Environmental Pollution

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Invited paper

Organohalogenated contaminants in type 2 diabetic serum from Jeddah, Saudi Arabia

^*

Nadeem Ali

^a^,^*

, Nisreen Rajeh

^b

, Wei Wang

^c

, Khalid O. Abualnaja

^d

, Taha A. Kumosani

^d

, Hussain Mohammed Salem Albar

^e

, Syed Ali Musstjab Akber Shah Eqani

^f

,

Iqbal M.I. Ismail

^a^,^g

aCenter of Excellence in Environmental Studies, King Abdulaziz University, Jeddah, Saudi Arabia

bAnatomy Department, Medical College, King Abdul Aziz University, Jeddah, Saudi Arabia

cWadsworth Center, New York State Department of Health, Albany, NY, USA

dBiochemistry Department, Faculty of Science, Experimental Biochemistry Unit, King Fahd Medical Research Center and Bioactive Natural Products Research Group, King Abdulaziz University, Jeddah, Saudi Arabia

eFamily&Community Medicine Department, College of Medicine, King Abdulaziz University, Saudi Arabia

fPublic Health and Environment Division, Department of Biosciences, COMSAT Institute of Information&Technology, Islamabad, Pakistan

gDepartment of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia

a r t i c l e i n f o

Article history:

Received 7 December 2015 Received in revised form 28 January 2016 Accepted 28 January 2016 Available online xxx

Keywords:

Organohalogenated contaminants (OHCs) Human serum

Type 2 diabetes mellitus Saudi Arabia

a b s t r a c t

Most of the organohalogenated contaminants (OHCs) have high environmental stability and are lipo- philic in nature, thus bioaccumulate through the various routes e.g., inhalation, dermal contact and food intake. Human exposure to these OHCs can induce adverse health effects. Studies on the occurrence of OHCs in human samples from Saudi Arabia are scarce. Therefore, this study aimed at providing preliminary insight on the occurrence of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated biphenyl ethers (PBDEs) in diabetic and non-diabetic donors from KSA. Serum samples were collected from type 2 diabetic patients (n¼40) and control donors (n¼20) to study the impact of OHCs on their health. For theﬁrst time we studied the difference ofƩOHCs in type 2 diabetic and control participants. The order of obtained results wasƩOCPs (35e650 ng/g lw)>ƩPCBs (15e90 ng/

g lw)>ƩPBDEs (1.5e68 ng/g lw). The major contributors werep,p⁰-DDE (median 44 ng/g lw), PCB 153 (2.3 ng/g lw), PCB 138 (2.1 ng/g lw), BDE 153 (1.2 ng/g lw) and BDE 47 (0.85 ng/g lw). Exposure to different OHCs between male and female donors was not significantly different (p>0.05). However, ƩPCBs andƩOHCs were significantly higher(p<0.05) in diabetic donors than those of control group. We computed significantly positive correlations (p<0.05) among different OHCs and between OHCs and age factor. The current study highlights the presence of different OHCs in humans from Jeddah, KSA. This is a preliminary study based on small sample size but our results suggested that detailed studies are required to understand the sources of these pollutants and their impact on human health.

1. Introduction

Organohalogenated contaminants (OHCs) such as organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated biphenyl ethers (PBDEs) are a group of compounds that

are highly lipid-soluble and are persistent in the environment (Hites, 2004; UNEP, 2009; WHO, 1998, 2007). These chemicals have been widely used into various industrial, industrial and domestic applications during the past decades, and this result their ubiqui- tous presence in various different environmental compartments (Ali et al., 2015; Hites, 2004; WHO and UNEP, 2012). As a result most of OHCs are categorise as persistent organic pollutants (POPs) and are regulated byStockholm's convention (2009). In many re- gions levels of these contaminants are levelling off in the environment but their exposure to general population can still occurs through direct (i.e., food intake, inhalation, drinking water etc.) and

*This paper has been recommended for acceptance by Jay Gan.

*Corresponding author. Center of Excellence in Environmental Studies, King Abdulaziz University P.O Box: 80216 Jeddah 21589, Saudi Arabia.,

E-mail addresses:[email protected],[email protected](N. Ali).

Contents lists available atScienceDirect

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indirect routs (i.e., dermal contact) (Brasseur et al., 2014; Dirtu and Covaci, 2010; Kang et al., 2008; Mamun et al., 2007). Several studies have reported strong association between intake of certain foods e.g., fatty food,ﬁsh etc and consumer's serum concentrations of OCPs and PCB (Dirtu and Covaci, 2010; Tsukino et al., 2006; Qin et al., 2011). Moreover, high levels of PCB, OCPs and PBDEs have also been reported into indoor residential and occupational settings, people spend more time inside the home/ofﬁce, while indoor they are continuously exposed to chemicals and indoor dust samples could be a source for these chemicals (Ali et al., 2013a, Ali et al., 2014a, 2014b; Colt et al., 2004;Herrick et al., 2004; Jakobsson et al., 2003).

It is well documented in literature that OHCs are likely to act as endocrine disrupting chemicals in humans and wildlife (Gregoraszczuk and Ptak, 2013; Meeker, 2012; WHO and UNEP, 2012). Positive associations are demonstrated between OHCs and adverse health conditions including type 2 diabetes mellitus (T2DM), reproductive, developmental and neurological problems (Codru et al., 2007; Colt et al., 2005; Cox et al., 2007; Meeker et al., 2007, 2012;Tang et al., 2014; Taylor et al., 2013; Turyk et al., 2009).

The prevalence of T2DM is high among the Saudi population and increasing at alarming rate that represents a major clinical and public health problem (Alqurashi et al., 2011). There are well- established risk factors for T2DM e.g., obesity, lack of physical ac- tivity etc but several studies have shown that environmental chemicals might also contribute to its etiology (Taylor et al., 2013).

In a recent review of human epidemiological studies,Taylor et al.

(2013) concluded that there is support for positive associations between T2DM and certain chlorinated POPs.

Kingdom of Saudi Arabia (KSA) is a signatory of Stockholm Convention since 2002 but has ratiﬁed it recently in 2012 and due to weak legislation there is lack of data on the production and use of these chemicals in the KSA (Status of ratiﬁcation, Stockholm Convention on POPs, 2009). Industrial scale use of these chemicals in KSA is limited but their exposure through imported consumer products cannot be ignored (Khan, 2005). However, scarce data is available on the occurrence of these chemicals into the environment of KSA (Ali et al., 2014a, 2014b; Al-Othman et al., 2015; Khan, 2005). In order to investigate the potential health risk of OHCs exposure to humans, it is important to measure the levels of these chemicals in human samples such as serum (Codru et al., 2007; Dirtu et al., 2006; Meeker et al., 2007; Minh et al., 2006;

Taylor et al., 2013).

Well documented data is available from many countries on the occurrence of OHCs in their population (Ali et al., 2013b; Brasseur et al., 2014; Dirtu et al., 2006; Kang et al., 2008; Mamun et al., 2007; Meeker et al., 2007; Minh et al., 2006; Qin et al., 2011;

Thomas et al., 2006) but there is a knowledge gap exist on their occurrence in Saudi population. In the absence of data from the region, it was thought worthwhile to carry out a preliminary investigation of OHCs in T2DM and control Saudi population with case study from the city of Jeddah. The aim of the present study was to provide information on OHCs concentrations in serum, which will help to evaluate the baseline levels of OHCs in KSA population.

The relationship among different OHCs and with age was also investigated. Additionally, as per recommendation ofTaylor et al.

(2013)the levels of ƩOHCs and individual classes of OHCs were compared between diabetic and non diabetic donors.

2. Experiment methodology 2.1. Reagents and materials

Natives and internal standards of OCPs, PCBs, PBDEs were purchased from Wellington Laboratories, Guelph, Ontario, Canada).

Solvents and chemicals used during the analysis were of pesticide- grade obtained from purchased from Macron Chemicals, USA.

Anhydrous sodium sulphate (Na2SO4) and silica gel were washed with n-hexane and used after heating overnight at 140C. Oasis^® HLB extraction cartridges (6 mL/500 mg) were obtained from Alt- mann analytik GmbH & Co. KG, Munich, Germany and empty polypropylene columns for clean-up (3 mL) were purchased from Supelco (Bellefonte, PA, USA).

2.2. Sampling and sample preparation

Human blood samples typically 5 mL (n¼60; female (n¼40) and male (n¼20) were collected from city of Jeddah, Kingdom of Saudi Arabia in February 2015 by venipuncture at local clinics following overnight fasting. The samples were collected from diabetic donors (n ¼40) and control (n¼20). A random selection criterion was employed and donors were among the general population who were residents of Saudi Arabia and were not acci- dentally and/or occupationally exposed to selected studied chemicals. Demographic information of the donors are given in Table S1. The serum was separated by centrifugation and trans- ferred to contamination free tubes and were kept frozen at20C until analysis. A written consent was obtained from each participant and general information regarding age, height, weight, gender, place of residence, and occupation were also recorded at the time of sample collection from each participant. The study was approved by the King Abdulaziz University-unit of biomedical ethics research committee (reference No. 341-14).

Total cholesterol (CHOL) and triglycerides (TG) were determined in a separate serum aliquots at the collection clinics using routine laboratory analysis. Total lipids (TL) were calculated using the for- mula TL¼2.27TGþ1.12CHOLþ1.48 (in g/L) as described by Phillips et al. (1989). Consequently, concentrations of selected contaminants were expressed per lipid weight (lw) basis.

2.3. Sample preparation and instrumentation

The procedure for extraction and clean-up of selected contaminants from serum was based on previously described method (Ali et al., 2013b). Labelled internal standards for BDEs and PCBs were added in glass tubes followed by accurately measured volumes of thawed and homogenized serum (typically between 1.5 and 2 mL), and then mixed with 2 mL of milliQ-H₂O and 50mL of formic acid.

Samples were equilibrated by ultrasonic treatment for 20 min.

Prior to the sample application, the Oasis HLB cartridges were washed with dichloromethane (DCM) and activated with methanol (MeOH) and milliQ-H2O. After sample loading, the HLB cartridges were rinsed with 4 mL of milliQ-H2O and dried under vacuum.

Afterwards, the HLB cartridges were eluted with 10 mL of DCM:

MeOH (4:1, v/v) and 2 mL of hexane. Elute was dried under gentle nitrogen streaming to incipient dryness and resolubilized in 500m^L of hexane and 50m^{L of DCM.}

For clean up, the empty polypropylene columns (3 mL) were ﬁlled with 800 mg of washed silica topped with 100 mg of 10% acid silica and then washed with 22 mL hexane. Resolubilized elute was loaded on the pre-washed silica cartridge and fraction was collected with 10 mL hexane: DCM (4:1). Elute was concentrated under a gentle nitrogen stream at room temperature until dryness and resolubilized in 80mL of iso-octane for GCeMS analysis.

The analysis of analytes was performed by 6890 Agilent (Palo Alto, CA, USA) gas chromatography (GC) coupled to a 5973 mass spectrometer (MS) operated in electron impact (EI). A DB-5 column (15 m0.25 mm0.10mm) was used for separation and the MS was run in selected ion monitoring (SIM) mode.

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2.4. Quantiﬁcation and quality assurance

Multi-level calibration curves were created for the quantification and good linearity (R²> 0.996) was achieved for the whole concentration range found in the samples. The analytes identifi- cation was based on relative retention times and ion chromato- grams to the standards. A deviation of the ion intensity ratios within 15% of the mean values of the calibration standards was considered acceptable. Method limit of detection (LODs) and limits of quantification (LOQs) were calculated as 3 and 10standard deviation of the analytes value in procedural blanks, respectively.

For analytes that were not detected in procedural blanks, LOD and LOQs were calculated for a signal-to-noise ratio equal to 3 and 10 based on the signal obtained in the standard, respectively. As a part of quality assurance, procedural blanks (n¼5) and pooled serum (n¼3) were analysed in parallel with the serum samples to assess the inﬂuence of any possible contamination during sample preparation and instrumental analysis and to evaluate method accuracy and precision. Glass wares used were baked at 400C overnight to eliminate any possible contamination.

2.5. Statistical analysis

To better understand the estimation of the total body burdens, lipid-adjusted serum concentrations were used in the statistical analysis. The undetected values were assigned as ½ LOQ for calculating the total concentrations of chemicals and statistical analysis. Descriptive statistics were carried out by using Microsoft Excel 2007. Using online GraphPad tool, Grubb test was performed to eliminate outliers and two sample t-test was used to verify the signiﬁcant differences of chemicals concentrations between male, female, diabetic and non-diabetic donors (Table 3). For correlation studies among chemicals, with age and BMI online tool http://

vassarstats.net/corr_rank.html was used to conduct spearman rank-order correlation coefﬁcient, p values less than 0.05 were considered statistically signiﬁcant.

3. Results and discussion

This study reports the levels of selected organic pollutants i.e., OCPs, PCBs, PBDEs,ƩOHCs in human serum from Jeddah, KSA. The descriptive statistics of major pollutants is presented inTable 1, and detailed information for each chemical is given in supplementary information (Table S2).

3.1. Levels of OCPs and PCBs in serum

The major OCPs found in the serum samples were p,p⁰-

dichlorodiphenyldichloroethylene (p,p⁰-DDE), and HCB which were above LOQ in>80% of all studied samples. The concentrations (ng/g lw) of important OCPs for male and female groups are presented in Table 1. The major contributor (>50%) to theP

DDTs wasp,p⁰-DDE, which ranged between<LODe560 (ng/g lw) with median value of 44 (ng/g lw). The ratio(s) ofp,p⁰-DDT/PDDTs were ranged between

<LOD and 0.7 and suggest both recent and past DDTs exposure.

Indicative ratios revealed both recent and past exposure, although the levels are not very high but scenario suggested that the recent exposure might be going on through secondary sources derived from fatty food and some imported foods. The distinct patterns of DDTs occurrence in samples indicate different time of exposure among donors. Another possible reason could be the differences in the metabolic efﬁciency of the donors forp,p⁰-DDT, together with sporadic DDTs sources within the studied donors (Ali et al., 2013b;

Dirtu et al., 2006). Moreover, higher levels ofp,p⁰-DDE than other DDTs are understandable by the fact thatp,p⁰-DDE has a median half-life of more than 8 years in humans (Wolff et al., 2000). Among other investigated OCPs; o,p⁰-DDE, o,p⁰-DDD, HCB and oxychlordane were frequently detected, although their levels were<8 (ng/g lw). Oxychlordane is the metabolic product of chlordane compounds, this is why among chlordane related compounds it was predominantly detected in serum samples.

The serumƩPCB concentrations found in present study for male and female donors are summarized inTable 1. TheƩPCB concentrations (ng/g lw) ranged between 15 - 90 and 20e60 for female and male donors, respectively. PCB-153, 138, 180, and 118 were the dominant congeners of the all analysed 20 PCB congeners (Table S2). Dioxin-like PCBs contributed<30% in toward total PCBs and were<LOQ in most of the samples.

Table 1

Descriptive statistics of selected important analytes in analysed serum samples. Levels are given in ng/g lw.

Analytes Female (n¼40) Male (n¼20)

Median Mean STD Range Median Mean STD Range

BDE-47 0.8 1.7 2.6 <LODe16 0.85 1.1 0.75 0.5e8

BDE-99 0.4 1.1 1.9 <LODe9 0.4 0.9 1.45 <LODe6

BDE-153 1.0 1.7 3.0 <LODe19 1.2 1.25 0.95 <LODe6

Penta-BDEs 3.6 6.1 11 1.5e68 4.5 7.6 9.1 2.5e42

p,p⁰-DDE 57 91 115 8e560 37.5 65 77.4 <LODe285

p,p⁰-DDT 19.5 30 24.2 4e132 31.5 34.9 16.3 10e70.0

HCB 4.5 4.8 3.1 0.4e14 6.9 6.7 4.6 0.4e14

POCPs 105 155 122 35e620 101 140 86.6 65e365

PDDTs 91.8 135 120 25e600 84 116 87 35e345

PPCBs 33.6 37.5 17 15e90 44 37.2 12.6 20e60

PDL-PCBs 8.6 11.6 8.6 5.0e45 14 15.6 7.45 5e35.7

ƩOHCs 152 198 125.5 70e700 145 178 83.5 115e450

Table 2

Spearman's rank order correlation among analytes, between analytes, age and BMI.

Bold values represent signiﬁcant correlations.

Analytes ƩOHCs ƩPCBs p,p⁰-DDE ƩDDTs ƩOCPs Penta-BDE BMI Age R 0.432 0.348 0.494 0.455 0.437 0.242 0.016

P 0.000 0.004 0.000 0.000 0.000 0.035 0.452 BMI R 0.145 0.171 0.187 0.124 0.133 0.010

P 0.134 0.103 0.082 0.178 0.161 0.470 Penta-BDE R 0.339 0.279 0.141 0.210 0.268

P 0.004 0.018 0.149 0.058 0.022 Ʃ

ƩOCPs R 0.959 0.240 0.899 0.983 P 0.000 0.037 0.000 0.000 Ʃ

ƩDDTs R 0.930 0.242 0.939 P 0.000 0.035 0.000 p,p′-DDE R 0.853 0.224

P 0.000 0.045 Ʃ

ƩPCBs R 0.363 P 0.002

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Recently, two studies have reported DDTs and HCHs in Saudi participants from Riyadh, KSA (Al-Othman et al., 2014, 2015).

However, to the best of our knowledge, this isﬁrst incidence of reporting PCBs in human serum samples from KSA. The serum concentrations (ng/g lw) of important OCPs andƩPCB from previously published literature are compared inFig. 1(Table S3). It is difﬁcult to compare our results with other studies because the year of survey ranged from 2006 to 2015 and since regulations levels of these compounds are levelling off in recent years (Glynn et al., 2004; Hagmar et al., 2006; Link et al., 2005). As shown inFig. 1, the median levels of organochlorine contaminants in this study were lowest compare to studies from literature (Ali et al., 2013b; Bi et al., 2007; Dirtu et al., 2006; Kang et al., 2008; Mamun et al., 2007;

Meeker et al., 2007; Qin et al., 2011; Thomas et al., 2006). It is noteworthy that levels of PCBs and OCPs in this study were multiple times lower than those reported in human serum from Bangladesh, Romania, China and Korea (Bi et al., 2007; Dirtu et al., 2006; Kang et al., 2008; Mamun et al., 2007; Qin et al., 2011). KSA does not have a long history of pesticide use in agriculture and public health sectors. There is no reliable data available for the industrial use of

PCBs from KSA. In contrary to KSA other countries have extensive historical use of these organochlorine chemicals in agricultural, industrial and public health sectors (Bi et al., 2007; Dirtu et al., 2006; Kang et al., 2008; Mamun et al., 2007; Qin et al., 2011).

Living closer to the proximities of contamination source (production and storage points) and ingestion of contaminated food have been established as major exposure pathways for organochlorine chemicals (Asplund et al., 1999). In this study donors were from Jeddah, KSA, which is an industrialized city but the noticeable industrial growth has occurred in last three decades. The usage of these chemicals were already regulated therefore the direct source of contamination is minimal. Furthermore,ﬁsh is not a major part of regular diet in KSA, therefore indirect source of contamination is also limited. Agricultural activities are limited around Jeddah region but strict regulations are not followed for the imported foods.

Therefore, imported food which form bulk of the total food supply might be one of the source of pesticide residues in Saudi population (Khan, 2005). KSA, especially Jeddah is characterized by extreme hot climatic conditions, high temperature may induce the degra- dation and mobilization of these chemicals across the country's Table 3

Two sample t-test between control and diabetic donors. Bold values represent signiﬁcant difference. Values are given in ng/g lw. Control (n¼20), diabetic (n¼40), female (n¼40), and male (n¼20).

Statistics Groups Penta BDEs OCPs DDTs p,p⁰-DDE PCBs DL-PCBs ƩOHCs

Mean Control (n¼40) 8.5 127 110 70 30 11.6 145

Diabetic (n¼20) 5.6 162 139 90.5 41 13.5 210

SD Control 15.5 90 88 83.5 7 8.6 66

Diabetic 6.5 121 120 115 17.5 8.3 142

P value 0.413 0.282 0.507 0.176 0.009 0.132 0.021

Mean Female (n¼40) 6.1 155 135 91 37.5 11.6 198

Male (n¼20) 7.6 140 116 65 37.2 15.5 178

SD Female 11 122 120 115 17 8.6 125.5

Male 9.1 87 87 77 12.5 7.5 83.5

P value 0.601 0.626 0.532 0.365 0.945 0.090 0.522

Mean Female diabetic (n¼25) 4.2 185 165 115 45 12 230

Female control (n¼15) 9.2 110 95 58 29 11 146

SD Female diabetic 2.5 185 135 135 20 8 140

Female diabetic 17.5 75 75 75 7 9.5 76

P value 0.165 0.144 0.074 0.143 0.005 0.723 0.039

0 100 200 300 400 500 600

pp-DDE pp-DDT HCB PCBs

KSA Romania Pakistan Hong Kong China Korea Bangladesh UK USA 1975 3600

Fig. 1.The median concentrations (Y-axis; ng/g lw) of organochlorinated analytes in serum samples of different countries. Romania (Dirtu et al., 2006), Pakistan (Ali et al., 2013b), Hong Kong (Qin et al., 2011), China (Bi et al., 2009), Korea (Kang et al., 2008), Bangladesh (Mamun et al., 2007), UK (Thomas et al., 2006), USA (Meeker et al., 2007).

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border and towards the colder associated areas. Consequently, levels of these chemicals are lower in this study compare to other reported levels in literature (Dirtu et al., 2006; Kang et al., 2008;

Mamun et al., 2007; Meeker et al., 2007; Qin et al., 2011; Thomas et al., 2006).

3.2. PBDEs

PPBDEs (47, 100, 99, 154, 153 and 183) ranged between 1.5 and 68 (ng/g lw) with median concentrations of 3.6 and 4.5 (ng/g lw) in serum samples of female and male donors, respectively. Penta- BDEs i.e., BDE 47, 153 and 99 were the major BDEs with median levels of 0.85, 1.2 and 0.4 ng/g lw, respectively and presented as Table S2. Whereas other congeners i.e., BDE 100, 154 and 183 were also detected in most of the samples. Given consideration to short half life, large molecular size and high octanolewater partition coefﬁcient, BDE-209 was suspected to be present at lower levels into human serum (Boon et al., 2002; Hites, 2004; Jakobsson et al., 2003). In this study BDE 209 was detected at median concentration of 23 ng/g lw (ranged<LODe 500 ng/g lw). However, targeted signals were not consistent in the blanks, therefore BDE 209 quantiﬁcation data is only indicative readings are not reliable.

The levels of PBDEs, as indicated inFig. 2and Table S3, were lower or similar to those reported in the recent literature (Ali et al., 2013b; Brasseur et al., 2014; Kim et al., 2012; Leijs et al., 2008;

Mazdai et al., 2003; Qin et al., 2011; Thomas et al., 2006; Zhu et al., 2009). Some of these studies also suggested that along with food intake, indoor dust ingestion is also considered as the major exposure route for PBDEs (Ali et al., 2014a; Coakley et al., 2013).

Concentration ofP

PBDEs in indoor dust from KAS (median 350 ng/

g) was reported byAli et al. (2014b)and found many folds lower than those from USA (median 3500 ng/g) (Harrad et al., 2008). USA was one of the major producer and consumer of PBDEs due to its strictﬁre safety regulations, and widespread occurrence of these chemicals in its environment may have resulted high levels in humans as reported elsewhere (Schecter et al., 2003; Mazdai et al., 2003). In contrary, KSA did not produce PBDEs and nor the use was regulated in locally produced consumer products. This is one possible explanation for the low levels ofP

PBDEs in human serum

from KSA compare to USA (Fig. 2&Table S3). Even though KSA never produce and use these chemicals on industrial scale but the use of imported home stuff from other countries such as China, Japan, USA and EU countries, whereﬁre safety are regulated, might be the source of exposure to the local population.

3.3. Correlations among chemicals and with age

In literature it has been reported that the levels of PCB and OCPs in human serum tend to increase with the age (Ali et al., 2013b;

Dirtu et al., 2006; Kang et al., 2008). To study this phenomenon, we pooled results from both male and female groups for spearman's rank order correlation. We computed correlations between contaminants, age and BMI (Table 2). Our results revealed signiﬁ- cantly positive correlations between age and penta-BDE,P

OCPs, PDDTs,P

PCBs, andƩOHCs (p<0.05). Although these chemicals have bioaccumulative potential but no positive association was observed between BMI and contaminants (p>0.05), no particular information and factors associated with these samples could explain thisfinding. Most of these OHCs primarily deposit in lipids but not all studies in literature have reported positive correlation between BMI and OHCs (Dirinck et al., 2011). As suggested in literature diabetogenic effect of low-dose exposure to OHCs might be more complicated than a simple obesogenic effect Small number of samples might be one reason for no correlation between contaminants and BMI, this definitely warrant further investigation in large cohort study. Tofind out similar source of exposure for these chemicals, spearman's rank order correlation was performed among levels of these chemicals. Significantly positive correlations were observed among all important chemicals i.e., penta-BDE, POCPs, PDDTs, PPCBs, and POHCs (Table 2), this suggested similar source of exposure for these chemicals.

3.4. Difference between gender, diabetic and control

In present study, organochlorine pollutants showed inconsis- tent associations with gender (Tables 1and3). The two sample t- test indicated that OCPs concentrations, with the few exceptions of p,p⁰-DDE, were higher in males, though not statistically signiﬁcant

0 2 4 6 8 10

BDE 47 BDE 99 BDE 153 Penta BDEs

KSA France Pakistan Hong Kong China Korea Netherlands UK USA 28 37

Fig. 2.The median concentrations of Penta BDEs in serum samples of different countries (ng/g lw). France (Brasseur et al., 2014), Pakistan (Ali et al., 2013b), Hong Kong (Qin et al., 2011), China (Zhu et al., 2007), Korea (Kim et al., 2012), Netherlands (Leijs et al., 2008), UK (Bramwell et al., 2014), USA (Mazdai et al., 2003).

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(p > 0.05), this is in agreement with another study from Korea (Kang et al., 2008).ƩPCBs and penta-BDE concentrations were also higher in male than female group but again the difference was not signiﬁcant (p>0.05). Similar gender differences were also reported in other studies reported from Korea, Japan and Romania (Dirtu et al., 2006; Minh et al., 2006; Park et al., 2007).

The prevalence of diabetes is high among the Saudi population and increasing at an alarming rate that represents a major clinical and public health problem (Alqurashi et al., 2011). There are well- established risk factors for diabetes e.g., obesity, and several studies have shown that environmental chemicals might also contribute to its etiology (Taylor et al., 2013). A recent review of human epidemiological studies concluded that there is support for positive associations between diabetes and certain chlorinated POPs (Taylor et al., 2013). In this study, we applied two sample t-test between diabetics and control (Table 3). We identified a significantly higher levels ofƩPCBs,ƩOHCs in diabetic donors (p<0.05) (Table 3). No such difference (p>0.05) (Table 3) were observed for other chemicals, although in literature positive associations have been reported between diabetes and OCPs (Al-Othman et al., 2014, 2015; Cox et al., 2007; Turyk et al., 2009). Ourfindings are partly due to the small number of samples therefore it suggest more detailed studies are required to understand the role of chemicals in Saudi diabetic population. Diabetes is a debilitating disease that affects both young and adults. In terms of medical cost and loss of productivity, this disease has enormous economic impact. Thus, understanding the impact of environmental contaminants on human health needs a high-priority research goal. Disease incidence of diabetes and its overall associated health and economic burden can be reduced if we indentify exposure levels and routes to these chemicals in the environment and design prevention program accordingly (Taylor et al., 2013).

4. Conclusion

This is thefirst study reporting several classes of OHCs in human from KSA, which indicates ongoing exposure to already regulated POPs. First for thefirst time in literature we reportedƩOHCs burden linked with T2DM. Levels of analysed pollutants were generally on the lower side than studies from different countries. All analysed classes of contaminants showed significant correlation with each other, suggesting common exposure pathways. There were minimal differences among the levels of selected contaminants between male and female donors, which suggest similar scale on-going exposure to these chemicals for both genders. Considering the lack of data on POPs in different environmental compartments of KSA, this study necessitate future detailed bio-monitoring and exposure assessment studies of OHCs in different environmental compartments of KSA.

Acknowledgements

Nadeem Ali acknowledges Center of Excellence in Environ- mental Studies, King Abdulaziz University, Jeddah, KSA forﬁnancial support. We thank Prof. Kurunthachalam Kannan, Wadsworth Center, New York State Department of Health, for technical assis- tance and help with sample analysis. We are grateful to all of the volunteers who participated in the study.

Appendix A. Supplementary data

Supplementary data related to this article can be found athttp://

dx.doi.org/10.1016/j.envpol.2016.01.087.

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