Assessment of occupational exposure to polycyclic aromatic hydrocarbons via involuntary ingestion of soil from contaminated soils in Lagos, Nigeria

Abstract

Soils from 12 sites in Lagos area, Nigeria impacted by anthropogenic activities were extracted by ultrasonication and analysed for the concentration of 16 priority polycyclic aromatic hydrocarbons (PAHs) by gas chromatograph-mass spectrometer (GC-MS). The concentration of the sum of PAHs ranged from 0.2 to 254 μg/g at these sites. The sum benzo[a]pyrene-equivalent dose (BaPeq) at the sites ranged from 0.0 (K, forest soil) to 16.7 μg/g (C, the lubricating oil depot soil). Mean daily intake (MDI) for the composite soils samples when compared that of food revealed that some of the individual PAH in samples from sites A (Dump site), C (Depot and loading point for used for black oil), F (Dump site), G(petroleum depot), H (Roadside) and L (Car park) exceeded the recommended the recommended MDI threshold for food, indicating some risk associated with activities on these sites based on this ingestion estimate exceeded value. 8.2 × 10(-6), 7.1 × 10(-7), 1.2 × 10(-4), 4.9 × 10(-7), 7.3 × 10(-7), 1.4 × 10(-5), 7.9 × 10(-5), 4.6 × 10(-6), 3.4 × 10(-7), 2.4 × 10(-7), 2.2 × 10(-7) and 1.1 × 10(-4) estimated theoretical cancer risk (ER) for an adult with a body weight of 70 kg working on sites were composite soil samples A, B, C, D, E, F, G, H, I, J, K and L respectively were sampled. The ER from occupational exposure to surface soil based on oral ingestion were all higher than the target risk of 1 × 10(-6) for normal exposure but were all within the 1 × 10(-4) for extreme exposure for most of the sites except for site C and L. The differences in concentration and risk were related to the different activities (e.g., handling of petroleum products, open burning, bush burning) undertaken at these locations. However, it should be noted here that the resultant risk could be overestimated, since these calculations were based on an exhaustive extraction technique which may be different from uptake by the human guts (bioavailability study).

Bioaccessibility-Based Risk Assessment of PAHs in Soils from Sites of Different Anthropogenic Activities in Lagos, Nigeria Using the Fed Organic Estimation Human Simulation Test Method

“…The total ER combining the childhood (5 years) and adult (40 years) exposure periods was 2.3 × 10 -05 based on sum PAHs (ODH 2011). ER values for an adult working at the on these sites were between 7.3 × 10 -07 and 1.2 × 10 -04 according to Adetunde et al (2014). However, these values were based on the concentration of total 16 priority PAHs in soil.…”

“…16.79 µg g -1 (petroleum product handling site) (Adetunde et al 2014). A sum BaPeq dose of 0.048 µg g -1 was found for rural soil from Delhi, India (Agarwal, 2009), 0.892 µg g -1 for roadside soil in Shanghai, China (Jiang et al 2009), 1.009 µg g -1 for traffic dust in Delhi India and 0.650 µg g -1 for surface soils in Agra, India (Masih and Taneja, 2006) and 0.124 µg g -1 for soil from Tarragona, Spain (Nadal et al 2004).…”

“…The concentration of PAHs in soil is a good indicator of the overall degree of environmental pollution (Adetunde et al 2014). Therefore, contaminant levels in soils are of concern to regulatory agencies in most countries.…”

“…the overall estimated theoretical cancer risk (ER), mean dietary intake (MDI), or benzo(a)pyrene equivalence dose (BaPeq). This approach, however, can lead to overestimation of any risk, since only a fraction of the total concentration of the chemical is absorbed into the systemic circulation (Adetunde et al 2014;Gomez-Eyles et al 2010;Turkall et al 2009). The most important factor in predicting or assessing the health risk of lipophilic organic chemicals, such as PAHs, is the bio-available and bio-accessible fractions (Tao et al 2009).…”

“…This information is important for regulators in order to make valid hazard and risk assessments. We undertook a study to assess occupational exposure to PAHs via involuntary ingestion of soil from different sites around the city of Lagos (Adetunde et al 2014).…”