Characteristics and Carcinogenic Risk of PM2.5-Bound Polycyclic Aromatic Hydrocarbons from Charcoal Barbecue (Moo Kratha) Restaurants in Chiang Mai, Thailand

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

Polycyclic aromatic hydrocarbons (PAHs) exposure in children has been associated with various health impacts, including increased risk of asthma, skin diseases and allergies. In this study, we investigated the distribution, possible sources, and potential health risks of PAHs bound to fine particulate matter (PM2.5) collected in urban primary school environments. PM2.5 samples were collected using two identical low-volume samplers (LVS) equipped with quartz fibre filters (QMA) in both indoor and outdoor environments. The samples underwent ultrasonic extraction with a mixture of dichloromethane/n-Hexane (1:1) before analysis using gas chromatography-mass spectrometry (GC-MS). The results showed the mean total concentration of PAHs (∑PAHs) for indoor and outdoor environments were 4.34 ± 2.39 ng m− 3 and 5.62 ± 2.39 ng m− 3, respectively. High molecular weight (HMW) PAHs with five- and six-rings accounted for over 60% of outdoor and indoor ∑PAHs. Diagnostic ratio and source identification by principal component analysis revealed that traffic-related emissions from both gasoline and diesel-powered engines, as the primary contributors to ∑PAHs in school environments. The results of the total carcinogenic risk for children aged 7–12 years in all schools caused by the presence of PAHs compounds in outdoor environments was acceptable. In some indoor environments, the values at certain schools exceeded the standard threshold of 10− 6-10− 4, indicating potential health risks. Given that PAHs are primarily generated from transportation activities, it is necessary to monitor and control the sources of their emissions, particularly in schools that are significantly impacted by these pollutants.

Occurrence, Health Risk and Source Apportionment of Polycyclic Aromatic Hydrocarbons in Borehole Water Around Fuel Stations in Owerri West Local Government Area, Imo State, Nigeria

Borehole water is a major drinking water source in Owerri West LGA, Imo State, Nigeria, but fuel stations within residential areas raise concerns over groundwater contamination by polycyclic aromatic hydrocarbons (PAHs). This study assessed concentrations of the 16 USEPA priority PAHs in borehole water near three fuel stations (Nekede, Orogwe, Obinze), evaluated health risks to adults and children, and identified probable contamination sources. Twenty-seven samples were collected in the dry season from fuel-station and nearby residential boreholes (25–625 m away). Physicochemical parameters were analyzed per APHA (2017); PAHs were extracted (USEPA Method 3510C) and quantified by GC-MS. Health risk was assessed using the USEPA (2014) deterministic model, with source apportionment via diagnostic ratios and PCA. All physicochemical parameters met WHO/USEPA limits. Total PAHs (Σ16PAHs) ranged from 0.112–0.217 mg/L, with benzo(a)pyrene exceeding the USEPA limit (0.01 µg/L) in all fuel-station boreholes. Hazard quotients were below 1, but benzo(a)pyrene cancer risk (7.15×10⁻⁵ adults; 1.67×10⁻⁴ children, Nekede) exceeded the USEPA threshold (1×10⁻⁶), with children ~2.3 times more at risk. Diagnostic ratios indicated predominantly pyrogenic sources with petrogenic contribution from fuel leaks. Despite meeting potability standards, the water posed unacceptable carcinogenic risk, warranting setback regulations and household treatment.

Assessment of ambient polycyclic aromatic hydrocarbons in Egbedi dumpsite in Osogbo, Nigeria

The open burning system of municipal solid waste (MSW) disposal releases varying concentrations of emissions into the atmosphere. One of such, Polycyclic Aromatic Hydrocarbons (PAHs) in the atmosphere have been documented to be a threat to humans. This study assessed the concentration of the ambient air PAHs in a MSW dumpsite at Egbedi, Osun State. A polyurethane foam (PUF) passive sampler was installed in 10 locations for 28 days to trap PAHs. The PAH results were subjected to a toxicity equivalence (TEQ), sources were identified by employing the existing diagnostic ratios, and inhalation dosage was investigated using the Excess Lifetime Cancer Risk Assessment (ELCR). The summation of the carcinogenic PAHs and the highest toxicity equivalence for rain and dry seasons were 0.241 µg/m3 and 0.369 µg/m3, and 0.070 and 0.110, respectively. The analysis revealed that the PAHs were mainly from the combustion of MSW. The ELCR values were (9.1 × 10–4) and (5.8 × 10–4), which were above the acceptable carcinogenic risk level of 1.0 × 10–6. The concentration of PAHs released is at a carcinogenic level and the TEQ and diagnostic ratio show that the emission source is from certain wastes. The PCA score plot showed a single cluster that was close to the center, indicating that the burning of MSW was the only source of emissions from the study location that added to the majority of the PAHs in the surrounding atmosphere. There is an urgent need to develop the dumpsite into a standard landfill.

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

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.

Urinary biomarkers of PAHs, VOCs, OPEs, and metal(loid)s in firefighters responding in the wildland urban interface (WUI)

Firefighters suppressing wildland urban interface (WUI) fires may be exposed to smoke from burning vegetation as well as structures and vehicles. To better understand firefighters’ internal dose exposures in the WUI environment, 250 firefighters from Southern California were enrolled into the Fire Fighter Cancer Cohort Study (FFCCS) in 2019, providing urine samples at enrollment and post-fire. One-hundred and twenty-five post-fire samples were collected from 89 participants. Samples were analyzed for metal(loid)s and metabolites of polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), and organophosphate esters (OPEs). We assessed the difference between creatinine-corrected urine concentrations for each chemical at enrollment compared with post-fire, controlling for the individual participant. We also compared these concentrations to the general U.S. population concentrations from the National Health and Nutrition Examination Survey (NHANES) and the American Conference of Governmental Industrial Hygienists Biological Exposure Indices (BEIs) when available. All seven PAH and 11 VOC metabolite concentrations increased significantly from enrollment to post-fire. Diphenyl phosphate, antimony, and cadmium also significantly increased from enrollment to post-fire. Maximum post-fire concentrations in firefighters also exceeded the BEI for 1-hydroxyprene and trans,trans-muconic acid (a metabolite of benzene). Firefighters assigned to structure defense had significantly higher increases in PAH metabolites compared to those assigned to wildland firefighting tasks. Personal protective equipment (PPE) usage was not evaluated in this study, but future studies could combine personal sampling with the collection of detailed PPE usage to develop effective practices and decontamination strategies during WUI fire responses.