International Journal of Scientific Research in Environmental Sciences, 4(5), pp. 0123-0135, 2016 Available online at http://www.ijsrpub.com/ijsres ISSN: 2322-4983; ©2016; Author(s) retain the copyright of this article http://dx.doi.org/10.12983/ijsres-2016-p0123-0135

Full Length Research Paper Levels of Polycyclic Aromatic Hydrocarbons (PAHs) and Associated Health Risk in Tilapia zilli from Qua Iboe River Estuary, Niger Delta, Nigeria Bassey Anie Etuk, Eno Anietie Moses, Godwin Asukwo Ebong* Department of Chemistry, University of Uyo, Uyo, Akwa Ibom State *Corresponding Author E-mail address: [email protected]; [email protected] Received 24 May 2016; Accepted 01 August 2016

Abstract. Intensive oil activities within the study area have elevated the level of toxic substances in both aquatic and terrestrial environments of the host communities. Levels of polycyclic aromatic hydrocarbons in Tilapia zilli from Qua Iboe River estuary (QIRE) Nigeria and the carcinogenic health risk induced by its consumption were studied. Fish samples were collected from five stations and a Control during wet and dry seasons and analyzed for PAHs using gas chromatography with flame ionization detector. Carcinogenic health risk assessment using recommended models by USEPA was done. Concentrations of total PAHs ranged from 1.527E-03 to 5.986E-02 mg/kg, high molecular weight PAHs recorded a range of 1.239E-03 to 1.424E-01 mg/kg while low molecular weight PAHs ranged from 2.814E-04 to 3.166E-03 mg/kg. Concentrations of C-PAHs at the study area were higher than at the Control site. Levels of B(a)P in Tilapia zilli for both seasons were lower than the EU limit however, the potency equivalent concentrations due to exposure to C-PAHs via its at all locations in both seasons were above the screening value. Thus, consumption of Tilapia zilli from the area studied may result in carcinogenic health effect. The study also identified presence of anthropogenic inputs of PAHs and pyrogenic PAHs originated from gas flaring in the area. Regulatory legislation on environment should be instituted to forestall sub lethal effect on aquatic flora, fauna and human. Keyword: Health Risk Assessment; Nigeria; Polycyclic Aromatic Hydrocarbon; Qua Iboe River Estuary and Tilapia zilli.

associated with endocrine disruption in marine organisms, neurotoxicity and alteration of ecosystem levels (Frenna et al., 2012). The consumption of aquatic organisms such as fish can result in the accumulation of high molecular weight PAHs which are known to be carcinogenic (Arvo, 1995). PAHs are organic compounds with two or more fused aromatic ring that are mainly formed from incomplete combustion of organic compounds. Other sources of PAHs include drilling operations, land-based sources and other activities related to petroleum industry (Nozar et al., 2013). PAHs have been identified as carcinogenic, mutagenic and tetratogenic pollutants of public health concern (Anyakora et al., 2005). Out of the sixteen priority PAHs, USEPA has classified seven PAH compounds as more probable human carcinogens. They are: benzo(b) fluoranthene, benzo (a) anthracene, benzo (a) pyrene, benzo(k) fluoranthene, chrysene, dibenzo (a,h) anteracene and indeno (1,2,3-cd) pyrene and some of them can cause tumours in human (ASTDR, 2011). Qua Iboe River estuary (QIRE) is one of the rivers in the Niger Delta region of Nigeria with history of oil spill caused by equipment failure, corrosion and vandalisation of oil

1. INTRODUCTION In the coastal areas of most developing countries, fish consumption is a major source of protein, omega-3fatty acid and vitamins. Fish caught from the Niger Delta may be contaminated with PAHs due to oil exploration and exploitation activities in the region. Ellman et al. (2012) reported that PAHs found in crude oil have the potential to accumulate in aquatic organisms, presenting a health risk via ingestion of the contaminated food. PAHs in the aquatic environment have been linked with industrial effluents and petroleum oil spills (Nasr et al., 2012). Ingestion of contaminated food and diffusion from water across their gills and skins are the major routes of PAHs exposures to fish. Also, PAHs are rapidly adsorbed on suspended material and sediments due to their hydrophobic nature and become available to fish and other marine organisms through food chain. Most times uptake is followed by bioaccumulation in fatty tissues due to the lipophilic nature of PAHs and this result in acute or chronic effects and induction of cancer (neoplastic effects) in fresh and marine water fish (Gorleku et al., 2013). PAHs in water are 123

Etuk et al. Levels of Polycyclic Aromatic Hydrocarbons (PAHs) and Associated Health Risk in Tilapia zilli from Qua Iboe River Estuary, Niger Delta, Nigeria

pipeline installations. Also, a petrochemical processing plant is located at the proximity of the lower reach of the river. There is limited or no information on the carcinogenic health risk induced by the consumption of Tilapia zilli from QIRE. This study was conducted to determine the level of PAHs in Tilapia zilli from QIRE and assess the potential health risk induced by the consumption of the above fish.

Ibeno local government area close to a petrochemical effluent treatment and discharge plant while Control site is located at Ekpene Ukpa in Etinan local government area of Akwa Ibom State, about 27km from the examined sites and is free from oil exploration and production activities. Ibeno lies on the eastern side of Qua Iboe River about 3km from the river and is one of the largest fishing settlements in the Nigerian coast. The global positioning system (GPS) coordinates of the different sites are : Okoroutip (4o55’5”N - 7o54’47”E), Ukpenekang (4o27’2”N - 8o 3’5”E), Iwochang ( 4o36’50”N – 7o50’03”E), Douglas creek (4o30’55”N – 8o07’E), Stubb creek (4o34’41”N – 7o59’47”E), Ekpene Ukpa (4o47’90”N – 7o50’03”E). Figure 1 is a map of the study area indicating the sampling sites

2. MATERIALS AND METHODS 2.1. The study area and site description Qua Iboe River covers about 60% of the local governments in Akwa Ibom state. Five sampling sites are located at the lower reach of Qua Iboe River in

Fig.1: Study Area SP1 = Okoroutip, SP2 = Ukpenekang, SP3 = Iwoachang, SP4 = Douglas creek SP5 = Stubb creek SP6 = Ekpene Ukpa

pre-cleaned polyethylene bags and were immediately transferred to a thermo-insulated flask filled with iceblocks, taken to the laboratory and preserved at-18oC. The frozen samples were washed with water after removing the scales and the muscle portion were removed by a stainless steel knife for further processing.

2.2. Samples and sampling Fish samples were obtained from the six sampling sites within the spread of Qua Iboe river system. At each location, 10 samples of Tilapia zilli with length between (15- 18cm) and weight between (50 – 75g) were obtained monthly using fishing net and local traps. Sampling was conducted monthly from November, 2013 to October, 2014. The fish samples were washed with distilled water and collected into 124

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2.4.2. Carcinogenic risk from exposure to PAHs in fish

2.3. Extraction and Clean up The extraction of the analyte was carried out using a soxhlet extractor according to the method described by Olabemiwo et al. (2011) and Anyakoraa et al. (2005).

The carcinogenic health risk induced by the consumption of Tilapia zilli was assessed using the USEPA guidelines described by Cheng et al (2007) and Nyarko et al. (2011). In this guideline, the product of PAH concentration (mg/kg) and its TEF values give a B(a)P equivalent concentration for each PAH. All the individual B(a)P equivalent concentrations were summed up to give a carcinogenic potency equivalent concentration (PEC) of all the PAHs according to the equation below:

2.4. Determination of PAHs concentration The concentration of PAHs was determined using standard protocol described by Nkpa et al. (2013). The sample was automatically detected as it emerges from the column by a flame ionization detector (FID) by measuring the retention time. Usually the identification of the PAH compounds (analyte peaks) was achieved using Chemsubstation software and was based on matching their retention time with a mixture of PAH standards (16 USEPA priority PAHs) while quantification was obtained from the corresponding areas of the respective chromatograms. The surrogates namely acenaphthened10, phenanthrene-d10, chrysene-d12 and perylene-d12 from Smart solutions, USA were used as internal standard. Procedural blanks and solvent blanks were analysed and quantified with no PAHs found in these blanks. Prior to use, the GC was calibrated using a five point calibration curve established using dichloromethanebased standards (Accustandard PAH mix, 1000g/ml in CH2Cl2). The coefficient of determination values (R2) were greater than 0.87.

The carcinogenic risk is obtained by comparing the potency equivalent concentration (PEC) values with the screening value for carcinogenic PAHs stipulated by USEPA and adopted by Nyarko et al. (2011) and Nozar et al. (2013). Screening value is the threshold concentration of total PAHs in fish that is of potential public health concern and was obtained from the model proposed by Nkpa et al. (2013) and Nozar et al. (2013) as shown below:

(Eq. 2) SV = screening value, RL = maximum acceptable risk level (dimensionless) [0.00001], SF = USEPA oral slope factor for PAHs (7.30mg/kg/day) BW = average body weight for adult population (70kg), CR = consumption rate of fish is 68.5g/day in Nigeria (Nkpa et al., 2013).

2.4.1. Chromatographic Conditions (Tobiszewski and Namiesnik, 2012). The gas chromatograph was Agilent Hewlett Packard 5890 series II, coupled with flame ionization detector (FID) powered with HP Chemsubstation Rev. A. 0901 (10206) software. To identify and quantify PAH components, the following GC operating conditions was utilized: Detector: Hydrogen at 35 ml/min; air at 250ml/mins and nitrogen at 30 ml/min. Oven: Initial temperature 65oC; final temperature; 325oC, Run time: 30 minute Inlet: Splitless injection was adopted using a rubber septum and the volume injected was 1l. The inlet temperature was 275oC, with a pressure of 14.8 Psi and total flow of 65.4ml / min. Column: The column was lined with 1, 3-dimethyl polysiloxane with capillary HPS type of 30m length, 0.32mm wide bore diameter, 0.25m film diameter

2.5. Statistical Analysis All values are expressed as mean of three determinations ± standard deviation. Student’s t-test was used to compare between the mean of total PAH values in both the dry and wet seasons and a P < 0.05 was considered statistically significant. Pearson correlation coefficient was used to examine the relationship between PAH pairs in fish and cluster analysis was used to assess common pollution sources between sampling sites. Statistical analyses were performed using SPSS statistics 17.0 windows 3. RESULTS AND DISCUSSIONS 3.1. Results The level of 16 priority PAHs, their summation and diagnostic ratio in Tilapia zilli from QIRE in both the dry and wet season are shown in Tables 1 and 2. The individual PAHs ranged from 5.007E – 08 recorded for chrysene at Iwochang to 2.152E-01 for B(b)F at 125

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Douglas creek during the wet season. In the dry season, the least value was recorded for B(a)A (2.712E-06) at the Control site and the highest value was recorded for B(b)F (9.780E-02) at Douglas creek. The total PAHs in the dry season ranged from 5.288E-03 at the Control site to 1.456E-01 at Douglas creek. The trend for the individual PAHs in the different sampling site decreased as follows: Douglas creek > Stubbs creek > Ukpenekang > Iwochang > Okoroutip > Ekpene Ukpa. The total PAHs in the wet season ranged from 1.527E-03 at the control site to 2.2058 E-01 at Douglas creek and the trend for the different sampling sites decreased according to the trend: Douglas creek > Okoroutip > Iwochang > Ukpenekang > Stubbs creek > Ekpene Ukpa. The total PAHs in dry season was compared with total PAH concentration in the wet season using student t-test and no significant difference in the mean value of the seasons was observed between the two seasons. For both seasons, ΣLMW/ΣHMW was less than one indicating possible pyrogenic source of PAH contamination and dominance by HMW PAHs (Rocher et al., 2004). This is a clear case of anthropogenic pollution of PAHs in QIRE. Results obtained for all the stations except at Ukpenekang in

both seasons, indicated that, the ratio Anthracene/Anthracene + Phenantrene was greater than 0.1indicating pyrogenic pollution source. However, when the ratio Fluorathene/Fluoranthere + Pyrene was used for source apportionment in this study, this ratio was less than 0.5 at stations such as Okoroutip, Douglas, Ekpene Ukpa in the dry season and Douglas creek, Stubb creek and Ekpene Ukpa in the wet season. Other sampling station recorded values greater than 0.5 for both seasons indicating mixed sources of PAH pollution. 3.2. Carcinogenic Health Risk Induced by PAHs via the consumption of Tilapia zilli The result for the computation of potency equivalent concentration of PAH at all the sample locations in both seasons is presented in Figure 2 below. The carcinogenic potency equivalent concentration of PAHs in Tilapia zilli from QIRE ranged from 3.610E04 to 1.398E-02 and 1.685E-04 to 2.207E-02 during the dry and wet seasons respectively. In this study the highest cancer risk from Tilapia zilli consumption was recorded at Douglas creek while the least risk was recorded at Ekpene Ukpa (Control site).

Fig. 2: Potency equivalent concentration of carcinogenic PAHs in Tilapia zilli from QIRE

following PAH pairs B(b)F/B(k)F (r = 0.729), B(a)P/ B(b)F (r = 0.612), B(a)P/ B(k)F ( r = 0.519). Significant positive correlation was recorded between the following PAH pairs in the wet season: B(a)P/ B(a)A (r = 0.821, P = 0.05), Ind(1,2,3-cd)P/ B(a)A (r = 0.831, P = 0.05) and D(ah)A/ B(b)F (r = 0.762, P = 0.05). The dendrogram showing the similarities between sampling sites due to the concentration of PAHs in Tilapia zilli is presented in Figures 3 and 4 while the

3.3. PAH interrelationship and Hierarchal clusters analysis for PAHs in Tilapia zilli from QIRE The associations between individual PAHs in Tilapia zilli during the dry and wet seasons are presented in Tables 3 and 4. During the dry season, strong positive correlation was recorded between D(ah)A and Ind(1,2,3-cd)P (r = 0.870, P = 0.05) while strong positive correlation was observed between the 126

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Ukpenekang

Stubbs

Iwoachang

Okoroutip

Ekpeneukpa

indicate that concentration of the total C-PAHs in the dry season followed the trend: group I > group II > group III > group IV while the variation in the wet season followed the pattern: group I > group II > group III. In an attempt to classify the C-PAH using hierarchical cluster analysis, three primary clusters were identified in both season (Figures 5 and 6). The first and second groups comprised B(b)F and Ind (1,2,3-cd)P respectively while the third group consisted of the remaining carcinogenic PAHs.

Douglas Similarity

cluster analysis showing similarities/ differences between individual C-PAHs in Tilapia zilli are presented in Figures 5 and 6. In the dry season, four (4) groups were identified; group I consist of Douglas creek, group II is made up of Ukpenekang and Stubbs creek, group III is made up of Iwoachang and Okoroutip while group IV is the Control site. For the wet season, three clusters were identified; group I (Douglas creek), group II (Okoroutip, Iwoachang, Ukpenekang ) and group III ( Stubbs creek and Ekpene Ukpa ). The clusters in Figures 3 and 4

1

2

3

4

5

6

0.002 0.001 0 -0.001 -0.002 -0.003 -0.004 -0.005 -0.006 -0.007 -0.008 -0.009 -0.01 -0.011 -0.012 -0.013 -0.014 -0.015 -0.016 -0.017 -0.018 -0.019 -0.02 -0.021 -0.022 -0.023 -0.024 -0.025 7

Fig. 3: Cluster analysis showing the spatial distribution of PAHs in T. zilli along different sampling sites at QIRE during the dry season

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Table 1: PAH concentrations (mg/kg) in Tillapia zilli from QIRE during the dry season PAH Mixture Naphthalene Acenapthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Benzo(a) Anthracene Chrysene Benzo(b) Fluoranthene Benzo(k) Fluoranthene Benzo(a) Pyrene Indeno(1,2,3cd)Pyrene Dibenzo(ah) Anthracene Benzo(ghi) Perylene Total PAHs ∑LMW-PAHs ∑HMW-PAHs ∑C-PAHs ∑ nonC-PAHs LMW-PAHs HMW-PAHs Flu/ Flu + Pyrene Anth/ Anth + Phenanthrene

Okoroutip 3.033E-042.645E06 2.288E-055.859E07 3.492E-053.251E06 3.435E-043.740E05 6.657E-056.107E06 3.257E-056.216E06 9.108E-041.400E05 3.253E-035.315E04 3.878E-052.023E04 1.320E-044.628E05 2.037E-025.282E03 9.668E-054.041E07 8.274E-054.041E07 2.838E-024.041E03 3.911E-045.291E06 1.560E-055.686E06 5.447E-02 8.038E-04 5.367E-02 4.946E-02 5.000E-02 1.490E-02

Ukpenekang 1.333E-032.516E05 2.293E-054.041E07 6.136E-062.000E07 1.6043E042.000E-06 1.092E-035.859E05 2.449E-056.658E07 2.430E-03 3.271E04 1.878E-03 5.890E05 1.107E-05 4.041E07 2.449E-05 5.507E07 6.658E-02 1.950E03 4.705E-044.041E06 7.726E-055.512E06 4.373E-053.605E04 5.399E-065.006E07 6.694E-055.859E07 7.850E-02 2.640E-03 7.591E-02 7.159E-02 6.960E-03 3.470E-02

Iwoachang 1.272E-034.509E05 2.265E-056.110E07 2.77285E054.163E-07 1.319E-043.055E06 7.756E-045.657E05 3.818E-052.165E06 1.838E-03 4.809E05 2.482E-04 5.033E06 8.310E-06 3.055E08 1.865E-04 4.809E06 4.423E-02 6.658E04 3.814E-043.605E06 2.233E-041.587E05 1.165E-025.977E03 5.063E-065.550E07 5.470E-045.824E05 6.159E-02 2.269E-03 5.932E-02 5.932E-02 4.364E-03 3.820E-02

Douglas Creek 2.392E-034.725E05 4.325E-054.765E06 1.411E-052.516E06 4.763E-044.000E06 1.551E-047.234E06 5.571E-052.856E06 1.918E-033.511E05 3.548E-035.507E05 9.382E-05 5.507E07 2.644E-044.041E06 9.780E-02 4.041E03 3.500E-043.511E06 1.546E-047.971E05 3.723E-022.008E03 2.810E-044.001E06 8.137E-045.608E05 1.456E-01 3.166E-03 1.424E-01 1.368E-01 8.726E-03 2.220E-02

Stubb Creek 2.308E-034.509E05 2.055E-043.214E06 6.864E-051.216E06 1.0415E045.519E-05 6.362E-054.593E06 4.122E-056.806E07 1.676E-03 7.937E05 2.502E-045.131E06 8.871E-06 6.557E08 1.872E-04 1.135E03 8.669E-02 3.055E03 2.767E-042.000E06 1.8404E045.033E-06 9.357E-033.511E05 9.116E-054.750E06 5.883E-044.358E06 1.020E-01 2.791E-03 9.930E-02 9.734E-02 4.726E-03 2.800E-02

Ekpene Ukpa 2.394E046.027E-06 2.756E045.291E-06 4.162E064.358E-08 4.353E055.2915E-07 5.418E055.311E-06 6.764E065.632E-07 1.0583E045.889E-05 7.85E-041.276E05 2.712E061.4468E-07 1.999E-04 6.245E-06 3.180E-03 5.200E-04 2.254E054.725E-07 3.701E064.582E-08 2.685E044.509E-06 9.801E062.645E-07 8.670E052.253E-06 5.288E-03 6.236E-04 4.665E-03 3.770E-03 1.518E-03 1.336E-01

2.187E-01

5.744E-01

8.811E-01

3.508E-01

9.853E-01

1.156E-01

3.463E-01

2.193E-02

8.369E-01

2.313E-01

3.931E-01

1.109E-01

N/B: (Values are mean of three determination ± standard deviation)

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Table 2: PAH concentrations (mg/kg) in Tillapia zilli from QIRE during the wet season PAH Mixture Naphthalene Acenapthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Benzo(a) Anthracene Chrysene Benzo(b) Fluoranthene Benzo(k) Fluoranthene Benzo(a) Pyrene Indeno(1,2,3cd)Pyrene Dibenzo(ah) Anthracene Benzo(ghi) Perylene Total PAHs ∑LMW-PAHs ∑HMW-PAHs ∑C-PAHs ∑ nonC-PAHs LMW-PAHs HMW-PAHs Flu/ Flu + Pyrene Anth/ Anth + Phenanthrene

Okoroutip 2.373E-041.001E05 1.245E-045.723E05 5.615E-065.661E07 3.446E-055.524E06 1.246E-058.087E07 3.870E-052.665E06 8.140E-044.014E07 2.109E-045.147E05 3.334E-055.603E07 2.624E-055.902E06 3.432E-024.486E03 8.758E-061.928E07 2.495E-053.055E07 2.715E-027.571E03 1.492E-045.567E06 5.162E-066.011E06 6.324E-02 4.530E-04 6.278E-02 6.173E-02 1.511E-03 7.200E-03

Ukpenekang 1.944E-063.055E08 1.358E-046.557E06 1.131E-043.785E06 7.362E-066.882E07 7.624E-065.081E07 1.874E-045.567E06 2.013E-054.582E07 1.818E-054.883E07 3.388E-055.131E07 2.965E-028.131E03 4.447E-064.725E08 1.129E-054.509E07 1.674E-038.144E05 7.909E-051.705E07 1.333E-056.506E07 3.195E-02 2.658E-04 3.169E-02 3.146E-02 4.917E-04 8.300E-03

Iwoachang 6.885E-051.322E06 1.094E-045.804E05 1.463E-045.033E06 1.499E-044.582E06 3.922E-056.001E07 2.538E-055.556E06 7.030E-044.728E07 3.253E-047.023E06 1.576E-055.033E07 5.007E-055.488E06 2.958E-023.605E04 7.905E-046.173E05 9.069E-061.457E07 7.950E-035.131E04 1.945E-073.605E07 2.214E-044.725E06 4.015E-02 5.368E-04 3.964E-02 3.857E-02 5.809E-03 7.350E-02

Douglas Creek 1.980E-047.937E06 1.739E-051.040E06 6.289E-066.184E07 1.512E-043.055E06 3.843E-043.797E05 7.178E-055.204E07 1.295E-045.001E06 5.224E-044.014E06 6.840E-064.636E07 1.392E-047.135E05 2.152E-013.785E03 1.134E-042.330E05 1.375E-053.511E07 3.366E-034.045E04 1.880E-047.932E06 2.252E-054.509E07 2.205E-01 8.289E-04 2.197E-01 2.190E-01 1,487E-03 3.700E-03

Stubb Creek 5.348E-065.106E07 1.872E-057.578E07 4.165E-065.43E07 1.57E-045.859E06 2.061E-054.582E07 1.261E-055.132E07 1.585E-048.035E06 6.475E-043.789E05 2.255E-054.725E07 1.895E-043.055E06 1.215E-026.806E04 1.368E-057.002E07 2.401E-055.367E07 6.216E-036.027E04 3.383E-056.292E06 1.656E-034.000E05 2.131E-02 2.193E-04 2.109E-02 2.027E-02 1.042E-03 1.030E-02

Ekpene Ukpa 1.120E042.081E-06 5.194E065.426E-07 3.619E073.511E-09 1.568E043.005E-06 1.155E054.041E-07 1.560E062.627E-07 9.808E057.211E-07 8.175E053.511E-07 2.184E069.379E-07 6.115E065.688E-07 6.362E048.185E-05 8.338E055.608E-06 5.838E065.899E-07 2.421E043.571E-06 6.656E054.041E-07 1.708E052.516E-07 1.527E-03 2.874E-04 1.239E-03 1.057E-03 4.701E-04 2.318E-01

9.748E-01

9.022E-01

6.836E-01

1.986E-01

1.980E-01

1.071E-01

7.564E-01

……

4.054E-01

1.572E-01

3.795E-01

5.745E-01

N/B: (Values are mean of three determination ± standard deviation)

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Table 3: Correlation matrix for carcinogenic PAHs in Tillapia zilli from QIRE during the dry season B(a)A

Chrysene

B(b)F

B(k)F

B(a)P

Ind(1,2,3-cd)P

B(a)A

1

Chrysene

0.126

1

B(b)F

-0.117

0.161

1

B(k)F

0.325

-0.293

0.729

1

B(a)P

0.620

0.313

0.612

0.519

1

Ind(1,2,3-cd)P

-0.121

0.434

0.316

0.045

0.296

1

D(ah)A

-0.409

0.143

0.110

-0.236

-0.042

0.870*

D(ah)A

1

Table 4: Correlation matrix for carcinogenic PAHs in Tillapia zilli from QIRE during the wet season B(a)A

Chrysene

B(b)F

B(k)F

B(a)P

Ind(1,2,3-cd)P

B(a)A

1

Chrysene

0.036

1

B(b)F

-0.326

0.403

1

B(k)F

-0.158

-0,146

-0.048

1

B(a)P

0.821*

0.483

-0.016

-0.427

1

Ind(1,2,3-cd)P

0.830*

-0.177

-0.121

-0.056

0.696

1

D(ah)A

0.018

0.033

0.762*

-0.454

0.241

0.315

**Correlation is significant at 0.01 levels (2-tailed)

D(ah)A

1

*Correlation is significant at 0.05 levels (2-tailed)

et al. (2010) reported that the stability of PAH molecules and hydrophobicity are two factors which contribute to the persistence of HMW PAHs in the environment. Nyarko et al. (2011) attributed the dominance of HMW-PAHs in fish from Ghana to the degradation of LMW-PAHs during PAH transport and burial into sediments. Though the level of LMW-PAH is low, Neff (1985) has reported that at a particular level, LMW-PAHs are toxic to aquatic organisms. The highest level of total C-PAHs in fish was observed at Douglas creek and may be due to the high pollution status of the creek that receives direct discharge of oilfield effluents and is very close to a gas flaring site of a petrochemical facility.

3.4. Discussion of Results 3.4.1. Levels of PAHs in Tilapia zilli from QIRE The total PAH was higher in the wet season than the dry season and the result for total PAHs in this study is comparable to findings by other authors (Olabemiwo et al., 2011 and Cheng et al., 2007) while Nasr et al. (2012) recorded higher values. HMWPAHs were higher than LMW-PAHs in both the dry and wet seasons. Hence, the percentage occurrence of 2-3 ring PAHs was lower than that of 4-6 rings. The high level of HMW-PAHs in fish from these sample locations may be due to uptake and bioavailability of these contaminants in the studied environment. Eduok

130

Stubbs

Ekpeneukpa

Ukpenekang

Iwoachang

Okoroutip

Douglas

International Journal of Scientific Research in Environmental Sciences, 4(5), pp. 0123-0135, 2016

1

2

3

4

5

6

0

-0.01

Similarity

-0.02

-0.03

-0.04

-0.05

-0.06

-0.07

7

Fig. 4: Cluster analysis showing the spatial distribution of PAHs in T. zilli along different sampling sites at QIRE during the wet season.

Nkpa et al. (2013) reported that the level of contaminants such as PAHs in fish reflect the state of contamination of the medium or environment where the fish is caught. According to Eduok et al. (2010) PAH residues in QIRE have been linked with atmospheric deposition, runoffs, sewage, industrial waste, municipal waste and petroleum exploration and production activities. Nyarko et al. (2011) also attributed PAH levels in fish to contact with fishing net contaminated with oil from oil slicks and PAH contaminated plastics dumped into the aquatic water body. The average value of B(a)P concentrations in this study was lower than the EU limit of 2µg/kg (0.002mg/kg) and JECFA limit of 20µg/kg (0.02mg/kg) for the safe consumption of fish in both seasons. Eventhough, the standard for other C-PAHs is not stipulated, carcinogenic PAHs recorded higher values in both seasons when compared with non-

carcinogenic PAHs. The bioaccumulation and biomagnification of carcinogenic PAHs along the aquatic food chain is envisaged. In both seasons, B(b)F and Ind(1,2,3-cd)P recorded the highest levels in Tilapia zilli. This is consistent with findings of other author who investigated the level of PAHs in water and fish from the Niger Delta region of Nigeria (Nkpa et al., 2013; Inam et al., 2014). Anthracene and carcinogenic PAHs have been linked with tumors in human and long term exposure to C-PAHs can result in several health effects such as kidney and liver damage, cataracts and jaundice, chronic bronchitis and decreased immune functions (Bohacova et al., 1999). The presence of PAHs in fish can produce cancer-like growth, tetratogenic and mutagenic effects in fish resulting in fibrosacoma, stomach papilloma along with other tumour (Okafor and Opuene, 2007).

131

B(k) F

D(ah) A

Chrysene

B(a) P

B(a) Anthra

Ind(1,2,3) P

B(b) F

Etuk et al. Levels of Polycyclic Aromatic Hydrocarbons (PAHs) and Associated Health Risk in Tilapia zilli from Qua Iboe River Estuary, Niger Delta, Nigeria

1

2

3

4

5

6

7

0

-0.01

Similarity

-0.02

-0.03

-0.04

-0.05

8

Fig. 5: Hierarchical dendrogram for carcinogenic PAHs in Tilapia zilli from QIRE during the dry season

Law et al. (1997) reported that high C-PAHs result in the formation of hepatocarcinomas in wild flat fish. According to Nyarko et al. (2011) PAH exposure can cause growth reduction, endocrine alteration, malfunction of embroyo and larvae and DNA damage in fish as well as human health effect such as cancer, mutation and birth defects. Food consumption is an important pathway of human exposure to many contaminants including PAHs (Olaji et al., 2014) and most human cancers such as prostrate and lung cancer are linked with dietary sources (Khoei et al., 2013). Apart from microbial agents, gastrointestinal disorder prevalent in the population around the lower reach of QIRE may be due to direct uptake of PAHs through the consumption of aquatic biota (Eduok et al., 2010). The result for the diagnostic ratio analysis in Tilapia zilli from QIRE revealed pyrogenic PAHs

origin and this is in accordance with the findings of other researchers (Nyarko et al., 2011; Nkpa et al., 2013; Nozar, et al., 2013). According to Nozar et al. (2013) pyrogenic source of PAH pollution in biota such as fish, crab, and shrimp is attributed to high traffic of marine transportation and discharge of urban and industrial wastewater into the marine ecosystem. However, mixed PAH source was observed with Fluorathene/Fluoranthere + Pyrene ratio and may be due to the complexity of parameters which govern PAH distributions in the environment. Sinae and Mashinchain (2014) reported results of mixed PAH sources similar to this studies when they investigated the source of PAHs in coastal sea water, surface sediment and mudskipper from Persian gulf using Fluorathene/Fluoranthere + Pyrene ratio.

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Fig. 6: Hierarchical dendrogram for carcinogenic PAHs in Tilapia zilli from QIRE during the wet season.

3.4.2. Carcinogenic health risk induced by the consumption of Tilapia zilli from QIRE

water which is higher than values recorded in this study.

The potency equivalent concentration (PEC) in fish samples from all the sampling station for both the dry and wet seasons were greater than the screening value of 1.00E-03 exception of the Control site. This indicates that the consumption of Tilapia zilli at the rate of 68g per day can result in adverse carcinogenic health effect. This study also show that, the people living at the lower reach of the Qua Iboe River estuary are exposed to higher cancer risk induced by the consumption of Tilapia zilli than those at the Control site. The consumption of Tilapia zilli could be a potential source of PAH exposure route among the people at the examined site as fish constitutes a major source of animal protein in their diet (FAO, 1983). Dietary intake has been identified as a major route of human exposure to PAHs (Yu et al., 2014) and recent studies have shown that most human cancers such as prostrate and lung cancer can be attributed to dietary sources (Dhananjayan and Murahdharan, 2012). Nkpa et al. (2013) reported PEC values of 0.003 to 0.012 for Tilapia quineesis and 0.002 to 0.011 for Liza falcipines from crude oil polluted water of Ogoni land. These values are within the range reported in this study for the examined sites and higher than values for the Control site. Nyarko et al. (2011) reported PEC values of 0.0239-0.1195 for fishes from Ghana coastal

3.4.3. Cluster analysis and correlation studies Results for the correlation analysis between individual PAHs in fish revealed that B(a)A, B(a)P, B(k)F, B(b)F, D(ah)A and Ind (1,2,3-cd)P are likely to originate from the same source in both seasons. This study corroborate with the findings of Meador (2003) who observed high correlation among PAH compounds and between C-PAHs. Also, some of the above C-PAHs pairs with positive correlation have the same number of rings, closely related molecular weight and close octanol-water partition coefficient. Tobaszewski and Namiesmik (2002) reported that pair of PAHs with similar molar mass and similar physicochemical properties may undergo similar environmental fate. The difference between the dendrogram for both seasons may be due to seasonal effect. Flooding and dilution may be responsible for the total C-PAHs in Stubbs creek being comparable to that in the Control site. The three primary clusters observed in Figures 4 and 5 reveals that B(b)F and Ind (1,2,3-cd)P may originate from different pollution sources while the remaining C-PAHs may have similar pollution sources. In addition, the above grouping may be due to the effect of concentration. 133

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Agricultural organisation of united nations, Rome – Italy. Frenna S, Mazzola A, Orecchio S, Tuzzolin N (2012). Comparison of different methods for extraction of PAHs from Sicilian (Italy) coastal area sediment. Environ. Monit. Assess. 185: 55515562. Gorleku MA, Carboo D, Palm L, Quasie W, Armah A (2014). Polycyclic aromatic hydrocarbon pollution in marine waters and sediments at Tema harbour, Ghana. Acad. J. of Environ. Sci., 2(7): 108-115. Inam E, Owhoeke E, Essien J (2014). Human carcinogenic risk assessment of polycyclic aromatic hydrocarbon in freshwater samples from Ogba/ Egbema / Andoni communities in River state, Nigeria. J. Chem. Soc. Nig., 39 (2): 15 -22. Khoei JK, Bastami AB, Farmohammed S (2013). Oil related PAHs in fish and sediment in Persian Gulf. World Appl. Sci. J., 24(10): 1378 – 1381. Law RJ, Dawes VJ, Woodhead RJ, Matthiessen P (1997). Polycyclic aromatic hydrocarbons (PAHs) in seawater around England and Wales. Mar. Poll. Bull., 34(5): 306 -322. Meador JP (2003). Bioaccumulation of PAHs in marine invertebrates : An ecotoxicological perspective. Douben, P. E. Ed. New York : John Wiley and sons, pp. 147 – 171. Nasr IN, Neveen H, El-Enaen A, Yosef T (2012).Study of some polycyclic aromatic hydrocarbon residues in fish at Sharkia Governorate market in relation to public health. Global veterinaria, 8(6): 670-675. Neff F (1985). Polycyclic aromatic hydrocarbons in : G. M. Rand and S. K. Petrocell (Eds). Fundamentals of aquatic toxicology. New York: Hemisphere publishing coporation, p.17. Nkpa KW, Wegwu MO, Essien EB (2013). Assessment of polycyclic hydrocarbons (PAHs) levels in two commercially important fish species from crude oil polluted waters of Ogoniland and their carcinogenic health risks. J. Env. Earth Sci., 3(8) : 128- 137. Nozar SC, Ismail WR, Zakaria MP (2013). Residual concentration of PAHs in seafood from Hormozgan province, Iran : Human health risk assessment for urban population. Int. J. Environ. Sci. and Dev., 4(4): 393- 397. Nyarko E, Botwe B, Klubi E ( 2011). Polycyclic aromatic hydrocarbon (PAHs) levels in two commercially important fish species from the coastal waters of Ghana and their carcinogenic risk. West African Journal of Applied Ecology, 19: 53-66.

4. CONCLUSION The average value of B(a)P concentrations at all the sampling sites in this study was lower than the EU limit and JECFA limit for the safe consumption of fish in both seasons. Apart from the Control site, the potency equivalent concentration (PEC) values in fish samples from all the locations for both the dry and wet seasons were greater than the screening value. REFERENCES Agency for Toxic Substances and Disease register (ASTDR) (2011). Toxicological profile for polycyclic aromatic hydrocarbon. US department of health and human services. Public health service centre for disease control. Atlanta G. A. Anyakora C, Ogbeche A, Palmer P, Coker A (2005). Determination of PAHs in marine samples of Siokolo fishing settlements. J. Chromat. A., 1073 : 323 – 330. Arvo T ( 1995). Response of Fish to Polycyclic Aromatic Hydrocarbons. Ann. Zool. Fennici, 32: 295 -309. Bohacova SL, Borska Z, Fiala S, Andry C (1999). Effect of Polycyclic aromatic hydrocarbon (PAHs) on the immune system. Acta medica, 42(1): 17 -23. Cheng KC, Leung HM, Kong KY, Wing MH (2007). Residual levels of DDTs and PAHS in fresh water and marine water fish from Hong Kong markets and their health risk assessment. Chemosphere, 66 (3): 460-468. Dhananjayan V, Murahdharan S ( 2012). Polycyclic aromatic hydrocarbon in various species of fishes from Mumbai habour, India and their dietary intake concentration to humans. Int. J. Ocean., 1: 1-6. Eduok SI, Ebong GA, Udoinyang EP, Njoku JN, Eyen EA ( 2010). Bacteriological and Polycyclic aromatic hydrocarbon accumulation in mangrove oysters (Crassostrea tulipa) from Douglas creek, Nigeria. Parkistan J. Nutr., 9(1): 35 – 42. Ellman MR, Wong KR, Solomon GM (2012).Seafood contamination after the BP Gulf oil spill and risk to vulnerable population: A critique of FDA risk assessment. Environ. Health Persp., 120: 159 – 161. Food and Agricultural Organisation (FAO). (1983). Compilation of legal limits for hazardous substances in fish and fisheries products. Fisheries circular No. 464 Foood and 134

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Paris-France : Stock, distributions and origins. Sci. Total Environ., 323: 107-122. Sinae M, Mashinchian A (2014). Polycyclic aromatic hydrocarbons in the coastal sea water, the surface sediment and mudskipper (Boleophthalmus dussumer) from coastal areas of Persian Gulf: Source investigation, composition pattern and spatial distribution. J. Environ. Health Sci. Engr., 12: 59 -63. Tobiszewski M, Namiesnik J (2012). PAH diagnostic ratios for the identification of pollution emission sources. Environ. Poll., 162 : 110-119. Yu G, Zhang Z, Yang G, Zheng W, Xu L, Cai Z (2014) Polycyclic aromatic hydrocarbon in urban soils of Hangzhou: Status, distribution, sources and potential risk. Environ. Monit. Assess., 186: 2775 – 2784.

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Bassey Anie Etuk is a lecturer with Akwa Ibom State polytechnic Ikot Osurua, Akwa Ibom State, Nigeria. He is married with children and has zeal for academic activities. He has a Ph. D degree in Analytical Chemistry and has publications in both local and international journals.

Eno Anietie Moses has a Ph.D in analytical chemistry. She is currently a senior lecturer at the Department of Chemistry University of Uyo, Nigeria, where she teaches analytical chemistry to undergraduate and postgraduate students. She is actively involved in research in the areas of environmental chemistry and chemical toxicology.

Godwin Asukwo Ebong is a lecturer with Chemistry Department, University of Uyo, Uyo, Nigeria. He has a Ph.D degree in Inorganic Chemistry (Environmental Option). He is married with children. He has published in reputable journals both in local and foreign journals.