Concentration, sources and human health risk of heavy metals and polycyclic aromatic hydrocarbons bound PM2.5 ambient air, Tehran, Iran

Probabilistic Health Risk Assessment and Grading Benchmark Estimation of Atmospheric PM2.5-Bound Heavy Metals in China

The formulation of reasonable concentration classification standards can significantly enhance the protection of populations against atmospheric heavy metals, and the development of these standards should be grounded in national-level probabilistic risk assessment to establish multiple grading benchmarks. In this study, the probabilistic health risk assessment model was used for the first time to assess the health risks of hazardous metals [arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), and vanadium (V)] based on a publication dataset containing 57,737 PM2.5-bound heavy metal samples from China. Our results showed that the average non-carcinogenic risk attributed to heavy metals in all provinces of China was less than 1. In contrast, the average carcinogenic risk was greater than 10-6 in all provinces. The logarithmic mean non-carcinogenic health risks for the eight non-carcinogenic metals were ranked as follows: V (- 1.55 ± 0.96) > As (- 1.79 ± 0.96) > Mn (- 1.84 ± 0.82) > Co (- 2.05 ± 0.89) > Cd (- 2.14 ± 0.94) > Ni (- 2.59 ± 0.92) > Cr (- 3.26 ± 0.93) > Hg (- 4.86 ± 0.91), while the logarithmic mean carcinogenic health risk for the seven carcinogenic metals was Cr (- 5.33 ± 0.93) > V (- 5.79 ± 0.96) > As (- 5.98 ± 0.96) > Co (- 6.32 ± 0.89) > Cd (- 6.89 ± 0.94) > Pb (- 7.02 ± 0.93) > Ni (- 7.22 ± 0.92). The metals that contributed most to the non-carcinogenic and carcinogenic risks were V (35.86%) and Cr (57.61%), respectively. Through probabilistic risk assessment, we constructed seven-level health benchmarks for carcinogenic metals (As, Cd, Co, Cr, Ni, Pb, V). These benchmarks of extremely low health risk for the seven carcinogenic metals (As, Cd, Co, Cr, Ni, Pb, V) were 0.00037 μg/m3, 0.0011 μg/m3, 0.00012 μg/m3, 0.00011 μg/m3, 0.0043 μg/m3, 0.025 μg/m3, and 0.00031 μg/m3, respectively. Overall, this study is the first nationwide comprehensive assessment of the probabilistic risk of atmospheric PM2.5-bound toxic metals and provides a theoretical basis for revising and improving China's air quality standards.

Investigation of the expression of Cis P-tau and Pin1 proteins following air pollution induction in the brain tissue of C57BL/6 mice

Alzheimer's disease (AD) is a multifactorial disease in which environmental factors play a role. Among environmental factors, air pollution is a vital issue in modern life. Despite extensive considerations, it remains uncertain how pollution mediates neurodegeneration in AD. Beta-amyloids and hyperphosphorylated tau proteins are the two main pathological markers that have been studied in AD so far. Tau protein is basically a phosphoprotein whose functions are controlled by phosphorylation. The function of tau protein is to be located on the surface of microtubules and stabilize them. Studies have shown that phosphorylated tau protein (p-tau) exists in cis and trans conformations at Thr231, among which cis is highly neurotoxic. The Pin1 enzyme performs the conversion of cis to trans or vice versa. In this study, an experimental mouse model was designed to investigate the formation of cis p-tau by inducing air pollution. In this way, mice were randomly exposed to pollution at 2-week, 1-month, and 2-month intervals. We investigated the formation of phosphorylated cis tau form during air pollution on mouse brains using Western blots and immunofluorescence. The fluorescent imaging results and Western blotting analysis of mouse brains revealed a significant accumulation of cis p-tau in pollution-treated mice models compared to the healthy control mice. According to Western blot results, air pollution induction caused a significant decrease in Pin1 protein. The results clearly show that the tauopathy observed during air pollution is mediated through the formation of cis tau. Our findings unravel tauopathy mysteries upon pollution and would help find a possible therapeutic target to fight the devastating disorder caused by modern life.

Carcinogenicity and non-carcinogenicity health risks due to PM2.5 bound trace metals at a sub urban site in Northwest Indo-Gangetic Plain

This study investigates the PM2.5 bound metals using yearlong measurements at a regionally representative suburban site in the Northwest Indo-Gangetic Plain (NWIGP). The order of the measured annual average concentrations of PM2.5 bound metals is Fe > Zn > Ba > Sn > Pb > Cd > Ni > Mn > Cr > Li. Lithium bound to airborne PM2.5 has been reported for the first time in NWIGP. Ni (72.4 ng m-3) and Cd (36.9 ng m-3) have exceeded the acceptable limits set by NAAQS, India. Estimated the hazard quotient (HQ > 1) of Mn and hazard index (HI > 1) of measured metals exceeded the threshold limits indicating the potential non-carcinogenic health risk due to inhalation exposure of PM2.5 bound trace metals. Further, excessive lifetime cancer risk due to inhalation exposure to Cd, Ni and Cr was estimated and found to exceed the threshold limit set by the USEPA for adults and children.

Establishment of a mouse model of allergic asthma sensitized and triggered with PM2.5

To establish a mouse model of asthma sensitized and challenged with PM2.5 extract, 48 female BALB/c mice were included in this analysis. They were divided into six groups: normal control, ovalbumin (OVA) control, three PM2.5 dose groups, and a PM2.5+OVA combined group. Mice received intraperitoneal injections of PBS, OVA, PM2.5, or OVA+PM2.5 every 7 days for three weeks, followed by a one-week intranasal challenge. Airway responsiveness to acetylcholine was measured 24 hours post-challenge. Lung and nasal tissues were analyzed for histopathology, and bronchoalveolar lavage fluid (BALF) was assessed for inflammatory cells and cytokines. Compared to controls, PM2.5 and PM2.5+OVA groups showed increased airway hyperresponsiveness, pathological changes, elevated serum IgE, and altered cytokine levels (higher IL-4, IL-13; lower IFN-γ). In conclusion, PM2.5 extract can successfully establish a mouse model of allergic asthma.

Exploring the characteristics and source-attributed health risks associated with polycyclic aromatic hydrocarbons and metal elements in atmospheric PM2.5 during warm and cold periods in the northern metropolitan area of Taiwan

Polycyclic aromatic hydrocarbons (PAHs) and metal elements are commonly considered hazardous air pollutants due to their toxic, mutagenic, and carcinogenic properties. However, few studies have simultaneously examined their potential sources and health effects. This study aimed to quantify the PAHs and metal elements in atmospheric PM2.5, investigating their characteristics and potential sources to assess associated health risks in the northern metropolitan area of Taiwan. The measurements indicated that the mean concentrations of total PAHs and metal elements in PM2.5 were 0.97 ± 0.52 ng m-3 and 590 ± 200 ng m-3, respectively. Utilizing the positive matrix factorization profiles, the PAH pollution was classified into two sources: industrial emissions, traffic emissions, and coal combustion (69%) were the predominant sources of PAHs, with petroleum volatilization and biomass burning (31%) making a lesser contribution. Similarly, we traced metal elements to three potential sources: natural sources (48%), a combined source of industrial emissions, coal combustion, and traffic exhaust (32%), and a blend of non-exhaust emissions from traffic and waste incineration sources (20%). Results from the potential source contribution function model suggested that the emissions of PAHs and metals could be influenced by the eastern regions of China, although local sources, including waste incinerators, traffic, shipping, and harbor activities, were identified as the primary contributors. Source-attributed excess cancer risk revealed that industry, traffic, and coal combustion had the highest cancer risk posed by PAHs in the cold period (1.0 × 10-5), while the greatest cancer risk among metal elements was linked to non-exhaust emissions from traffic and waste incineration emissions (2.0 × 10-5). This research underscores the importance of considering source contributions to health risk and emission reduction when addressing PM2.5 pollution. These findings have direct implications for policymakers, providing them with valuable insights to develop strategies that protect public health from the detrimental effects of PAH and metal element exposure.

Chemical Characterization and Assessment of Public Health Risk due to Inhalation of PM2.5 in the City of Salamanca, Guanajuato

In this study, we conducted an analysis of health risks faced by residents of Salamanca, Mexico, who were exposed to fine particulate matter with a diameter of 2.5 μm (PM2.5) through inhalation. The characterization and analysis of these particulate matter samples were undertaken. A total of 131 samples were collected from two different sites: 65 from the Red Cross site (RC) and 66 from the Integral Family Development site (DIF) in 2014-2015. These samples were analyzed for a set of chemical components, including metals and ions. Non-cancerous health risk levels associated with PM2.5 exposure through the human respiratory system, as per the WHO benchmark (assigned a value of 1), revealed notable risk values for two elements: Manganese (Mn) with a range of 1.19-2.12 in the adult population and 1.59-2.84 in the child population, and Nickel (Ni) with a uniform risk value of 1.39 for both evaluated population groups. However, concerns arose regarding potential non-cancerous effects as the cumulative risk levels for various assessed elements showed elevated indices. These ranged from 3.81 to 4.4 in adults and 4.48-5.24 in children. This study provided comprehensive data on composition and its potential impact on human health, offering valuable insights for the implementation of mitigation measures aimed at reducing inhalation-related exposure.

Associations between atmospheric PM2.5 exposure and carcinogenic health risks: Surveillance data from the year of lowest recorded levels in Beijing, China

Scant research has pinpointed the year of minimum PM2.5 concentration through extensive, uninterrupted monitoring, nor has it thoroughly assessed carcinogenic risks associated with analyzing numerous components during this nadir in Beijing. This study endeavored to delineate the atmospheric PM2.5 pollution in Beijing from 2015 to 2022 and to undertake comprehensive evaluation of carcinogenic risks associated with the composition of atmospheric PM2.5 during the year exhibiting the lowest concentration. PM2.5 concentrations were monitored gradually in 9 districts of Beijing for 7 consecutive days per month from 2015 to 2022, and 32 kinds of PM2.5 components collected in the lowest PM2.5 concentration year were analyzed. This comprehensive dataset served as the basis for carcinogenic risk assessment using Monte Carlo simulation. And we applied the Positive Matrix Factorization (PMF) method to identity the sources of atmospheric PM2.5. Furthermore, we integrated this source appointment model with risk assessment model to discern the origins of these risks. The findings revealed that the annual average PM2.5 concentration in 2022 stood at 43.1 μg/m3, marking the lowest level recorded. The mean carcinogenic risks of atmospheric PM2.5 exposure calculated at 6.30E-6 (empirical 95% CI 1.09E-6 to 2.25E-5) in 2022. The PMF model suggested that secondary sources (35.4%), coal combustion (25.6%), resuspended dust (15.1%), biomass combustion (14.1%), vehicle emissions (7.1%), industrial emissions (2.0%) and others (0.7%) were the main sources of atmospheric PM2.5 in Beijing. The mixed model revealed that coal combustion (2.41E-6), vehicle emissions (1.90E-6) and industrial emissions (1.32E-6) were the main sources of carcinogenic risks with caution. Despite a continual decrease in atmospheric PM2.5 concentration in recent years, the lowest concentration levels still pose non-negligible carcinogenic risks. Notably, the carcinogenic risks associated with metals and metalloids exceeded that of PAHs. And the distribution of risk sources did not align proportionally with the distribution of PM2.5 mass concentration.

Sources and Specified Health Risks of 12 PM2.5-Bound Metals in a Typical Air-Polluted City in Northern China during the 13th Five-Year Plan

The continuous monitoring of PM2.5 (including 12 metal elements) was conducted in Jinan, a city with poor air quality in China, during the 13th Five-Year Plan (2016-2020). Positive matrix factorization (PMF) was used to identify emission sources of PM2.5-bound metals, and the health risks of the metals and their emission sources were assessed. During the study period, the concentration of most metals showed a decreasing trend (except Al and Be), and a significant seasonal difference was found: winter > fall > spring > summer. The PMF analysis showed that there were four main sources of PM2.5-bound metals, and their contributions to the total metals (TMs) were dust emissions (54.3%), coal combustion and industrial emissions (22.3%), vehicle emissions (19.3%), and domestic emissions (4.1%). The results of the health risk assessment indicated that the carcinogenic risk of metals (Cr and As) exceeded the acceptable level (1 × 10-6), which was of concern. Under the influence of emission reduction measures, the contribution of emission sources to health risks changes dynamically, and the emission sources that contribute more to health risks were coal combustion and industrial emissions, as well as vehicle emissions. In addition, our findings suggest that a series of emission reduction measures effectively reduced the health risk from emission sources of PM2.5-bound metals.

Health risk assessment of occupational exposure to heavy metals among green space workers in Iran

Exposure to heavy metals can result in various adverse health effects. Tehran is rated as one of the world's most polluted cities. Green space workers are continuously exposed to such pollutants in this city. Thus, this study aimed to estimate the health risks caused by exposure to heavy metals among green space workers. Eighty-eight workers and office personnel in two regions with different air quality levels were chosen for sampling. Air samples were collected using the NIOSH-7300 method and analyzed using an Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) instrument. The hazard quotient (HQ) and the lifetime cancer risk (LTCR) were calculated to assess carcinogenic and non-carcinogenic risk levels. The results revealed that the rank order of heavy metals was determined as Zn, Pb, Mn, Ni, Co, and Cd. Workers were subjected to higher concentrations of Ni, Pb, Zn, and Co than office personnel. Furthermore, the Cd, Co, and Zn exposure levels stood significantly higher in region 6 than in region 14. Non-carcinogenic risk levels for all participants fell within the acceptable range. Moreover, no employee had a carcinogenic risk level within the acceptable range when exposed to Cd. Also, 2.3% of individuals demonstrated Ni's acceptable carcinogenic risk level. Owing unacceptable risk levels, proper interventions are required to minimize occupational exposure to heavy metals. These interventions include optimizing shift schedules, using personal protective equipment, and conducting regular health assessments.

Sources-attributed contributions to health risks associated with PM2.5-bound polycyclic aromatic hydrocarbons during the warm and cold seasons in an urban area of Eastern Asia

Despite the well-established recognition of the health hazards posed by PM2.5-bound PAHs, a comprehensive understanding of their source-specific impact has been lacking. In this study, the health risks associated with PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) and source-specific contributions were investigated in the urban region of Taipei during both cold and warm seasons. The levels of PM2.5-bound PAHs and their potential health risks across different age groups of humans were also characterized. Diagnostic ratios and positive matrix factorization analysis were utilized to identify the sources of PM2.5-bound PAHs. Moreover, potential source contribution function (PSCF), concentration-weighted trajectory (CWT) and source regional apportionment (SRA) analyses were employed to determine the potential source regions. Results showed that the total PAHs (TPAHs) concentrations ranged from 0.08 to 2.37 ng m-3, with an average of 0.69 ± 0.53 ng m-3. Vehicular emissions emerged as the primary contributor to PM2.5-bound PAHs, constituting 39.8 % of the TPAHs concentration, followed by industrial emissions (37.6 %), biomass burning (13.8 %), and petroleum/oil volatilization (8.8 %). PSCF and CWT analyses revealed that industrial activities and shipping processes in northeast China, South China Sea, Yellow Sea, and East China Sea, contributed to the occurrence of PM2.5-bound PAHs in Taipei. SRA identified central China as the primary regional contributor of ambient TPAHs in the cold season and Taiwan in the warm season, respectively. Evaluations of incremental lifetime cancer risk demonstrated the highest risk for adults, followed by children, seniors, and adolescents. The assessments of lifetime lung cancer risk showed that vehicular and industrial emissions were the main contributors to cancer risk induced by PM2.5-bound PAHs. This research emphasizes the essential role of precisely identifying the origins of PM2.5-bound PAHs to enhance our comprehension of the related human health hazards, thus providing valuable insights into the mitigation strategies.

Sources appointment and health risks of PM2.5-bound trace elements in a coastal city of southeastern China

To gain a comprehensive understanding of sources and health risks of trace elements in an area of China with high population densities and low PM2.5 concentrations, 15 trace elements (Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Sn, Ba, Pb) in PM2.5 were monitored from December 2020 to November 2021 in a representative city, Xiamen. The concentrations of trace elements in Xiamen displayed an obvious seasonal variation and were dominated by K, Fe, Al, Ca and Zn. Based on Positive Matrix Factorization analysis, source appointment revealed that the major sources of trace elements in Xiamen were traffic, dust, biomass and firework combustion, industrial manufacture and shipping emission. According to health risk assessment combined with the source appointment results, it indicated that the average noncarcinogenic risk was below the threshold and cancer risk of four hazardous metals (Cr, Ni, As, Pb) exceeded the threshold (10-6). Traffic-related source had almost half amount of contribution to the health risk induced by PM2.5-bound trace elements. During the dust transport period or Spring Festival period, the health risks exceeded an acceptable threshold even an order of magnitude higher, suggesting that the serious health risks still existed in low PM2.5 environment at certain times. Health risk assessment reminded that the health risk reduction in PM2.5 at southeastern China should prioritize traffic-related hazardous trace elements and highlighted the importance of controlling vehicles emissions in the future.

Reduction of ovarian reserves and activation of necroptosis to in vivo air pollution exposures

We investigated the association between air pollution and changes in ovarian follicles, anti-mullerian hormone (AMH) levels, the occurrence of necroptosis cell death by activation of receptor-interacting protein kinase 3 (RIPK3) and, the activation of mixed lineage kinase domain-like (MLKL) proteins. Forty-two female Wistar rats were divided into three groups of 14 each, which were exposed to real-ambient air, filtered air and purified air (control) in two periods of 3 and 5 months. The results showed that the number of ovarian follicles decreased in the group exposed to real-ambient air versus the control group (P < 0.0001). The trend of age-related AMH changes with respect to exposure to air pollutants was affected and its levels decreased after 3 months of exposure. The MLKL increased in the group exposed to the real-ambient air compared to the control group (P = 0.033). Apparently long-term exposure to air pollution can reduce ovarian reserves.

Investigating the temporal dynamics of sub-micron particles and particle-bound transition metals in indoor air of a metropolitan city

The present study portrays an association between particle-bound transition metals and children's health. The indoor air quality of the urban metropolitan city households was monitored for four PM sizes, namely PM1.0-2.5, PM0.50-1.0, PM0.25-0.50 and PM<0.25, in major seasons observed in the city; summer and winter. Further transition/heavy metals, viz. Cr, Cu, Fe, Mn, Ni, Pb and Zn, were analysed in PM1-2.5 samples. In order to evaluate the effect, health risk assessment was performed using mathematical and computational model for assessing dermal exposure and dose estimation (multiple path particle dosimetry model version3.0). The study principally targeted the children aged 2-15 years for the health risk assessment. According to the results, for the largest particle size i.e. PM1.0-2.5 the highest deposition was in the head region (49.1%) followed by pulmonary (43.6%) and tracheobronchial region (7.2%), whereas, for the smallest particle size i.e. PM<0.25 the highest deposition was obtained in the pulmonary region (73.0%) followed by the head (13.6%) and TB region (13.2%). Also, the most imperilled group of children with highest dose accumulation was found to be children aged 8-9 years for all particle sizes. Moreover, the dermal exposure dose as evaluated was found to be preeminent for Ni, Zn and Pb. Besides, seasonal variation gesticulated towards elevated concentrations in winter relative to the summer season. Altogether, the study will provide a conception to the researchers in the fields mounting season-specific guidelines and mitigation approaches. Conclusively, the study commends future work focussing on defining the effects of other chemical components on particles and associated transition metal composition along with proper extenuation of the same.

Carcinogenic and non-carcinogenic risk of exposure to metal fume in different types of welding processes

The international agency for cancer research (IARC) has classified welding fumes as definitive carcinogens. The aim of the present study was to assess health risk due to exposure to welding fumes in different welding types. In this study, exposure to fumes of iron (Fe), chromium (Cr), and nickel (Ni) in the breathing zone air of 31 welder engaged in arc, argon and CO2 welding was assessed. Carcinogenic and non-carcinogenic risk assessments due to exposure to fumes were performed using the method proposed by the Environmental Protection Agency (EPA) by Monte Carlo simulation. The results showed that in the CO2 welding, concentration of Ni, Cr, and Fe was lower than the 8-h Time-Weighted Average Threshold Limit Value (TWA-TLV), recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). In argon welding, Cr and Fe concentrations were higher than the TWA-TLV. In arc welding, concentrations of Ni and Fe were more than the TWA-TLV. In addition, the risk of non-carcinogenicity due to exposure to Ni and Fe in all three types of welding was more than standard level (HQ>1). The results indicated that the welders are at health risk due to exposure to metal fumes. Preventive exposure control measures such as local ventilation need to be implemented in welding workplaces.

Inhalational exposure to formaldehyde, carcinogenic, and non-carcinogenic risk assessment: A systematic review

Formaldehyde is one of the most widely used substances in a variety of industries, although it was classified as a human carcinogen by the International Agency for Research on Cancer (IARC). The present systematic review was conducted to retrieve studies related to occupational exposure to formaldehyde until November 2, 2022. Aims of the study were to identify workplaces exposed to formaldehyde, to investigate the formaldehyde concentrations in various occupations and to evaluate carcinogenic and non-carcinogenic risks caused by respiratory exposure to this chemical among workers. A systematic search was done in Scopus, PubMed and Web of Science databases to find the studies done in this field. In this review, studies that did not meet the criteria specified by Population, Exposure, Comparator, and Outcomes (PECO) approach were excluded. In addition, the inclusion of studies dealing with the biological monitoring of FA in the body and review studies, conference articles, books, and letters to the editors were avoided. The quality of the selected studies was also evaluated using the Joanna Briggs Institute (JBI) checklist for analytic-cross-sectional studies. Finally, 828 studies were found, and after the investigations, 35 articles were included in this study. The results revealed that the highest formaldehyde concentrations were observed in waterpipe cafes (1,620,000 μg/m³) and anatomy and pathology laboratories (4237.5 μg/m³). Carcinogenic and non-carcinogenic risk indicated the potential health effects for employees due to respiratory exposure as acceptable levels of CR = 1.00 × 10^-4 and HQ = 1, respectively were reported to be exceeded in more than 71% and 28.57% of the investigated studies. Therefore, according to the confirmation of formaldehyde's adverse health effects, it is necessary to adopt targeted strategies to reduce or eliminate exposure to this compound from the occupational usage.

Effects of maternal urban particulate matter SRM 1648a exposure on birth outcomes and offspring growth in mice

The association between exposure to particulate matter (PM) during pregnancy and abnormal birth outcomes is still inconclusive. This study aims to provide more evidence for this public health concern by investigating birth outcomes and the growth of offspring in mice exposed to PM during pregnancy. C57BL/6 J pregnant mice were exposed to PM via nasal drip at three doses or solvent control. The dam weight gain was recorded during pregnancy. The number of pups, pup weight, and placental weight were recorded at embryonic day 18.5 (E18.5) necropsy. For mice that gave birth naturally, we calculated the gestation length and measured the body weight of offspring once a week from the 1st to the 6th week after birth. The results showed that there were no significant differences in maternal body weight gain, conception rate, pregnancy duration, and litter size among different groups. There were no significant differences in fetal weight, placental weight, and fetal/placental weight ratio at E18.5. Weight gain in offspring was reduced after birth. The average body weight of offspring in the high-dose group was significantly lower than that in the control group at weeks 5 in female pups. There were no significant differences in the body weight of male offspring among groups from 1st to the 6th. Together, our study indicated that maternal exposure to PM did not significantly impact birth outcomes of C57BL/6 J mice but affected growth trajectories in offspring after birth in a dose- and fetal sex-dependent manner.

Health risk assessment of inorganic and organic constituents of the coarse and fine PM in an industrialized region of Brazil

A health risk assessment of inorganic and organic species associated with coarse and fine particulate matter (PM) was conducted in Southeastern Brazil. TSP, PM₁₀, and PM_2.5 samples were collected, and their elemental (metals/metalloids) and organic (PAHs) composition were determined by EDXRF and GC-MS. The health risks were determined through hazard quotient (HQ) and cancer risk (CR). It was found that different elements and routes of exposure lead to different health risks, even for the PM concentration in compliance with air quality standards. The major routes of exposure for adults were inhalation and dermal contact whereas for children were ingestion and dermal contact. High non-cancer risks (HQ) caused by Cl and Fe exposure were associated with coarser fractions, PM₁₀ and TSP, respectively, whereas high HQ for Se, Sb, and V exposure were associated with PM_2.5. HQ values for children were near twice that for adults, and CR values were 65 % to 130 % higher for children than for adults. CR posed by PAHs was negligible. The results highlighted that the HQ might be over- or underestimated depending on the form in which the element Cl is determined (elemental or ion), reinforcing the need for an embracing chemical characterization of the PM. High HQ values were found related to the exposure to some elements present in the TSP, showing that this PM fraction should not be neglected.

Occupational Exposure to Metal Fumes Among Iranian Welders: Systematic Review and Simulation-Based Health Risk Assessment

There have been numerous reports of welder's worker exposure to metal fumes. Carcinogenic and non-carcinogenic (neurological, dermal, and etc.) effects are the adverse outcomes of exposure to welding fumes. In this review study, data were collected from previous studies conducted in Iran from 1900 to 2020. The risk of carcinogenicity and non-carcinogenicity due to exposure to welding metal fumes was assessed using the United States Environmental Protection Agency (USEPA) method based on the Monte Carlo simulation (MCS). Results showed mean of metal fume concentration in gas welding was in the range of 1.8248 to 1060.6 (µg/m³) and in arc welding was 54.935 to 4882.72 (µg/m³). The mean concentration of fumes in gas welding is below the recommended American Conference of Governmental Industrial Hygienists (ACGIH) standard exposure limit except for manganese, and in the arc welding, all metal fume concentrations are below the standard exposure limit except for manganese and aluminum. The results showed that the risk of carcinogenicity due to exposure to nickel, manganese in both gas and arc welding, and cadmium in gas welding was higher than standard level (hazard quotient (HQ) more than 1). Cancer risk due to exposure to nickel in both gas and arc welding was probable (1 × 10^-6 < cancer risk (CR) < 1 × 10^-4). Health risk assessment showed that welders are exposed to health risks. Preventive measures should be applied in welding workplaces to reduce the concentrations of metal fumes.

Chemical Characteristics and Cytotoxicity to GC-2spd(ts) Cells of PM2.5 in Nanjing Jiangbei New Area from 2015 to 2019

PM_2.5 is an air pollutant with complex components. After entering the body through respiration, PM_2.5 can not only cause respiratory diseases, but also break through the blood-testis barrier and influence the reproductive system. PM_2.5 with different components may result in different toxic effects. In the first five years of Nanjing Jiangbei New Area, industrial transformation would change the concentration and chemical fraction of PM_2.5 in the local environment to a certain extent. In this study, PM_2.5 collected in Nanjing Jiangbei New Area every autumn and winter from 2015 to 2019 was analyzed. PM_2.5 concentration generally decreased year by year. The large proportion of secondary inorganic ions indicated the presence of secondary pollution at the sampling site. PM_2.5 was mainly emitted from fossil fuel combustion and vehicle exhaust. The cytotoxicity of PM_2.5 samples was evaluated by PM_2.5 exposure to mouse spermatocytes (GC-2spd(ts) cells). Cell viability was relatively low in 2016 and 2018, and relatively high in 2017 and 2019. Reactive oxygen species levels and DNA damage levels followed similar trends, with an overall annual decrease. The cytotoxicity of PM_2.5 on GC-2spd(ts) cells was significantly correlated with water-soluble ions, water-soluble organic carbon, heavy metals and polycyclic aromatic hydrocarbons (p < 0.01). According to principal component analysis and multiple linear regression, fossil fuel combustion, secondary transformation of pollutants and construction dust were identified as the major contributors to cytotoxic effects, contributing more than 50%.

Bibliometric Analysis Reveals the Progress of PM2.5 in Health Research, Especially in Cancer Research

PM_2.5 has an aerodynamic diameter of less than or equal to 2.5 microns due to its inherent physical and chemical properties so that it can enter the alveoli through the respiratory tract for blood gas exchange. Numerous studies have shown that PM_2.5 is a serious air pollutant that poses a wide range of health risks, especially for cancer. Bibliometric methods were employed to have comprehensively analyzed the research of PM_2.5 in cancer for about a decade in Web of Science to identify hotspots and trends using VOSviewer, CiteSpace, and R. The field has undergone overall growth in the past decade. As research on PM_2.5 in health deepens, cancer related to it expanded beyond the respiratory system to the digestive system, urinary system, female gonadal axis, breast cancer and other cancers. Another observation is that research on PM_2.5 in cancer has progressed in the mechanisms of deterioration, such as the role of matrix metalloproteinases in cancer. In addition, research on the risks of PM_2.5 in combination with polycyclic aromatic hydrocarbons and heavy metals has also emerged. Results showed that there are relatively more studies on PM_2.5 in high-latitude countries, which may be due to different national conditions, such as climate and coal combustion. Our research has combed through the progress of PM_2.5 in cancer research and provided a supplement for developing pollution prevention ideas with different national conditions in this field.

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

A risk assessment and a source apportionment of the particulate- and gas-phase PAHs were conducted in a high vehicular traffic and industrialized region in southeastern Brazil. Higher concentrations of PAHs were found during summer, being likely driven by the contributions of PAHs in the vapor phase caused by fire outbreaks during this period. Isomer ratio diagnostic and Principal Component Analysis (PCA) identified four potential sources in the region, in which the Positive Matrix Factorization (PMF) model confirmed and apportioned as gasoline-related (31.8%), diesel-related (25.1%), biomass burning (23.4%), and mixed sources (19.6%). The overall cancer risk had a tolerable value, with ∑CR = 4.6 × 10^-5, being ingestion the major via of exposure (64% of the ∑CR), followed by dermal contact (33% of the ∑CR) and inhalation (3%). Mixed sources contributed up to 45% of the overall cancer risk (∑CR), followed by gasoline-related (up to 35%), diesel-related (up to 15%), and biomass burning (up to 10%). The risk assessment for individual PAH species allowed identifying higher CR associated with BaP, DBA, BbF, BaA, and BkF, species associated with gasoline-related and industrial sources. Higher risks were associated with PM_2.5-bound PAHs exposure, mainly via ingestion and dermal contact, highlighting the need for measures of mitigation and control of PM_2.5 in the region.

Meteorological dependence, source identification, and carcinogenic risk assessment of PM2.5-bound Polycyclic Aromatic Hydrocarbons (PAHs) in high-traffic roadside, urban background, and remote suburban area

The Polycyclic Aromatic Hydrocarbons (PAHs) bound to ambient fine Particular Matter (PM2.5) are currently drawing a lot of attention due to their adverse health effects increasing lung cancer risk in humans. In this study, The PM2.5 samples were collected by high volume air samplers simultaneously from three different sites (high-traffic roadside, urban background, and remote suburban) in Tehran, Iran during warm and cold seasons (from July 2018 to March 2019), and 16 PAHs were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). Unlike previous studies, a remote suburban area was chosen so as to observe the spatial differentiation in PM2.5-bound PAH characteristics. In high-traffic roadside site, the average concentration of total PM2.5-bound PAHs (ƩPAHs) was 3.7 times the concentration value in remote suburban area. Average (ƩPAHs) ranged from 5.54 ng/m3 for remote suburban area to 20.67 ng/m3 for high-traffic roadside site. In all sites, seasonal trends of PAH concentrations elucidated high concentrations in the cold season and low concentrations in the warm season. Correlation analysis between ƩPAHs and atmospheric factors (meteorology parameters and criteria air pollutants) indicated the heterogeneous processes play an important role in the level of PAHs. The results of diagnostic ratio (DR) analysis disclosed that the dominant source of PM2.5-bound PAHs was the combustion of liquid fossil fuels. Despite the fact that incremental lifetime cancer risk (ILCR) via inhaling PM2.5-bound PAHs varied significantly in high-traffic roadside site and remote suburban site, its value was beyond the acceptable risk level in both sites. Our results suggested that effective regulations are needed to monitor PAHs concentrations and reduce PAHs emissions from liquid fossil fuel combustion so as to mitigate the potential carcinogenic risk of PAHs in ambient air.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40201-022-00821-2.

Chemical characterization of PM10 and PM2.5 combusted firecracker particles during Diwali of Lucknow City, India: air-quality deterioration and health implications

Urban air pollution is a growing menace leading to human discomfort, increased hospitalizations, morbidity, and mortality. This study deals with deteriorated air quality due to firecracker bursting during Diwali in Lucknow. Inhalable particulates and gaseous pollutants were monitored during Diwali 2020 using air samplers. Elements, ions, and surface morphology of particles were analyzed using ICP-MS, ion chromatograph, and SEM-EDX, respectively. PM₁₀, PM_2.5, SO₂, and NO₂ were 558, 352, 44, and 86 μg/m³ during Diwali night and 233, 101, 17, and 40 μg/m³ on pre-Diwali night while 241, 122, 24, and 43 μg/m³ on Diwali day. Concentrations surged for PM₁₀: 139% and 132%, PM_2.5: 249% and 189%, SO₂: 159% and 83%, and NO₂: 115% and 100% on Diwali night compared to pre-Diwali night and corresponding Diwali day, respectively. Al, K, Ba, and B showed dominance in PM₁₀ whereas Zn, Al, Ba, and K in PM_2.5 on Diwali night. The order of metal abundance in PM_2.5 was Cd < Co < Ag < As < Cr < Ni < Cu < Bi < Pb < Mn < Sr < Fe < B < Zn < Al < Ba < K. Cations NH₄⁺, K⁺, Mg²⁺, Ca²⁺, and anions F^-, Cl^-, NO₃^-, Br^-, NO₂^-, SO₄^-2, PO₄^3- showed a 2-8 fold increase on Diwali night relative to pre-Diwali night. Average metal concentrations varied by 2.2, 1.6, and 0.09 times on Diwali than pre-Diwali in residential, commercial, and industrial areas, respectively. PM₁₀ concentration increased by 458% and 1140% while PM_2.5, 487%, and 2247% than respective NAAQS and WHO standards. Tiny firecracker particles vary in toxicity as compared to vehicular emissions and have enhanced bioavailability leading to severe threat in terms of LRI, COPD, and atherosclerosis for city dwellers. It is imperative to recognize the present status of ambient air quality and implement regulatory strategies for emission reduction.

Size distribution, meteorological influence and uncertainty for source-specific risks: PM2.5 and PM10-bound PAHs and heavy metals in a Chinese megacity during 2011-2021

This study aims at exploring size distribution, meteorological influence and uncertainty for source-specific risks of atmospheric particulate matter (PM), which can improve risk-mitigation strategies for health protection. Heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) in PM_2.5 and PM₁₀ were detected in a Chinese megacity during 2011-2021. A new method named as PMFBMR, which combines the Positive Matrix Factorization, Bootstrapping, Mote Carlo and Risk assessment model, was developed to estimate uncertainty of source-specific risks. It was found that PAH risks concentrated in fine PM, while HMs showed high risks in both fine and coarse PMs. For PM_2.5, HQ (non-cancer risk hazard quotient) of gasoline combustion (GC), diesel and heavy oil combustion (DC), coal combustion (CC), industrial source (IS), resuspended dust (RD) and secondary and transport PM (ST) were 0.6, 1.4, 0.9, 1.6, 0.3, and 0.3. ILCR (lifetime cancer risk) of sources were IS (9.2E-05) > DC (2.6E-05) = CC (2.6E-05) > RD (2.2E-05) > GC (1.7E-05) > ST (6.4E-06). PM_2.5 from GC, DC, CC and IS caused higher risks than coarse PM, while coarse PM from RD caused higher risks. Source-specific risks were influenced not only by emissions, but also by meteorological condition and dominant toxic components. Risks of GC and DC were usually high during stable weather. Some high risks of CC, IS and RD occurred at strong WS due to transport or wind-blown resuspension. GC and DC risks (influenced by both PAHs and HMs) showed strong relationship with T, while IS and RD risks (dominated by HMs) showed weak link with meteorological conditions. For uncertainty of source-specific risks, HQ and ILCR were sensitive for different variables, because they were dominated by components with different uncertainties. When using source-specific risks for risk-mitigation strategies, the focused toxic components, used toxic values, PM sizes and uncertainty are necessary to be considered.

Autism-like symptoms by exposure to air pollution and valproic acid-induced in male rats

Exposure to air pollution during prenatal or neonatal periods is associated with autism spectrum disorder (ASD) according to epidemiology studies. Furthermore, prenatal exposure to valproic acid (VPA) has also been found to be associated with an increased prevalence of ASD. To assess the association between simultaneous exposure to VPA and air pollutants, seven exposure groups of rats were included in current study (PM2.5 and gaseous pollutants exposed - high dose of VPA (PGE-high); PM2.5 and gaseous pollutants exposed - low dose of VPA (PGE-low); gaseous pollutants only exposed - high dose of VPA (GE-high); gaseous pollutants only exposed - low dose of VPA (GE-low); clean air exposed - high dose of VPA (CAE-high); clean air exposed - low dose of VPA (CAE-low) and clean air exposed (CAE)). The pollution-exposed rats were exposed to air pollutants from embryonic day (E0) to postnatal day 42 (PND42). In all the induced groups, decreased oxidative stress biomarkers, decreased oxytocin receptor (OXTR) levels, and increased the expression of interleukin 6 (IL-6), interleukin 1β (IL-1β), and tumor necrosis factor alpha (TNF-α) were found. The volumes of the cerebellum, hippocampus, striatum, and prefrontal decreased in all induced groups in comparison to CAE. Additionally, increased numerical density of glial cells and decreased of numerical density of neurons were found in all induced groups. Results show that simultaneous exposure to air pollution and VPA can cause ASD-related behavioral deficits and air pollution reinforced the mechanism of inducing ASD ̉s in VPA-induced rat model of autism.

Contamination of breast milk with lead, mercury, arsenic, and cadmium in Iran: a systematic review and meta-analysis

Breast milk is a complete food for the development of the newborn, but it can also be an important route for environmental pollutants transmission to the infants. This study was aimed to evaluate the status of heavy metals including lead (Pb), mercury (Hg), cadmium (Cd) and arsenic (As) in the breast milk of Iranian mothers. The international databases including Scopus, PubMed, Web of Science and the Persian electronic databases including Scientific Information Database, IranMedex and Magiran were examined to find relevant articles published until July 2021. A total of 23 studies examined the levels of toxic metals in Iranian breast milk samples. According to the findings, the pooled average concentrations (µg/L) of Pb, Cd, Hg and As were 25.61, 2.40, 1.29 and 1.16, respectively. The concentration of Hg and Pb in colostrum milk was more than twice of mature milk. The Hg mean concentration in the breast milk of mothers with at least one amalgam-filled tooth was approximately three times that of mothers without amalgam-filled teeth. Risk assessment analysis indicated that the intake of Pb and Hg by infants through breastfeeding can be considered a health concern in Iran. It seems necessary to reduce the Pb exposure of pregnant and lactating women in Iran. However, more extensive studies are needed to clarify the toxic metals' exposure status of infants through breast milk in other parts of the country.

Health Risk Assessment of Occupational Exposure to Hexavalent Chromium in Iranian Workplaces: a Meta-analysis Study

Occupational exposure to hexavalent chromium (Cr⁺⁶) has reported in different industries. The Cr⁶⁺ has the carcinogenic and non-carcinogenic effects. The aim of this study was to provide a meta-analysis and health risk assessment of occupational exposure to Cr⁶⁺ in Iranian workplaces. Databases including Scopus, Web of Sciences (WOS), and Scientific Information Database (SID), as a national database, were searched from 2000 to February 2021. The related studies to occupational exposure to Cr⁶⁺ were selected by Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. Lung cancer and non-cancer risk (nasal mucosal irritation, atrophy, and perforation) of Cr⁶⁺ were estimated by Environmental Protection Agency (EPA) method, based on the Monte Carlo simulation (MCS). Also, the results of spirometry and biomonitoring of previous studies were reviewed. We found 14 articles based on inclusion criteria. Pooled concentration of Cr⁶⁺ was estimated 0.037 ± 0.002 mg/m³ which was higher than the recommended exposure limit by the ACGIH (0.002 mg/m³). The mean lung cancer risk was estimated to be 5.49E-2, which was considerable risk. In the Cr⁶⁺-exposed workers, all parameters of pulmonary function had decreased. The level of Cr⁶⁺ in urinary and blood samples was higher than threshold limit. Results indicated that exposure to Cr⁶⁺ and its health risk were more than recommended exposure limit. The results of present study could be helpful for health policy maker to control exposure to Cr⁶⁺ in workplaces.

The exposure to formaldehyde in industries and health care centers: A systematic review and probabilistic health risk assessment

Formaldehyde is classified as a definitive human carcinogen by the International Agency for Research on Cancer (IARC). The workers in several industries such as foundry, melamine, resin, and health care centers (pathology and anatomy laboratories and operating rooms) are exposed to airborne formaldehyde. In this systematic review, studies conducted from 2000 to 2020 on occupational exposure to airborne formaldehyde in Iran were collected and analyzed. The carcinogenic and non-carcinogenic risk assessments of exposure to airborne formaldehyde were estimated using the recommended United State Environmental Protection Agency (USEPA) method by Monte-Carlo simulation. Results demonstrated that in both health care centers and industrial settings, mean concentrations of airborne formaldehyde were higher than that 8- hour time-weighted average threshold limit value (TWA-TLV) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). Also, results showed that cancer and non-cancer risks due to exposure to airborne formaldehyde (Neurological, dermal, respiratory effects and so on) were considerable in both industrial settings and health care settings. The results of this study could be used by health policy makers to eliminate or reduce exposure to airborne formaldehyde in workplaces.

Indoor/outdoor relationships, signatures, sources, and carcinogenic risk assessment of polycyclic aromatic hydrocarbons-enriched PM2.5 in an emerging port of northern China

Humans spend most of their time in indoor environments, thus a thorough understanding of indoor and outdoor PM_2.5-bound polycyclic aromatic hydrocarbons (PAHs) origins for accurate assessment of health risks is required. In the present study, 84 pairs of PM_2.5 samples from indoor (laboratory) and outdoor (campus) locations were collected from April to December 2018 in Caofeidian, China. The annual median concentration of PM_2.5 outdoors was 90.80 µg/m³, 9.08 times higher than the annual standard of WHO guideline (10 µg/m³). Indoor PM_2.5 annual median concentration (41.80 µg/m³) was also higher than the annual standard of ASHRAE guideline (15 µg/m³). The annual median concentrations of ∑₁₈PAHs indoors (44.23 ng/m³) and outdoors (189.6 ng/m³) were highest in winter and descended in the order of autumn > spring > summer. Contrary to summer and autumn, indoor/outdoor concentration ratios were less than 1 in spring and winter, indicating that the contribution of outdoor particle infiltration was more significant than that of indoor sources. The positive matrix factorization model suggested that indoor PAHs came from three sources: vehicle emissions (43%), biomass burning (37%), industry emissions, and coal combustion (20%). Outdoor PAHs came from four sources: petroleum volatilization (39%), vehicle emissions (30%), coal combustion (18%), and biomass burning (13%). The incremental lifetime cancer risk values of indoor and outdoor PAHs in winter exceeded the acceptable level (10^-6), and the carcinogenic risk of adults was higher than that of children and teenagers. These results indicated that simultaneous monitoring of indoor and outdoor PAHs is recommended for accurate assessment of health risk, and the analysis in the current work should be helpful to formulate policies to reduce PAHs emissions.

Phase distribution and risk assessment of PAHs in ambient air of Hamadan, Iran

In the present study, both gaseous and particulate (PM with dae <2.5 µm) phases of polycyclic aromatic hydrocarbons (PAHs) were measured in the ambient air of Hamadan city, Iran. For this reason, two low-volume samplers equipped with glass fiber filters were used for sampling of particulate phase (N = 30) and XAD-2 sorbent tubes were applied for sampling gaseous phase of PAHs (N = 30). The sampling was conducted during warm and cold seasons in 2019. The average of cold/warm season ratios for Σ₁₆PAH and PM concentrations were 1.14 and 0.62, respectively. Summed PAHs concentration were determined to be in the range 0.008-59.46 (mean: 11.61) ng/m³ and 0.05-40.83 (mean: 10.22) ng/m³ for the cold and warm seasons, respectively. A negative Pearson correlation coefficient was obtained for wind speed and relative humidity. The average Benzo (a) Pyrene equivalent carcinogenic (BaP_eq) levels in the cold season were lower than the maximum permissible risk level of 1 ng/m³ for BaP. The BaP toxicity equivalency (ΣBaP_TEQ) and BaP mutagenicity equivalency (ΣBaP_MEQ) appeared to be significantly higher in the cold season (averaging 0.35 and 1.65 ng/m³, respectively) than those in warm season. Health risk assessment was performed for children and adults based on BaP_eq, inhalation cancer risk. The diagnostic ratios of individual PAHs concentration showed that the significant sources of PAH emissions may be related to light duty vehicles (LDVs) in Hamadan. Although, some other sources such as pyrogenic source and petrol combustion were also suggested.

The concentration of benzene, toluene, ethylbenzene, and xylene in ambient air of the gas stations in Iran: A systematic review and probabilistic health risk assessment

Exposure to benzene, toluene, ethylbenzene, and xylene (BTEX) has been reported in gas stations. Exposure to BTEX can result in adverse health outcomes in workers such as cancer and neurological effects. The health risk assessments of exposure to BTEX could be useful in choosing suitable control measures. In this review, data from previous studies of gas station environments in Iran were collected from years 2000 to 2020. The health risk assessments were conducted through the estimation of cancer and noncancer risks using a Monte Carlo simulation based on the US Environmental Protection Agency method. The results showed that exposure to BTEX in some cities of Iran was greater than the occupational exposure limits. The results of cancer risk assessments demonstrated that cancer risk was not increased. However, results of noncancer risk assessments demonstrated that neurological toxicity from exposure to BTEX was significant in different cities of Iran. The health risk assessments indicated that workers at gas station are at health risk.

Human health risk assessment for toxic elements in the extreme ambient dust conditions observed in Sistan, Iran

This study evaluates the bioaccessibility and health risks related to heavy metals (Cd, Cr, Co, Cu, Mn, Ni, Pb, Zn and metalloid As) in airborne dust samples (TSP and PM_2.5) in Zabol, Iran during the summer dust period, when peak concentration levels of PM are typically observed. High bioaccessibilities of carcinogenic metals in PM_2.5 (i.e. 53.3%, 48.6% and 47.6% for Ni, Cr and As, respectively) were calculated. The carcinogenic and non-carcinogenic health risks were assessed for three exposure pathways (inhalation, ingestion and dermal contact), separately for children and adults. Non-carcinogenic inhalation risks were very high (Hazard Index: HI > 1) both for children and adults, while the carcinogenic risks were above the upper acceptable threshold of 10^-4 for adults and marginally close (5.0-8.4 × 10^-5) for children. High carcinogenic risks (>10^-4) were found for the ingestion pathway both for children and adults, while HI values > 1 (8.2) were estimated for children. Carcinogenic and non-carcinogenic risk estimates for dermal contact were also above the limits considered acceptable, except for the carcinogenic risk for children (7.6 × 10^-5). Higher non-carcinogenic and carcinogenic risks (integrated for all elements) were associated with the inhalation pathway in adults and children with the exception of carcinogenic risk for children, where the ingestion route remains the most important, while As was linked with the highest risks for nearly all exposure pathways. A comparative evaluation shows that health risks related with toxic elements in airborne particles in Sistan are among the highest reported in the world.

The acute effects of short term exposure to particulate matter from natural and anthropogenic sources on inflammation and coagulation markers in healthy young adults

Airborne particulate matter is associated with increasing the risk of cardiovascular diseases. The purpose of this study was to investigate the association between air pollution conditions and MDA, vWF, and fibrinogen markers in the blood of two panels of healthy young individuals in an urban area in Tehran city with a high air pollution background and another group was living in a rural area (Ahmad Abad Mostofi), with a low air pollution background. In each group, 4 blood samples were taken as follows: one in inversion days, the second in winter, but during the existence of normal condition in terms of air pollution, the third sample in the spring during the normal condition in terms of air pollution and the fourth sample during the dust storm conditions. In the urban and rural groups, there was a significant difference between the concentration of MDA, vWF, fibrinogen between inversion and cold season control conditions, and between dust storm conditions and warm season control conditions (p < 0.05). The results showed that the association of dust storm condition on the measured biomarkers was stronger than the inversion condition, which health consideration in the dust conditions be taken into account similar to the inversion conditions.

Levels, sources, isotope signatures, and health risks of mercury in street dust across China

Spatial distribution and isotope signature of mercury (Hg) in street dusts across China were investigated by collecting dust samples from 14 cities and reviewing previously published data from an additional 46 cities. Potential sources of street dust and the associated health risks to humans were also assessed. The total Hg (THg) concentrations in street dust ranged from 0.020-39.1 mg kg^-1 with an average of 0.433 ± 0.185 mg kg^-1 in the 60 cities. Street dust samples collected from 14 cities were characterized by slightly negative δ²⁰²Hg (-0.61 ± 0.92‰) and near-zero Δ¹⁹⁹Hg (-0.03 ± 0.08‰) values, and coal combustion and industrial activities were estimated to be the major sources of Hg in street dust. The estimated average probable daily intake (PDI) of THg from street dust exposure for adults and children (1.36E-03 and 1.27E-02 μg d^-1 kg^-1, respectively) were comparable to their respective exposures via rice consumption in China. Children being exposed to THg in dust is a major concern in mercury mining areas (e.g., Wangshan and Xunyang), and may also be a concern in cities with major coal-based industries and nonferrous metal smelting. Results from this study suggest that exposure to street dust is not a primary MeHg exposure pathway in China.

Cardiovascular effects of airborne particulate matter: A review of rodent model studies

In recent year, animal models have been growingly used to increase our knowledge about the toxicity of PM and underlying mechanisms leading to cardiovascular diseases. In this article, we review the current state of knowledge and findings of studies investigating the cardiovascular effects of PM in rats and mice. The six main areas covered in this review include: I) nature of particulate matter and toxicity mechanisms, II) systemic inflammation, III) heart rate and heart rate variability, IV) histopathological effects, V) atherosclerosis, VI) thrombosis, and VI) myocardial infarction. This review showed that animal model studies have been successful to bring new insights into the mechanisms underlying PM-induced cardiovascular diseases. However, there are some areas that the exact mechanisms are still unclear. In conclusion, investigating the cardiovascular effects of PM in vivo or interpreting the results should attempt to justify the role of different PM compositions, which may vastly affect the overall cytotoxicity of particles.

Associations of ambient air pollutant exposure with seminal plasma MDA, sperm mtDNA copy number, and mtDNA integrity

BACKGROUND

Current available evidence regarding the detrimental effects of low-level ambient air pollution on conventional semen parameters is inconclusive. In nonreproductive systems, air pollutant exposure has been demonstrated to induce oxidative stress (OS), which is a crucial mechanism that mediates sperm damage and male infertility. Thus, it may be essential to investigate the effects of air pollution on sperm quality in terms of the perspectives of OS and relative molecular damage.

OBJECTIVES

We assessed the associations of major air pollutant exposure to oxidative stress-mediated alterations in semen, including seminal plasma malondialdehyde (MDA), sperm mtDNA copy number, and integrity.

METHODS

The present study used data gathered from 516 young men participating in the Male Reproductive Health in Chongqing College student (MARCHS) cohort study during the follow-up stage in 2014 (n = 427 on the old campus, which is located in an urban area and has worse air quality, and n = 89 on the new campus, which is not urban and has better air quality). Data regarding major air pollutant exposure during 0-90, 0-9, 10-14 and 70-90 days before each semen examination (corresponding to the entire and three key periods of sperm development, respectively) were collected. The Mann-Whitney U nonparametric test was employed to compare distributions of major air pollutants and to explore differences in MDA, mtDNA copy number, and mtDNA integrity between the two campuses. A linear regression model was used as multivariable analysis to investigate associations of major air pollutant exposure with these biomarkers of oxidative damage to sperm and to adjust for potential confounders.

RESULTS

During all four key periods of sperm development, compared with college students on the new campus, college students on the old campus were exposed to higher levels of PM10, PM2.5, NO₂, and CO, and had higher air quality index (AQI) values, indicating that these participants suffered from worse air quality. The levels of seminal plasma MDA in college students on the old campus were higher than those for the new campus (2.0 nmol/ml; 0.7, 3.6 vs. 1.6 nmol/ml; 0.4, 3.4, p < 0.001) (medians with 5th and 95th percentiles). There were no significant differences in sperm mtDNA copy number and mtDNA integrity between the two campuses. Furthermore, daily average PM10 exposure during 0-90 days before semen ejaculation was found to be significantly and positively associated with seminal plasma MDA level (10.4; 95% CI, 4.4, 16.4) (percentage change per 10-unit increase in air pollutant concentration; same meanings for the results below); daily average SO₂ exposure for 70-90 days and NO₂ exposure for 0-9 days prior to sampling were also positively associated with MDA level (74.7; 95% CI, 32.1, 119 and 11.9; 95% CI, 4.8, 19.0, respectively). AQI for 0-90 days and 70-90 days prior to sampling positively correlated with seminal plasma MDA concentrations (11.4; 95% CI, 4.7, 18.1 and 12.2; 95% CI, 5.3, 19.1, respectively). Additionally, daily average SO₂ exposures for 10-14 and 0-9 days prior to sampling were negatively associated with sperm mtDNA copy number and mtDNA integrity, respectively (-9.0; 95% CI, -16.4, -1.6 and -38.3; 95% CI, -64.1, -11.8, respectively). However, only the correlations between SO₂ exposure and AQI value for 70-90 days prior to sampling and MDA levels remained significant after multiplicity adjustment.

CONCLUSIONS

The results indicate that bad air quality, especially SO₂ exposure during certain periods of sperm development, might be correlated with oxidative damage to sperm. These findings can deepen the understanding of the potential impacts of air pollution on sperm quality.

Estimation of air pollutants emission (PM10, CO, SO2 and NOx) during development of the industry using AUSTAL 2000 model: A new method for sustainable development

There is well-documented relationship between industrial development and environmental pollution, but there are no enough studies that have predicted development impacts on pollutants emission. In the current study, impacts of three development periods of Bojnourd cement factory on pollutants emission (CO, SO₂, NO_x, and PM₁₀) were investigated using the AUSTAL 2000 model. The collected emission data during 19 years were classified for each period and analyzed via the model, separately. Two sets of monitoring point (each contains 5 points) determined at the model; first set for estimation of pollutants concentration in residential areas (three villages, one suburban, and one city), and the second set for model validity assessment which located near the factory.

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According to model results, the second development period had the highest emission load per unit area for PM₁₀ and SO₂ by 164% and 262%, respectively. However, by applying the bag filter at the beginning of the third period, SO₂ and PM₁₀ concentrations were reduced significantly to the same as the first period.

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Unlike the two previous pollutants, emissions load of NO_x and CO per unit area were increased in both the second period (167% and 154%, respectively) and third period (182% and 337%, respectively). Moreover, the model showed a good agreement compared with the field measured data that it could be usable to predict pollutants emission.

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The findings of this paper prove the predicting importance of the emissions prior to construction or any stages of industries upgrading and development. In other words, it emphasizes environmental protection during economic boost to maintain harmony between nature and sustainable development. Also, the model showed how the use of pollution control equipment (bag filter) during development can be effective to reduce the pollutants emission.