Human Health Risk of Polychlorinated Biphenyls in Some Brackish and Marine Fish Species from Ondo South-West Nigeria

Seas-7 on POPS ABSTRACT Globally aquatic environment polluted with polychlorinated biphenyls (PCBs) poses health risk to humans via consumption of its aquatic resources. This study evaluated the polychlorinated biphenyls in brackish and marine fish species and its associated health risk through the consumption of fish from Ondo coastal waters. The health risks were assessed using a risk quotient (RQ) of the fish consumption. A total of ten (10) fish samples were collected from April – December 2018, analyzed, identified and quantified using gas chromatography-mass spectrophotometer (GC/MS) for PCBs. Twenty-eight (28) PCB congeners were screened in the fish samples using standard methods. The mean levels of indicator PCBs ranged from 3.70 ng/g ww ( Arius ) to 8.60 ng/g ww ( Sphyraenapiscatorum ) and Dioxin-like PCB ranged from 0.20 ng/g ww ( Pentanemusquinquarius ) to 6.21 ng/g ww (Tilapia sp). The total PCB levels in the fish were relatively below 1000 µg/kg by WHO/FAO guideline. The Estimated daily intake and risk quotient were below 1 which implies no associated health risks in humans due to the


Introduction
Polychlorinated biphenyls (PCBs) are synthetic chemicals consisting of 209 isomers classified as persistent organic pollutants (POPs) [1]. Polychlorinated biphenyls (PCBs) are a class of aromatic chemical compounds in which some or all hydrogen atoms attached to the biphenyl ring are substituted by chlorine atoms (m + n = 1-10). They can bioaccumulate easily into tissues of aquatic biota and sediment, causing serious damage to the aquatic ecosystems [2]. The main source of PCBs compounds in humans is via dietary fish, which tends to accumulate by direct absorption through the gills, exposure to contaminated sediments, and consumption of insects/ other forms of macroinvertebrates and smaller fish [1].
PCBs have basic resistance to acids, bases as well as heat, and as such are utilized extensively for insulating materials in electrical equipment, heat transfer fluids and as lubricants [3]. Global concerns over the toxicity of PCBs in the aquatic environment and its classification as Persistent Organic Pollutant (POP) led to the ban by the United States Congress in 1979. The key properties of PCBs are environmental stability, biological persistence and lipophilicity which facilitate bioaccumulation along the food chain in a complex manner [4]. Humans are exposed to POP contaminants in several ways: mainly via food ingestion, inhalation, though outdoors and indoors [5]. PCBs are regulated by the European Union, WHO and FAO, as to the level of PCBs present in our food even at low levels. Some of the reported effects of PCBs in humans include skin discoloration, liver dysfunction, reproductive defects, dermatitis, dizziness, and endocrine disruptors in exposed humans [6]. Specific congeners may be monitored in an aquatic environment as suggested by the Stockholm Convention and International Council for the Exploration of the Seas-7 (ICES-7) on POPS which recommended

ARTICLE INFO ABSTRACT
Globally aquatic environment polluted with polychlorinated biphenyls (PCBs) poses health risk to humans via consumption of its aquatic resources. This study evaluated the polychlorinated biphenyls in brackish and marine fish species and its associated health risk through the consumption of fish from Ondo coastal waters. The health risks were assessed using a risk quotient (RQ) of the fish consumption. A total of ten (10) fish samples were collected from April -December 2018, analyzed, identified and quantified using gas chromatography-mass spectrophotometer (GC/MS) for PCBs. Twenty-eight (28) PCB congeners were screened in the fish samples using standard methods. The mean levels of indicator PCBs ranged from 3.70 ng/g ww (Arius heudeloti) to 8.60 ng/g ww (Sphyraenapiscatorum) and Dioxin-like PCB ranged from 0.20 ng/g ww (Pentanemusquinquarius) to 6.21 ng/g ww (Tilapia sp). The total PCB levels in the fish were relatively below 1000 µg/kg by WHO/FAO guideline. The Estimated daily intake and risk quotient were below 1 which implies no associated health risks in humans due to the intake of PCB contaminants via fish consumption.

Study area
The study area lies in 6°21ʹ1.6ʹʹ N latitude and 4°48ʹ11.8ʹʹ E longitude which falls within the transgressive mud beach zone of the Nigerian coastline. The area lies east of the West African Lagoon system and on the western Flank of the Niger Delta Basin.
The general stratigraphy of Ondo State coast therefore differs from that of the Niger Delta by having about 60m mud overlying the Benin sands [7]. The fish species were collected from the Igbokoda fish landing site located in Ilaje local government area, Ondo state Nigeria. The community is vastly known for their fishing activities both inland and extensively into the sea via Mahin Lagoon. The GPS coordinate of the sampling location is presented in Figure 1.

Sampling Procedure
The fish species were collected from fisher folks at the Igbokoda fish landing site, Ondo state (April -December 2018). The caught fish species from the sea and brackish waters were collected and stored in an ice container before transporting to the laboratory and stored at a temperature of -20 0 C until ready for further analysis. The analytical standards (>98% purity) were used to prepare fortification and standard solutions. The extracted samples were subjected to gas chromatography for identification/quantification.
The compounds were analyzed using a gas chromatography mass spectrophotometer (GC/MS).

Statistical Analysis
The statistical analysis of the data was based on the variation of average values by ANOVA and a significance level of p<0.05 was used. When the p-value was lower than 0.05, it was considered statistically significant. All statistical tests were performed using SPSS 22 software.

Dietary Intake Estimation
Human exposure assessment of PCBs through oral ingestion is generally estimated using the daily intake of the contaminant. The estimated total daily intake (EDI) of the contaminants in a given fish species was calculated as follows [8] EDI = C x Intake / BW Where EDI is the estimated daily intake (ng/kg body wt./day), C is the average concentration of measured PCBs (ng/g wet weight), Intake is the daily food consumption of fish (0.0548 kg/capita/day) (FAO, 2014) and BW is the average consumer body weight (70 kg for adult men).

Risk Assessment
The potential risks of non-carcinogenic effects were evaluated by the risk assessment index known as the risk quotient (RQ). The RQ is defined as the ratio of daily fish exposure level (EDI) in relation to reference dose (RfD) considering non-carcinogenic effects of the contaminants. The RQ was calculated as follows [9] RQ = EDI / RfD where EDI is the estimated daily intake (ng/kg body wt./day); and RfD is the reference dose (ng/kg day). The RfD applied in this study was 20 ng/kg day [9].

Biometric Data of Fish Sample
The mean biometric data of the weight, total length and standard length of the fish species are presented in

Indicator PCBs in Fish Samples
The mean distribution pattern of the indicator PCBs varied greatly between fish species (Figure 2 daily intake (EDI) and risk quotient (RQ) are shown in Table 3.   Table 4. The EDI values in our study were lower compared to the EDI of I-PCBs in fish from Black Sea that was calculated between 1.36 and 5.14 ng/kg bw day through consumption of goby and shad, respectively [5]. The RfD values adopted in this study are the criteria of the USEPA (Environment Agency of the United States) [9]. The RQ values in this study (Table 2) is less than 1, no obvious health risks due to the intake or uptake of contaminants via fish consumption would be experienced. The comparison of our results for TEQ values in fish with those in the literature showed lower levels than the TEQs in sardine from the Spanish Atlantic southwest coast (0.75 pg TEQ /g ww) [11] and lower than those in salmon from the Baltic Sea (12.6 pg TEQ /g ww) [12]. The European Union has set a limit of 3.0 pg TEQ/g wet weight in the muscle meat of fish for the sum of dioxin-like PCBs [10]. In our study TEQs of the seven dl-PCBs for all investigated fish species did not exceed this limit. The EDI dl PCBs value in this study were low, while the WHO set for TDI for the sum of TEQ and l-PCB-TEQ of 1-4 pg TEQ kg/ body weight [13], which is comparable with a tolerable weekly intake of 14 pg TEQ/kg body weight as fixed by the European Union Scientific Committee on Food [14,15].

Conclusion
The total PCBs (indicator and dioxin-like) levels in the fish samples from Igbokoda fish landing site were relatively low at <1000 µg/kg, below the WHO/FAO guideline of 1000 µg/kg fresh weight. All the RQ values were much lower than 1, suggesting that consumption of the fish species would not pose any non-cancer risk. However, there is need for periodic biomonitoring of the Mahin lagoon and its adjoining creeks.