Polycyclic aromatic hydrocarbons in indoor mosques dust in Saudi Arabia: Levels, source apportionment, human health and carcinogenic risk assessment for congregators.

Mosques are important places for Muslims where they perform their prayers. The congregators are exposed to hazardous pollutants such as polycyclic aromatic hydrocarbons (PAHs) associated with dust. However, studies on PAHs exposure in religious places are scarce. Air-condition filter (ACF) dust can correspond to air quality to a certain extent, since dust particles derived from indoor and outdoor places stick to it. Therefore, the present study aimed to evaluate the 16 EPA PAHs in ACF dust from mosques to determine their levels, profiles, sources and risks. Average Σ16 PAHs concentrations were 1039, 1527, 2284 and 5208 ng/g in AC filter dust from mosques in residential (RM), suburban (SM), urban (UM) and car repair workshop (CRWM), respectively, and the differences were statistically significant (p < 0.001). Based on the molecular diagnostic PAH ratios, PAHs in mosques dust is emitted from local incomplete fuel combustion, as well as complete fossil fuels combustion sources (pyrogenic), petroleum spills, crude and fuel oil, traffic emissions, and other possible sources of industrial emissions in different functional areas. The incremental lifetime cancer risks (ILCRs) values for children and adults across the different types of mosques follow the order: CRWM > UM > SM > RM. ILCRs values for both children and adults were found in order: dermal contact > ingestion > inhalation. The cancer risk levels via ingestion for children were relatively higher than the adults. The values of cancer risk for children and adults via dermal contact and ingestion (except in RM) were categorized in the 'potentially high risk' category (> 10-4). The mean values of total cancer risks (CR) for children (5.74 × 10-3) and adults (5.07 × 10-3) in mosques also exceeded the accepted threat value (>10-4). Finally, it is recommended that regular and frequent monitoring of PAHs should be carried out in mosques to improve the quality and maintain the health of congregators around the globe.

Potentially Harmful Elements Associated with Dust of Mosques: Pollution Status, Sources, and Human Health Risks.

Potentially harmful elements (PHEs) associated with dust generated from anthropogenic sources can be transported into mosques and deposited on the filters of the air-conditioners (AC); thereby, children and adults are exposed to such PHEs while visiting mosques. Data dealing with the assessment of PHEs pollution and its human health risk in mosques dust in Saudi Arabia are scarce. Therefore, this work aims to examine the levels and pollution status of PHEs in AC filter dust (ACFD) of mosques and their associated human health risk in three Saudi cities: Jubail, Jeddah, and Dammam metropolitan. A similar concentration pattern of PHEs is observed in three cities' mosques with noticeably higher concentrations than both global crustal and local background values for Zn, Cu, Pb, As, and Cd only. Except for Fe, Al, and Mn, the highest PHEs concentrations were found in Jeddah (1407 mg/kg), followed by Dammam (1239 mg/kg) and Jubail (1103 mg/kg). High PHEs' concentrations were also recorded in mosques located near workshops and suburban areas compared to urban areas. Based on the spatial pattern, enrichment factor, geo-accumulation index, pollution load index, and ecological risk values, Jubail, Jeddah, and Dammam have shown moderate pollution levels of Cd, As, Pb, and Zn. On the other hand, Cu. Zn, Cu, Cr, Pb, Ni, As, and Cd had degrees of enrichment levels that varied from significantly enriched to extremely highly enriched in the ACFD of the three cities. Heavy pollution is found in Jubail, which posed a higher potential ecological risk than in Jeddah and Dammam. Cd presents the highest ecological risk factors (ER) in the three cities. Carcinogenic and non-carcinogenic risks for children and adults follow the order: Jeddah > Dammam > Jubail, and the ingestion pathway was the main route for exposure. Carcinogenic and con-carcinogenic risks in the mosques of the various studied cities were generally within the acceptable range.

Effect of restricted emissions during COVID-19 on atmospheric aerosol chemistry in a Greater Cairo suburb: Characterization and enhancement of secondary inorganic aerosol production.

To prevent the rapid spreading of the COVID-19 pandemic, the Egyptian government had imposed partial lockdown restrictions which led emissions reduction. This served as ideal conditions for a natural experiment, for study the effect of partial lockdown on the atmospheric aerosol chemistry and the enhanced secondary inorganic aerosol production in a semi-desert climate area like Egypt. To achieve this objective, SO2, NO2, and PM2.5 and their chemical compositions were measured during the pre-COVID, COVID partial lockdown, and post-COVID periods in 2020 in a suburb of Greater Cairo, Egypt. Our results show that the SO2, NO2, PM2.5 and anthropogenic elements concentrations follow the pattern pre-COVID > post-COVID > COVID partial lockdown. SO2 and NO2 reductions were high compared with their secondary products during the COVID partial lockdown compared with pre-COVID. Although, PM2.5, anthropogenic elements, NO2, SO2, SO4 2-, NO3 -, and NH4 + decreased by 39%, 38-55%, 38%, 32.9%. 9%, 14%, and 4.3%, respectively, during the COVID partial lockdown compared with pre-COVID, with the secondary inorganic ions (SO4 2-, NO3 -, and NH4 +) being the dominant components in PM2.5 during the COVID partial lockdown. Moreover, the enhancement of NO3 - and SO4 2- formation during the COVID partial lockdown was high compared with pre-COVID. SO4 2- and NO3 - formation enhancements were significantly positive correlated with PM2.5 concentration. Chemical forms of SO4 2- and NO3 - were identified in PM2.5 based on their NH4 +/SO4 2- molar ratio and correlation between NH4 + and both NO3 - and SO4 2-. The particles during the COVID partial lockdown were more acidic than those in pre-COVID.

On the nature of polycyclic aromatic hydrocarbons associated with sporting walkways dust: Concentrations, sources and relative health risk.

Sporting walkways (SW) are a new innovation which may prove popular in many cities. As there is currently no information on possible health risks associated with their use, concentrations of polycyclic aromatic hydrocarbons (PAHs) associated with deposited dust sampled on SW in Jeddah, Saudi Arabia, have been measured and interpreted in relation to sources and cancer risk. The average ∑PAHs (16 compounds) ranged between 1357 ng/g in residential areas and 3764 ng/g in central urban areas, with suburban areas between. The congener profile and diagnostic ratios of PAHs indicate a predominant source associated with petroleum combustion (pyrogenic source), most probably vehicular emissions. Carcinogenic potential is estimated from the sum of carcinogenic compound concentrations weighted by their individual potency relative to benzo(a)pyrene, and is found to be similar to household dust sampled in the same city, and lower than many other indoor and outdoor (road) dusts sampled across the world.

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.

Risk Assessment and Implications of Schoolchildren Exposure to Classroom Heavy Metals Particles in Jeddah, Saudi Arabia.

Classrooms Air Conditioner Filter (CACF) particles represent all of the exposed particles that have migrated to the interior environment. This study was conducted to assess the heavy metals contamination in CACF particles from Jeddah primary schools located in urban, suburban and residential areas; and to evaluate their health risks of children exposure (non-carcinogenic and carcinogenic). Heavy metals levels in CACF particles of schools were in the following order: urban schools > suburban schools > residential schools. Fe, Mn and Zn were the dominant species. Geo-accumulation index (Igeo), contamination factor (CF) and pollution load index (PLI) values indicated that the contamination levels was in the following order Cd > Pb > Zn > As > Cu > Ni > Mn > Cr > Co >V > Fe. School CACF particles was moderately contaminated with As and Zn and moderately to heavily contaminated with Pb and Cd. Enrichment factors (EFs) indicated that Zn, Cd, Pb, As and Cu in CACF particles were severe enriched. The hazard quotient (HQs) and hazards index (HI) values for heavy metals were lower than the acceptable level of one. As, Pb, Cr and Mn were exhibited high non-cancer effects for children. The lifetime cancer risk (LCR) and total lifetime cancer risk (TLCR), HQs and HI values for the different exposure pathways of heavy metals decreased in the following order: ingestion > dermal contact > inhalation. Carcinogenic and non-carcinogenic risk rank order of schools were urban schools > suburban schools > residential schools. The LCR and TLCR of heavy metals was in the following order: Co > Ni >Cr > Cd > As > Pb. The ingestion lifetime cancer risk (LCRing) and TLCR values from exposure to Ni and Cr in urban and suburban schools, Cd in urban schools, and Co in all Jeddah schools only exceed the acceptable range (1 × 10-6-1 × 10-4) Only LCRing and TLCR values from exposure to ∑ carcinogens exceed the acceptable level.

A Predictive Model for Steady State Ozone Concentration at an Urban-Coastal Site.

Ground level ozone (O3) plays an important role in controlling the oxidation budget in the boundary layer and thus affects the environment and causes severe health disorders. Ozone gas, being one of the well-known greenhouse gases, although present in small quantities, contributes to global warming. In this study, we present a predictive model for the steady-state ozone concentrations during daytime (13:00⁻17:00) and nighttime (01:00⁻05:00) at an urban coastal site. The model is based on a modified approach of the null cycle of O3 and NOx and was evaluated against a one-year data-base of O3 and nitrogen oxides (NO and NO2) measured at an urban coastal site in Jeddah, on the west coast of Saudi Arabia. The model for daytime concentrations was found to be linearly dependent on the concentration ratio of NO2 to NO whereas that for the nighttime period was suggested to be inversely proportional to NO2 concentrations. Knowing that reactions involved in tropospheric O3 formation are very complex, this proposed model provides reasonable predictions for the daytime and nighttime concentrations. Since the current description of the model is solely based on the null cycle of O3 and NOx, other precursors could be considered in future development of this model. This study will serve as basis for future studies that might introduce informing strategies to control ground level O3 concentrations, as well as its precursors' emissions.

Street Dust-Bound Polycyclic Aromatic Hydrocarbons in a Saudi Coastal City: Status, Profile, Sources, and Human Health Risk Assessment.

Polycyclic aromatic hydrocarbons (PAHs) in street dust pose a serious problem threatening both the environment and human health. Street dust samples were collected from five different land use patterns (traffic areas TRA, urban area URA, residential areas REA, mixed residential commercial areas MCRA and suburban areas SUA) in Jeddah, a Saudi coastal city, and one in in Hada Al Sham, a rural area (RUA). This study aimed to investigate the status, profile, sources of PAHs and estimate their human health risk. The results revealed an average concentration of total PAHs of 3320 ng/g in street dust of Jeddah and 223 ng/g in RUA dust. PAHs with high molecular weight represented 83.38% of total PAHs in street dust of Jeddah, while the carcinogenic PAH compounds accounted 57.84%. The highest average concentration of total PAHs in street dust of Jeddah was found in TRA (4980 ng/g) and the lowest in REA (1660 ng/g). PAHs ratios indicated that the principal source of PAHs in street dust of Jeddah is pyrogenic, mainly traffic emission. Benzo(a)anthracene/chrysene (BaA/CHR) ratio suggests that PAHs in street dusts of Jeddah come mainly from emission of local sources, while PAHs in RUA might be transported from the surrounding urban areas. The estimated Incremental Lifetime Cancer Risk (ILCR) associated with exposure to PAHs in street dusts indicated that both dermal contact and ingestion pathways are major contributed to cancer risk for both children and adults. Based on BaPequivalence concentrations of total PAHs, ILCRIngestion, ILCRdermal and cancer risk values for children and adults exposed to PAHs in street dust of different areas in Jeddah were found between 10-6 and 10-4, indicating potential risk. The sequence of cancer risk was TRA > URA > MCRA > SUA > REA. Only exposure to BaP and DBA compounds had potential risk for both children and adults.

Temporal variations of fine and coarse particulate matter sources in Jeddah, Saudi Arabia.

This study provides the first comprehensive analysis of the seasonal variations and weekday/weekend differences in fine (aerodynamic diameter <2.5 µm; PM2.5) and coarse (aerodynamic diameter 2.5-10 µm; PM2.5-10) particulate matter mass concentrations, elemental constituents, and potential source origins in Jeddah, Saudi Arabia. Air quality samples were collected over 1 yr, from June 2011 to May 2012 at a frequency of three times per week, and analyzed. The average mass concentrations of PM2.5 (21.9 µg/m3) and PM10 (107.8 µg/m3) during the sampling period exceeded the recommended annual average levels by the World Health Organization (WHO) for PM2.5 (10 µg/m3) and PM10 (20 µg/m3), respectively. Similar to other Middle Eastern locales, PM2.5-10 is the prevailing mass component of atmospheric particulate matter at Jeddah, accounting for approximately 80% of the PM10 mass. Considerations of enrichment factors, absolute principal component analysis (APCA), concentration roses, and backward trajectories identified the following source categories for both PM2.5 and PM2.5-10: (1) soil/road dust, (2) incineration, and (3) traffic; and for PM2.5 only, (4) residual oil burning. Soil/road dust accounted for a major portion of both the PM2.5 (27%) and PM2.5-10 (77%) mass, and the largest source contributor for PM2.5 was from residual oil burning (63%). Temporal variations of PM2.5-10 and PM2.5 were observed, with the elevated concentration levels observed for mass during the spring (due to increased dust storm frequency) and on weekdays (due to increased traffic). The predominant role of windblown soil and road dust in both the PM2.5 and PM2.5-10 masses in this city may have implications regarding the toxicity of these particles versus those in the Western world where most PM health assessments have been made in the past. These results support the need for region-specific epidemiological investigations to be conducted and considered in future PM standard setting. IMPLICATIONS: Temporal variations of fine and coarse PM mass, elemental constituents, and sources were examined in Jeddah, Saudi Arabia, for the first time. The main source of PM2.5-10 is natural windblown soil and road dust, whereas the predominant source of PM2.5 is residual oil burning, generated from the port and oil refinery located west of the air sampler, suggesting that targeted emission controls could significantly improve the air quality in the city. The compositional differences point to a need for health effect studies to be conducted in this region, so as to directly assess the applicability of the existing guidelines to the Middle East air pollution.

Risk Assessment and Implication of Human Exposure to Road Dust Heavy Metals in Jeddah, Saudi Arabia.

Data dealing with the assessment of heavy metal pollution in road dusts in Jeddah, Saudi Arabia and its implication to human health risk of human exposure to heavy metals, are scarce. Road dusts were collected from five different functional areas (traffic areas (TA), parking areas (PA), residential areas (RA), mixed residential commercial areas (MCRA) and suburban areas (SA)) in Jeddah and one in a rural area (RUA) in Hada Al Sham. We aimed to measure the pollution levels of heavy metals and estimate their health risk of human exposure applying risk assessment models described by United States Environmental Protection Agency (USEPA). Using geo-accumulation index (Igeo), the pollution level of heavy metals in urban road dusts was in the following order Cd > As > Pb > Zn > Cu > Ni > Cr > V > Mn > Co > Fe. Urban road dust was found to be moderately to heavily contaminated with As, Pb and Zn, and heavily to extremely contaminated with Cd. Calculation of enrichment factor (EF) revealed that heavy metals in TA had the highest values compared to that of the other functional areas. Cd, As, Pb, Zn and Cu were severely enriched, while Mn, V, Co, Ni and Cr were moderately enriched. Fe was considered as a natural element and consequently excluded. The concentrations of heavy metals in road dusts of functional areas were in the following order: TA > PA > MCRA > SA > RA > RUA. The study revealed that both children and adults in all studied areas having health quotient (HQ) < 1 are at negligible non-carcinogenic risk. The only exception was for children exposed to As in TA. They had an ingestion health quotient (HQing) 1.18 and a health index (HI) 1.19. The most prominent exposure route was ingestion. The cancer risk for children and adults from exposure to Pb, Cd, Co, Ni, and Cr was found to be negligible (≤1 × 10-6).

Polycyclic aromatic hydrocarbons (PAHs) in the settled dust of automobile workshops, health and carcinogenic risk evaluation.

There are studies available on the occurrence of PAHs in indoor settled dust from residential and different occupational settings in literature but limited data is available on their occurrence and potential health risk assessment in automobile workshops. In recent decades Saudi Arabia has experienced tremendous growth in the petroleum industry and as a result, the automobile industry is booming. People working in automobile workshops are at a greater risk of exposure to chemicals releasing from the petroleum products. The main objective of this study was to report PAHs in settled dust from different automobile workshops of Jeddah, Saudi Arabia, and evaluate health risk for workers through dust exposure. Pyrene (1585-13500ng/g), Benz[a]anthracene (

Evaluation of the Effects of Airborne Particulate Matter on Bone Marrow-Mesenchymal Stem Cells (BM-MSCs): Cellular, Molecular and Systems Biological Approaches.

Particulate matter (PM) contains heavy metals that affect various cellular functions and gene expression associated with a range of acute and chronic diseases in humans. However, the specific effects they exert on the stem cells remain unclear. Here, we report the effects of PM collected from the city of Jeddah on proliferation, cell death, related gene expression and systems of biological analysis in bone marrow mesenchymal stem cells (BM-MSCs), with the aim of understanding the underlying mechanisms. PM2.5 and PM10 were tested in vitro at various concentrations (15 to 300 µg/mL) and durations (24 to 72 h). PMs induced cellular stress including membrane damage, shrinkage and death. Lower concentrations of PM2.5 increased proliferation of BM-MSCs, while higher concentrations served to decrease it. PM10 decreased BM-MSCs proliferation in a concentration-dependent manner. The X-ray fluorescence spectrometric analysis showed that PM contains high levels of heavy metals. Ingenuity Pathway Analysis (IPA) and hierarchical clustering analyses demonstrated that heavy metals were associated with signaling pathways involving cell stress/death, cancer and chronic diseases. qRT-PCR results showed differential expression of the apoptosis genes (BCL2, BAX); inflammation associated genes (TNF-α and IL-6) and the cell cycle regulation gene (p53). We conclude that PM causes inflammation and cell death, and thereby predisposes to chronic debilitating diseases.

Association between Exposure to Ambient Air Particulates and Metabolic Syndrome Components in a Saudi Arabian Population.

Recent epidemiological evidence suggests that exposure to particulates may be a factor in the etiology of metabolic syndrome (MetS). In this novel study, we investigated the relationship between particulate levels and prevalence of MetS component abnormalities (hypertension, hyperglycemia, obesity) in a recruited cohort (N = 2025) in Jeddah, Saudi Arabia. We observed significant associations between a 10 µg/m³ increase in PM2.5 and increased risks for MetS (Risk Ratio (RR): 1.12; 95% Confidence Interval (CI): 1.06-1.19), hyperglycemia (RR: 1.08; 95% CI: 1.03-1.14), and hypertension (RR: 1.09; 95% CI: 1.04-1.14). PM2.5 from soil/road dust was found to be associated with hyperglycemia (RR: 1.12; 95% CI: 1.06-1.19) and hypertension (RR: 1.11; 95% CI: 1.05-1.18), while PM2.5 from traffic was associated with hyperglycemia (RR: 1.33; 95% CI: 1.05-1.71). We did not observe any health associations with source-specific mass exposures. Our findings suggest that exposure to specific elemental components of PM2.5, especially Ni, may contribute to the development of cardiometabolic disorders.

Polycyclic aromatic hydrocarbons (PAHs) in indoor dust samples from Cities of Jeddah and Kuwait: Levels, sources and non-dietary human exposure.

This study reports levels and profiles of polycyclic aromatic hydrocarbons (PAHs) in dust samples collected from three different microenvironments (cars, air conditioner (AC) filters and household floor dust) of Jeddah, Saudi Arabia (KSA) and Kuwait. To the best of our knowledge, this is first study reporting PAHs in indoor microenvironments of KSA, which makes these findings important. Benzo(b)fluoranthene (BbF), benzo(a)pyrene (BaP), phenanthrene (Phe), and pyrene (Pyr) were found to be the major chemicals in dust samples from all selected microenvironments. ΣPAHs occurred at median concentrations (ng/g) of 3450, 2200, and 2650 in Saudi AC filter, car and household floor dust, respectively. The median levels (ng/g) of ΣPAHs in Kuwaiti car (950) and household floor (1675) dust samples were lower than Saudi dust. The PAHs profile in Saudi dust was dominated by high molecular weight (HMW) (4-5 ring) PAHs while in Kuwaiti dust 3 ring PAHs have marked contribution. BaP equivalent, a marker for carcinogenic PAHs, was high in Saudi household floor and AC filter dust with median levels (ng/g) of 370 and 455, respectively. Different exposure scenarios, using 5th percentile, median, mean, and 95th percentile levels, were estimated for adults and toddlers. For Saudi and Kuwaiti toddlers worst exposure scenario of ΣPAHs was calculated at 175 and 85ng/kg body weight/day (ng/kgbw/d), respectively. For Saudi toddlers, the calculated worst exposure scenarios for carcinogenic BaP (27.7) and BbF (29.3ng/kgbw/d) was 2-4 times higher than Kuwaiti toddlers. This study is based on small number of samples which necessitate more detailed studies for better understanding of dynamics of PAHs in the indoor environments of this region. Nevertheless, our finding supports the ongoing exposure of organic pollutants to population that accumulates indoor.

Association between sleeping hours and cardiometabolic risk factors for metabolic syndrome in a Saudi Arabian population.

OBJECTIVES: Epidemiological and molecular studies have shown that sleep duration is associated with metabolic syndrome (MtS), a disease that is on the rise in the Kingdom of Saudi Arabia. We aim to investigate the association between sleep duration and selected cardiometabolic risk factors of MtS in a Saudi Arabian population. SETTING: Secondary care was given to the participants. There were 2 participating centres, shopping malls in North and South Jeddah, Saudi Arabia. PARTICIPANTS: We recruited 2686 participants over a 1-year study period. Participants were selected based on their willingness. The only criterion for exclusion was living in the area (North or South Jeddah) for less than 15 years. PLANNED AND PRIMARY OUTCOME MEASURES: Participants were measured for blood sugar levels, blood pressure and body mass index. All participants were asked to fill out a questionnaire. RESULTS: There was a positive association between longer sleep duration and obesity, hypertension and hyperglycaemia. The adjusted ORs for obesity, hypertension and hyperglycaemia were 1.54 (95% CI 1.20 to 1.98), 1.89 (95% CI 1.45 to 2.48) and 1.59 (95% CI 1.19 to 2.13), respectively, in participants sleeping >8 h/night, as compared with those sleeping 7 h. The positive associations between longer sleep duration, defined as sleeping >7 h, and the disease status, did not differ from other risk factors such as physical activity and nutrition. CONCLUSIONS: This is the first epidemiological study reporting on the association between sleep duration and cardiometabolic risk factors of MtS in a Saudi Arabian population. Sleep durations of 8 h or greater were found to be associated with all 3 cardiometabolic risk factors: obesity, hypertension and hyperglycaemia, and this relationship was not confounded by quality of nutrition or physical activity levels.

In Vivo Exposures to Particulate Matter Collected from Saudi Arabia or Nickel Chloride Display Similar Dysregulation of Metabolic Syndrome Genes.

Particulate matter (PM) exposures have been linked to mortality, low birth weights, hospital admissions, and diseases associated with metabolic syndrome, including diabetes mellitus, cardiovascular disease, and obesity. In a previous in vitro and in vivo study, data demonstrated that PM(10µm) collected from Jeddah, Saudi Arabia (PMSA), altered expression of genes involved in lipid and cholesterol metabolism, as well as many other genes associated with metabolic disorders. PMSA contains a relatively high concentration of nickel (Ni), known to be linked to several metabolic disorders. In order to evaluate whether Ni and PM exposures induce similar gene expression profiles, mice were exposed to 100 µg/50 µl PM(SA) (PM-100), 50 µg/50 µl nickel chloride (Ni-50), or 100 µg/50 µl nickel chloride (Ni-100) twice per week for 4 wk and hepatic gene expression changes were determined. Ultimately, 55 of the same genes were altered in all 3 exposures. However, where the two Ni groups differed markedly was in the regulation (up or down) of these genes. Ni-100 and PM-100 groups displayed similar regulations, whereby 104 of the 107 genes were similarly modulated. Many of the 107 genes are involved in metabolic syndrome and include ALDH4A1, BCO2, CYP1A, CYP2U, TOP2A. In addition, the top affected pathways, such as fatty acid α-oxidation, and lipid and carbohydrate metabolism, are involved in metabolic diseases. Most notably, the top diseased outcome affected by these changes in gene expression was cardiovascular disease. Given these data, it appears that Ni and PM(SA) exposures display similar gene expression profiles, modulating the expression of genes involved in metabolic disorders.

Urinary metabolites of polycyclic aromatic hydrocarbons in Saudi Arabian schoolchildren in relation to sources of exposure.

Polycyclic aromatic hydrocarbons contain a number of known carcinogenic compounds, and urinary biomarkers have been widely used as a measure of exposure but quantitative relationships with exposure variables have proved elusive. This study aimed to quantify the relationship between exposures to phenanthrene and pyrene from atmospheric and dietary sources with the excretion of 1-hydroxypyrene and hydroxyphenanthrenes in urine as biomarkers of exposure. The study population consisted of 204 male schoolchildren attending three schools in different parts of Jeddah, Saudi Arabia who provided urine samples on each of three consecutive days. Outdoor air measurements of polycyclic aromatic hydrocarbons were made at the schools and the children provided information on diet, exposure to environmental tobacco smoke and incense, and various lifestyle factors through a questionnaire. Mixed models with random effects for subjects nested within site were fitted in order to examine the relationship between exposure variables and urinary PAH metabolites. A unit increase (1 ng m(-3)) in ambient pyrene (particulate plus gaseous phase) was associated with a 3.5% (95% CI: 1.01%, 5.13%) increase in urinary 1-hydroxypyrene concentration. A unit increase in ambient phenanthrene was associated with a 1.01% (95% CI: 0.03%, 2.02%) increase in total hydroxyphenanthrene concentrations. Consumption of chargrilled food increased the 1-hydroxypyrene and hydroxyphenanthrene concentrations by 24% (95% CI: 11%, 37%) and 17% (95% CI: 8%, 26%) respectively. We did not find evidence of association for environmental tobacco smoke exposure or incense burning. It is concluded that both respiratory exposure and consumption of chargrilled food are considerable sources of PAH exposure in this population as reflected by concentrations of urinary biomarkers.

Effects of airborne particulate matter on alternative pre-mRNA splicing in colon cancer cells.

Alternative pre-mRNA splicing plays key roles in determining tissue- and species-specific cell differentiation as well as in the onset of hereditary disease and cancer, being controlled by multiple post- and co-transcriptional regulatory mechanisms. We report here that airborne particulate matter, resulting from industrial pollution, inhibits expression and specifically affects alternative splicing at the 5' untranslated region of the mRNA encoding the bone morphogenetic protein BMP4 in human colon cells in culture. These effects are consistent with a previously reported role for BMP4 in preventing colon cancer development, suggesting that ingestion of particulate matter could contribute to the onset of colon cell proliferation. We also show that the underlying mechanism might involve changes in transcriptional elongation. This is the first study to demonstrate that particulate matter causes non-pleiotropic changes in alternative splicing.

Polycyclic aromatic hydrocarbons, brachial artery distensibility and blood pressure among children residing near an oil refinery.

BACKGROUND: Polycyclic aromatic hydrocarbons (PAH) are produced by the burning and processing of fuel oils, and have been associated with oxidant stress, insulin resistance and hypertension in adults. Few studies have examined whether adolescents are susceptible to cardiovascular effects of PAHs. OBJECTIVE: To study associations of PAH exposure with blood pressure (BP) and brachial artery distensibility (BAD), an early marker of arterial wall stiffness, in young boys attending three schools in Jeddah, Saudi Arabia in varying proximity to an oil refinery. METHODS: Air samples collected from the three schools were analyzed for PAHs. PAH metabolites (total hydroxyphenanthrenes and 1-hydroxypyrene) were measured in urine samples from 184 adolescent males, in whom anthropometrics, heart rate, pulse pressure, brachial artery distensibility and blood pressure were measured. Descriptive, bivariate and multivariable analyses were performed to assess relationships of school location and urinary PAH metabolites with cardiovascular measures. RESULTS: Total suspended matter was significantly higher (444 ± 143 µg/m(3)) at the school near the refinery compared to a school located near a ring road (395 ± 65 µg/m(3)) and a school located away from vehicle traffic (232 ± 137 µg/m(3)), as were PAHs. Systolic (0.47 S D units, p = 0.006) and diastolic (0.53 SD units, p < 0.001) BP Z-scores were highest at the school near the refinery, with a 4.36-fold increase in prehypertension (p = 0.001), controlling for confounders. No differences in pulse pressure, BAD and heart rate were noted in relationship to school location. Urinary total hydroxyphenanthrenes and 1-hydroxypyrene were not associated with cardiovascular outcomes. CONCLUSIONS: Proximity to an oil refinery in Saudi Arabia is associated with prehypertension and increases in PAH and particulate matter exposures. Further study including insulin resistance measurements, better control for confounding, and longitudinal measurement is indicated.

Receptor modelling study of polycyclic aromatic hydrocarbons in Jeddah, Saudi Arabia.

Measurements of 14 polycyclic aromatic hydrocarbons (PAH) have been made in Jeddah, Saudi Arabia, with a view to establishing the concentrations in this major city, and quantifying the contributions of major sources. Particulate and vapour forms have been sampled and analysed separately. The concentrations are compared to measurements from other sites in the Middle Eastern region and are towards the lower end of the range, being far lower than concentrations reported from Riyadh (Saudi Arabia), Assiut (Egypt) and Tehran (Iran) but broadly similar to those measured in Damascus (Syria) and higher than those measured in Kuwait. The partitioning between vapour and particle phases is similar to that in data from Egypt and China, but with many compounds showing a higher particle-associated percentage than in Birmingham (UK) possibly reflecting a higher concentration of airborne particulate matter in the former countries. Concentrations in Jeddah were significantly higher at a site close to the oil refinery and a site close to a major ring road than at a suburban site to the north of the city. Application of positive matrix factorisation to the pooled data elicited three factors accounting respectively for 17%, 33% and 50% of the measured sum of PAH and these are interpreted as arising from gasoline vehicles, industrial sources, particularly the oil refinery, and to diesel/fuel oil combustion.