Polycyclic aromatic hydrocarbons in PM1, PM2.5 and PM10 atmospheric particles: identification, sources, temporal and spatial variations

The key characteristics of cardiotoxicity for the pervasive pollutant phenanthrene

The key characteristic (KCs) framework has been used previously to assess the carcinogenicity and cardiotoxicity of various chemical and pharmacological agents. Here, the 12 KCs of cardiotoxicity are used to evaluate the previously reported cardiotoxicity of phenanthrene (Phe), a tricyclic polycyclic aromatic hydrocarbon (PAH), and major component of fossil fuel-derived air pollution. Phe is a semi-volatile pollutant existing in both the gas phase and particle phase through adsorption onto or into particulate matter (PM). Phe can translocate across the airways and gastrointestinal tract into the systemic circulation, enabling body-wide effects. Our evaluation based on a comprehensive literature review, indicates Phe exhibits 11 of the 12 KCs for cardiotoxicity. These include adverse effects on cardiac electromechanical performance, the vasculature and endothelium, immunomodulation and oxidative stress, and neuronal and endocrine control. Environmental agents that have similarly damaging effects on the cardiovascular system are heavily regulated and monitored, yet globally there is no air quality regulation specific for PAHs like Phe. Environmental monitoring of Phe is not the international standard with benzo[a]pyrene being frequently used as a proxy despite the two PAH species exhibiting significant differences in sources, concentration variations and toxic effects. The evidence summarised in this evaluation highlights the need to move away from proxied PAH measurements and develop a monitoring network capable of measuring Phe concentration. It also stresses the need to raise awareness amongst the medical community of the potential cardiovascular impact of PAH exposure. This will allow the production of mitigation strategies and possibly the development of new policies for the protection of the societal groups most vulnerable to cardiovascular disease.

Investigating PM2.5 toxicity in highly polluted urban and industrial areas in the Middle East: human health risk assessment and spatial distribution

Exposure to particulate matter (PM) can be considered as a factor affecting human health. The aim of this study was to investigate the concentration of PM2.5 and heavy metals and their influence on survival of A549 human lung cells in exposure to PM2.5 breathing air of Ahvaz city. In order to assess the levels of PM2.5 and heavy metals, air samples were collected from 14 sampling stations positioned across Ahvaz city during both winter and summer seasons. The concentration of heavy metals was determined using ICP OES. Next, the MTT assay [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] was employed to ascertain the survival rate of A549 cells. The findings from this research demonstrated that average PM2.5 of the study period was (149.5 μg/m3). Also, the average concentration of PM2.5 in the urban area in winter and summer was (153.3- and 106.9 μg/m3) and in the industrial area this parameter was (191.6 and 158.3 μg/m3). The average concentration of metals (ng/m3) of urban areas against industrial, Al (493 vs. 485), Fe (536 vs. 612), Cu (198 vs. 212), Ni (128 vs. 129), Cr (48.5 vs. 54), Cd (118 vs. 124), Mn (120 vs. 119), As (51 vs. 67), Hg (37 vs. 50), Zn (302 vs. 332) and Pb (266 vs. 351) were obtained. The results of the MTT assay showed that the highest percentage of cell survival according to the exposure concentration was 25 > 50 > 100 > 200. Also, the lowest percentage of survival (58.8%) was observed in the winter season and in industrial areas with a concentration of 200 μg/ml. The carcinogenic risk assessment of heavy metals indicated that except for Cr, whose carcinogenicity was 1.32E-03, other metals were in the safe range (10-4-10-6) for human health. The high concentration of PM2.5 and heavy metals can increase respiratory and cardiovascular diseases and reduce the public health level of Ahvaz citizens.

PAHs bound to submicron particles in rural Chinese homes burning solid fuels

Inhalation exposure to polycyclic aromatic hydrocarbons (PAHs) from indoor solid fuel combustion poses a high health risk, and PAHs bound to particles with smaller sizes (e.g., PM_1.0, aerodynamic diameter ≤ 1.0 µm) should be of particular concern since they can penetrate deep into pulmonary alveoli. However, PAHs bound to PM_1.0 was less studied compared with PAHs in total suspended particles or PM_2.5. In this study, multiple provincial field measurements were conducted to investigate 28 PAHs bound to PM_1.0 in rural Chinese homes. Daily averaged PM_1.0-PAH₂₈ concentrations ranged from 27 ng/m³ to 3795 ng/m³ (median: 233 ng/m³) and from 10 ng/m³ to 2978 ng/m³ (median: 87 ng/m³) in indoor and outdoor air, respectively. Higher concentrations were found in northern China in winter due to increased solid fuels consumption for space heating. The ambient pollution was lower during the non-heating season in Eastern China, where clean energy was preferred. Highly toxic congeners were more abundant in indoor air compared with outdoor air. The results of source apportionment revealed that solid fuel combustion was the primary contributor to rural household PM_1.0-PAHs, but other sources such as vehicles cannot be overlooked. The transition to cleaner energy can reduce the indoor PM_1.0-PAH₂₈ and BaP_eq-28 concentrations by 87% and 98%, respectively, and more efficient reduction was observed for highly toxic congeners. The estimated Incremental Lifetime Cancer Risk (ILCR) based on PM_1.0-PAH₂₈ ranged from 4.6 × 10^-5 to 3.4 × 10^-2, far exceeding the acceptable level of 10^-6. Over 60% of the ILCR could be attributed to inhalation exposure during childhood and adolescence.

Association between Polycyclic Aromatic Hydrocarbon Exposure and Diarrhea in Adults

Objective: Polycyclic aromatic hydrocarbons (PAHs) are not only natural but also anthropogenic contaminants that exist in many places in the environment. Human beings often accidentally ingest PAHs via smoking. Furthermore, smoking may increase the risk of bowel disorder, including diarrhea and other gastrointestinal problems. Therefore, PAH exposure is hypothesized to be related to diarrhea risk. This study discusses the association between diarrhea and PAH exposure in the United States adult population. Method: 10,537 participants from the National Health and Nutrition Examination Survey (NHANES 2001–2006) were involved in this cross-sectional analysis. Bowel disorders were assessed via examination of stool frequency and stool type. The concentrations of urinary PAH metabolites were used to evaluate PAH exposure. The association between bowel habits and PAH exposure was assessed using a multivariate logistic regression model with covariate assessment of gender, age, race, liver function, kidney function, and common chronic health diseases. Results: All PAH metabolites except 1-hydroxynaphthalene, 1-hydroxypyrene, and 9-hydroxyfluorene were substantially correlated with an increased risk of diarrhea (p < 0.05) after modification of relevant covariables. This study also revealed significant association in the group of females (p < 0.05). Furthermore, all PAH metabolites except 1-hydroxynaphthalene, 2-hydroxyphenanthrene, 1-hydroxypyrene, and 9-hydroxyfluorene show significantly positive association in the non-obesity group (BMI < 30, p < 0.05). Conclusions: PAH exposure is highly associated with risk of bowel disorders among the adult population in the United States, especially in female and non-obesity populations. More research is necessary to shed light on the pathophysiological mechanisms associated to PAH exposure and diarrhea.