Chimezie Anyakora

Urinary 1-Hydroxypyrene as a Biomarker to carcinogenic polycyclic Aromatic Hydrocarbon exposure

In order to capture the extent of exposure to polycyclic aromatic hydrocarbons (PAHs), various biomarkers have been employed. The biomarkers employed for PAHs include PAHs genetoxic end points in lymphocytes, urinary metabolites, PAH-DNA adducts, and PAH-Protein adducts. Of these, excretory 1-hydroxypyene, a metabolite of pyrene, has been used extensively as a biological monitoring indicator of exposure to PAHs. This study attempts to assess the level of this biomarker in the body fluid of 68 exposed subjects using high performance liquid chromatography HPLC. The subjects screened included auto mechanics, drivers, and fuel attendants. 1-hydroxypyrene was extracted from the urine of the subjects using solid phase extraction method. The HPLC analysis was done in isocratic mode using water:methanol (12:88 v/v) mobile phase. The stationary phase was XBridge C18 (150 × 4.6 mm) 5 μm column. The wavelength was 250 nm at a flow rate of 1.2 mL/min. The oven temperature was 30 °C and the injection volume was 20 μL. The run time was 3 minutes. The level of urinary 1-hydroxypyrene detected varied for the different categories of occupation studied. About 27% of sampled fuel attendants and 22% of auto mechanics had detectable 1-hydroxypyrene in their urine samples. There was no detectable 1-hydroxypyene in the urine samples of commercial drivers or in the urine samples of students used as controls. The results of this study showed that fuel attendants and auto mechanics have significant exposures to PAHs. So far, there is no established benchmark for level of PAHs in urine, but our findings indicate the possibility of future cancer cases in this population as a result of their occupational exposure. The study was not able to link the level of 1-hydroxypyene with the smoking habits of the subjects.

Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons (PAH) comprise the largest class of cancer-causing chemicals and are ranked ninth among chemical compounds threatening to humans. Although interest in PAH has been mainly due to their carcinogenic property, many of these compounds are genotoxic, mutagenic, teratogenic, and carcinogenic. They tend to bioaccumulate in the soft tissues of living organisms. Interestingly, many are not directly carcinogenic, but act like synergists. PAH carcinogenicity is related to their ability to bind DNA thereby causing a series of disruptive effects that can result in tumor initiation. Thus, any structural attribute or modification of a PAH molecule that enhances DNA cross linking can cause carcinogenicity. In part I, we review exposure to these dangerous chemicals across a spectrum of use in the community and industry.

Polycyclic Aromatic Hydrocarbons: Part I. Exposure.

Polycyclic aromatic hydrocarbons (PAH) comprise the largest class of cancer-causing chemicals and are ranked ninth among chemical compounds threatening to humans. Although interest in PAH has been mainly due to their carcinogenic property, many of these compounds are genotoxic, mutagenic, teratogenic, and carcinogenic. They tend to bioaccumulate in the soft tissues of living organisms. Interestingly, many are not directly carcinogenic, but act like synergists. PAH carcinogenicity is related to their ability to bind DNA thereby causing a series of disruptive effects that can result in tumor initiation. Thus, any structural attribute or modification of a PAH molecule that enhances DNA cross linking can cause carcinogenicity. In part I, we review exposure to these dangerous chemicals across a spectrum of use in the community and industry.

Assessment of the PAHs contamination threat on groundwater: a case study of the Niger Delta region of Nigeria

Contamination of the environment by polynuclear aromatic hydrocarbon (PAHs) is becoming a rising environmental concern. The interest this subject attracts has continually increased by the day because of the threat these compounds pose to human health. Water samples from several hand-dug wells in the Niger Delta region of Nigeria where extensive crude oil production activities take place were analysed for the presence of 16 US EPA priority PAHs and their consequent health implication on the population extrapolated. The analyses were done using a gas chromatograph coupled to an ion trap mass spectrometer. Individual PAHs were identified through both retention time match with authentic standards and simultaneous maximisation of several ions from GC/MS data. The quantitation was done by means of internal standardisation using four isotopically labelled internal standards namely acenaphthene-d10, chrysene-d12, phenanthrene-d10 and perylene-d12. The sums of the 16 PAHs in the samples vary depending on the proximity of the sample source to crude oil production facility. The concentrations ranged from 1.92 μg/L to 40.47 μg/L. High molecular mass PAHs such as benzo(ghi)perylene, dibenz(a,h)anthracene and indeno(1,2,3-cd)pyrene were mostly absent confirming low water solubility of these compounds. These concentrations were above the WHO recommended maximum for safe drinking water.

1-hydroxypyrene levels in blood samples of rats after exposure to generator fumes.

Polynuclear Aromatic Hydrocarbons (PAHs) are a major component of fuel generator fumes. Carcinogenicity of these compounds has long been established. In this study, 37 Swiss albino rats were exposed to generator fumes at varied distances for 8 hours per day for a period of 42 days and the level of 1-hydroxypyrene in their blood was evaluated. This study also tried to correlate the level of blood 1-hyroxypyrene with the distance from the source of pollution. Plasma was collected by centrifuging the whole blood sample followed by complete hydrolysis of the conjugated 1-hydroxypyrene glucuronide to yield the analyte of interest, 1-hydroxypyrene, which was achieved using beta glucuronidase. High performance liquid chromatography (HPLC) with UV detector was used to determine the 1-hydroxypyrene concentrations in the blood samples. The mobile phase was water:methanol (12:88 v/v) isocratic run at the flow rate of 1.2 mL/min with CI8 stationary phase at 250 run. After 42 days of exposure, blood concentration level of 1-hydroxypyrene ranged from 34 μg/mL to 26.29 μg/mL depending on the distance from source of exposure. The control group had no 1-hydroxypyrene in their blood. After the period of exposure, percentage of death correlated with the distance from the source of exposure. Percentage of death ranged from 56% to zero depending on the proximity to source of pollution.

Polycyclic Aromatic Hydrocarbons: Part II, Urine Markers.

There has been increasing demand for simple, rapid, highly sensitive, inexpensive yet reliable method for detecting predisposition to cancer. Human biomonitoring of exposure to the largest class of chemical carcinogen, polycyclic aromatic hydrocarbons (PAHs) that are rapidly transformed into detectable metabolites (eg, 1-hydroxypyrene), can serve as strong pointers to early detection of predisposition to cancer. Given that any exposure to PAH is assumed to pose a certain risk of cancer, several biomarkers have been employed in biomonitoring these ninth most threatening ranked compounds. They include metabolites in urine, urinary thioethers, urinary mutagenicity, genetoxic end points in lymphocytes, hemoglobin adducts of benzo(a)pyrene, PAH-protein adducts, and PAH-DNA adducts among others. In this chapter, the main focus will be on the urine metabolites since urine samples are easily collected and there is a robust analytical instrument for the determination of their metabolites.

Electrospun nanofiber sorbents for the pre-concentration of urinary 1-hydroxypyrene

BackgroundSynthetic polymers have some qualities that make them good candidates for pre concentration of trace analytes biological fluids because of their great potentials to be functionalized and electrospun into nanofibres.MethodsIn this study, Electrospun nanofiber sorbents fabricated from 11 polymers {poly(styrene-co-methacrylic acid), poly(styrene-co-divinylbenzene) (SDVB), poly(styrene-co-acrylamide), poly(styrene-co-p-sodium styrene sulfonate), polystyrene, poly(vinyl benzyl chloride), cellulose acetate, polyethylene terephthalate (PET), polysulfone, nylon 6} were evaluated for the extraction and pre-concentration of 1-hydroxypyrene from a water sample.ResultsScanning electron microscopy (SEM) studies revealed the formation of continuous fine bead-free and randomly arrayed fibers with their average diameters ranging from 110 to 650 nm. The percentage recoveries were highest for nylon 6 with 72%, SDVB with 70%, whereas PET achieved the lowest recovery at 34%. Under optimized conditions, the analyte followed a linear relationship for all sorbents in the concentration range of 1 to 1,000 μg/L. The coefficient of determination (r2) was between 0.9990 to 0.9999, with precision (%relative standard deviation (RSD)) ≤ 9.51% (n = 6) for all the analysis. The %RSD for intra- and inter-day precision at three different concentrations, 10, 25, and 50 μg/L, was ≤7.88% for intraday and ≤8.04% inter-day (3 days), respectively, for all evaluated sorbents. The LOD and LOQ were found to be between 0.054 and 0.16 μg/L and 0.18 and 0.53 μg/L, respectively, using a fluorescent detector.ConclusionsThe study suggested that if packed into cartridges, nylon 6 and SDVB nanofiber sorbents could serve as alternatives to the conventional C-18 sorbents in the pre-concentration and clean-up of the tumorigenic biomarker, 1-hydroxypyrene in human urine. The fabrication of selective nanofibers could also extend and simplify sample preparation for organic and biological analytes.