVE We characterized PFAS levels in primary school indoor air and estimated inhalation exposure among children and school staff. METHODS We collected 36 indoor and 8 outdoor air samples from 8 primary schools in Porto (the second-largest city in Portugal) and analyzed them for 64 PFAS, including perfluoroalkyl acids (PFAAs) and PFAA precursors. RESULTS PFAA precursors predominated over terminal PFAAs, accounting for 66.5% and 64.6% of total PFAS in indoor and outdoor air, respectively. Among PFAAs, perfluoroalkyl carboxylic acids (PFCAs) were the dominant class in both indoor and outdoor air (median: 3822.3 and 495.1 pg/m3, respectively), whereas polyfluoroalkyl phosphate esters (PAPs; median: 2811.6 and 732.0 pg/m3) and fluorotelomer alcohols (FTOHs; median: 1436.6 and 313.5 pg/m3) were the predominant PFAA precursors. Trifluoroacetic acid (TFA), perfluorooctane sulfonate (PFOS), nonafluoro-3,6-dioxaheptanoic acid (NFDHA), di-sulfonamido polyfluoroalkyl phosphate (diSAmPAP), and 8:2 fluorotelomer alcohol (8:2 FTOH) were the major individual PFAS detected indoors. All PFAS classes showed indoor enrichment relative to outdoor air. Children had higher body-weight-normalized inhalation exposure than adults. Under the low-exposure scenario, FTOHs contributed most to total EDI, whereas PFCAs predominated under the high-exposure scenario. CONCLUSION Primary schools constitute important indoor microenvironments for PFAS exposure. Although PFAA precursors predominated in indoor air, PFAAs accounted for the largest share of estimated inhalation exposure under the high-exposure scenario, highlighting the importance of considering both PFAA precursors and PFAS in comprehensive exposure assessments.

Polycyclic Aromatic Hydrocarbon (PAHs) Pollution Status of Soil, Water, and Edible Vegetables Within Cashew Nut Processing Clusters in Enugu, Nigeria

This study evaluated the concentrations of polycyclic aromatic hydrocarbons (PAHs) in soil, water, and edible plants within cashew nut processing clusters in Enugu, Nigeria. Following liquid–liquid and solid–liquid extractions, the concentration of sixteen PAHs congeners were determined using gas chromatography coupled with a flame ionization detector (GC‐FID). To predict the potential sources of these PAHs, a diagnostic ratio guide was employed and principal component analysis was performed. Mutagenic equivalent concentration, human health risk assessment, and ecological risk assessment were performed. The identified PAHs had concentration range: 786.31–2589.46 µg/kg in soil, 33.78–5476.37 µg/L in water, and 561.47–3047.84 µg/kg in vegetables. Except for one location, the vegetables had higher levels of low molecular weight PAHs, while high molecular weight PAHs were more prevalent in the water. The results showed that the studied location has a fair amount of PAH pollution, mostly from pyrogenic sources though the source apportionment models predicted multi‐sources. The ecological risk assessment indicated acenaphthene to be the most contributing contaminant while the health risk evaluations indicated that consumers of water and vegetables from this area may have risk for non‐carcinogenic health problems. There were substantial mutagenic equivalent quantities, and BaP metabolites were probably responsible. The study reveals that inefficient burning of biomass and fossil fuels has resulted in significant levels of PAH contamination in the surrounding cashew nut processing clusters, and these activities should be controlled.

Inhalation Bioaccessibility, Pollution Assessment, and Speciation of Heavy Metals in PM2.5RD Road Dust from Urban and Semi-Urban Areas of Pakistan

Ambient exposure to fine particulate matter (PM2.5) remains a critical global public health concern; however, the speciation and bioaccessibility mechanisms of particle-bound heavy metals within the lung environment are still insufficiently understood. In particular, the role of soluble and insoluble metal species in simulated lung fluids requires further clarification. Road dust, a major contributor to PM2.5, contains heavy metals that pose significant inhalation risks, leading to oxidative stress, DNA damage, and systemic toxicity. This study investigated the contamination characteristics, bioaccessibility, pollution level, and speciation of heavy metals in PM2.5-fractionated road dust (PM2.5RD) collected from Karachi (a megacity with >27 million inhabitants) and Shikarpur (a medium-sized city of ~0.3 million) in Pakistan. A grid-based sampling approach was applied across four functional zones (residential, school, hospital, and office), yielding 48 samples. Inhalation bioaccessibility was evaluated using artificial lysosomal fluid (ALF; pH 4.5, 37 °C, 24 h), revealing moderate bioaccessibility of Cr, As, and Pb. Pollution status was assessed using contamination factor (CF), integrated pollution index (IPI), pollution load index (PLI), and potential ecological risk index. Geochemical modeling with PHREEQC 3.0 and Visual MINTEQ 3.1 was employed to simulate metal speciation, release behavior, and mineral saturation states. Overall, this study provides mechanistic insights into speciation-driven toxicity of As, Pb, and Cr in simulated lung environments, offering a scientific basis for improved risk assessment and regulatory strategies for PM2.5-associated metal exposure.

Polycyclic aromatic hydrocarbon (PAH) contamination in clinical nutrition: Levels and associated health risks in enteral nutrition formulas.

This study aimed to determine the levels of 16 priority PAHs in commercial enteral nutrition formulas (ENFs) marketed in Türkiye and to assess dietary exposure and associated carcinogenic and non-carcinogenic health risks under different consumption scenarios. Across all products, most PAH concentrations were either below the limit of detection or present only at trace levels, demonstrating very low contamination. Although a limited number of samples showed relatively higher concentrations of high-molecular-weight PAHs, such as ∑4PAHs reaching up to 3.06 μg/kg and ∑16PAHs up to 5.48 μg/kg, overall PAH levels remained low and did not suggest significant toxicological concern. Exposure modelling demonstrated that estimated PAH intakes were negligible in both partial- and full-dependence consumption scenarios (A and B, respectively). Hazard Index values remained well below the threshold for non-carcinogenic effects (Reference value: 1), while Incremental Lifetime Cancer Risk values fell within negligible ranges (3.55×10-8-4.76×10-7). The Margin of Exposure calculations (1,854,054-249,000,000) further supported the absence of carcinogenic concern, remaining well above the benchmark across all PAH groupings. These findings collectively suggest that currently marketed ENFs do not pose a significant PAH-related health risk for adult consumers. However, given the vulnerability of ENF users, continued monitoring of raw materials, processing, and packaging remains warranted to ensure product safety.