Pollution Characteristics and Health Risk Assessment of Heavy Metals in Ambient Air Around Mkpanek Gas Flaring Plant

concentrations , (ii) To estimate their potential health risks, such as using the carcinogenic (CR) and non-carcinogenic health indices (HQ and HI), To calculate the additional lifetime cancer cases in the study area. IJEMT 2. Material and Methods 2.1 Study Site Mkpanak is situated in Ibeno Local Government Area of Akwa Ibom State, Nigeria, which lies between latitude 4° 33’N – 4° 59’N and longitude 7° 59E’ – 7° 26’ E, and is one of the largest fishing settlements on the Nigerian coast (Andem et. al., 2013). Figure 2.1 shows Mkpanak Gas Flaring Plants. Ibeno is locates in the Mangrove Forest Belt of the Niger Delta Area of Nigeria, bounded to the south by Atlantic Ocean, to the west by Eastern Obolo Local Government Area, and to the north by Onna, Esit Eket and Eket (Taiwo and Tse 2009). Ibeno occupies more than 129 km2 of Akwa Ibom State, the largest Atlantic coastline in the area. Ibeno has rainfall all the year round with the peak between May and September and the climatic condition of the area favours fishing and farming. The soil type in Ibeno is Anthrosol type according to the International Union of Soil Sciences World Reference Base (IUSS-WRB) Working Group classifications of soil (IUSS – WRB 2014). This area of Akwa Ibom State is impacted significantly by the gas flared by the oil industries operating in the region. Mkpanak is one of the communities in Ibeno Local government of Akwa Ibom State that witness the negative impact of gas flaring, damaged rooftops of houses within the studied communities among other communities like (Ukpenekang, Atabrikang, Inua-Eyet Ikot, and Okorutip). The coordinate of the studied location is shown in Table 1.1 Figure 2.1: Mkpanak Gas Flaring Plants. Table 1.1 Sample Location Location Coordinate Name Latitude Longitude Mkpanak 4° 33’N - 4°59’N 7° 59’E - 7° 26’E 2.2. Collection of Sample Heavy metals in particulate matter in ambient air was collected on glass fiber filters using a high- volume sampler at an average flow rate of 1.70 m3/min (60 ft3/min) at a constant air flow controller over a 24-hr period at three sampling points (100, 200 and 500m) away from the flare at a height of 1.5 m above ground surface in the December, 2024. The air was drawn into a covered housing and through a filter by means of a high-flow rate blower at a flow rate [1.13 to 1.70 m3/min. (40 to 60 ft3/min)] that allows suspended particles having diameters less 100 μm (Stokes equivalent diameter) to pass to the filter surface. Particles 100-0.1 μm in diameter are ordinarily collected on glass fiber filters. The mass concentration (μg/m3) of suspended particulates in the ambient air was computed by measuring the mass of collected particulates and the volume of air sampled. After the mass was measured, the filter was IJEMT ready for extraction to determine metal concentration. The final results were later converted to (mg/m3) to enable the comparison with inhalation reference concentrations of (ATSDR (ATSDR, 2023) guidelines reported, and computation of average daily dose via ingestion (mg/kg-day), exposure concentration via inhalation (EC) μg/m3 and dermal absorption dose (mg/kg-day) in order to evaluate the carcinogenic, non-carcinogenic health risk and lifetime cancer risk. 2.3 Sample Extraction Samples collected on glass fiber filters were extracted by microwave extraction. In operation, a 1' x 8' strip is cut from the 8' x 10' filter as described in the Federal Reference Method for Lead. The metals are extracted from the filter strip by a hydrochloric/nitric acid solution using a laboratory microwave digestion system. After cooling, the digestate was mixed and filtered with Acrodisc syringe filters to remove any insoluble material. 2.4 Sample Analysis Heavy metals including As, Cd, Cr, Pb, Mn, Hg, Ni, Cu, Zn and V in each sample were determined by atomic absorption spectrometry. 2.5 Health Risk Assessment The carcinogenic and non-carcinogenic health risk and lifetime cancer risk were evaluated based on ingestion, inhalation and dermal routes of exposure to metals. Human exposure is measured in terms of average daily dose via ingestion (mg/kg-day) (Eq. 1), exposure concentration via inhalation (EC) μg/m3 (Eq. 2) and dermal absorption dose (mg/kg-day) (Eq. 3), (Khan et al., 2020; Zhang et al., 2021). The definitions and the constant factors included in Eqs. (1, 2), and (3) are given in Table 2.1. ADD = (Ci × IngR × EF ×ED × 10-6) / (BW × AT) (1) EC = (Ci × ET × EF × ED) / (2) DAD = (Ci × SA × AF × ABF × EF × ED × 10-6) / (BW × AT) (3) Table 2.1 Definitions and Values of Parameters used for Carcinogenic and Non- Carcinogenic Risk (non-CRs) Assessment. Parameter Definition Unit Values References Children Adults Ci The mean concentrations of HMs (μg/m3) for EC, (mg/kg) for ADD and DAD From the present study From the present study This Study IngR Ingestion rate mg/day 200 100 (USEPA, 2002) EF Exposure frequency days/year 180 180 (Zhang et al., 2021) ED Exposure duration Years 6 24 (USEPA, 2004) ET Exposure time hours/day 24 24 (USEPA, 2004) IJEMT AT Average lifetime Days ED×365 (non- carcinogens) ED×365 (non- carcinogens) (USEPA, 2004) 70×365 (carcinogens) 70×365 (carcinogens) ATn Average lifetime Hours ED×365×24 (non- carcinogens) ED×365×24 (non- carcinogens) (USEPA, 2004) 70×365×24 (carcinogens) 70×365×24 (carcinogens) BW Body weight Kg 15 70 (USEPA, 2004) SA Skin surface area cm2 2800 5700 (USEPA, 2004) AF Adherence factor mg/cm2 0.2 0.07 (USEPA, 2004) ABF Absorption factor - 0.1 (Pb), 0.03 (As), 0.001 (Cd), 0.01 (Zhang et al., 2021) 2.5.1 Carcinogenic and Non-Carcinogenic Health Risk Carcinogenic and Non-carcinogenic health risk assessment of PM2.5-bound heavy metals was estimated using hazard quotient (HQ) which is calculated based on Eqs (4-6) (Khan et al., 2020; Zhang et al., 2021) HQing = ADD / (4) HQinh = EC / (RfC×1000) (5) HQder = DAD / (6) Where HQing, HQinh, and HQder are the hazard quotient via ingestion, inhalation, and dermal contact respectively. RfD is the reference dose (mg/kg-day), and RfC is the reference concentration of the heavy meter (mg/m3). The values of RfD and RfC for investigated heavy metals were obtained from Zhang et al. (2021). HQ values ≤1 indicate no significant or acceptable risk, while HQ values >1 indicate the potential for adverse health effects (USEPA 2001). Hazard index (HI) is used for the estimation of health risks associated with exposure to multiple metals. Hazard index (HI) is the summation of hazard quotients of individual metal “k”, which can be calculated using the following equation (Khan et al., 2020), HI = ∑ HQk (7) 2.5.2 Lifetime Cancer Risk The probability of developing cancer because of human exposure to these carcinogens over the lifetime can be estimated using Eqs (8, 9), and (10) for ingestion, inhalation, and dermal contact respectively (Morakinyo et al., 2021). ILCRing = ADD × SF (8), ILCRinh = EC × IUR (9) ILCRder = DAD × SF (10) Where: ILCRing, ILCRinh, ILCRder are incremental lifetime cancer risks via ingestion, inhalation, and dermal contact, respectively. SF is the slope factor (mg/kg-day)-1, and IUR is the inhalation unit risk (μg/m3). The values of SF and IUR for carcinogenic metals were taken from the California Office of Environmental Health Hazard Assessment (OEHHA, 2021). The ILCR can IJEMT be classified as very low (ILCR≤1 x 10-6), low (10-6≤ILCR<10-4), moderate (10-4≤ILCR<10-3), high (10-3≤ILCR<10-1), and very high (ILCR≥10-1). The cumulative ILCR for different carcinogenic metals (i) is given by Eq. (11), (Sun et al., 2021). Cumulative ILCR = ∑ ILCRi (11) The cumulative ILCR for different carcinogenic metals should be maintained below 10-4 (Chalvatzaki et al., 2019). 3. Results and Discussion 3.1 Concentrations of Heavy Metals in Ambient Air Table 1, Figure 3.1a and b present the average concentrations of heavy metals in ambient air in (mg/m3) compared with inhalation reference concentrations of (ATSDR (ATSDR, 2023), OEHHA (California Environmental Protection Agency, 2009) guidelines. The results show that the average concentration at 100 m (mg/m3) > 200 m (mg/m3) > 500 m (mg/m3), with a decrease in concentrations of metals with an increase in distance away from the flare. The mean concentrations of all the measured parameters As, Cd, Cr, Pb, Mn, Hg, Ni, Cu, Zn and V (mg/m3), respectively, as can be seen from the figures, are greater than inhalation reference concentrations of (ATSDR (ATSDR, 2023) guidelines reported. As, Cd, Cr, Pb, Mn, Hg, Ni, Cu, Zn and V call for concern that gas flaring may contribute significantly to poor environmental and human health quality around the vicinity of the flares and overall environmental degradation in the study area. The reason for this may be due to operating conditions and chemical composition of petroleum-associated gas. Similarly, inefficient technology in the flare systems means that many of them burn without sufficient oxygen or with small amounts of oil mixed in with the gas, creating soot that is deposited on nearby land and buildings and inhaled by local residents. Table 1: Concentrations of the Heavy Metals (mg/m3) Heavy Metals 100 m (mg/m3) 200 m (mg /m3) 500 m (mg/m3) ATSDR, 2023 (mg/m3) As 1.60E-4 1.20E-4 5.00E-5 1.50E-05 Cd 1.20E-4 8.00E-5 5.00E-5 1.00E-05 Cr 4.50E-4 3.20E-4 1.70E-4 1.00E-04 Pb 1.50E-3 1.20E-3 5.00E-4 5.00E-04 Mn 8.60E-4 6.20E-4 3.20E-4 5.00E-05 Hg 4.00E-5 2.00E-5 1.00E-5 NR Ni 8.00E-4 5.00E-4 3.00E-4 1.40E-05 Cu 1.30E-3 1.00E-4 7.00E-5 2.00E-05 Zn 2.30E-3 1.70E-3 8.00E-4 9.00E-04 V 7.00E-4 5.00E-4 3.00E-4 1.00E-04 NR – Not Reported IJEMT 3.2 Heavy Metal Risk assessment 3.2.1 Non-Carcinogen Risks (non-CRs) The results on non-CRs related with ingestion, inhalation, and dermal contact with heavy metals around Mkpanek gas flaring plant are presented in Table 3.2, 3.3 and 3.4. The results showed hazard quotient (HQ) for ingestion, inhalation and dermal contact for studied heavy metals was below the safe level (HQ = 1), suggesting no significant non-CRs for adults and children in Mkpanek from ingestion, inhalation and dermal contact exposure. The cumulative non-CRs, which are expressed in terms of the hazard index (HI), were calculated for ingestion, inhalation and dermal contact exposure and presented in Table 3.2, 3.3 and 3.4. The results of HI for adults and children showed no significant health effects via ingestion, inhalation and dermal contact exposure (HI ˂ 1). The HI values of the examined heavy metals were <1.0 for adult and children through ingestion, inhalation and dermal contact suggesting no cumulative non-CRs from adult’s and children’s exposure to these metals. Hg Ni Cu Zn V Figure 3.1a Concentration of Heavy Metals (mg/m3) 100 m (mg/m3) 200 m (mg /m3) 500 m (mg/m3) ATSDR, 2023 (mg/m3) Hg Ni Cu Zn V Figure 1b: Concentration of Heavy Metals (mg/m3) 100 m (mg/m3) 200 m (mg /m3) 500 m (mg/m3) ATSDR, 2023 (mg/m3) IJEMT Table 3.2 Non-CRs Assessment of Heavy Metals via Ingestion Exposure Distan ce ADD @ 100 m ADD @ 200 m ADD @ 500 m HQing @ 100 m HQing @ 200 m HQing @ 500 m HMs Adult Childr en Adult Childr en Adult Childr en Adult Childr en Adult Childr en Adult Childre n As 1.127 E-7 1.052 E-6 8.454 E-8 7.890 E-7 3.522 E-8 3.287 E-7 3.756 E-4 3.506 E-3 2.818 E-4 2.630 E-3 1.174 E-4 1.095E -3 Cd 8.454 E-8 7.890 E-7 5.636 E-8 5.260 E-7 3.522 E-8 3.287 E-7 8.454 E-5 7.890 E-4 5.636 E-5 5.260 E-4 3.522 E-5 3.287E -4 Cr 3.170 E-7 2.958 E-6 2.254 E-7 2.104 E-6 1.197 E-7 1.117 E-6 1.056 E-4 9.860 E-4 7.513 E-5 7.013 E-4 3.990 E-5 3.723E -4 Pb 1.056 E-6 9.863 E-6 8.454 E-7 7.890 E-6 3.522 E-7 3.287 E-6 3.017 E-4 2.818 E-3 2.414 E-4 2.254 E-3 1.006 E-4 9.391E -4 Mn 6.058 E-7 5.654 E-6 4.367 E-7 4.076 E-6 2.254 E-7 2.104 E-6 4.327 E-6 4.038 E-5 3.119 E-6 2.911 E-5 1.610 E-6 1.502E -5 Ni 5.636 E-7 5.260 E-6 3.522 E-7 3.287 E-6 2.113 E-7 1.972 E-6 2.818 E-5 2.630 E-4 1.761 E-5 1.643 E-4 1.056 E-5 9.869E -5 Cu 9.158 E-7 8.547 E-6 7.045 E-8 6.575 E-7 4.931 E-8 4.602 E-7 2.289 E-5 2.136 E-4 1.761 E-6 1.643 E-5 1.232 E-6 1.150E -5 Zn 1.620 E-6 1.512 E-5 1.197 E-6 1.117 E-5 5.636 E-7 5.260 E-6 5.400 E-6 5.040 E-5 3.990 E-6 3.723 E-5 1.878 E-6 1.753E -5 V 4.931 E-7 4.602 E-6 3.522 E-7 3.287 E-6 2.113 E-7 1.972 E-6 9.783 E-5 9.130 E-4 6.988 E-5 6.521 E-4 4.192 E-5 3.912E -4 (HI) 1.026 E-3 9.579 E-3 7.511 E-4 7.010 E-3 3.503 E-4 3.268E -3 Table 3.3 Non-CRs Assessment of Heavy Metals via Inhalation Exposure Dista nce EC @ 100 m EC @ 200 m EC @ 500 m HQinh @ 100 m HQinh @ 200 m HQinh @ 500 m HMs Adult Child ren Adult Child ren Adult Child ren Adult Child ren Adult Child ren Adult Childr en As 7.890 E-5 7.890 E-5 5.917 E-5 5.917 E-5 2.465 E-5 2.465 E-5 5.261 E-3 5.260 E-3 3.944 E-3 3.944 E-3 1.643 E-3 1.643 E-3 Cd 5.917 E-5 5.917 E-5 3.945 E-5 3.945 E-5 2.465 E-5 2.465 E-5 5.917 E-3 5.917 E-3 3.945 E-3 3.945 E-3 2.465 E-3 2.465 E-3 Cr 2.219 E-4 2.219 E-4 1.578 E-4 1.578 E-4 8.383 E-5 8.383 E-5 2.219 E-3 2.219 E-3 1.578 E-3 1.578 E-3 8.383 E-4 8.383 E-4 Pb 7.397 E-4 7.397 E-4 5.917 E-4 5.917 E-4 2.465 E-4 2.465 E-4 2.101 E-4 2.101 E-4 1.680 E-4 1.680 E-4 7.002 E-5 7.002 E-5 Mn 4.241 E-4 4.241 E-4 3.057 E-4 3.057 E-4 1.578 E-4 1.578 E-4 1.060 E-3 1.060 E-3 7.642 E-4 7.642 E-4 3.945 E-4 3.945 E-4 Ni 3.945 E-4 3.945 E-4 2.465 E-4 2.465 E-4 1.479 E-4 1.479 E-4 2.817 E-2 2.817 E-2 1.760 E-2 1.760 E-2 1.056 E-2 1.056 E-2 Cu 6.410 E-4 6.410 E-4 4.931 E-5 4.931 E-5 3.452 E-5 3.452 E-5 1.602 E-5 1.602 E-5 1.232 E-6 1.232 E-6 8.630 E-7 8.630 E-7 Zn 1.134 E-3 1.134 E-3 8.383 E-4 8.383 E-4 3.945 E-4 3.945 E-4 3.780 E-6 3.780 E-6 2.794 E-6 2.794 E-6 1.315 E-6 1.315 E-6 IJEMT V 3.452 E-4 3.452 E-4 2.465 E-4 2.465 E-4 1.479 E-4 1.479 E-4 3.452 E-3 3.452 E-3 2.465 E-3 2.465 E-3 1.479 E-3 1.479 E-3 (HI) 4.630 E-2 4.630 E-2 3.046 E-2 3.046 E-2 1.745 E-2 1.745 E-2 Table 3.4 Non-CRs Assessment of Heavy Metals via dermal Exposure Dista nce DAD @ 100 m DAD @ 200 m DAD @ 500 m HQder @ 100 m HQder @ 200 m HQder @ 500 m HMs Adult Child ren Adult Child ren Adult Child ren Adult Child ren Adult Child ren Adult Childr en As 1.349 E-8 8.837 E-8 1.011 E-8 6.627 E-8 4.216 E-9 2.761 E-8 Cd 3.373 E-10 2.209 E-9 2.248 E-10 1.472 E-9 1.405 E-10 9.205 E-10 3.373 E-5 2.209 E-4 2.248 E-5 1.472 E-4 1.405 E-5 9.205 E-5 Cr 1.264 E-8 8.284 E-8 8.995 E-9 5.891 E-8 4.778 E-9 3.129 E-8 2.106 E-4 1.380 E-3 1.499 E-4 9.818 E-4 7.963 E-5 5.215 E-4 Pb 4.216 E-7 2.761 E-6 3.373 E-7 2,209 E-6 1.405 E-7 9.205 E-7 8.030 E-4 5.259 E-3 6.424 E-4 4.207 E-3 2.676 E-4 1.753 E-3 Mn 2.417 E-8 1.583 E-7 1.742 E-8 1.141 E-7 8.995 E-9 5.891 E-8 Ni 2.248 E-8 1.472 E-7 1.405 E-8 9.205 E-8 8.432 E-9 5.523 E-8 4.162 E-6 2.725 E-5 2.601 E-6 1.704 E-5 1.561 E-6 1.022 E-5 Cu 3.654 E-8 2.393 E-7 2.810 E-9 1.841 E-8 1.967 E-9 1.288 E-8 1.660 E-6 1.087 E-5 1.277 E-7 8.368 E-7 8.940 E-8 5.854 E-7 Zn 6.465 E-8 4.234 E-7 4.778 E-8 3.129 E-7 2.248 E-8 1.472 E-7 1.077 E-6 7.056 E-6 7.963 E-7 5.215 E-6 3.746 E-7 2.453 E-6 V 1.967 E-8 1.288 E-7 1.405 E-8 9.205 E-8 8.432 E-9 5.523 E-8 2.810 E-4 1.840 E-3 2.007 E-4 1.315 E-3 1.204 E-4 7.890 E-4 (HI) 1.380 E-3 9.040 E-3 1.052 E-3 6.895 E-3 4.978 E-4 3.261 E-4 3.2.2 Carcinogen Risks The CRs of Cd, Cr (VI), As, Ni, and Pb via ingestion, inhalation and dermal contact exposure were calculated and presented in Table 3.5, 3.6 and 3.7. The cumulative ILCRing, ILCRinh and ILCRder values of metal for adult and children at 100, 200 and 500 m sampling distance away from the gas flaring plant were above (ILCR≤1×10-6) (very high) respectively except ILCRing for children at 100m, ILCRinh for children at 100 and 200 m indicating that the probability of developing cancer because of human exposure to these carcinogens over the lifetime was significant suggesting carcinogenic risk from exposure to investigated metals collectively. IJEMT This brings us to the conclusion that exposure to gas flaring via ingestion, inhalation and dermal contact exposure has health-threat in terms of CRs in the study area.This can be attributed to the fact that there is an escape of oil in their flare. Table 3.5 CRs Assessment of Heavy Metals via Ingestion Exposure Distan ce ADD @ 100 m ADD @ 200 m ADD @ 500 m ILCRing @ 100 m ILCRing @ 200 m ILCRing @ 500 m HMs Adult Child ren Adult Child ren Adult Child ren Adult Child ren Adult Child ren Adult Childr en As 3.864 E-8 9.017 E-8 2.898 E-8 6.763 E-8 1.207 E-8 2.818 E-8 5.796 E-8 1.352 E-7 4.347 E-8 1.014 E-7 1.810 E-8 4.227 E-8 Cd 2.898 E-8 6.763 E-8 1.932 E-8 4.508 E-8 1.207 E-8 2.818 E-8 1.738 E-7 4.057 E-7 1.159 E-7 2.704 E-7 7.242 E-8 1.690 E-7 Cr 1.086 E-7 2.536 E-7 7.729 E-8 1.803 E-7 4.106 E-8 9.581 E-8 5.430 E-3 1.268 E-7 3.864 E-8 9.015 E-8 2.053 E-8 4.790 E-8 Pb 3.623 E-7 8.454 E-7 2.898 E-7 6.763 E-7 1.207 E-7 2.818 E-7 3.079 E-9 7.185 E-9 2.463 E-9 5.748 E-9 1.025 E-9 2.395 E-9 Ni 1.932 E-7 4.508 E-7 1.207 E-7 2.818 E-7 7.246 E-8 1.690 E-7 1.622 E-7 3.786 E-7 1.013 E-7 2.367 E-7 6.089 E-7 1.419 E-7 ∑ILR Cing 5.430 E-3 1.053 E-6 3.017 E-7 7.043 E-7 7.206 E-7 4.034 E-7 Table 3.6 CRs Assessment of Heavy Metals via Inhalation Exposure Distan ce EC @ 100 m EC @ 200 m EC @ 500 m ILCRinh @ 100 m ILCRinh @ 200 m ILCRinh @ 500 m HMs Adult Child ren Adult Child ren Adult Child ren Adult Childr en Adult Childr en Adult Childr en As 2.705 E-5 6.763 E-6 2.028 E-5 5.072 E-6 8.454 E-6 2.113 E-6 1.163 E-7 2.908E -8 8.720 E-8 2.180E -8 3.635 E-8 9.085E -9 Cd 2.028 E-5 5.072 E-6 1.352 E-5 3.381 E-6 8.454 E-6 2.113 E-6 3.650 E-8 9.129E -9 2.433 E-8 6.085E -9 1.521 E-8 3.803E -9 IJEMT Cr 7.608 E-5 1.902 E-5 5.410 E-5 1.352 E-5 2.874 E-5 7.185 E-6 6.390 E-6 1.597E -6 4.544 E-6 1.135E -6 2.414 E-6 6.035E -7 Pb 2.536 E-4 6.340 E-5 2.028 E-4 5.072 E-5 8.454 E-5 2.113 E-5 3.043 E-9 7.608E -10 2.433 E-9 6.086E -10 1.014 E-9 2.535E -10 Ni 1.352 E-4 3.381 E-5 8.454 E-5 2.113 E-5 5.072 E-5 1.268 E-5 3.244 E-8 8.114E -9 2.028 E-8 5.071E -9 1.217 E-8 3.043E -9 ∑ILR Cinh 6.578 E-6 1.644E -6 4.678 E-6 1.168E -6 2.478 E-6 6.196E -7 Table 3.7 CRs Assessment of Heavy Metals via Dermal Exposure Dista nce DAD @ 100 m DAD @ 200 m DAD @ 500 m ILCRder @ 100 m ILCRder @ 200 m ILCRder @ 500 m HMs Adult Childr en Adult Child ren Adult Child ren Adult Childr en Adult Childr en Adult Childr en As 4.626 E-9 7.574E -9 3.469 E-9 5.681 E-9 1.445 E-9 2.367 E-9 6.939 E-9 1.136E -8 5.203 E-9 8.521E -9 2.167 E-9 3.550E -9 Cd 3.469 E-9 1.893E -10 7.71E -11 1.26E -10 4.81E -11 7.89E -11 2.116 E-8 1.154E -9 4.70E -10 7.698E -10 2.93E -10 4.812E -10 Cr 4.336 E-9 7.101E -9 3.084 E-9 5.049 E-9 1.638 E-9 2.682 E-9 2.168 E-9 3.550E -9 1.542 E-9 2.524E -9 8.19E -10 1.341E -9 Pb 1.445 E-7 2.367E -7 1.156 E-7 1.893 E-7 4.818 E-8 7.890 E-8 1.228 E-9 2.011E -9 9.82E -10 1.609E -9 4.09E -10 6.706E -10 Ni 7.710 E-8 1.262E -8 4.818 E-8 7.890 E-9 2.891 E-8 4.734 E-9 6.476 E-8 1.060E -8 4.047 E-8 6.627E -9 2.428 E-8 3.976E -9 ∑ILR C 9.625 E-8 2.867E -8 4.866 E-8 2.005E -8 2.796 E-8 1.001E -8 4. Conclusion In the present study, the concentration level and health risk assessment associated with exposure to heavy metals around Mkpanek gas flaring plants were evaluated. The mean concentration of heavy metals was above inhalation reference concentrations guidelines for ambient air quality standards. Hazard quotient for ingestion, inhalation and dermal exposure for studied heavy metals was below the safe level (HQ = 1), suggesting no significant non-CRs for adults and children in Mkpanek from ingestion, inhalation and dermal contact exposure. HI for adults and children showed no significant health effects via ingestion, inhalation and dermal contact exposure (HI ˂ 1). The HI values of all the examined heavy metals were < 1.0 for adult and children through ingestion, inhalation and dermal contact suggesting no cumulative non-CRs from adult’s and children’s exposure to these metals.The cumulative ILCRing, ILCRinh and ILCRder values of metal for adult and children at 100, 200 and 500 m sampling distance away from the gas flaring plant were above (ILCR≤1×10-6) (very high) respectively except ILCRing IJEMT for children at 100m, ILCRinh for children at 100 and 200 m indicating that the probability of developing cancer because of human exposure to these carcinogens over the lifetime was significant suggesting carcinogenic risk from exposure to investigated metals collectively. The present study recommends continuous monitoring of the said heavy metals in the study area. Competing Interests Authors have declared that no competing interests exist. Authors’ Contributions This work was carried out in collaboration among all authors. 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