Science of the Total Environment 573 (2016) 1607–1614
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Polycyclic aromatic hydrocarbons (PAHs) in indoor dust samples from Cities of Jeddah and Kuwait: Levels, sources and non-dietary human exposure Nadeem Ali a,⁎, Iqbal Mohammad Ibrahim Ismail a,b, Mamdouh Khoder a,c, Magdy Shamy c, Mansour Alghamdi c, Max Costa d, Lulwa Naseer Ali e, Wei Wang f, Syed Ali Musstjab Akber Shah Eqani g a
Center of Excellence in Environmental Studies, King Abdulaziz University, Jeddah, Saudi Arabia Department of Chemistry, Faculty of Science, King Abdulaziz University, Saudi Arabia c Department of Environmental Sciences, Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah, Saudi Arabia d Department of Environmental Medicine, NYU School of Medicine, Tuxedo, NY, USA e Environmental Sciences Department, Kuwait Institute for Scientiﬁc Research, Kuwait f Wadsworth Center, New York State Department of Health, Albany, NY, USA g Public health and Environment Division, Department of Biosciences, COMSAT Institute of Information & Technology, Islamabad, Pakistan b
H I G H L I G H T S
G R A P H I C A L
A B S T R A C T
• PAHs were analyzed in three microenvironments of Saudi Arabia and Kuwait. • PAHs were higher in indoor dust from Saudi Arabia than Kuwait. • AC ﬁlter dust was the most contaminated with PAHs. • Estimated exposure to carcinogenic PAHs was higher for Saudi toddlers than Kuwaiti counterparts.
a r t i c l e
i n f o
Article history: Received 27 April 2016 Received in revised form 17 August 2016 Accepted 16 September 2016 Available online 24 September 2016 Editor: Dr. D. Barcelo Keywords: Polycyclic aromatic hydrocarbons Indoor dust
a b s t r a c t 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
⁎ Corresponding author at: Center of Excellence in Environmental Studies, King Abdulaziz University, P.O Box: 80216, Jeddah 21589, Saudi Arabia. E-mail addresses: [email protected]
, [email protected]
http://dx.doi.org/10.1016/j.scitotenv.2016.09.134 0048-9697/© 2016 Elsevier B.V. All rights reserved.
N. Ali et al. / Science of the Total Environment 573 (2016) 1607–1614
Kuwait Saudi Arabia Human exposure
(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 85 ng/kg body weight/day (ng/kg bw/d), respectively. For Saudi toddlers, the calculated worst exposure scenarios for carcinogenic BaP (27.7) and BbF (29.3 ng/kg bw/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. © 2016 Elsevier B.V. All rights reserved.
1. Introduction Polycyclic aromatic hydrocarbons (PAHs) are semi-volatile organic compounds (SVOCs) which are chieﬂy produced during incomplete combustion of fossil-fuels, biomass, domestic burning, power generation, and pyrosynthesis of organic materials (Dong and Lee, 2009; Haritash and Kaushik, 2009; Lohmann et al., 2000). PAHs enter into the environment by both natural processes and anthropogenic sources (Benner et al., 1989; Junker et al., 2000). In indoor PAHs are formed from various activities such as use of electric or gas stove for heating and cooking, coal and candle burning, smoking and parquet ﬂooring (Chao et al., 1997; Chen et al., 2005; Guo et al., 2003; He et al., 2005; Heudorf and Angerer, 2001; Huali et al., 2002; Huynh et al., 1991; Li et al., 2005; Ohura et al., 2004; Turner et al., 1992). Incense burning (Bakhoor) is a common practice in Gulf countries, as suggested by Gevao et al. (2007) might be an important source of PAHs to the indoor environment of this region. Inﬁltrating air and soil tracked in from outdoor with PAHs is also an important source of contamination (Chuang et al., 1995; Sanderson and Farant, 2004). Like other SVOCs, PAHs can partition between the vapour phase and airborne particles (room surfaces e.g. furniture and walls), and reabsorb in settled dust (Butte and Heinzow, 2002; Roberts et al., 2009; Weschler and Nazaroff, 2008). When trapped in the settled dust, especially dust deep in the carpeted ﬂoor, dust can be a permanent reservoir for these chemicals (Butte and Heinzow, 2002; Mercier et al., 2011; Roberts et al., 2009). Organic pollutants are known to build up in indoor environment due to the limited ventilation and lack of direct sunlight (Butte and Heinzow, 2002; Santillo et al., 2003). Such scenarios makes house dust as indoor pollution archive and the analyses of pollutants in house dust can give a reliable indication of the extent of indoor contamination (Butte and Heinzow, 2002). Indoor dust ingestion and inhalation have gained lot of attention as an important exposure pathway for many organic pollutants (Butte and Heinzow, 2002, Mercier et al., 2011). Chemical exposure via dust intake is particularly important for young children and women from Gulf region since they spend most of their time indoors (Ali et al., 2013). For toddlers it become even more important because of the time they spent in contact with the ﬂoor, and they could ingest dust through mouthing of hands, toys, and other objects (Butte and Heinzow, 2002; Deziel et al., 2013; Santillo et al., 2003). In literature it is shown that PAHs are likely to act as endocrine disrupting chemicals and can cause potential health risks, including reproductive function abnormalities, hormonal imbalance, testicular lesions, carcinogenicity, neurological disorders, premature birth, skin allergies, asthma, neuro developmental disorders etc. (Boström et al., 2002; Deziel et al., 2013; Kim et al., 2013; Yang et al., 2015). Due to extreme weather conditions in Gulf region, people spend N90% of their time indoors, either in the ofﬁce, at home, or travelling. In recent decades indoor environments have been investigated for different organic pollutants including PAHs in different parts of the world (Srogi, 2007; Yang et al., 2015). PAHs are important environmental contaminants and have been widely detected in different environmental compartments e.g., soil, sediments, air, meat, sea food, vegetables, and industrial efﬂuents etc. (Ashraf and Salam, 2012; Srogi, 2007). In the Kingdom of Saudi Arabia (KSA), an important source of PAHs to the atmosphere is from oil production operations (Gevao et
al., 2007). Irrespective of the importance of PAHs contamination data, in Gulf region little regulatory attention is paid to the importance of their occurrence in the environment and impact on human health. In KSA there are no studies available that have investigated the occurrence and proﬁle of PAHs in humans and indoor environments. With rapid industrialization and economic growth, life style has changed in this region and due to extreme hot weather conditions, air conditioning has become an integral part of every household and work place. In the presence of abundant and relatively cheap energy, per capita energy consumption is high in both vehicles and households. The selection of three microenvironments was made based on their importance in the daily life of general population. The main objectives of this study, therefore, were to establish baseline concentrations of PAHs in different indoor microenvironments of KSA and Kuwait. To achieve this, the concentrations and proﬁle of PAHs were investigated in vehicle, AC ﬁlter, and household ﬂoor dust collected from city of Jeddah, KSA and Kuwait City. 2. Material and methods 2.1. Chemicals Following PAHs namely: acenaphthene (Ace), acenaphthylene (Acy), anthracene (Ant), benz(a)anthracene (BaA), benzo(a)pyrene (BaP), benzo(b)ﬂuoranthene (BbF), benzo(g,h,i)perylene (BghiP), benzo(k)ﬂuoranthene (BkF), chrysene (Chr), dibenz(a,h)anthracene (DahA), ﬂuoranthene (Flu), indeno(1,2,3-cd)pyrene (I123cdP), naphthalene (Naph), phenanthrene (Phe), and pyrene (Pyr) and d-labeled internal standards anthracene-D10 (Ant-D10), benzo(a)pyrene-D12 (BaP-D12), benzo(g,h,i)perylene-D12 (BghiP-D12), chrysene-D12 (Chr-D12) were purchased from Sigma Aldrich, with a purity of N99%. All solvents used during the analysis were of pesticide-grade. Acetone (Ace) and n-hexane (Hex) was purchased from Macron Chemicals, USA. All glass-wares were kept at 400 °C overnight, and then at 100 °C before use. 2.2. Sampling Jeddah, a city in the Hijaz Tihamah region on the coast of the Red Sea, is second largest city of KSA and characterized by huge industrialization and population boom in last three decades. Similarly, with oil industry boom, Kuwait has seen tremendous growth both in industry and population. High growth came with high demand of energy and other environmental challenges. As a result of all the economic development life style of the general population has changed and so does their indoor environment of households and work places. However, little efforts have been made to understand the impact of this rapid development both on the quality of environment and human health. To study the presence of PAHs in indoor environment, dust samples were collected from Jeddah, KSA (household ﬂoor, AC ﬁlter and vehicle dust = 15 each) during 2014–2015 and Kuwait (household ﬂoor and vehicle dust = 15 each) during 2012. For household ﬂoor dust, vacuum cleaner bags were collected from volunteer houses. AC ﬁlters were cleaned with brush on aluminum foil to collect dust samples. To avoid cross contamination, brushes from the respective houses were used
Median (mini-max) Kuwaiti car dust
Mean ± SD
20 ± 25 55 ± 20 80 ± 190 215 ± 220 26 ± 45 170 ± 250 225 ± 150 35 ± 30 80 ± 100 50 ± 50 200 ± 245 30 ± 50 95 ± 90 15 ± 35 35 ± 40 7 ± 20 1350 ± 1050
after pre-cleaning. For car dust, inside of the car (dash board, seats, trunk) except ﬂoor was vacuumed and, before each sample, the vacuum cleaner was cleaned thoroughly to avoid any cross contamination. To insure quality control, ﬁeld blanks were collected after every ﬁve samples. For each blank sample, 2 g of pre-washed sodium sulphate (Na2SO4) was well spread on the aluminum foil and then collected with the vacuum cleaner in the same way as the dust samples. To achieve homogenized samples, 250 μm mesh was used to sieve all samples. Details collected on questionnaires are given in SI.
18 (bLOQ-85) 55 (bLOQ-80) 26 (bLOQ-750) 137 (bLOQ-850) 15 (8–185) 130 (bLOQ-1050) 155 (65–590) 25 (10−130) 45 (bLOQ-350) 30 (15–210) 110 (bLOQ-950) bLOQ (bLOQ-165) 75 (bLOQ-315) bLOQ (bLOQ-110) bLOQ (bLOQ-120) bLOQ (bLOQ-65) 950 (450–4050)
N. Ali et al. / Science of the Total Environment 573 (2016) 1607–1614
110 (bLOQ-1085) 60 (40–120) 60 (bLOQ-250) 80 (bLOQ-730) 25 (5–165) 410 (40–1770) 140 (35–1540) 17 (bLOQ-250) 55 (bLOQ-530) 40 (10−310) 210 (bLOQ-1070) 40 (bLOQ-350) 80 (35–750) bLOQ (bLOQ-675) bLOQ (bLOQ-770) bLOQ (bLOQ-135) 1675 (450–9100) 280 ± 350 65 ± 25 90 ± 80 165 ± 230 32 ± 42 510 ± 480 220 ± 375 35 ± 60 90 ± 125 55 ± 75 245 ± 275 70 ± 85 140 ± 175 55 ± 170 70 ± 200 15 ± 35 2150 ± 2100 60 (bLOQ-135) 95 (65–220) 20 (bLOQ-120) 210 (bLOQ-1520) 55 (15–175) 220 (35–580) 215 (65–1480) 235 (85–520) 60 (25–280) 115 (25–250) 275 (bLOQ-1570) 40 (bLOQ-370) 145 (bLOQ-460) 40 (bLOQ-175) 80(bLOQ-250) bLOQ (bLOQ-45) 2200 (480–8050) 60 ± 50 110 ± 45 25 ± 30 495 ± 520 65 ± 45 280 ± 200 395 ± 380 410 ± 315 75 ± 60 125 ± 75 340 ± 385 80 ± 100 145 ± 115 65 ± 60 85 ± 90 7 ± 15 2750 ± 2020 190 (55–4725) 115 (90–750) 80 (30–375) 190 (bLOQ-1930) 50 (15–315) 140 (60–1310) 325 (95–2210) 235 (85–520) 100 (10–240) 90 (50–350) 675 (bLOQ-1820) 155 (40–510) 355 (70–790) 260 (bLOQ-850) 430 (bLOQ-2146) bLOQ (bLOQ-215) 3450 (1150–14,500) 550 ± 1180 225 ± 200 125 ± 100 355 ± 470 70 ± 75 250 ± 320 560 ± 580 250 ± 120 120 ± 65 115 ± 80 680 ± 500 170 ± 120 410 ± 260 320 ± 270 580 ± 600 30 ± 70 4800 ± 3900 125 (bLOQ-660) 105 (65–165) 80 (bLOQ-845) 170 (bLOQ-1230) 50 (25–835) 160 (40–1970) 175 (95–2625) 160(75–2620) 80 (12−200) 85(35–160) 575 (bLOQ-2300) 105 (15–440) 290 (40–2400) bLOQ (bLOQ-160) 75 (bLOQ-370) bLOQ (bLOQ-90) 2650 (950–11,950) 175 ± 180 110 ± 35 160 ± 210 290 ± 320 105 ± 205 425 ± 600 425 ± 645 385 ± 650 90 ± 45 95 ± 45 700 ± 635 110 ± 110 550 ± 635 15 ± 45 105 ± 120 16 ± 30 3750 ± 3250 Naph Ace Acy Fln Ant Phe Flu Pyr BaA Chr BbF BkF BaP IcdP BghiP DahA ƩPAHs
Kuwaiti household ﬂoor dust
Median (mini-max) Saudi car dust
Mean ± SD Median (mini-max)
Saudi AC ﬁlter dust
Mean ± SD Median (mini-max)
Saudi household ﬂoor dust
Mean ± SD
For descriptive analysis Microsoft Excel 2007 was used. Non-detects were replaced by ½ LOQ and non-parametric tests were applied considering small dataset in this study. The signiﬁcance level for the result was set p b 0.05. To study correlations between the levels of analytes between household ﬂoor and AC dust, Spearman rank order correlation coefﬁcient was performed using the online tool http://vassarstats.net/ corr_rank.html. To study the difference of PAHs in two microenvironments two sample t-test was applied using GraphPad.
2.5. Statistical analysis
Table 1 PAHs concentrations in analyzed dust of different microenvironments of KSA and Kuwait (ng/g of dust).
2.4. QA/QC As a part of the quality assurance protocol, ﬁeld blanks (N = 3 for each set of vehicle dust samples), laboratory blanks (extraction and clean up producer in the same way as dust samples but without dust samples to insure no contamination coming from solvent or glass wares) (N = 10) and indoor dust standard reference materials (SRMs) from National Institute of Standards & Technology SRM 2585 (N = 3) were analyzed in parallel with the dust samples to account for eventual external contamination during sampling, sample preparation and instrumental analysis, and to evaluate method accuracy. To avoid any degradation, samples and SRM 2585 were kept at −18 °C, therefore any changes in the levels of Kuwait samples would show up in changes of PAHs SRM 2585 used was bought years back, so any changes in the samples of Kuwait Levels of targeted analytes were blank-corrected in all samples. The lowest point of calibrations curve was used as limits of quantiﬁcation (LOQ). To avoid photodegradation of analytes, extraction and clean up steps were performed using amber glass under fume hood without light. The values of PAHs in SRM 2585 were in agreement (RSD b 30%) with published values (Whitehead et al., 2013).
Mean ± SD
An accurately weighed aliquot of dust samples (typically between 50 and 100 mg) were extracted in a 12 mL glass centrifuge tube. Samples were spiked with internal standards and allowed to equilibrate overnight at room temperature. Samples were extracted three times by ultrasonication for 30 min each time, with 4 mL of hexane/acetone (4/1, v/v) followed by centrifugation at 2000 rpm for 10 min. The pooled extracts were concentrated under a gentle stream of nitrogen to 1 mL for instrumental analysis. Analysis was performed using gas chromatography (Agilent Technologies 6890 N) coupled with mass spectrometry (Agilent Technologies 5973) in the selective ion-monitoring (SIM) mode. A fused silica capillary column (DB-5 30 m × 0.25 mm × 0.25 μm) was used for separation. The temperatures of injector and ion source were 280 °C and 230 °C, respectively. The oven temperature was programmed from 80 °C (held for 1 min), raised to 180 °C @ 12 °C/min, increased to 230 °C @ 6 °C/min, then increased to 270 °C @ 8 °C/min (held for 2 min), and ﬁnally ramped up to 300 °C @ 30 °C/min (held for 12 min). Ions m/z 128, 136, 152, 154, 164, 166, 178, 188, 202, 228, 240, 256, 258, 264, 276, 278, and 288 were monitored for different PAHs.
2.3. Sample preparation and instrumentation
N. Ali et al. / Science of the Total Environment 573 (2016) 1607–1614
3. Results and discussion 3.1. Levels and proﬁle of PAHs in different microenvironments Overall, sixteen PAHs were analyzed with varied detection frequencies in dust samples. The concentration of individual PAHs is summarized in Table 1 for each microenvironment. ΣPAHs (ng/g) ranged between 950 and 11,950, 1150–14,500, 480–8050, 400–9100, 450– 4000 in Saudi household ﬂoor, AC ﬁlter, car, and Kuwaiti household ﬂoor and car dust, respectively. The ΣPAHs in Saudi household ﬂoor dust were high compare to Kuwaiti household ﬂoor dust but not statistically signiﬁcant (p N 0.05). However, ΣPAHs in Saudi car dust were signiﬁcantly high (p b 0.05) than Kuwait car dust. The levels of ΣPAHs in Saudi household ﬂoor and AC ﬁlter dust were not statistically signiﬁcant different (p N 0.05). However, using Spearman's rank order correlation, no positive correlations were obtained between individual and ΣPAHs in Saudi AC ﬁlter and household ﬂoor dust (p N 0.05). This indicates that emission sources for PAHs are different or exists a different loading behaviour in ﬂoor and AC ﬁlters. Additionally, most of the sampled AC were installed in windows and AC ﬁlter dust might have more contribution from outside than household ﬂoor dust. Some of the AC ﬁlter dust have relatively high levels of low molecular weight (LMW) Naph, Ace, and Fln (2 ring). LMW (2–3 rings) PAHs are known to be relatively more volatile, which results their less abundance in settled dust compare to air particles. AC ﬁlter dust composed of smaller particles and is moist in nature, which might results in trapping different proﬁle of PAHs than ﬂoor dust but this need careful assessment since no scientiﬁc data is available on this argument. In terms of compositional pattern, high-molecular weight (HMW) PAHs (4 to 6 rings) were the predominant PAHs in dust from KSA, while in Kuwaiti dust LMW contributed more than HMW PAHs. These ﬁndings are in contrast with literature where HMW PAHs predominantly contributed (Gevao et al., 2007; Qi et al., 2014). No particular information collected with these samples could explain these differences. BbF was the major chemical; however BaP, Phe, Flu and Fln also contributed substantially in Saudi microenvironments (Table 1 & Fig. 1). While, Phe
and BbF were the principle PAHs in Kuwaiti household ﬂoor dust (Table 1). Generally LMW PAHs are reported high in air due to their volatile nature and HMW PAHs in settled dust. This shows settled dust is important source of HMW PAHs, which are reported to more toxic and persistent in the environment. Therefore, settled dust is an important source of toxic PAHs via dust ingestion and dermal contact. 3.2. Source apportionment of PAHs Generally composition of PAHs emissions varies with the source; petrogenic and pyrogenic sources are considered as the most important sources of PAHs. For source apportionment diagnostic, distribution indexes relative to concentration ratios of some PAHs ratios were applied in similar way to other studies from literature Table 2. Petrogenic sources are uncombusted petroleum products and primarily composed of low molecular PAHs (2–3 rings PAHs), while high molecular PAHs (4–6 rings PAHs) are the pyrogenic products from the combustion of coal, fossil fuel, natural gas, diesel and gasoline combustion (Baumard et al., 1999; Budzinski et al., 1997). These calculations are indicative as primary sources affect these calculated ratios since transportation of PAHs in gaseous phase, adsorption to the dust particles and photolytic degradation may modify the distribution patterns and as result distribution indexes (Mannino and Orecchio, 2008; Yunker et al., 2002). The average values of Phe/Ant varied between 4.2 and 18.9 suggesting petrogenic as well as pyrogenic sources in analyzed microenvironments (Table 2). In Kuwaiti household and car dust the ratio N 9 indicate petrogenic pollution is the primary point source. While, in all three microenvironments of KSA the ratio obtained was b6 which suggested petrogenic as well as pyrogenic point sources. The ratio of Flu vs. Pyr discriminate source typing of gaseous and particle transported PAHs (Budzinski et al., 1997). For all dust samples collected from KSA and Kuwait, ratios Flu/(Flu + Pyr) ranged from 0.44 to 0.63 (Table 2). Flu/ (Flu + Pyr) ratio between 0.40 and 0.50 indicates emission of these PAHs from sources such as gasoline, diesel and fuel oil combustion, while N0.50 indicates sources such as grass, coal and wood combustion (Yunker et al., 2002). Obtained values of Flu and Pyr ratio was b0.50 for
SFD 1 SFD 2 SFD 3 SFD 4 SFD 5 SFD 6 SFD 7 SFD 8 SFD 9 SFD 10 SFD 11 SFD 12 SFD 13 SFD 14 SFD 15 SAD 1 SAD 2 SAD 3 SAD 4 SAD 5 SAD 6 SAD 7 SAD 8 SAD 9 SAD 10 SAD 11 SAD 12 SAD 13 SAD 14 SAD 15 SCD 1 SCD 2 SCD 3 SCD 4 SCD 5 SCD 6 SCD 7 SCD 8 SCD 9 SCD 10 SCD 11 SCD 12 SCD 13 SCD 14 SCD 15 KFD 1 KFD 2 KFD 3 KFD 4 KFD 5 KFD 6 KFD 7 KFD 8 KFD 9 KFD 10 KFD 11 KFD 12 KFD 13 KFD 14 KFD 15 KCD 1 KCD 2 KCD 3 KCD 4 KCD 5 KCD 6 KCD 7 KCD 8 KCD 9 KCD 10 KCD 11 KCD 12 KCD 13 KCD 14 KCD 15
Fig. 1. Proﬁle of analyzed PAHs in dust from selected microenvironments.
N. Ali et al. / Science of the Total Environment 573 (2016) 1607–1614
Table 2 Comparison of characteristic ratios of PAHs in different types of indoor dust.
Petroleum Coal combustion Diesel car Gasoline car Wood combustion Road dust Industrial furnaces Northern Greece, PM10 Palermo, Italy Shanghai, China Rural dust, China Urban dust, China Saudi household ﬂoor dust Saudi car dust Saudi AC ﬁlter dust Kuwaiti household ﬂoor dust Kuwaiti car dust
IcdP/(IcdP + BghiP)
BaA/(BaA + Chr)
Flu/(Flu + Pyr)
– 0.15–1.11b 1.2–2.2d 2.5–3.3d – 0.91d 0.02–0.06i 2.0–13.5j – 0.84–1.58l 1.59m 1.33m 0.4 1.18 0.69 0.25 0.36
0.2–0.5a N0.5a 0.35–0.70d 0.21–0.22g 0.62h 0.36d 0.36–0.57i 0.16–0.38j 0.19–0.44k 0.50–0.80l 0.46m 0.47m 0.04 0.31 0.42 0.34 0.13
b0.2a 0.5c 0.38–0.64f 0.22–0.55f 0.43e – 0.23–0.89i 0.21–0.43j 0.03–0.43k 0.38–0.57l 0.39m 0.49m 0.47 0.51 0.38 0.61 0.52
0.64–0.70f 0.4d – 0.42d 0.21–0.26i 0.37–0.46j 0.36–0.42k 0.51–0.58l 0.58m 0.61m 0.46 0.49 0.44 0.45 0.63
0.7f 0.6–0.8d 0.34e – – 0.79–0.94j 1.43-19k 0–5.5l 8.26m 9.91m 5.63 4.45 4.2 18.9 9.06
1.6e 0.33e 2.18e 4.7d 7.1–11.2i 0.52–1.14j – – 3.2m 4.4m 1.9 1.82 1.161 4.23 2.18
Bold values are from current study. a Yunker et al. (2002). b Guocai (1993). c Simcik et al. (1999). d Rogge et al. (1993). e Li and Kamens (1993). f Sicre et al. (1987). g Khalili et al. (1995). h Gogou et al. (1996). i Yang et al. (1998). j Manoli et al. (2004). k Mannino and Orecchio (2008). l Liu et al. (2007). m Qi et al. (2014).
all Saudi microenvironments and Kuwait household dust which indicates petroleum products as a primary source for these chemicals (Yunker et al., 2002). In Kuwaiti car dust this ratio was N 0.50 which indicates petroleum primarily diesel and pyrogenic sources of emission such as smoking etc. as major source of emission. The average ratios of BaA/(BaA + Chr), IcdP/(IcdP + BghiP), BFs/BghiP, and BghiP/BaP falls between 0.38 and 0.61, 0.04–0.42, 1.16–4.32, and 0.25–0.69, respectively for all studied microenvironments (Table 2). This indicates these PAHs have both petrogenic and pyrogenic emission sources. The obtained results were in line with ﬁndings reported in literature from other countries (Table 2). Cities of Jeddah and Kuwait are densely populated with high per capita energy consumption. Trafﬁc density is also very high in these cities and with relatively cheap availability of petroleum products. Average consumption of petroleum products is high in the region both in domestic and commercial sectors which greatly contribute to the release of PAHs in surrounding environment. With limited information available about samples it was difﬁcult to correlate the particular source of emission for analyzed PAHs in selected microenvironments. Instead it is more likely that a combination of emission sources such use of gas stoves for cooking, smoking inside the vehicle and house and burning
Table 3 Comparison of PAHs levels (ng/g of dust) in household ﬂoor dust from different countries. Country
Palermo, Italy Kuwait Berlin, Germany Ottawa, Canada Texas, USA California, USA China Jeddah, Saudi Arabia Kuwait
36–34,500 3–2920 100–1400 1500–325,000 1120–341,000 163–4390 1000–466,000 950–11,950 400–9100
5110 540 – 12,900 29,200 911 30,900 3750 2150
– – 300 9530 28,800 990 10,300 2650 1675
Bold values are from current study.
incense etc. contribute in the emission of PAHs. This study is based on limited number of samples, therefore to understand the contribution of different emission factors in the indoor environments more detailed studies are required. In an attempt to identify the sources a detailed questionnaire is needed with information that could include details on house characteristics such as year of construction, location of the household (close to road, restaurants etc.), apartment or villa, ventilation system, number of windows and how long they are opened during the day, lifestyle, smoking habits, and type of cooking facility etc. 3.3. Comparison with studies from other countries Studies are available from US and other countries where occurrence of PAHs have been reported in indoor dust of residential and occupational settings (Table 3 & Fig. 2). The levels of PAHs in this study were lower than those reported from Canada, Texas, China and Italy but were in line to higher than those reported from California, Maryland, Kuwait, Australia and Germany (Table 3 & Fig. 2). Similarly, as shown in Fig. 2, proﬁle of PAHs was varied in different countries. Even within US states, levels of and proﬁles of PAHs varied with high levels were reported in indoor dust from Texas, US (Mahler et al., 2010) compare to California (Whitehead et al., 2013), Maryland (Egeghy et al., 2005), and North Carolina (Wilson et al., 2003). Whitehead et al. (2013) suggested possible explanations for these differences are due to difference in automobile trafﬁc densities, heat sources (coal/wood burning/gas), indoor cigarette smoking regulations, and use of coal-tar in roads and seal parking. Ambient temperature and population density are the surrogate pointer of PAHs levels in the environment (Whitehead et al., 2013). Ambient temperature indicates the use of coal/gas/wood burning as a heat source and automobile trafﬁc density is linked with population density (Whitehead et al., 2013). A positive association was reported by Whitehead et al. (2013) between median dust levels of BaP and BaA and trafﬁc density. It was suggested that regional PAH concentrations may vary geographically and densely populated areas may have higher PAHs in indoor environment because of high automobile
N. Ali et al. / Science of the Total Environment 573 (2016) 1607–1614
Kuwait (this study) Jeddah, Saudi Arabia (this study) China (Qi et al., 2014) Kuwait (Gevao et al., 2007) Palmero, Italy (Mannino and Orecchio, 2008) Berlin, Germany (Fromme et al., 2004)
Ottawa, Canada (Maertens et al., 2008) Brisbane, Australia (Ayoko et al., 2005) North Carolina (Wilson et al., 2003)
Maryland, US (Egeghy et al., 2005) California, US (Whitehead et al., 2013) 0
Texas, US (Mahler et al., 2010)
Fig. 2. Comparison of PAHs in indoor dust from different countries. Levels on longitudinal axis are given in (ng/g of dust).
trafﬁc congestion (Whitehead et al., 2013). Different studies in literature have reported higher PAHs in dust from urban homes compared to rural homes (Chuang et al., 1999; Maertens et al., 2004; Mannino and Orecchio, 2008, Qi et al., 2014), in smoking compared with nonsmoking homes (Maertens et al., 2004; Mannino and Orecchio, 2008), in spring compared with summer (Mukerjee et al., 1997), and in homes with decreased cleaning frequency (Maertens et al., 2004). PAH concentrations are reported to be associated with residence age, gas heating, outdoor PAH air levels, residences adjacent to parking lots sealed with coal-tar containing products, and homes containing parquet ﬂoor, which had been installed with adhesives containing tar (Mahler et al., 2010; Whitehead et al., 2013; Hansen and Volland, 1998). In this study most of the sampled households have adjacent parking lots, linked with coal-tar roads, and use high amount of energy mainly coming from petroleum products to control the indoor temperature. The selected areas in this study are geographically and culturally different than the compared countries; moreover housing style in this region is also markedly different than other parts of the world. All different aspects discussed above might be the reasons for these observed differences but this needs further investigation to validate with further large scale studies.
increased risk of cancer (IARC, 1984; EPA US, 1984, 1990). As reported by Qi et al. (2014) BaP equivalent (BaPE values) is an index to evaluate the toxicity of PAHs, calculated by equation: BaPE ¼ BaA 0:06 þ ðBbF þ BkFÞ 0:07 þ BaP þ DahA 0:6 þ IcdP 0:08 The calculated BaPE values (Table 4) greatly varied among studied micro-environments. The mean value of BaPE for Saudi household ﬂoor dust was signiﬁcantly higher (p b 0.05) than the Kuwaiti household ﬂoor dust but no such difference was observed for car dust of the two countries. Similarly, higher median values were achieved for AC ﬁlter dust (Table 4). This indicates Saudi population in the studied area is at higher risk of exposure to carcinogenic PAHs compare to Kuwaiti counterparts. No signiﬁcant correlation (p N 0.05) was observed between Saudi household ﬂoor dust and AC ﬁlter dust, this suggest various source of emission for BaPE in two microenvironments. Thirteen out of ﬁfteen AC ﬁlter dust samples were collected from window ACs and they might have contribution from outside, almost all sampled households have connecting roads close to the building with heavy trafﬁc. 3.5. Estimation of human exposure via dust ingestion
3.4. Carcinogenicity Scientiﬁc literature has suggested that PAHs are toxic carcinogens (US EPA, 1993). Among PAHs, BaP is the most carcinogenic along with other high molecular-mass PAHs namely; BaA, BbF, BkF, IcdP and DahA have high carcinogenic potential (US EPA, 1993). Limited studies have speciﬁcally linked human exposure to BkF and its isomeric compounds with increased risk of cancer (DellaValle et al., 2016). Their emissions sources such as coke oven emissions, coal tar, cigarette smoke, soot, and petroleum production have been associated with
Table 4 Descriptive data of BaPE in studied microenvironments. Levels are given in ng/g of dust. Bold values are signiﬁcant. Micro-environment
Saudi household ﬂoor dust Kuwaiti household ﬂoor dust AC ﬁlter dust Saudi car dust Kuwaiti car dust
625 180 520 185 120
680 240 335 155 120
370 105 455 180 85
70–2600 45–1010 90–1020 5–630 2–455
Humans exposure to PAHs occur through various indoor sources such as wood burning, charred foods, gas appliances, ﬁreplaces, decorative candles, cigarette and shisha smoke, and during cross ventilation outdoor containing vehicle exhaust etc. (ATSDR, 1995; Orecchio, 2011). Several studies have estimated contribution of residential-dust ingestion to total PAH exposure (Chuang et al., 1999; Gevao et al., 2007). Gevao et al. (2007) calculated dust ingestion contributed ~ 42% of non-dietary PAH intake for children and 11% for adults. While Chuang et al. (1999) reported dust/soil ingestion contributing 24% of the total intake of carcinogenic PAHs for children and 7% for adults. For non-dietary exposure of PAHs we considered concentrations in dust of homes and vehicles to estimate the non-dietary exposure of residents of Kuwait and KSA. We used following logarithmic equation for exposure calculation; ∑Exposure ðng=kg bw=dayÞ ¼ ½ðCDH FH Þ þ ðCDC FC Þ IR =Body weight where IR is the dust ingestion rate, CDH and CDC are the concentrations of PAHs in house and car dust, respectively, FH and FC are the respective percentages of daily time spent in house and cars (Ali et al., 2013). We
N. Ali et al. / Science of the Total Environment 573 (2016) 1607–1614
Table 5 Assessment of human exposure to PAHs via dust ingestion, all values are provided in ng/kg bw/day.
Mean Median 5th 95th Mean Median 5th 95th Mean Median 5th 95th Mean Median 5th 95th
4.54 1.72 b0.01 14.5 0.19 0.07 b0.01 0.62 2.82 2.00 b0.01 7.90 0.12 0.09 b0.01 0.34
1.08 1.00 0.71 1.83 0.05 0.04 0.03 0.08 1.87 1.77 1.11 2.71 0.08 0.08 0.05 0.12
1.51 0.94 0.21 4.18 0.06 0.04 0.01 0.18 2.58 1.29 0.42 8.04 0.11 0.06 0.02 0.34
2.74 1.39 b0.01 9.78 0.12 0.06 b0.01 0.42 4.99 2.86 0.83 14.3 0.21 0.12 0.04 0.61
0.53 0.35 0.11 1.83 0.02 0.02 b0.01 0.08 1.73 0.80 0.40 5.57 0.07 0.03 0.02 0.24
8.23 6.62 1.52 24.5 0.35 0.28 0.07 1.05 7.00 2.69 0.83 29 0.30 0.12 0.04 1.24
3.68 2.34 0.73 11.3 0.16 0.10 0.03 0.48 7.05 2.96 1.59 22 0.30 0.13 0.07 0.94
0.60 0.29 0.09 1.78 0.03 0.01 b0.01 0.08 6.43 2.76 1.35 23.5 0.28 0.12 0.06 1.00
1.50 0.93 0.29 4.12 0.06 0.04 0.01 0.18 1.46 1.31 0.26 2.51 0.06 0.06 0.01 0.11
0.92 0.63 0.16 2.64 0.04 0.03 0.01 0.11 1.60 1.41 0.71 2.66 0.07 0.06 0.03 0.11
4.01 3.39 b0.01 11 0.17 0.15 b0.01 0.47 11.4 9.36 1.10 29.3 0.49 0.40 0.05 1.26
1.16 0.63 0.17 3.45 0.05 0.03 0.01 0.15 1.83 1.70 0.23 4.35 0.08 0.07 0.01 0.19
2.28 1.30 0.61 6.15 0.10 0.06 0.03 0.26 8.92 4.74 0.82 27.7 0.38 0.20 0.03 1.19
0.90 b0.01 b0.01 3.69 0.04 b0.01 b0.01 0.16 0.27 0.03 b0.01 1.38 0.01 b0.01 b0.01 0.06
1.11 b0.01 b0.01 4.74 0.05 b0.01 b0.01 0.20 1.70 1.27 b0.01 5.25 0.07 0.05 b0.01 0.22
Bold values represent worst case scenario pf PAHs to toddlers from Saudi Arabia and Kuwait.
assumed that an average person spend 4.2% of his time in cars and 95.8% indoor at home (Ali et al., 2013). In order to make a preliminary evaluation of the exposure via dust ingestion to selected PAHs, we considered household ﬂoor and car dust. For consistency we assumed 100% absorption of contaminants from ingested dust. We assumed an average body weight (bw) of 70 kg for adults and 12 kg for toddlers. Due to the extreme temperatures that are experienced in KSA, people spend negligible time outdoors. Therefore the time spend outdoor do not signiﬁcantly affect the calculations. The considered values are based on our previous published work (Ali et al., 2013). Kuwait and Jeddah, KSA have dry and dusty environment therefore for preliminary calculations we considered high dust intake of 50 and 200 mg/day for adults and toddlers, respectively. Different exposure scenarios were calculated using 5th percentile (low end exposure), mean, median, and 95th percentile (high end exposure) concentrations. The estimates exposure derived here represent the worst case scenario of PAHs exposure via dust ingestion (Table 5). Worst case scenario (with 95th percentile levels) exposure estimated to BaP, most carcinogenic, for Saudi toddlers was 27.7 ng/kg body weight/day (ng/kg bw/d), while for Kuwaiti toddlers it was 6.15 ng/kg bw/d. Similarly exposure estimate to other carcinogenic isomers BkF and BbF was also high in Saudi toddlers. From calculations (Table 5), it is evident from the estimates that the potential dose via dust ingestion is high for Saudi toddlers than those Kuwaiti toddlers. PAHs exposure risk to adults was much lower than that of young children. Young children are at high risk due to lower body weights and partly due to higher amount of dust ingestion. This study adds to the growing evidence that non-dietary exposure to PAHs contribute to the total body burden and this is of particular concern for infants due to their higher dust intake via frequent hand-to-mouth activities. Together with other exposure pathways i.e., indoor and outdoor air or food, exposure via dust ingestion/inhalation is a matter of concern for the chronic exposure to PAHs. However, due to the small number of samples analyzed in this study, it should be stressed that the range of exposure estimates is only an indication of the likely range for toddlers and adults within the studied population. The substantial inter–individual variation in exposure depends on the time spent in indoor and the quantity of the dust ingested. This study and other similar studies on indoor exposure to organic pollutants suggest that monitoring of indoor environment is important and measurements of pollutants only in food and outdoor environment can substantially underestimate exposures to chemicals. 4. Conclusion This preliminary study provides the ﬁrst insight on the occurrence of PAHs in dust samples from different microenvironments of Jeddah, KSA and Kuwait. These results evidenced the existence of carcinogenic
pollutants in the indoor environments of KSA and Kuwait, which is cause of concerns especially for young children. This study have several limitations in its sample size and sampling procedures, therefore these results cannot be assumed to be representative of all indoor environments of KSA and Kuwait. Yet with all limitations, our results provide evidence of PAHs occurrence in indoor environment of KSA and Kuwait. Considering people in this region spend most of their time indoor, exposure to these pollutants leads to an increase human health risk. This warrants a clear need for thorough investigations of these chemicals in different environmental compartments of this region. Acknowledgements This work was funded by King Abdulaziz University of Saudi Arabia (KAU), Jeddah, under grant number 4/00/00/252. The authors thank NYU and KAU for technical and ﬁnancial support. We thank Prof. Kurunthachalam Kannan, Wadsworth Center, New York State Department of Health, for technical assistance and help with sample analysis. We are grateful to all of the volunteers who participated in the study. Appendix A. Supplementary data Supplementary data to this article can be found online at http://dx. doi.org/10.1016/j.scitotenv.2016.09.134. References Ali, N., Ali, L., Mehdi, T., Dirtu, A.C., Al-Shammari, F., Neels, H., Covaci, A., 2013. Levels and proﬁles of organochlorines and ﬂame retardants in car and house dust from Kuwait and Pakistan: implication for human exposure via dust ingestion. Environ. Int. 55, 62–70. Ashraf, M.W., Salam, A., 2012. Polycyclic aromatic hydrocarbons (PAHs) in vegetables and fruits produced in Saudi Arabia. Bull. Environ. Contam. Toxicol. 88, 543–547. ATSDR, 1995. Agency for toxic substances and disease registry. Toxicological Proﬁle for Polycyclic Aromatic Hydrocarbons. Baumard, P., Budzinski, H., Garrigues, P., Dizer, H., Hansen, P.D., 1999. Polycyclic aromatic hydrocarbons in recent sediments and mussels (Mytilus edulis) from the western Baltic Sea: occurrence, bioavailability and seasonal variations. Mar. Environ. Res. 47, 17–47. Benner, B.A., Gordon, G.E., Wise, S.A., 1989. Mobile sources of atmospheric polycyclic aromatic hydrocarbons: a roadway tunnel study. Environ. Sci. Technol. 23, 1269–1277. Boström, C.E., Gerde, P., Hanberg, A., Jernström, B., Johansson, C., Kyrklund, T., et al., 2002. Cancer risk assessment, indicators and guidelines for polycyclic aromatic hydrocarbons in ambient air. Environ. Health Perspect. 110, 451–489. Budzinski, H., Jones, I., Bellocq, J., Pierard, C., Garrigues, P., 1997. Evaluation of sediment contamination by polycyclic aromatic hydrocarbons in the Gironde estuary. Mar. Chem. 58, 85–97. Butte, W., Heinzow, B., 2002. Pollutants in house dust as indicators of indoor contamination. Rev. Environ. Contam. Toxicol. 175, 1–46. Chao, H.R., Lin, T.C., Hsieh, J.H., 1997. Composition and characteristics of PAH emissions from Taiwanese Temples. J. Aerosol Sci. 28, S303–S304.
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