The levels of Cd, Pb, Cr, Ni, Cu, Co, Ba, Mn, Zn, Al and Fe were evaluated in indoor dusts from electronic workshops, cybercafés and offices in southern Nigeria. The study was aimed at providing ...information on the distribution patterns, and the associated risks that may arise from exposure of humans to these metals in indoor dusts from the three work environments. The dust samples were digested with aqua-regia and analyzed for the metal concentrations by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The metal concentrations (mg kg−1) in the indoor dusts from these work environments ranged from 0.2 to 20.5 Cd, 0.6–4810 Pb, 8.65–2210 Cr, 1.85–209 Ni, 6.75–2820 Cu, 0.25–19.6 Co, 22.7–597 Mn, 6.65–140 Ba, 43.3–7310 Zn, 1040–16,800 Al and 969–78,300 Fe. The metal distribution patterns in these dust samples followed the order: electronic workshops > cybercafés > offices. The concentrations of Cd, Pb and Cu in significant proportions of the dust samples from the electronic workshops and cybercafés surpassed their respective permissible limits in soils. The health risk assessment suggests considerable non-cancer risks arising from childhood contact with Pb in dust from the electronic workshops while no considerable non-cancer risk is associated with the adult and child exposure to dust from the cybercafés and offices. The results indicated that Cr and Pb are the main elements responsible for the non-carcinogenic risk arising from childhood exposure to electronic workshop dusts. The carcinogenic risk due to exposure of humans to metals in these dust samples were within the range regarded as safe by the USEPA.
•Considerable non-cancer risks for childhood contact with Pb in electronic workshop dusts.•Cr and Pb are the main elements responsible for the non-carcinogenic risk.•No considerable cancer risk from exposure of humans to dust-borne metals.
In this study, the concentrations of 28 polychlorinated biphenyl (PCB) congeners, including 12 dioxin-like PCBs and 7 indicator PCBs, were determined in sediments around oil production facilities in ...the Escravos River Basin of the Niger Delta in Nigeria. The aim was to describe the spatial patterns, sources, and ecosystem risks associated with exposure to PCBs in sediments of this river basin. Gas chromatography-mass spectrometry (GC–MS) was used to determine the concentrations of PCBs in the sediments. The Ʃ28 PCB concentrations in sediments from the Escravos River Basin ranged between 226 and 31,900 ng g−1 with a median concentration of 2300 ng g−1. The results indicated that sediments around crude oil production facilities, such as, wellheads, flow stations, and truck lines, had significantly higher levels of Ʃ28 PCBs (p < 0.05) than those collected near residential communities within the river basin. The median concentrations of PCB homologues in sediments from this river basin followed the sequence: hexaPCBs > penta-PCBs > tetra-PCBs > hepta-PCBs > tri-PCBs > di-PCBs > deca-PCBs > octa-PCBs > nona-PCBs. The risk assessment of PCBs in sediments from this river basin suggest very high potential risks for both organisms and humans.
•PCBs were measured in sediments from the Escravos River Basin.•Low chlorinated PCBs were dominant in the sediments.•Potential ecological risk exists for exposure of organisms to PCBs in sediments.•PCBs in the sediments are associated with inadvertent sources.
Chlorinated organic compounds, such as polychlorinated biphenyls (PCBs), are a threat to both humans and the environment because of their toxicity, persistence, and capacity for long-range ...atmospheric transport. The concentrations of 28 PCB congeners, including 12 dioxin-like and seven indicator PCBs, were investigated in soils, and indoor and outdoor dusts from Port Harcourt city, Nigeria, in order to evaluate the characteristic distribution patterns in these media, their sources, and possible risk. The PCB concentrations varied from 4.59 to 116 ng g−1 for soils, and from 1.80 to 23.0 ng g−1 and 2.73 to 57.4 ng g−1 for indoor and outdoor dusts respectively. The sequence of PCB concentrations in these matrices was soil > outdoor dust > indoor dust. The composition of PCBs in these matrices indicated the prevalence of lower chlorinated PCBs in indoor and outdoor dusts, while the higher chlorinated congeners were dominant in soils. Di-PCBs were the predominant homologues in indoor dusts, while deca-PCBs were the most prevalent homologues in outdoor dusts and soils. The TEQ values of dioxin-like PCBs in 60 % of the soils, 100 % of the indoor dust, and 30 % of the outdoor dust were above the indicative value of 4 pg TEQ g−1 established by the Canadian authority. The hazard index (HI) values for exposure of adults and children to PCBs in these media were mostly greater than one, while the total cancer risk (TCR) values exceeded the acceptable risk value of 10−6, which indicate probable non-carcinogenic and carcinogenic risks resulting from exposure to PCBs in these media. Source analysis for PCBs in these matrices shows that they originated from diverse sources.
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•PCB-contaminated dusts and soils from Port Harcourt city were investigated.•PCB concentrations in soils were higher than those of outdoor and indoor dusts.•Tri-, penta-, and deca-PCBs were the dominant homologues in these matrices.•Exposure to PCBs in these matrices poses a risk to the ecosystem and humans.•PCBs in these matrices originated from diverse sources.
In this study, we evaluated the concentrations, composition, sources, and potential risks of polycyclic aromatic hydrocarbons (PAHs) in soils, and indoor and outdoor dust from Port Harcourt city in ...Nigeria. Gas chromatography-mass spectrometry (GC-MS) was used for the detection and quantification of PAH species in the samples. The concentrations of the US EPA 16 PAHs plus 2-methyl-naphthalene (∑17 PAHs) in soils, and indoor and outdoor dust from Port Harcourt city ranged from 240 to 38 400, 276 to 9130 and 44 to 13 200 μg kg
−1
(dry weight, d.w.) respectively. The PAH concentrations in these matrices followed the sequence: soil > indoor dust > outdoor dust. The composition of PAHs in soils and dust (indoor and outdoor) showed remarkable differences with prominence of 3- and 5-ring PAHs. The estimated carcinogenic risk to the residents arising from exposure to these concentrations of PAHs in soils, and indoor and outdoor dust from Port Harcourt was above the acceptable target cancer risk value of 10
−6
. We concluded that these sites require clean-up, remedial actions and implementation of stringent pollution control measures with the intention of reducing the undesirable impacts of PAHs on both the ecosystem and humans.
This study evaluated the concentrations, composition, sources, and potential risks of polycyclic aromatic hydrocarbons (PAHs) in soils, and indoor and outdoor dust from Port Harcourt city in Nigeria.
•PAHs were measured in vegetable oils fried three times and fish fried therein.•PAH concentrations/compositions changed markedly with oil types and frying cycles.•High molecular weight PAHs were ...dominant in both the oils and fried fish.•Concentrations of PAHs in the fresh and fried vegetable oils exceeded EU limits.•Cancer risk values for oils after three frying cycles exceeded the acceptable risk.
The use of the same batch of oil for deep-frying on several occasions is a common practice. This study sought to determine the effects of repeated frying cycles on the composition, concentrations and risk of polycyclic aromatic hydrocarbons (PAHs) in six types of vegetable oils and the samples of fish fried therein. The PAH concentrations in the oils were measured before use and after each of three successive cycles of frying. Fish was fried at each time of use of the oils and, also, monitored for their PAH content. The PAH content in all samples was determined by gas chromatography-mass spectrometry (GC–MS). The concentrations of Ʃ22 PAHs in the unused oils ranged from 43.3–2107 μg kg−1, while those in the used oil ranged from 40.8–4090 μg kg−1. There were significant changes (p < 0.05) in the concentrations and composition of PAHs with respect to vegetable oil types and number of frying cycles. The cancer risk values for the vegetable oils (10−4 to 10−5) after three frying cycles exceeded the acceptable risk value of 10-6 indicating a probable lifetime carcinogenic risk. However, adverse non-carcinogenic risks through consumption of these oils and fried fish were low.
This study investigates the concentrations, sources, and ecological and human health risks resulting from exposure to polycyclic aromatic hydrocarbons (PAHs) in soils of rural communities around gas ...flaring points in Delta State, Nigeria. PAHs were extracted from these soil samples with hexane/dichloromethane by ultra-sonication and the extracts were cleaned on a silica gel/alumina-packed column. The PAH concentrations in the extracts were quantified by gas chromatography-mass spectrometry (GC-MS). The 16 PAH concentrations in soils from these communities varied from 2370134000, 461389000, and 213034900 g kg
1
for Emu-Ebendo (EME), Otu-Jeremi (OTJ) and Ebedei (EBD), respectively. The estimated lifetime carcinogenic risk values recorded in this study were above the acceptable limit of 10
6
, indicating a high potential carcinogenic risk resulting from human exposure to PAHs in these soils. The isomeric ratio and principal component analysis results suggest that emissions from high-temperature combustion, potentially gas flaring, vehicular emissions, burning of wood/biomass, and fossil fuel combustion are responsible for the high concentrations of PAHs in soils of these rural communities. This study recommends implementing remediation and source control measures to minimise the impact of PAHs in the affected soils on humans and the environment.
This study investigates the concentrations, sources, and ecological and human health risks from exposure to polycyclic aromatic hydrocarbons (PAHs) in soils of rural communities around gas flaring points in Delta State, Nigeria.
Indoor and outdoor dust from three rural communities (Emu-Ebendo, EME, Otu-Jeremi, OTJ, and Ebedei, EBD) around gas flaring points, and a rural community (Ugono Abraka, UGA) without gas flare points, ...in the Niger Delta of Nigeria, was analysed for the concentrations and distribution of polycyclic aromatic hydrocarbons (PAHs), their sources, and possible health risk resulting from human exposure to PAHs in dust from these rural communities. The PAHs were extracted from the dust with a mixture of dichloromethane/
n
-hexane by ultrasonication, and purified on a silica gel/alumina packed column. Gas chromatography-mass spectrometry was employed to determine the identity and concentrations of PAHs in the cleaned extracts. The Σ16PAH concentrations in the indoor dust ranged from 558 to 167 000, 6580 to 413 000, and 2350-37 500 μg kg
−1
for EME, OTJ and EBD respectively, while those of their outdoor counterparts varied from 347 to 19 700, 15 000 to 130 000, and 1780 to 46 300 μg kg
−1
for EME, OTJ and EBD respectively. On the other hand, the UGA community without gas flare points had Σ16PAH concentrations in the range of 444-5260 μg kg
−1
for indoor dust, and 154-7000 μg kg
−1
for outdoor dust. The lifetime cancer risk values for PAHs in these matrices surpassed the acceptable limit of 10
−6
suggesting a potential carcinogenic risk resulting from human exposure to PAHs in indoor and outdoor dust from these rural communities. Principal component analysis suggested that PAH contamination of dust from these communities arises principally from gas flaring, combustion of wood/biomass, and vehicular emissions.
Indoor and outdoor dust from three rural areas around gas flaring points, and a rural area without such points in the Niger Delta of Nigeria, was analysed for the concentrations and distribution of PAHs, their sources, and possible health risk.
This study provides data on the characteristic levels, spatial patterns, sources, and risk of
n-
alkanes (AHs) octane,
n-
C
8
, to tetracontane,
n-
C
40
and polycyclic aromatic hydrocarbons (PAHs) ...in surficial sediments from the Escravos River Basin (ERB), Nigeria. The
n-
alkane and PAH concentrations in sediments were quantified by chromatographic methods. The concentrations of AHs and PAHs in the ERB sediments varied from 95 to 3430 µg g
−1
and from 0.75 to 213 µg g
−1
, respectively. Both the concentrations of AHs and PAHs in ERB sediments exceeded their respective guideline values. The carbon preference index and other AH markers provide evidence that the AHs in the ERB sediments originated from petroleum sources. Ecological risk assessment indicated that the ecological risk relating to an organism’s contact with PAHs in the ERB sediments was high. The possible carcinogenic risk arising from human exposure with PAHs in surface sediments through accidental oral ingestion and skin contact exceeded the safe level of 10
–6
, indicating a considerable probable cancer risk for fishermen and other inhabitants of the ERB. PAH isomer ratios and multivariate statistics suggested that the PAHs in sediments from the ERB originated from gas flaring inputs, discharges from oil drilling platforms, diesel engines, ships, and speed boats, and combustion of wood and other biomass.
The concentrations of the sixteen United States Environmental Protection Agency polycyclic aromatic hydrocarbons (PAHs) were determined in dusts from different land-use types in Benin City by means ...of gas chromatography–mass spectrometry. The results obtained were used to assess the ecological and human health risk and to determine the source apportionment. The Ʃ16 PAH concentrations in dusts from Benin City ranged from 230 to 2300 µg kg
−1
for industrial areas, 211–1330 µg kg
−1
for commercial areas, 153–1170 µg kg
−1
for residential areas, and from 216 to 1970 µg kg
−1
for school playgrounds/parks. The ecological risk assessment suggested that the levels of PAHs in dusts from these land-use types are of low-to-moderate risk to organisms. The benzo(a)pyrene carcinogenic potency BaP
TEQ
(70.5–131 µg kg
−1
) and benzo(a)pyrene mutagenic potency BaP
MEQ
(62.9–122 µg kg
−1
) concentrations were below the Canadian soil quality guideline value of 600 µg kg
−1
. The incremental lifetime carcinogenic risk (ILCR) arising from exposure of adults and children to PAHs in dusts from Benin City were in the magnitude of 10
–4
–10
–2
, which exceeded the safe target levels of 10
–6
, implying a considerable cancer risk for residents of this city. The PAH source apportionment derived from isomeric ratios and multivariate statistics indicated that burning of biomass, wood, and charcoal, and vehicular traffic were the predominant sources of PAHs in dusts from Benin City.
The present study presents the results for the determination of the concentrations of the 16 USEPA polycyclic aromatic hydrocarbons (PAHs) in 30 samples of different types of vegetable oil (palm, ...groundnut, palm olein, soybean, cotton and castor seed oils) and shea butter in Nigeria. In addition, information is provided on the compositional patterns and sources of PAHs, as well as possible risks through consumption of contaminated products. Detection and quantification of the PAHs was carried out by means of gas chromatography-mass spectrometry (GC-MS). The PAH concentrations in the samples varied from 126 to 865 µg kg
−1
. The compositional patterns of the PAHs in the oil samples followed the order: 4R > 3R > 5R > 6R > 2R. The majority of the samples had individual PAH concentrations above the 2 µg kg
−1
limit and all the samples surpassed the German Society for Fat Science limit of 25 µg kg
−1
for the total PAHs. The estimated dietary intakes based on a 11.1 kg per capita consumption rate ranged from not detected to 133 ng BaP kg
−1
bw day
−1
, 3.0 to 154 ng PAH2 kg
−1
bw day
−1
, 11.7 to 178 ng PAH4 kg
−1
bw day
−1
and 13.2 to 234 ng PAH8 kg
−1
bw day
−1
. The results indicate 5 to 669 chances in a million population of the risk of developing cancer. Source apportionment, as derived from PAH isomeric ratios, suggests that combustion processes, contamination by petroleum from transport trucks, as well as pyrolysis of fats, are the main sources of PAHs in these vegetable oils and shea butter.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
