Human Health Risk Assessment of Polycyclic Aromatic Hydrocarbons in Water Samples around Eket Metropolis, Akwa Ibom State, Nigeria

Abstract

Aims: Polycyclic aromatic hydrocarbons (PAHs) are very toxic and persistent environmental contaminants. The paper is aimed at investigating the cancer risk exposure of PAHs in borehole water collected around five automobile repair workshops within Eket metropolis.
 Place and Duration of Study: Samples were collected between June - August (2018) in wet season and November (2018) – January (2019) in dry season from boreholes around the vicinity of five automobile repair workshops within Eket metropolis. 
 Methodology: The water samples were prepared in the laboratory following standard procedures and analysed for 16 United States Environmental Protection Agency (US EPA) priority PAHs using Gas Chromatography–Mass Spectrometer (GC–MS). A total of fifteen PAH congeners were detected in the samples.
 Results: Total PAHs concentrations in borehole water from all sampling sites were in the range of 1.71–16.07 mg/L and 1.07–12.97 mg/L for both dry and wet seasons respectively. The low PAHs levels recorded in water for the wet season was linked to dilution effect. Low molecular weight PAHs were more dominant in all samples. The estimated cancer risks of exposure to PAHs by ingestion in the water samples ranged from 7.10 × 10-7 to 1.12 × 10-4 and 6.76 × 10-6 to 3.69 × 10-1 for adults and children respectively in both seasons. The estimated cancer risks due to dermal exposure to PAHs in the water samples ranged from to 7.18 × 10-3 to 1.07 × 10-1 and 5.67 × 10-3 to 1.08 × 10-1 for adults and children respectively in both seasons. 
 Conclusion: Carcinogenic risks due to dermal exposure calculated for both adults and children were higher than the US EPA acceptable cancer risk and much higher for children, which suggest that children could be prone to cancer and need to be monitored.

Health Risk Assessment of PAHs from Estuarine Sediments in the South of Italy

“…The incremental lifetime cancer risk (ILCR) due to exposure by direct ingestion and skin contact to PAHs present in the sediment was evaluated [ 49 ]. First, the doses of contaminants taken up by human receptors through the two different exposure pathways considered were calculated according to Equations (1) and (2) [ 50 ]: where:…”

Estimation of Polycyclic Aromatic Hydrocarbons in Groundwater from Campania Plain: Spatial Distribution, Source Attribution and Health Cancer Risk Evaluation

“…The population’s health is at risk from exposure to PAHs, which is categorized as a cancer risk. In this paper, the incremental lifetime cancer risk (ILCR) due to exposure by direct ingestion and skin contact to PAHs present in the groundwater samples was evaluated [ 39 ] The initial phase was to determine the doses of pollutants that were taken up by the human body via the two distinct means of exposure that were evaluated according to Equations (1) and (2) [ 40 ]: Dose ingestion = (C g × IRs × RAF oral × D hours × D days × D weeks × ED years )/BW × LE Dose dermal = (C g × SA h × SL h × RAF derm × EF × D days × D weeks × ED years )/BW × LE where: Dose ingestion (mg/kg-day) explains the dose from groundwater ingestion; Dose dermal (mg/kg-day) is the dose from skin contact with groundwater; C g (mg/kg) describes the amount of the pollutant in the groundwater; IR g (kg/day) is the rate of groundwater ingestion; RAF oral explains the relative absorption factor for the gastrointestinal tract; RAF derm (dimensionless) expresses the relative absorption factor for the skin; D hours refers to 0–16/16 h for accidental ingestion; D days refers to days in a week with exposure [(0–7)/7 days]; D weeks refers to weeks in a year with exposure [(0–52)/52 weeks]; ED years refers to total years with exposure; SA h refers to the surface of hands (assuming only hands are exposed); SL h refers to the load rate on exposed skin; EF (event/day) refers to the number of skin exposures per day; BW (kg) refers receptor body weight; LE refers life expectancy/average life expectancy expressed in years; and CF (conversion coefficient) = 1 × 10 −6 kg/mg ( Table S1 ). Moreover, to determine the doses of pollutants taken up by human receptors, the incremental lifetime cancer risk by oral ingestion (ILCR ingestion ) and dermal contact (ILCR dermal ) was estimated according to Equations (3) and (4) [ 39 , 41 ]: ILCR ingestion = (C s × SF ingestion × (BW/70) × IR ingestion × EF × D years )/(BW × AT × 10 6 ) ILCR dermal = (C s × SF dermal × (BW/70) × AS × AF × ABS × EF × D years )/(BW × AT × 10 6 ) where SF ingestion (Kg-day/mg) shows the oral slope factor; SF dermal (Kg-day/mg) is the dermal slope factor; SA (cm 2 /kg) explains the area of dermal contact with the groundwater; AF (mg/cm 2 ) is the skin absorption coefficient; ABS is the skin absorption coefficient for pollutants; and AT (years) is the average lifespan ( Table S1 ).…”

“…The population's health is at risk from exposure to PAHs, which is categorized as a cancer risk. In this paper, the incremental lifetime cancer risk (ILCR) due to exposure by direct ingestion and skin contact to PAHs present in the groundwater samples was evaluated [39] The initial phase was to determine the doses of pollutants that were taken up by the human body via the two distinct means of exposure that were evaluated according to Equations ( 1) and (2) [40]:…”

The Trend in Fertilizer Consumption and Its Impact on Crop Outputs in Nigeria

“…A prominent constraint to higher productivity among farmers in the region is tailored to "soil infertility" related mainly to the low nutrient status of the soils and continuous cultivation without planned replenishment of depleted soil nutrients (Wanyama et al, 2009). Increasing agricultural productivity in Sub Saharan Africa especially in Nigeria is an urgent necessity; and one of the fundamental ways of improving agricultural productivity is through the introduction and optimal use of improved agricultural technologies (Olukunle, 2013;Kolawole and Omobitan, 2014;Olomola and Nwafor 2018;Akpan et al, 2019).…”