Cancer risk assessment and source apportionment of the gas- and particulate-phase of the polycyclic aromatic hydrocarbons in a metropolitan region in Brazil

Current levels, sources, and risks of human exposure to PAHs, PBDEs and PCBs in South American outdoor air: A critical review

This study provides a comprehensive overview of the current levels, sources and human exposure risks to hazardous polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs) in South American outdoor air. Research documents were obtainable for only 6 countries within the target period (2014-2024). For all contaminants, urban concentrations exceeded that of rural/remote locations. PAHs were extensively reported with concentration reaching 1100 ∑16PAHs/m3 in Southwest of Buenos Aires province, Argentina. The health risk data also exceeded the threshold level in several locations. The profiles and seasonal fluctuations across all studies were widely influenced by the prevalent local/domestic sources. Biomass combustion (particularly of sugar cane/agricultural wastes and wood/coal for residential heating), vehicular emission, and industrial emission were accounted for most PAH sources. Regulations targeting biomass combustion for improved air quality seem not to currently have significant impacts on current PAH levels. PBDEs were widely reported within 0.3-55 pg ∑4-14BDE/m3, albeit high concentrations were documented in Concepción Bay, Chile (maximum = 1100 pg ∑4BDE/m3) and Córdoba, Argentina (maximum = 120 pg ∑4BDE/m3). Most notable source of PBDEs is solid municipal wastes. Similar to other global studies, BDE-47, 99 and 209 dominated the congeners reported. PCBs were reported with the highest concentrations measured in Córdoba, Argentina (maximum = 1700 pg ∑30PCBs/m3), but data remain limited in other important locations such as São Paulo, Brazil. Sources of PCBs were broadly associated with solid wastes, electric transformers, and re-volatilization from polluted environment. PAHs, PCBs and PBDEs were all within average to top global concentrations. This study underscores potential rise in atmospheric level of the target contaminants without sustainable regulatory structure and the need for continuous monitoring of these contaminants as a measure of policy impacts. We provide sustainable recommendations.

A novel approach to source apportionment of VOCs with high potential for ozone and SOA formation using high-resolution data and intraday variability

Volatile organic compounds (VOCs) include a wide range of chemicals, some of which act as precursors to tropospheric ozone and secondary organic aerosols. These compounds are released into the atmosphere from a wide range of sources. We conducted a source apportionment analysis of the hourly concentrations of 16 VOCs with the highest potential to contribute to O3 and SOA formation. VOCs were monitored over an 18-month period in an urbanized and industrialized coastal region in Brazil. A novel approach not previously utilized in the literature, incorporating the Positive Matrix Factorization (PMF) model while accounting for intraday VOC patterns and their dependence on wind direction was used. This method enabled us to identify source contributions during specific times of the day when certain sources had stronger impact. The analysis revealed five factors representing contributions from solvent usage (6-13 %), industrial processes (11-13 %), fuel evaporation (4-13 %), vehicular exhaust (43-46 %), and coke ovens (25-26 %). Some VOCs exhibited hourly variations influenced by both time of day and wind direction, and their respective lifetimes, with long-lived species such as benzene, n-pentane, and ethylbenzene being prevalent between 00:00 and 11:59, correlating with aged air masses, while short-lived species like 1,2,4-trimethylbenzene showed greater directional variability, linked to prevailing winds, indicating recent contributions, suggesting the likely locations of sources. This intraday variation resulted in unique source impacts, highlighting a time dependence that influences source apportionment throughout the day. As a result, source apportionment based on these periodic VOC variations provided valuable insights for developing targeted mitigation strategies.

Seasonality, sources apportionment, human health risks assessments, and potential implications on the atmospheric chemistry of polycyclic aromatic hydrocarbons in size-segregated aerosols from a Romanian metropolitan area

Urbanization and industrialization are important transformations shaping the current statement of the society, enhancing significantly the combustion emissions which are threatening the global climate system, air quality, and human health. These emissions contain polycyclic aromatic hydrocarbons (PAHs) which are well known for their high toxicity. The present study is the first assessing the seasonal variation of 17 PAHs in size segregated fractions of atmospheric aerosol particles from a Romanian metropolitan area. In addition to sources apportionment and health risks, the potential role of PAHs on the atmospheric chemistry in the area was also addressed. Higher PAHs concentrations were determined in winter season, the highest values being quantified for benzo[b]fluoranthene, benzo[a]pyrene, and indeno[1,2,3-cd]pyrene. Each analyzed PAH exhibited a dominant peak in the accumulation mode (0.1-1.0 μm), with maxima at 381 nm. Gasoline combustion was identified as a significant contributor to the PAHs levels in the atmospheric aerosols from the area. Biomass-burning contributions were highlighted during the winter and autumn seasons. The positive matrix factorization (PMF) model apportioned four PAHs sources, as follows: vehicular (31%), mixed combustion (33%), biomass and wood burning (19%), and coal and natural gas combustion (18%) sources. Concentration-weighted trajectory (CWT) analysis method revealed clear contributions to PAHs abundances from local and regional air masses. Alveolar region of adults seems to have the highest susceptibility for PAHs deposition. Values exceeding acceptable limits for carcinogenic risk throughout the year are associated with benzo[a]pyrene, benzo[b]fluoranthene, indeno[1,2,3-cd]pyrene, benzo[a]anthracene etc. The present study can be considered as a reference in the region in order measures of mitigation and control for PAHs emission sources to be introduced.

It's time to reevaluate the list of priority polycyclic aromatic compounds: Evidence from a large urban shallow lake

Monitoring only 16 priority PAHs (Pri-PAHs) may greatly underestimate the pollutant load and toxicity of polycyclic aromatic compounds (PACs) in aquatic environments. There is an urgent need to reevaluate the list of priority PACs. To determine which PACs deserve priority monitoring, the occurrence, sources, and toxicity of 78 PACs, including 24 parent PAHs (Par-PAHs), 49 alkylated PAHs (Alk-PAHs), 3 oxygenated PAHs (OPAHs), carbazole, and dibenzothiophene were investigated for the first time in Lake Chaohu sediments, China. Concentrations of ∑Par-PAHs, ∑Alk-PAHs, and ∑OPAHs ranged from 35 to 165, 3.4-26, and 7.7-26 ng g-1, respectively. Concentrations of 16 Pri-PAHs have decreased by 1-2 orders of magnitude compared to a decade ago, owing to the effective implementation of PAHs emission control measures. Comparisons with the sediment quality guidelines indicated that 16 Pri-PAHs have negligible adverse effects on benthic organisms. Positive matrix factorization (PMF) model results showed that coal combustion was the major source of PACs (accounting for 23.5 %), followed by traffic emissions (23.4 %), petroleum volatilization (21.9 %), wood/biomass combustion (18.2 %), and biological/microbial transformation (13.1 %). The toxicity of PACs was assessed by calculating the BaP toxic equivalent concentrations (TEQBaP) and toxic units. It was found that Par-PAHs were the predominant toxic substances. In addition, monomethyl-BaPs, OPAHs, BeP, and 7,12-DMBaA should be prioritized for monitoring due to their noticeable contributions to overall toxicity. The contributions of different sources to the toxicity of PACs were determined based on PMF model results and TEQBaP values, which revealed that combustion sources mainly contributed to the comprehensive toxicity of PACs in Lake Chaohu sediments.

Source-specific probabilistic health risk assessment of dust PAHs in urban parks based on positive matrix factorization and Monte Carlo simulation

Understanding the health risks of polycyclic aromatic hydrocarbons (PAHs) in dust from city parks and prioritizing sources for control are essential for public health and pollution management. The combination of Source-specific and Monte Carlo not only reduces management costs, but also improves the accuracy of assessments. To evaluate the sources of PAHs in urban park dust and the possible health risks caused by different sources, dust samples from 13 popular parks in Kaifeng City were analyzed for PAHs using gas chromatograph-mass spectrometer (GC-MS). The results showed that the surface dust PAH content in the study area ranged from 332.34 µg·kg-1 to 7823.03 µg·kg-1, with a mean value of 1756.59 µg·kg-1. Nemerow Composite Pollution Index in the study area ranged from 0.32 to 14.41, with a mean of 2.24, indicating that the overall pollution warrants attention. Four pollution sources were identified using the positive matrix factorization (PMF) model: transportation source, transportation-coal and biomass combustion source, coke oven emission source, and petroleum source, with contributions of 33.74%, 25.59%, 22.14%, and 18.54%, respectively. The Monte Carlo cancer risk simulation results indicated that park dust PAHs pose a potential cancer risk to all three populations (children, adult male and adult female). Additionally, the cancer risk for children was generally higher than that for adult males and females, with transportation sources being the main contributor to the carcinogenic risk. Lastly, sensitivity analyses results showed that the toxic equivalent concentration (CS) is the parameter contributing the most to carcinogenic risk, followed by Exposure duration (ED).

Remediation of carcinogenic PAHs from landfill leachate by Electro-Fenton process - Optimization and modeling

PAHs is the group of emerging micro-pollutants present in most environmental matrices that has the tendency to bioaccumulate and cause carcinogenic effects to human health. The present research involved the quantification and treatment of leachate produced from secured landfill, to eliminate the PAHS. Electro-Fenton process, a class of advanced oxidation process, is adopted to degrade the PAHs using titanium electrodes as both anode and cathode. Artificial intelligence based statistical tool "Central Composite Design" a module of JMP -19 software was used to design the experiments and optimize the critical parameters involved in the research. It was observed that the value of P is significant (P < 0.05) for all the independent variables evidencing the significant correlation between experimental values and predicted values of the software. The value of R2 obtained was 0.96 and 0.97 for COD and PAHs respectively. The maximum removal efficiency of COD and PAH was found to be 84.24% and 90.78% respectively. The optimized conditions obtained from the central composite design were: pH = 5; Fe2+ = 0.1 g/L; H2O2 = 2 g/L; reaction time = 60 min; and electric intensity = 0.2 A. Additionally, optimized experimental conditions were used to study the removal efficiencies of individual 16 PAHs and are also reported. From the close proximity of experimental and predicted results of the software it can be proved that central composite design is efficient enough to be used as a statistical tool in design and analysis for treatment of landfill leachate.

Occurrence of BTX and PAHs in underground drinking water of coking contaminated sites: Linkage with altitude and health risk assessment by boiling-modified models

The safety of underground drinking water has received widespread attention. However, few studies have focused on the occurrence and health risks of pollutants in underground drinking water of coking contaminated sites. In this study, the distribution characteristics, sources, and human health risks of benzene, toluene, xylene (BTX) and polycyclic aromatic hydrocarbons (PAHs) in underground drinking water from a typical coking contaminated site in Shanxi of China were investigated. The average concentrations of BTX and PAHs in coking plant (CP) were 5.1 and 4.8 times higher than those in residential area (RA), respectively. Toluene and Benzene were the main BTX, while Acenaphthene, Fluorene, and Pyrene were the main PAHs. Concentrations of BTX/PAHs were negatively correlated with altitude, revealing altitude might be an important geological factor influencing spatial distribution of BTX/PAHs. PMF model demonstrated that the BTX/PAHs pollution in RA mainly originated from coking industrial activities. Health risk assessments were conducted by a modified US EPA-based model, in which environmental concentrations were replaced by residual concentrations after boiling. Residual ratios of different BTX/PAHs were determined by boiling experiments to be 9.4-93.8 %. The average total carcinogenic risks after boiling were decreased from 2.6 × 10-6 to 1.4 × 10-6 for adults, and from 4.3 × 10-6 to 2.1 × 10-6 for children, suggesting boiling was an effective strategy to reduce the carcinogenic risks from BTX/PAHs, especially for ingestion pathway. Monte Carlo simulation results matched well with the calculated results, suggesting the uncertainty was acceptable and the risk assessment results were reliable. This study provided useful information for revealing the spatial distribution of BTX/PAHs in underground drinking water of coking contaminated sites, understanding their linkage with altitude, and also helped to more accurately evaluate the health risks by using the newly established boiling-modified models.

Breathing in danger: Unveiling the link between human exposure to outdoor PM2.5-bound polycyclic aromatic hydrocarbons and lung cancer risk in an urban residential area of China

Numerous studies have extensively examined the risk of lung cancer associated with polycyclic aromatic hydrocarbons (PAHs), with particular emphasis on the 16 priority PAHs. However, this may underestimate the actual risk. This study seeks to enhance the current risk assessment framework by integrating four additional parent PAHs such as Dibenzo[a,h]pyrene, Dibenzo[a,l]pyrene, Dibenzo[a,e]pyrene, 7H-benzo[c]fluorene with potentially high risk of causing cancer. By considering their physicochemical properties, metabolism, and bioavailability, the study also examines the relationship between low molecular weight (LMW) - and high molecular weight (HMW)-PAH doses and the risk of developing cancer in the human lungs. The study was conducted in Ningbo, China and identified five PAH sources: natural gas combustion (NGC), vehicular exhaust (VE), coal combustion (CC), biomass burning (BB), and volatilization of unburnt fuel (VUF). This study emphasizes the elevated risk associated with highly carcinogenic PAHs, as they consistently exceed acceptable limits for lung cancer risk throughout the year. Based on the study's estimation, approximately 324 out of every one million individuals exposed to PAHs face an increased cancer risk over their lifetime. This research emphasizes the importance of identifying source specific lung cancer risk in residential areas to protect the exposed population. Moreover, while there is a moderate connection between LMW-PAH doses and lung cancer risk, a strong relationship is observed with HMW-PAHs.

A critical insight into occurrence and fate of polycyclic aromatic hydrocarbons and their green remediation approaches

Over the last century, the tremendous growth in industrial activities particularly in the sectors of pharmaceuticals, petrochemicals and the reckless application of fertilizers and insecticides has raised the contamination of polyaromatic hydrocarbons (PAHs) tremendously. For more than a decade, the main focus of environmental experts is to come up with management approaches for the clean-up of sites polluted with PAHs. These are ubiquitous in nature i.e., widely distributed in ecosystem ranging from soil, air and marine water. Most of the PAHs possess immunotoxicity, carcinogenicity and genotoxicity. Being highly soluble in lipids, they are readily absorbed into the mammalian gastro intestinal tract. They are widely distributed with marked tendency of getting localized into body fat in varied tissues. Several remediation technologies have been tested for the removal of these environmental contaminants, particularly bioremediation has turned out to be a hope as the safest and cost-effective option. Therefore, this review first discusses various sources of PAHs, their effect on human health and interactions of PAHs with soils and sediments. In this review, a holistic insight of current scenario of existing remediation technologies and how they can be improvised along with the hindrances in the path of these technologies are properly addressed.