Polycyclic aromatic hydrocarbons (PAHs) in indoor dusts of Guizhou, southwest of China: status, sources and potential human health risk

Health risks of environmentally persistent free radicals in atmospheric particulate matter during the spring festival travel season in Tainan, Taiwan

Environmentally persistent free radicals (EPFRs) and polycyclic aromatic hydrocarbons (PAHs) are persistent pollutants in atmospheric particulate matter that are detrimental to human health. This study collected atmospheric particulate matter during and after the spring festival travel season in Tainan, Taiwan, from various locations and analyzed the carbon composition and PAH isomeric ratios to identify the sources. In this study, EPFR concentrations were measured using electron paramagnetic resonance spectroscopy, with the highest concentration found to be 3.04 × 10(12) spins/m3. EPFRs contained predominantly oxygen-centered radicals in PM2.5, which are mainly existed in PM1. The results show that EPFR concentrations on PM, measured per unit volume (spins/m3) or mass (spins/g), were highest during the spring festival travel season. The daily inhalation exposure to the sum of EPFRs and PAHs in PM2.5 was estimated to be equivalent to inhaling 0.11-0.15 cigarette tar EPFRs per day. This report is the first to document EPFRs in environmental atmospheric particulate matters in Taiwan, which has significantly contributed to local air pollution control and reduced exposure risks to public health in Tainan.

Characterization and risk assessment of polycyclic aromatic hydrocarbons from the emission of different power generator

Epileptic power supply in Sub-Saharan countries of Africa has warranted the use of power generators as an alternative source of power supply. Exhaust emission from these generators is associated with Polycyclic Aromatic Hydrocarbon (PAHs). Hence, this study focused on the determination of levels of PAHs in the emission of different brands of power generators used in Nigeria. Exhaust emissions of different power generators were sampled using a filter-sorbent sampling system with polyurethane foam (PUF) as an adsorbent material. Analysis of PAHs was carried out using a Gas Chromatograph coupled to a mass selective detector (GC- MS) operated on Electron Ionization (EI) mode. The results showed the ∑ PAHs range 14.91-26.0 μ g m - 3 . Bap was the most abundant of all the compounds with a concentration of 2.6 μ g m - 3 with a range of 2.08-3.07 μ g m - 3 . The Incremental Life Cancer Risk (ILCR) values of all the generator's emission sampled are higher than 10- 4 for both children and adult which indicate a high potential cancer risk from inhalation of emission from these generators while Hazard Quotient (HQ) values from all the power generating set in this study are all above 1 which indicated high associated non-carcinogenic. The study revealed the levels of PAHs associated with the emission of power generators in Nigeria.

Polycyclic aromatic hydrocarbons in dust from rural communities around gas flaring points in the Niger Delta of Nigeria: an exploration of spatial patterns, sources and possible risk

Indoor and outdoor dust from three rural communities (Emu-Ebendo, EME, Otu-Jeremi, OTJ, and Ebedei, EBD) around gas flaring points, and a rural community (Ugono Abraka, UGA) without gas flare points, in the Niger Delta of Nigeria, was analysed for the concentrations and distribution of polycyclic aromatic hydrocarbons (PAHs), their sources, and possible health risk resulting from human exposure to PAHs in dust from these rural communities. The PAHs were extracted from the dust with a mixture of dichloromethane/n-hexane by ultrasonication, and purified on a silica gel/alumina packed column. Gas chromatography-mass spectrometry was employed to determine the identity and concentrations of PAHs in the cleaned extracts. The Σ16PAH concentrations in the indoor dust ranged from 558 to 167 000, 6580 to 413 000, and 2350-37 500 μg kg-1 for EME, OTJ and EBD respectively, while those of their outdoor counterparts varied from 347 to 19 700, 15 000 to 130 000, and 1780 to 46 300 μg kg-1 for EME, OTJ and EBD respectively. On the other hand, the UGA community without gas flare points had Σ16PAH concentrations in the range of 444-5260 μg kg-1 for indoor dust, and 154-7000 μg kg-1 for outdoor dust. The lifetime cancer risk values for PAHs in these matrices surpassed the acceptable limit of 10-6 suggesting a potential carcinogenic risk resulting from human exposure to PAHs in indoor and outdoor dust from these rural communities. Principal component analysis suggested that PAH contamination of dust from these communities arises principally from gas flaring, combustion of wood/biomass, and vehicular emissions.

A nationwide survey of polycyclic aromatic hydrocarbons (PAHs) in household dust in China: spatial distribution, sources, and health risk assessment

As a carrier of toxic substances, household dust has a great impact on human health. Here we collected 73 household dust samples from 27 provinces and 1 municipality in China to investigate the levels, spatial distribution, sources, and carcinogenic risk of 16 polycyclic aromatic hydrocarbons (PAHs). The total concentrations of 14 detected PAHs (∑₁₄ PAHs) ranged from 3.72 to 60,885 ng g^-1. High ∑₁₄ PAHs were found in Northeast and Southwest China. High molecular weights (HMW) PAHs (4-6 rings) were predominant PAHs in most dust samples, accounting for 93.6% of ∑₁₄ PAHs. Household fuel, cooking frequency, air conditioning, and smoking were the main factors influencing PAH concentrations in household dust. Principal component analysis model indicated that fossil combustion (81.5%) and biomass combustion and vehicle exhaust (8.1%) are the primary sources of PAHs. Positive matrix factorization model suggested that household cooking and heating contributed about 70% of ∑₁₄ PAHs, and smoking contributed another 30%. The values of benzo[a]pyrene equivalent in rural dust were found to be higher than those in urban dust. The sum of toxic equivalents (TEQs) of 14 PAHs were in range of 0.372-7241 ng g^-1, in which 7 HMW PAHs accounted for 98.0 ± 1.98% of the total TEQs. Monte Carlo Simulation showed a low to moderate potential carcinogenic risk of PAHs in household dusts. This study documents comprehensive information on human exposure to PAHs in household dust at a national-scale.

Co-occurrence of polycyclic aromatic hydrocarbons and their oxygenated derivatives in indoor dust from various microenvironments in Guangzhou, China: levels, sources, and potential human health risk

For decades, the presence and potential health risk of polycyclic aromatic hydrocarbons (PAHs) in indoor dust have been extensively investigated while with limited attention to oxygenated PAHs (OPAHs). In this study, we collected 45 indoor dust from four microenvironments in Guangzhou City, China, and then focused on the co-occurrence of 16 PAHs and 8 OPAHs and their potential carcinogenic risk to humans. The ΣPAHs concentrations, dominated by 4-6 ring PAHs, ranged from 1761 to 14,290 ng/g (mean of 6058 ng/g) without significant difference in the different microenvironments (Tukey, p > 0.05). The OPAHs were observed with concentrations from 250 to 5160 ng/g (mean of 1646 ng/g), and anthraquinone (AQ) was identified as the main OPAHs with significantly high levels in the residential environment than in instrumental rooms. Notably, AQ dominated over the other target analytes in dust in this study. Our results indicated that PAHs and OPAHs in indoor dust were from outdoor environments, which mainly originated from vehicular exhaust and biomass/coal combustion. A potential cancer risk of PAHs and OPAHs to local adults and children was observed via inhalation, ingestion, and dermal absorption, with the main contribution from benzo[a]pyrene and dibenz[a,h]anthracene.

Emission and distribution profiles of polycyclic aromatic hydrocarbons in solid residues of municipal and industrial waste incinerators, Northern Vietnam

The concentrations and profiles of 18 polycyclic aromatic hydrocarbons (PAHs) in particulate matter (PM₁₀), fly ash (FA), and bottom ash (BA) were examined in three incineration residues. Samples were collected from different municipal and industrial solid waste incinerators in Northern Vietnam. The average concentrations of total PAHs in PM₁₀, fly ash, and bottom ash were 9.55 × 10³ ng/Nm³, 215 × 10³ ng/g, and 2.38 ng/g, respectively. Low-molecular-weight PAHs (2 to 3 rings) were predominant in most samples. The emission factor of total PAHs decreased in the order of FA > BA > PM₁₀. A higher concentration of total PAHs was found in industrial facilities than that in municipal ones. The high carcinogenic proportion of PAHs together with significantly high annual emissions reflect the high pollution risk to the ecosystem by PAHs in the case of reuse of incineration ashes (e.g., brick production). Regarding the carcinogenic risk of PAH-bounded ashes or particles, calculations from this study imply the significant threat for workers who have been manipulated in the incineration facilities, directly exposed to fly and bottom ashes. Meanwhile, the risk from PAH-bound particulate was not considered a significant threat for both normal adults and children. Further study on PAHs contained in incinerator waste dumps should be conducted in Vietnam to assess the potential contamination risk of these incineration by-products.

Impact of Atmospheric Polycyclic Aromatic Hydrocarbons (PAHs) of Falling Dust in Urban Area Settings: Status, Chemical Composition, Sources and Potential Human Health Risks

The present work is considered to investigate the sources, concentration, and composition of polycyclic aromatic hydrocarbons (PAHs) and associated health risk assessment of road dust in Riyadh City, Saudi Arabia. The study region included an urban area, strongly affected by traffic, a bare and an industrial area. A total of 50 locations were selected for sampling and 16 different PAHs were determined. The concentration of PAHs in road dust and their estimated lifetime average daily dose (LADD) for adults (human) ranged from 0.01 to 126 ng g−1 and 1950 to 16,010 mg kg−1 day−1, respectively. The ADDing was calculated separately for children (>6), teenagers (6−12), and adults (>12) for all PAHs with each collected sample. Moreover, the average daily exposure dose by ingestion (ADDing) and average daily exposure dose by dermal absorption (ADDder) were more in children (<6 years) as compared to teenagers (6−12 years) and adults (>12 years). Likewise, total equivalency factor based on BaP (TEQBaP) calculations pointed out that PAHs having more benzene rings or having high molecular weight showed high TEQBaP as compared to low molecular weight PAHs. The data revealed that the children population is at high risk for asthma, respiratory and cardiovascular diseases, and immunity suppression as compared to adults in the particular area of investigated region. These outcomes of this study can be used to deliver significant policy guidelines concerning habitants of the area for possible measures for controlling PAHs contamination in Riyadh City to protect human health and to ensure environmental sustainability.

Is Poland at risk of urban road dust? Comparison studies on mutagenicity of dust

Depopulation concerns many polish cities, with the exception of a few metropolises such as Wrocław (Lower Silesia) and Katowice (Upper Silesia) where investments are growing and therefore more humans are exposed to urban environmental pollution. Accumulation of toxic substances on road surfaces is a major global challenge requiring methods of assessing risk that initiate the proper management strategies. In this study urban road dust (URD) has been collected at seventeen sites in Lower and Upper Silesia regions in Poland renowned for their elevated level of pollution. The aim of the study was: (i) to determine PAH concentration in URD in both regions with the identification of their possible sources based on diagnostic ratio; (ii) to assess possible mutagenic effects of URD with the application of Ames test (Salmonella assay); (iii) to define a possible carcinogenic risk related to URD in both studied regions. We found that the total PAH content of collected URD samples ranged from 142.4 to 1349.4 ng g^-1. The diagnostic ratio of PAHs in URD for all studied sites showed that pyrogenic combustion predominated indicating traffic-related and biomass sources of pollution. The Ames assay, which has never been used in studies of URD in Poland, demonstrated that in both regions, URD samples (from eight sites), were characterised by the highest mutagenicity values. Additionally, Incremental Lifetime Cancer Risk (ILCR) values, based on PAH content only, were between 10 and 6 to 10-4 indicating potential risk of cancer. Reassuming, humans in both agglomerations are exposed to factors or compounds with carcinogenic properties which may have an adverse health effect through the urban road dust mainly due to vehicular traffic, heating systems and industrial activities.

Polycyclic Aromatic Hydrocarbons in Indoor Dust in Croatia: Levels, Sources, and Human Health Risks

Compounds that contribute to indoor pollution are regularly investigated due to the fact that people spend most of their time indoors. Worldwide investigations have shown that polycyclic aromatic hydrocarbons (PAHs) are present in indoor dust, but to the best of our knowledge, this paper reports for the first time the presence of PAHs in Croatian households. Eleven PAHs were analysed in house dust samples collected in the city of Zagreb and surroundings (N = 66). Their possible indoor sources and the associated health risks were assessed. Total mass fraction of detected PAHs ranged from 92.9 ng g^-1 to 1504.1 ng g^-1 (median 466.8 ng g^-1), whereby four-ring compounds, Flu and Pyr, contributed the most. DahA was the only compound that did not show statistically significantly positive correlation with other analysed PAHs, indicating that it originated from different sources. Based on diagnostic ratios and principal component analysis (PCA), mixed sources contributed to PAHs levels present in Croatian households. Although our results indicate that Croatian house dusts are weakly polluted with PAHs, total ILCR values calculated for children and adults revealed that people exposed to the highest mass fractions of PAHs measured in this area are at elevated cancer risk.

Health Risk Assessment on Exposure to PM2.5-bound PAHs from an Urban-industrial Area in Rayong City, Thailand

BACKGROUND: A city's industrial area's air quality has become a major priority. PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) are one of the most common pollutants in urban-industrial area, and can be linked to health problems. AIM: This study aims to 1) investigate PM2.5 and PAHs emitted from roadside area (RS) and industrial estate (IE) in Rayong city 2) assess the inhalation of PM2.5 and PAHs on the human health of the age group. METHODS: PM2.5-bound PAHs were investigated and thier carcinogenic risk was evalued in this study. PM2.5 samples were collected on quartz filters contained in a mini-volume air sampler and analyzed for PAHs by GC-MS. RESULTS: The average PM2.5 concentrations at RS and IE were 43.3±26.8 and 40.4±21.7 µg/m3, while the values of total PAHs in both sites were 1.68±1.53 and 1.34±1.22 ng/m3, respectively. However, it was found that the PM2.5 and PAHs values were not significantly different (p>0.05). The results revealed that the individual lifetime cancer risk (Ric) of PM2.5 values for children and adults at both sites indicated acceptable cancer risk (10-6 to10-4). According to the incremental lifetime cancer risk (ILCR) values of PAHs for different age groups, exposure to PAHs in PM2.5 through the inhalation pathway was a negligible (<10-6). CONCLUSION: As a result, the PM2.5 concentrations have substantial implications for Rayong city’s environmental management and protection, relating to car emissions and coal combustion.

Polycyclic aromatic hydrocarbons in road dusts of a densely populated African city: spatial and seasonal distribution, source, and risk assessment

Road dust is a principal source and depository of polycyclic aromatic hydrocarbons (PAHs) in many urban areas of the world. Hence, this study probed the spatial and seasonal pattern, sources, and related cancer health risks of PAHs in the road dusts sampled at ten traffic intersection (TIs) of a model African city. Mixed PAHs sources were ascertained using the diagnostic ratios and positive matrix factorization (PMF) model. The results showed fluctuations in mean concentrations from 36.51 to 43.04 µg/g. Three-ring PAHs were the most abundant PAHs with anthracene (Anth) ranging from 6.84 ± 1.99 to 9.26 ± 4.42 µg/g being the predominant pollutant in Ibadan. Benzo(k)Fluoranthene (BkF) which is a pointer of traffic emission was the most dominant among the seven carcinogenic PAHs considered, varying from 2.68 ± 0.43 to 4.59 ± 0.48 µg/g. Seasonal variation results showed that PAH concentrations were 20% higher during dry season than rainy season. The seven sources of PAHs identified by PMF model include the following: diesel vehicle exhausts, gasoline combustion, diesel combustion, coal tar combustion, gasoline vehicle exhausts, coal and wood (biomass) combustion, and emissions from unburnt fossil fuels. Employing the incremental lifetime cancer risk (ILCR) model, the city's cancer risk of 5.96E-05 for children and 6.60E-05 for adults were more than the satisfactory risk baseline of ILCR ≤ 10^-6 and higher in adults than in Children.

PM-Bound Polycyclic Aromatic Hydrocarbons and Nitro-Polycyclic Aromatic Hydrocarbons in the Ambient Air of Vladivostok: Seasonal Variation, Sources, Health Risk Assessment and Long-Term Variability

Total suspended particles (TSP) were collected in Vladivostok, Russia, which is a typical port city. This study investigated the concentration, potential sources, and long-term variation in particle PAHs and NPAHs in the atmosphere of Vladivostok. The PAH and NPAH concentrations were higher in winter than in summer (PAHs: winter: 18.6 ± 9.80 ng/m3 summer: 0.54 ± 0.21 ng/m3; NPAHs: winter: 143 ± 81.5 pg/m3 summer: 143 ± 81.5 pg/m3). The diagnostic ratios showed that PAHs and NPAHs mainly came from vehicle emissions in both seasons, while heating systems were the main source of air pollution in winter. The TEQ assessment values were 2.90 ng/m3 and 0.06 ng/m3 in winter and summer, respectively, suggesting a significant excess cancer risk in the general population in winter. The ILCR values conveyed a potential carcinogenic risk because the value was between 1 × 10-5 and 1 × 10-7 and ingestion was a main contributor in Vladivostok. However, it is worth noting that the concentrations of PAHs and NPAHs showed an overall downward trend from 1999 to 2020. An important reason for this is the cogenerations project implemented by the Far Eastern Center for Strategic Research on Fuel and Energy Complex Development in 2010. This research clarified the latest variations in PAHs and NPAHs to provide continuous observation data for future chemical reaction or model prediction research.

Correlation of Occupational Exposure to Carcinogenic Polycyclic Aromatic Hydrocarbons (cPAHs) and Blood Levels of p53 and p21 Protiens

Carcinogenic polycyclic aromatic hydrocarbons (cPAHs) are considered the most serious cancer risk. This study was conducted to assess the effect of acute exposure to cPAHs on cancer biomarker proteins p53 and p21 in occupational workers during the hajj season in Makkah. One hundred five participants were recruited, including occupational workers and apparently healthy individuals; air samples were collected using personal sample monitors to identify the subjects’ exposure to cPAHs. Quantitative analyses of benzo(a)anthracene (BaA), benzo(b)fluoranthene (BbF), benzo(a)pyrene (BaP), dibenzo(a,h)fluronathene (DBA), indeno(1,2,3-c,d)pyrene (IND) and chyresene (CRY) were carried out using the GC/Mass technique. Serum p53 and p21 proteins were analyzed using ELISA. The ambient air samples collected by the occupationally exposed group were more highly polluted by cPAHs, (90.25 ± 14.1) ng/m³, than those of the unexposed control groups, (30.12 ± 5.56) ng/m³. The concentration of distributive cPAHs was markedly more elevated in the air samples of the exposed group than in those taken from the non-exposed group. The study results demonstrated significant links between short-term exposure to cPAHs and serum p53 and p21 levels. Serum p53 and p21 proteins potentially influence biomarkers when exposed to ambient air cPAHs.

Ecological and human health risks assessment of some polychlorinated biphenyls (PCBs) in surface soils of central and southern parts of city of Tehran, Iran

PURPOSE

The present study was conducted to evaluate the carcinogenic and non-carcinogenic hazards of polychlorinated biphenyls (PCBs) in topsoil across business districts, public green space, cultural and educational areas, and roadside and residential areas in city of Tehran, in 2019.

METHOD

A total of 30 surface urban soil specimens were collected and after preparing them in the laboratory, PCBs contents were determined using gas chromatography-mass spectrometry.

RESULTS

Based on the results of data analyses, the median concentrations of PCB18, PCB28, PCB 29, PCB 31, PCB 44, PCB 52, PCB 101, PCB 138, PCB 141, PCB 149, PCB 153, PCB 189 and PCB 194, were found to be 6.81, 0.759, 0.005, 1.75, 2.51, 0.059, 2.31, 3.76, 5.82, 0.599, 0.408, 0.008 and 0.008 µg/kg, respectively. Also, the overall daily PCBs intakes via soil ingestion, inhalation and skin contact were 5.48E-04, 1.19E + 00 and 1.62E-04 µg/kg, respectively. Thus it was decided that the inhalation of soil could be the main pathway of exposure to PCBs, and that, based on the carcinogenic risk outcomes, children would be more at risk of cancer than adults would.

CONCLUSIONS

In general, considering that among the studied urban spaces, the contents of PCBs in public green spaces were more than their rates in other areas, and considering that children normally play in the green areas are, it is recommended that special attention be paid to these areas in controlling and removing pollution caused by PCBs in urban areas.

Polycyclic Aromatic Hydrocarbons (PAHs) in Indoor Dust Across China: Occurrence, Sources and Cancer Risk Assessment

In this study, the occurrence of 16 polycyclic aromatic hydrocarbons (PAHs) was investigated in 31 household dusts that were sampled from 27 areas located in 10 provinces, China. The total concentrations of PAHs (∑ PAHs) were in the range of 613-10,111 ng·g^-1 with a median of 2565 ng·g^-1. The predominant PAHs were 2 to 3 ringed compounds, accounting for 85.3% of ∑ PAHs. The geographical location had little impact on the contents of PAHs. Higher concentrations of ∑ PAHs and individual homologues of PAHs except for naphthalene (NAP) were observed in rural areas, which is related to the higher usage of coal or biomass for cooking. Cooking method played a major role in contributing to the concentrations of PAHs. Both household cooking and petrogenic sources from outdoors were the primary sources of PAHs in household dust. Cancer risk assessment indicated that dermal contact and ingestion are the main exposure pathways to indoor residents. Furthermore, the average values of sum of incremental lifetime cancer risks (ILCRs) were 2.22 × 10^-7 for adults and 2.51 × 10^-7 for children, suggesting that there is a low health risk posed by PAHs in indoor dust. The contribution percentage of 4 to 6 rings PAHs to ILCRs was up to 96.3%, indicating that higher molecular weight PAHs in indoor dust, especially benzo[a]pyrene (BaP) and dibenzo[a,h]anthracene (DahA), are major factors contributing to cancer risk.

A review on analysis methods, source identification, and cancer risk evaluation of atmospheric polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) have gained attention because of their environmental persistence and effects on ecosystems, animals, and human health. They are mutagenic, carcinogenic, and teratogenic. The review provides background knowledge about their sources, metabolism, temporal variations, and size distribution in atmospheric particulate matter. The review article briefly discusses the analytical methods suitable for the extraction, characterization, and quantification of nonpolar and polar PAHs, addressing the challenges. Herein, we discussed the molecular diagnostic ratios (DRs), stable carbon isotopic analysis (SCIA), and receptor models, with much emphasis on the positive matrix factorization (PMF) model, for apportioning PAH sources. Among which, DRs and PCA identified as the most widely employed method, but their accuracy for PAH source identification has received global criticism. Therefore, the review recommends compound-specific isotopic analysis (CSIA) and PMF as the best alternative methods to provide detailed qualitative and quantitative source analysis. The compound-specific isotopic signatures are not affected by environmental degradation and are considered promising for apportioning PAH sources. However, isotopic fractions of co-eluted compounds like polar PAHs and aliphatic hydrocarbons make the PAHs isotopic fractions interpretation difficult. The interference of unresolved complex mixtures is a limitation to the application of CSIA for PAH source apportionment. Hence, for CSIA to further support PAH source apportionment, fast and cost-effective purification techniques with no isotopic fractionation effects are highly desirable. The present review explains the concept of stable carbon isotopic analysis (SCIA) relevant to PAH source analysis, identifying the techniques suitable for sample extract purification. We demonstrate how the source apportioned PAHs can be applied in assessing the health risk of PAHs using the incremental lifetime cancer risk (ILCR) model, and in doing so, we identify the key factors that could undermine the accuracy of the ILCR and research gaps that need further investigation.

Distribution, sources and exposure risk of polycyclic aromatic hydrocarbons in soils, and indoor and outdoor dust from Port Harcourt city, Nigeria

In this study, we evaluated the concentrations, composition, sources, and potential risks of polycyclic aromatic hydrocarbons (PAHs) in soils, and indoor and outdoor dust from Port Harcourt city in Nigeria. Gas chromatography-mass spectrometry (GC-MS) was used for the detection and quantification of PAH species in the samples. The concentrations of the US EPA 16 PAHs plus 2-methyl-naphthalene (∑17 PAHs) in soils, and indoor and outdoor dust from Port Harcourt city ranged from 240 to 38 400, 276 to 9130 and 44 to 13 200 μg kg^-1 (dry weight, d.w.) respectively. The PAH concentrations in these matrices followed the sequence: soil > indoor dust > outdoor dust. The composition of PAHs in soils and dust (indoor and outdoor) showed remarkable differences with prominence of 3- and 5-ring PAHs. The estimated carcinogenic risk to the residents arising from exposure to these concentrations of PAHs in soils, and indoor and outdoor dust from Port Harcourt was above the acceptable target cancer risk value of 10^-6. We concluded that these sites require clean-up, remedial actions and implementation of stringent pollution control measures with the intention of reducing the undesirable impacts of PAHs on both the ecosystem and humans.

Assessment of incremental lifetime cancer risks of ambient air PM10-bound PAHs in oil-rich cities of Iran

This study investigates the concentrations of PM₁₀-bound PAHs and their seasonal variations in three cities of Ahvaz, Abadan, and Asaluyeh in Iran. The mean concentrations of PM₁₀ in two warm and cold seasons in Ahvaz were higher and in Abadan and Assaluyeh were lower than the national standard of Iran and the guidelines of the World Health Organization. The Σ16 PAHs concentration in ambient air PM₁₀ during the cold season in Ahvaz, Abadan and Asaluyeh was 244.6, 633, and 909 ng m^- 3, respectively, and during the warm season in Ahvaz, Abadan, and Asaluyeh was 242.1, 1570 and 251 ng m^- 3, respectively. The high molecular weight PAHs were the most predominant components. The most abundant PAHs species were Pyr, Chr, B [ghi] P, and Flt. The results showed that the total PAHs concentration in the cold and warm seasons was dependent on industrial activities, particularly the neighboring petrochemical units of the city, vehicular exhausts, traffic and use of oil, gas, and coal in energy production. The total cancer risk values as a result of exposure to PAHs in ambient air PM₁₀ in all three cities for children and adults and in both cold and warm seasons were between 1 × 10^- 6 and 1 × 10^- 4, and this indicates a potential carcinogenic risk. Therefore, considering the various sources of air pollutants and its role on people's health, decision makers should adopt appropriate policies on air quality to reduce the ambient air PAHs and to mitigate human exposure.

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.

Source, Characterization of Indoor Dust PAHs and the Health Risk on Chinese Children

Polycyclic aromatic hydrocarbons (PAHs) in indoor dust are one of the common exposure sources for children worldwide. The aim of this study is to explore PAHs pollution status in indoor dust and estimate health risk on Chinese children with big data. Weighted average concentration was used to analyze source and characterization of PAHs in indoor dust based on peer-reviewed literature. According to specific inclusion criteria, 17 studies were included finally to analyze weighted average concentration. The national average concentration of Σ₁₆PAHs was approximately 25.696 µg/g. The highest concentration of Σ₁₆PAHs was in Shanxi (2111.667 µg/g), and the lowest was in Hong Kong (1.505 µg/g). The concentrations in Shanxi and Guangdong were higher than national level and the over standard rate was 18.18%. The concentrations of individual PAHs varied greatly across the country, and Flu in Shanxi was the highest (189.400 µg/g). The sources of PAHs varied in different regions and combustion processes played a leading role. PAHs exposure through ingestion and dermal contact was more carcinogenic than inhalation. The incremental lifetime cancer risk model indicated that children lived in Shanxi were found in the highest health risk coupled with the highest BaPE concentration (54.074 µg/g). Although PAHs concentrations of indoor dust showed a downward trend from 2005 to 2018, indoor environmental sanitation should be improved with multidisciplinary efforts. Health standard should be possibly established to minimize children exposure to PAHs in indoor dust in China.

Characterization of adipogenic, PPARγ, and TRβ activities in house dust extracts and their associations with organic contaminants

In this study, we sought to expand our previous research on associations between bioactivities in dust and associated organic contaminants. Dust samples were collected from central NC homes (n = 188), solvent extracted, and split into two fractions, one for analysis using three different bioassays (nuclear receptor activation/inhibition and adipocyte development) and one for mass spectrometry (targeted measurement of 124 organic contaminants, including flame retardants, polychlorinated biphenyls, perfluoroalkyl substances, pesticides, phthalates, and polycyclic aromatic hydrocarbons). Approximately 80% of dust extracts exhibited significant adipogenic activity at concentrations that are comparable to estimated exposure for children and adults (e.g. ~20 μg/well dust) via either triglyceride accumulation (65%) and/or pre-adipocyte proliferation (50%). Approximately 76% of samples antagonized thyroid receptor beta (TRβ), and 21% activated peroxisome proliferator activated receptor gamma (PPARγ). Triglyceride accumulation was significantly correlated with TRβ antagonism. Sixty-five contaminants were detected in at least 75% of samples; of these, 26 were correlated with adipogenic activity and ten with TRβ antagonism. Regression models were used to evaluate associations of individual contaminants with adipogenic and TRβ bioactivities, and many individual contaminants were significantly associated. An exploratory g-computation model was used to evaluate the effect of mixtures. Contaminant mixtures were positively associated with triglyceride accumulation, and the magnitude of effect was larger than for any individually measured chemical. For each quartile increase in mixture exposure, triglyceride accumulation increased by 212% (RR = 3.12 and 95% confidence interval: 1.58, 6.17). These results suggest that complex mixtures of chemicals present in house dust may induce adipogenic activity in vitro at environmental concentrations and warrants further research.

Characterization of adipogenic, PPARγ, and TRβ activities in house dust extracts and their associations with organic contaminants

In this study, we sought to expand our previous research on associations between bioactivities in dust and associated organic contaminants. Dust samples were collected from central NC homes (n = 188), solvent extracted, and split into two fractions, one for analysis using three different bioassays (nuclear receptor activation/inhibition and adipocyte development) and one for mass spectrometry (targeted measurement of 124 organic contaminants, including flame retardants, polychlorinated biphenyls, perfluoroalkyl substances, pesticides, phthalates, and polycyclic aromatic hydrocarbons). Approximately 80% of dust extracts exhibited significant adipogenic activity at concentrations that are comparable to estimated exposure for children and adults (e.g. ~20 μg/well dust) via either triglyceride accumulation (65%) and/or pre-adipocyte proliferation (50%). Approximately 76% of samples antagonized thyroid receptor beta (TRβ), and 21% activated peroxisome proliferator activated receptor gamma (PPARγ). Triglyceride accumulation was significantly correlated with TRβ antagonism. Sixty-five contaminants were detected in at least 75% of samples; of these, 26 were correlated with adipogenic activity and ten with TRβ antagonism. Regression models were used to evaluate associations of individual contaminants with adipogenic and TRβ bioactivities, and many individual contaminants were significantly associated. An exploratory g-computation model was used to evaluate the effect of mixtures. Contaminant mixtures were positively associated with triglyceride accumulation, and the magnitude of effect was larger than for any individually measured chemical. For each quartile increase in mixture exposure, triglyceride accumulation increased by 212% (RR = 3.12 and 95% confidence interval: 1.58, 6.17). These results suggest that complex mixtures of chemicals present in house dust may induce adipogenic activity in vitro at environmental concentrations and warrants further research.

The occurrence and levels of polycyclic aromatic hydrocarbons (PAHs) in African environments-a systematic review

In the African continent, several studies have been conducted to determine PAH pollution levels with their associated health risks in the environment. However, these studies are very much disconnected. The objective of this study is to conduct a systematic review that serves as a comprehensive report on the PAH-related studies conducted in the African continent. Data sources are from Google Scholar and PubMed. English language studies that reported on PAH levels in smoked fish and meat, soils and dust, aquatic environments, indoor and outdoor air, and ready-to-eat food items were selected. Specific PAHs included the following: 33 PAHs comprising of the 16 USEPA PAHs, non-alkylated PAHs, non-alkylated PAHs, oxygenated PAHs (OPAHs), and azaarenes (AZAs). Study appraisal and synthesis methods: The Newcastle-Ottawa Scale (NOS) was adapted to assess the quality of the selected studies basing on their sampling methods, analytical techniques, and results. A total of 121 studies were reviewed, with the majority (56) being from Nigeria. PAH levels in smoked fish and meat, soils and dust, aquatic environments, indoor and outdoor air, and ready-to-eat food items recorded total concentrations of PAHs ranging from 5 to 3585 μg/kg, BDL to 6,950,000 μg/kg, 0 to 10,469,000 μg/kg, 0 to 7.82 ± 0.85 μg/m³, and 2.5 to 7889 ± 730 μg/kg respectively. Carcinogenic risk assessment for children and adults ranged from very low to very high levels when compared to the ILCR range (10^-6 to 10^-4) defined by the USEPA. Out of 54 African countries, only 19 were represented. The majority of selected studies failed to apply any standard protocols for sample collection and analysis. The low to very high PAH levels reported in studies calls for effective actions on environmental health. Similar systematic reviews are expected to be performed in other continents for a global assessment of PAH pollution.

Concentration levels and carcinogenic and mutagenic risks of PM2.5-bound polycyclic aromatic hydrocarbons in an urban-industrial area in South Africa

Concerns over the health effects of exposure to particulate matter of aerodynamic diameter of less than 2.5 μm (PM_2.5) led the South African Government to establish the national standard for PM_2.5 in the year 2012. However, there is currently no exposure limit for polycyclic aromatic hydrocarbons (PAHs) and PM_2.5-bound PAHs. The understanding of the concentration levels and potential health risks of exposure to PM_2.5-bound PAHs is important in ensuring a suitable risk assessment and risk management plans. This study, therefore, determined the concentration levels and carcinogenic and mutagenic health risks of PM_2.5-bound PAHs. A hundred and forty-four PM_2.5 samples were collected over 4 months during the winter and summer seasons of 2016 in an industrial area. The concentrations of 16 PAHs were analysed by gas chromatography-mass spectrometry, and their carcinogenic and mutagenic risks were determined using the Human Health Risk Assessment model. The mean winter (38.20 ± 8.4 μg/m³) and summer (22.3 ± 4.1 μg/m³) concentrations of PM_2.5 levels were lower than the stipulated 40 μg/m³ daily limit. The daily inhalation and ingestion exposure to PAHs for all age groups were higher than the daily exposure through the dermal contact. Children and adults are more likely to inhale and ingest PAHs in PM_2.5 than infants. The excess cancer risk and excess mutagenic risk values were below the priority risk level (10^-4). There is a potential risk of 1-8 per million persons developing cancer from exposure to benzo[a]anthracene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, and dibenz[a,h]anthracene over a lifetime of 70 years.

Nationwide health risk assessment of juvenile exposure to polycyclic aromatic hydrocarbons (PAHs) in the water body of Chinese lakes

The high emissions of polycyclic aromatic hydrocarbons (PAHs) pose a serious threat to the lake ecosystem and human health, and the human health risk assessment of PAH exposure is expected as an urgent project in China. This paper focused on 44 Chinese lakes in 6 lake zones to investigate the occurrence, composition and source of 19 PAHs in water body and estimate the human health risk under PAH exposure. The "List of PAH Priority Lakes" in China was generated based on the combination of incremental lifetime cancer risk (ILCR) model and Monte Carlo simulation. Our results showed that the Σ₁₇ PAHs ranged from 3.75 ng·L^-1 to 368.68 ng·L^-1 with a median of 55.88 ng·L^-1. Low-ring PAHs were the predominant compounds. PAH profiles varied significantly at lake zone level. Diagnostic ratios showed that PAHs might derive from petroleum and coal or biomass combustion. Benzo[a]pyrene-equivalent toxic concentrations (BaPeq) of the Σ₁₇ PAHs ranged from 0.07 ng·L^-1 to 2.26 ng·L^-1 (0.62 ± 0.52 ng·L^-1, mean ± standard deviation) with a median of 0.47 ng·L^-1. Benzo[a]anthracene (BaA), benzo[a]pyrene (BaP) and benzo[e]pyrene (BeP) were the main toxic isomers. Juvenile exposure to PAHs via oral ingestion (drinking) and dermal contact (showering) had negligible and potential health risks, respectively. Juveniles were the sensitive population for PAH exposure. 15 lakes were screened into the "List of PAH Priority Lakes" in three priority levels: first priority (Level A), moderate priority (Level B) and general priority (Level C). Lake Taihu, Lake Chaohu and Lake Hongze were the extreme priority lakes. Optimizing the economic structures and reducing the combustion emissions in these areas should be implemented to reduce the population under potential health risk of PAHs.

Classroom Dust-Bound Polycyclic Aromatic Hydrocarbons in Jeddah Primary Schools, Saudi Arabia: Level, Characteristics and Health Risk Assessment

Data concerning polycyclic aromatic hydrocarbons (PAHs) in Jeddah's schools, Saudi Arabia, and their implications for health risks to children, is scarce. Classroom air conditioner filter dusts were collected from primary schools in urban, suburban and residential areas of Jeddah. This study aimed to assess the characteristics of classroom-dust-bound PAHs and the health risks to children of PAH exposure. Average PAH concentrations were higher in urban schools than suburban and residential schools. Benzo (b)fluoranthene (BbF), benzo(ghi)perylene (BGP), chrysene (CRY) and Dibenz[a,h]anthracene (DBA) at urban and suburban schools and BbF, BGP, fluoranthene (FLT) and indeno (1, 2, 3, -cd)pyrene (IND) at residential schools were the dominant compounds in classroom dust. PAHs with five aromatic rings were the most abundant at all schools. The relative contribution of the individual PAH compounds to total PAH concentrations in the classroom dusts of schools indicate that the study areas do share a common source, vehicle emissions. Based on diagnostic ratios of PAHs, they are emitted from local pyrogenic sources, and traffic is the significant PAH source, with more significant contributions from gasoline-fueled than from diesel cars. Based on benzo[a]pyrene equivalent (BaPequi) calculations, total carcinogenic activity (TCA) for total PAHs represent 21.59% (urban schools), 20.99% (suburban schools), and 18.88% (residential schools) of total PAH concentrations. DBA and BaP were the most dominant compounds contributing to the TCA, suggesting the importance of BaP and DBA as surrogate compounds for PAHs in this schools. Based on incremental lifetime cancer risk (ILCingestion, ILCRinhalation, ILCRdermal) and total lifetime cancer risk (TLCR)) calculations, the order of cancer risk was: urban schools > suburban schools > residential schools. Both ingestion and dermal contact are major contributors to cancer risk. Among PAHs, DBA, BaP, BbF, benzo(a)anthracene (BaA), benzo(k)fluoranthene (BkF), and IND have the highest ILCR values at all schools. LCR and TLCR values at all schools were lower than 10-6, indicating virtual safety. DBA, BaP and BbF were the predominant contributors to cancer effects in all schools.

Atmospheric particulate matters in an Indian urban area: Health implications from potentially hazardous elements, cytotoxicity, and genotoxicity studies

The nature of the atmospheric particulate matters (PMs) varies depending on their sizes and their origin from different activities in the background environment. These PMs are associated with potentially hazardous elements (PHEs) such as organic compounds (e.g. Polyaromatic Hydrocarbons) that can be harmful to health. The main objective of this work is the identification and investigation of the toxicological aspects of PHEs in PMs during pre-monsoon and post-monsoon season in an urban area of Northeast region (NER) of India. In the course of the study, the 24 -hs average concentrations of PMs were detected to be more than two-times higher than the Indian standard limit (NAAQ, category) which indicates poor air quality in both the seasons around the sampling sites. This study demonstrates that the concentrations of PM-bound PAHs are mutagenic and that the Excess Cancer Risks exceed the USEPA standard limits. PMs cause cytotoxicity and can also induce genotoxicity to human health analyzed by cell culture and gel electrophoresis. This study helps to promote research to evaluate the PMs bound PHEs toxicity in diverse human cell lines and also their relationship with climatic factors as well as quantitative source apportionment for mitigation purposes.

Polycyclic aromatic hydrocarbons (PAHs) in indoor air and dust samples of different Saudi microenvironments; health and carcinogenic risk assessment for the general population

In this study, the presence of polycyclic aromatic hydrocarbons (PAHs) was studied in indoor air (PM10) and settled dust collected from different indoor microenvironments of Saudi Arabia. Limited data is available on the indoor quality of Saudi Arabia and to the best of our knowledge, this is the first study reporting PAHs in indoor air from Saudi Arabia. The main objectives were to study the levels and profile of selected PAHs in indoor dust and PM10 samples from different microenvironments of Saudi Arabia and to estimate health risk assessment to the local population via inhalation, dust ingestion and dermal contact. To study PAHs, indoor dust and PM10 samples were collected from different households, offices and hotel roomsPM10.Pyrene, benz(a)anthracene, chrysene, and phenanthrene were the major PAHs in both settled dust and PM10 samples. Profile of PAHs in dust samples was dominated by 3 and 4 ring PAHs while in PM10 sample 5-6 aromatic ring PAHs also contributed significantly. PM10 collected from kitchens and AC filter dust samples were the most contaminated with PAHs. PM10Health risk assessment was made for adults and young based on benzo(a)pyrene equivalent carcinogenic power (BaPE) and incremental lifetime cancer risk (ILCR). BaPE revealed major toxicity threat associated with PAHs is all microenvironments samples (dust and PM10) is from 5 and 6 aromatic rings PAHs. ILRC calculated using ingestion, inhalation and dermal contact was within the limits set by USEPA and although using max concentration it was up to 8.0E-05, which can have significant impact long term if other exposure pathways such as food and outdoor exposure, etc. are considered.

Household Dust: Loadings and PM10-Bound Plasticizers and Polycyclic Aromatic Hydrocarbons

Residential dust is recognized as a major source of environmental contaminants, including polycyclic aromatic hydrocarbons (PAHs) and plasticizers, such as phthalic acid esters (PAEs). A sampling campaign was carried out to characterize the dust fraction of particulate matter with an aerodynamic diameter smaller than 10 µm (PM10), using an in situ resuspension chamber in three rooms (kitchen, living room, and bedroom) of four Spanish houses. Two samples per room were collected with, at least, a one-week interval. The PM10 samples were analyzed for their carbonaceous content by a thermo-optical technique and, after solvent extraction, for 20 PAHs, 8 PAEs and one non-phthalate plasticizer (DEHA) by gas chromatography-mass spectrometry. In general, higher dust loads were observed for parquet flooring as compared with tile. The highest dust loads were obtained for rugs. Total carbon accounted for 9.3 to 51 wt% of the PM10 mass. Plasticizer mass fractions varied from 5 µg g−1 to 17 mg g−1 PM10, whereas lower contributions were registered for PAHs (0.98 to 116 µg g−1). The plasticizer and PAH daily intakes for children and adults via dust ingestion were estimated to be three to four orders of magnitude higher than those via inhalation and dermal contact. The thoracic fraction of household dust was estimated to contribute to an excess of 7.2 to 14 per million people new cancer cases, which exceeds the acceptable risk of one per million.

Air quality and PM10-associated poly-aromatic hydrocarbons around the railway traffic area: statistical and air mass trajectory approaches

Diesel engine railway traffic causes atmosphere pollution due to the exhaust emission which may be harmful to the passengers as well as workers. In this study, the air quality and PM₁₀ concentrations were evaluated around a railway station in Northeast India where trains are operated with diesel engines. The gaseous pollutant (e.g. SO₂, NO₂, and NH₃) was collected and measured by using ultraviolet-visible spectroscopy. The advanced level characterizations of the PM10 samples were carried out by using ion chromatography, Fourier-transform infrared, X-ray diffraction, inductively coupled plasma optical emission spectrometry , X-ray photoelectron spectroscopy, field-emission scanning electron microscopy with energy-dispersive spectroscopy, and high-resolution transmission electron microscopy with energy-dispersive spectroscopy techniques to know their possible environmental contaminants. High-performance liquid chromatography technique was used to determine the concentration of polycyclic aromatic hydrocarbons to estimate the possible atmospheric pollution level caused by the rail traffic in the enclosure. The average PM₁₀ concentration was found to be 262.11 µg m^-3 (maximum 24 hour) which indicates poor air quality (AQI category) around the rail traffic. The statistical and air mass trajectory analysis was also done to know their mutual correlation and source apportionment. This study will modify traditional studies where only models are used to simulate the origins.

Polycyclic aromatic hydrocarbons in urban road dust, Afghanistan: Implications for human health

Polycyclic aromatic hydrocarbons (PAHs) were analyzed in road and aerial dust to assess their concentration, composition profile, distribution, emission sources, and potential human health risks. Sixteen priority PAHs and Benzo [e]pyrene (BeP) were analyzed in 13 aerial dust samples from Jalalabad, and 78 road dust samples from Kabul and Jalalabad cities, Afghanistan. The mean concentration of ∑17PAHs in road dust from Kabul and Jalalabad were 427  μg kg^-1 and 288  μg kg^-1, respectively whereas ∑17PAHs in aerial dust from Jalalabad averaged 200  μg kg^-1. Fluoranthene (Flu), Chrysene (Chr), Benzo [b]fluoranthene (BbF), Benzo [k]fluoranthene (BkF) and BeP were major individual PAH species. The composition patterns of the PAHs were dominated by 5-6-ring PAHs (51% in road dust from Kabul; 44% in road dust from Jalalabad; and 44% in aerial dust) followed by 4-ring and 2-3-ring PAHs. Source apportionment of the road dust PAHs by the molecular diagnostic ratios (MDR) and principal component analysis (PCA), indicated signatures of PAHs sources (including vehicular exhaust, coal/wood combustion and oil spill). The Benzo [a]pyrene (BaP) toxicity equivalent values (BaP_eq17PAHs) for road dust were 75  μg kg^-1 (Kabul) and 36 μg kg^-1 (Jalalabad); and 35 μg kg^-1 for aerial dust (Jalalabad). BaP and Dibenz [a,h]anthracene (DahA) together contributed > 50% of the BaP_eq associated cancer risk. All incremental lifetime cancer risk (ILCR) due to human exposure to road and aerial dust PAHs were in the order of 10^-7, which is one-fold lower than the threshold (10^-6). The noncancerous risk (Hazard Index < 1) on exposure to dust was also negligible for both subpopulations.

Chemical profiling of PM10 from urban road dust

Road dust resuspension is one of the main sources of particulate matter with impacts on air quality, health and climate. With the aim of characterising the thoracic fraction, a portable resuspension chamber was used to collect road dust from five main roads in Oporto and an urban tunnel in Braga, north of Portugal. The PM₁₀ samples were analysed for: i) carbonates by acidification and quantification of the evolved CO₂, ii) carbonaceous content (OC and EC) by a thermo-optical technique, iii) elemental composition by ICP-MS and ICP-AES after acid digestion, and iv) organic speciation by GC-MS. Dust loadings of 0.48±0.39mgPM₁₀m^-2 were obtained for asphalt paved roads. A much higher mean value was achieved in a cobbled pavement (50mgPM₁₀m^-2). In general, carbonates were not detected in PM₁₀. OC and EC accounted for PM₁₀ mass fractions up to 11% and 5%, respectively. Metal oxides accounted for 29±7.5% of the PM₁₀ mass from the asphalt paved roads and 73% in samples from the cobbled street. Crustal and anthropogenic elements, associated with tyre and brake wear, dominated the inorganic fraction. PM₁₀ comprised hundreds of organic constituents, including hopanoids, n-alkanes and other aliphatics, polycyclic aromatic hydrocarbons (PAH), alcohols, sterols, various types of acids, glycerol derivatives, lactones, sugars and derivatives, phenolic compounds and plasticizers. In samples from the cobbled street, these organic classes represented only 439μgg^-1PM₁₀, while for other pavements mass fractions up to 65mgg^-1PM₁₀ were obtained. Except for the cobbled street, on average, about 40% of the analysed organic fraction was composed of plasticizers. Although the risk via inhalation of PAH was found to be insignificant, the PM₁₀ from some roads can contribute to an estimated excess of 332 to 2183 per million new cancer cases in adults exposed via ingestion and dermal contact.

Enhanced biodegradation of mixed PAHs by mutated naphthalene 1,2-dioxygenase encoded by Pseudomonas putida strain KD6 isolated from petroleum refinery waste

Polycyclic aromatic hydrocarbons (PAHs) are a group of environmental pollutant that are given top priority to maintain water and soil quality to the most amenable standard. Biodegradation of PAHs by bacteria is the convenient option for decontamination on site or off site. The aim of the present study was to isolate and identify naturally occurring bacteria having mixed PAHs biodegradation ability. The newly isolated Pseudomonas putida strain KD6 was found to efficiently degrade 97.729% of 1500 mg L-1 mixed PAHs within 12 days in carbon-deficient minimal medium (CSM). The half-life (t1/2) and degradation rate constant (k) were estimated to be 3.2 and 0.2165 days, respectively. The first-order kinetic parameters in soil by strain KD6 had shown efficient biodegradation potency with the higher concentration of total PAHs (1500 mg kg-1 soil), t1/2 = 10.44 days-1. However, the biodegradation by un-inoculated control soil was found slower (t1/2 = 140 days-1) than the soil inoculated with P. putida strain KD6. The enzyme kinetic constants are also in agreement with chemical data obtained from the HPLC analysis. In addition, the sequence analysis and molecular docking studies showed that the strain KD6 encodes a mutant version of naphthalene 1,2-dioxygenase which have better Benzpyrene binding energy (-9.90 kcal mol-1) than wild type (-8.18 kcal mol-1) enzyme (chain A, 1NDO), respectively, with 0.00 and 0.08 RMSD values. The mutated naphthalene 1,2-dioxygenase nahAc has six altered amino acid residues near to the ligand binding site. The strain KD6 could be a good bioresource for in situ or ex situ biodegradation of polycyclic aromatic hydrocarbon.

Comprehensive review on toxicity of persistent organic pollutants from petroleum refinery waste and their degradation by microorganisms

Control and prevention of environmental pollution has become a worldwide issue of concern. Aromatic hydrocarbons including benzene, toluene, ethyl benzene, xylene (BTEX) and polyaromatic hydrocarbons (PAHs) are persistent organic pollutants (POPs), released into the environment mainly by exploration activities of petroleum industry. These pollutants are mutagenic, carcinogenic, immunotoxic and teratogenic to lower and higher forms of life i.e. microorganisms to humans. According to the International Agency for Research on Cancer (IARC) and United States Environmental Protection Agency (U.S. EPA), Benzo[a]pyrene (BaP) is carcinogenic in laboratory animals and humans. Aromatic hydrocarbons are highly lipid soluble and thus readily absorbed from environment in gastrointestinal tract of mammals. Treatment and remediation of petroleum refinery waste have been shown either to reduce or to eliminate genotoxicity of these pollutants. Bioremediation by using microorganisms to treat this waste is showing a promising technology as it is safe and cost-effective option among various technologies tested. The main aim of this review is to provide contemporary information on variety of aromatic hydrocarbons present in crude oil (with special focus to mono- and poly-aromatic hydrocarbons), exposure routes and their adverse effects on humans. This review also provides a synthesis of scientific literature on remediation technologies available for aromatic hydrocarbons, knowledge gaps and future research developments in this field.

Indigenous 14C-phenanthrene biodegradation in "pristine" woodland and grassland soils from Norway and the United Kingdom

In this study, the indigenous microbial mineralisation of ¹⁴C-phenanthrene in seven background soils (four from Norwegian woodland and three from the UK (two grasslands and one woodland)) was investigated. ∑PAHs ranged from 16.39 to 285.54 ng g^-1 dw soil. Lag phases (time before ¹⁴C-phenanthrene mineralisation reached 5%) were longer in all of the Norwegian soils and correlated positively with TOC, but negatively with ∑PAHs and phenanthrene degraders for all soils. ¹⁴C-phenanthrene mineralisation in the soils varied due to physicochemical properties. The results show that indigenous microorganisms can adapt to ¹⁴C-phenanthrene mineralisation following diffuse PAH contamination. Considering the potential of soil as a secondary PAH source, these findings highlight the important role of indigenous microflora in the processing of PAHs in the environment.

Distribution, sources, and ecological risk assessment of polycyclic aromatic hydrocarbons in surface sediments from the Haihe River, a typical polluted urban river in Northern China

The distribution, sources, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) were investigated in surface sediments from the Haihe River. Total PAH concentrations varied from 171.4 to 9511.2 ng g^-1 with an average of 2125.4 ng g^-1, suggesting serious pollution of the Haihe River in comparison with other reported rivers worldwide. PAH contaminants differed significantly among 17 sampling locations with high values occurring in industrial areas and densely populated areas. The composition of PAHs was characterized by high abundance of 4-ring and 5-ring PAHs, and benzo[a]anthracene, chrysene, and benzo[a]pyrene were the predominant components. Molecular diagnostic ratios have confirmed that PAHs in Haihe River sediments resulted from mixed sources, primarily including various combustion processes. Ecological risk assessment using the Sediments Quality Guidelines indicated that PAHs in sediments could cause certain negative effects on aquatic organisms in most survey regions.

Assessment of polycyclic aromatic hydrocarbons in indoor dust from varying categories of rooms in Changchun city, northeast China

Sixteen polycyclic aromatic hydrocarbons (PAHs) were isolated from indoor dust from various categories of rooms in Changchun city, northeast China, including dormitory, office, kitchen, and living rooms. PAH concentrations ranged from 33.9 to 196.4 μg g^-1 and 21.8 to 329.6 μg g^-1 during summer and winter, respectively, indicating that total PAH concentrations in indoor dust are much higher than those in other media from the urban environment, including soils and sediments. The percentage of five- to six-ring PAHs was high, indicating that PAHs found in indoor dust mainly originate from pyrolysis rather than a petrogenic source. Rooms were divided into three groups using cluster analysis on the basis of 16 PAH compositions, namely smoke-free homes, homes exposed to smoke and offices. Results showed that the source of PAHs in smoke-free residential homes is primarily the burning of fossil fuels. In addition to the burning of fossil fuels, biomass combustion and cooking contributed to PAHs in houses exposed to smoke (including kitchens). Motor vehicles are an additional source of PAHs in offices because of greater interactions with the outdoor environment. The results of health risk assessment showed that the cancer risk levels by dermal contact and ingestion are 10⁴- to 10⁵-fold higher than that by inhalation, suggesting that ingestion and dermal contact of carcinogenic PAHs in dust are more important exposure routes than inhalation of PAHs from air. Although the results showed high potential of PAH concentrations in indoor dust in Changchun for human health risk, caution should be taken to evaluate the risk of PAHs calculated by USEPA standard models with default parameters because habitation styles are different in various categories of rooms.

Polycyclic aromatic hydrocarbons in traditional Chinese medicines: an analytical method based on different medicinal parts, levels, distribution, and sources

Analytical method of PAHs in TCMs based on different medicinal parts, levels, distribution, and sources.

Effect through inhalation on human health of PM1 bound polycyclic aromatic hydrocarbons collected from foggy days in northern part of India

We investigated the health risk from 16 polycyclic aromatic hydrocarbons (PAHs) adsorbed on submicron particles and also reported their concentrations, spatial distribution and possible sources during foggy days at Kanpur. Twenty-four urban foggy day's samples gathered from Kanpur, an urban center in North India and most densely populated city in the Indo-Gangetic plain of India, were examined for 16 PAHs (2-6 rings).The mean concentration of PM1 was found to be 160.16±37.70μg/m(3). ∑16PAHs concentrations were 529.17ng/m(3) with a mean of 33.07ng/m(3). The compounds of higher molecular weight (4-6 rings) added to 70.67% of ∑PAHs mass concentration in the foggy day's samples. The results of source identification by using principle component analysis (PCA) and diagnostic ratios proposed that the primary sources of PAHs were vehicular emission (primarily driven by diesel fuel) and coal combustion and the secondary source. Exposure to total PAHs in the ambient air resulted in, 95% probability total Incremental Lifetime Cancer Risk (TILCR) 3.57×10(-5) for adults and 2.08×10(-5) for children or (∼35 cancer case per million in adults and ∼20 cancer case per million in children) due to inhalation in terms of ILCR were higher than the baseline value of acceptable risk (one cancer case per million people) suggesting moderate health risk to resident human population.

An Investigation on Formaldehyde Emission Characteristics of Wood Building Materials in Chinese Standard Tests: Product Emission Levels, Measurement Uncertainties, and Data Correlations between Various Tests

As a large producer and consumer of wood building materials, China suffers product formaldehyde emissions (PFE) but lacks systematic investigations and basic data on Chinese standard emission tests (CST), so this paper presented a first effort on this issue. The PFE of fiberboards, particleboards, blockboards, floorings, and parquets manufactured in Beijing region were characterized by the perforator extraction method (PE), 9–11 L and 40 L desiccator methods (D9, D40), and environmental chamber method (EC) of the Chinese national standard GB 18580; based on statistics of PFE data, measurement uncertainties in CST were evaluated by the Monte Carlo method; moreover, PFE data correlations between tests were established. Results showed: (1) Different tests may give slightly different evaluations on product quality. In PE and D9 tests, blockboards and parquets reached E1 grade for PFE, which can be directly used in indoor environment; but in D40 and EC tests, floorings and parquets achieved E1. (2) In multiple tests, PFE data characterized by PE, D9, and D40 complied with Gaussian distributions, while those characterized by EC followed log-normal distributions. Uncertainties in CST were overall low, with uncertainties for 20 material-method combinations all below 7.5%, and the average uncertainty for each method under 3.5%, thus being acceptable in engineering application. A more complicated material structure and a larger test scale caused higher uncertainties. (3) Conventional linear models applied to correlating PFE values between PE, D9, and EC, with R² all over 0.840, while novel logarithmic (exponential) models can work better for correlations involving D40, with R² all beyond 0.901. This research preliminarily demonstrated the effectiveness of CST, where results for D40 presented greater similarities to EC—the currently most reliable test for PFE, thus highlighting the potential of Chinese D40 as a more practical approach in production control and risk assessment.