Study and Determination of Aryl Hydrocarbon Receptor with Some Trace Elements in Fuel Filling Station Workers

E233 Study and Determination of Aryl Hydrocarbon Receptor with Some Trace Elements in Fuel Filling Station Workers لبقتسم ريدقتو ةسارد ليرلأا  رصانعلا ضعبو نوبراكورديه ةرزنلا  دوقولا تاطحم ةئبعت لامع يف  Bassem Abd Al-Raheem Twaij, Dr. Muthana Salam Mashkour, Dr.Hussein Kadhem Al-Hakeim Refinery of Najaf, Iraq. Department of Chemistry, Faculty of science, University of Kufa, Iraq. Corresponding Author E-mail: bassemtwij2@gmail.com

a significant increase (p<0.001) as compared with the control group. While Fe 3+ , Na + and Mg 2+ in FSW group revealed a significant decrease (p<0.001) as compared with the control group. Correlation study indicated a significant negative correlation between serum Pb and AHR while other trace elements showed no significant correlation with AHR in FSW group.
There is a significant negative correlation between serum Cu 2+ with age while there is significant increase correlation between Zn 2+ , Mg 2+ and Pb with age in FWS group.
Conclusion of study is The role of increase AHR on the health in FSW group, attention to use safety gloves and face mask is recommended for FSW and a long follow-up to the studied group is necessary to explore the prognosis of increase AHR in FSW.

Introduction
Air pollution is a complex mixture of gases, fumes and odors in amounts which could be harmful to human health or other ecosystems [1]. It is a well-documented fact that polluted air causes ill effect on the health, with urbanization and the rapidly increasing number of automobiles in most of the cities, there is an increase in air pollution. Exposed to organic and inorganic substances present in the oil [2]. Fuel station attendants to innumerous risks and health. The environment of fuel stations exposes gas hazards, which should be considered harmful to the health status of these workers [3]. There are chemical products to which these workers are exposed, such as aromatic hydrocarbons, benzene, toluene and xylene (BTX) components of gasoline and chemical solvents [4]. The chemical agent benzene, which posses a high risk to human health, even in small amounts, is a colorless, volatile, soluble, flammable liquid with high carcinogenic potential [5].
Gasoline may or may not be employed to initiate or propagate the spread of a fire. The American Society for Testing and Materials (ASTM) has a classification scheme for ignitable liquids including compositional carbon ranges and common peaks observed for each [6].
Gasoline components include various aliphatic (straight-chain) hydrocarbons, paraffins, No.29-(12) 2020 Journal of Petroleum Research & Studies (JPRS) E236 olefins, benzenes and aromatic hydrocarbons including toluene,xylene and a large number of volatile compounds with boiling points <80°C [7]. Over 300 different hydrocarbon molecules used in gasoline were observed to have boiling points ranging from 40°C to 190°C, showing that many components are highly volatile. Further classifications of the individual include the length of the carbon chain backbone, the extent of branching, and the isotopes of carbon atoms [8].
AHR is involved in normal cell physiology as well as xenobiotic metabolism, that AHR could be activated in the absence of xenobiotics [9]. AHR exists in cell cytoplasma in a complex with a heat shock protein 90 (HSP90). Dimer and a chaperone denoted X-assoeciatd protein 2(XAP2). When binding to an agonist (such as Polycyclic aromatic hydrocarbons PAHs), the AHR complex enters the cell nucleus where ARNT mediates HSP90 displacement, the formation of the AHR-ARNT heterodimer, which can bind to dioxin-responsive elements for AHR target-genes. Co-activators can be recruited by both AHR and ARNT, leading to transcription of a wide variety of genes [10].
Cytochrome P450 (CYP1A) is a primary target gene for AHR, and is almost totally dependent on AHR activity for expression. As shown in Figure this can result in formation of DNA and subsequent mutagenesis as CYP1A metabolizes various pro-carcinogens, like Benzo(a)pyrene (BaP) [11]. The classical mechanism for AHR activation in (Figure 1) results in the transcription of a number of target genes, including CYP1A [12]. By inducing the transcription of different biotransformation enzymes, AHR is a very important xenobiotic sensor. In addition, ligand Activated AHR also has the ability to interact and affect the functioning of other transcription factors, intracellular signaling pathways, cell proliferation, and the cell cycles [13]. Through the genome sequencing of many different species, it has become evident that AHR possesses an important physiological role beyond being a xenobiotic sensor [14]. The term trace element refers to a group of metals and metalloids that occur naturally in the ecosystem at low concentrations [15] and includes copper (Cu), iron (Fe) and zinc (Zn). Industrialization and urbanization increase the anthropogenic contribution of trace elements to the environment [16] , and as elements do not biodegrade [17] they consequently circulate in biogeochemical cycles within the environment [18].
Heavy elements such as lead, it is normal compound that is found in several forms including elemental, mineral, and. organic [19]. Pb was used in various modern industries such as automotive industry, military, production of anti-corrosives, Pb salts as color stabilizer, battery production, and leaded gasoline. Workers in these industries are in direct exposure to lead [20].
The aims of the present study are study the level of AHR in serum of filling station workers (FSW) , to study the level of metal ions (Cu 2+ , Fe 3+ , K + , Mg 2+ , Na + , Pb, and Zn 2+ ) in

Materials and Methods
A-Patients: A blood samples were collected from 60 FSW males who work in fuel filling stations .and exposed to different fuel derivatives for not less than 9 years (12.65±2.62 years).
Their age range was (38.32± 6.12) years. Informed consent were obtained from all the participants. Questionnaires were precisely filled; candidates who met the criteria for participation in this study were enrolled in the study.The samples were collected from ten fuel stations located in Najaf city-Iraq.

B-Controls:
Thirty healthy adults were selected as a control group. Their age range was apparently comparable to that of FSW (41.53±5.24 years).

C-Exclusion Criteria:
The study excluded any participant with chronic hypertension, diabetes.
Mellitus, autoimmune disease and renal disorder.

Measurements
Five milliliters of venous blood samples were. drawn from each patient and control and were left at room temperature until complete clotting and then centrifuge at 3000 rpm for 5 minutes. Then. Serum was separated and transported into three new disposable plain tubes and stored at -20 ºC till analysis. Serum level of AHR was measured by using. ready for use ELISA kit supplied by Elabscience Co., USA. All other parameters metal ions Zn 2+ , Cu 2+ , Fe 3+ , Mg 2+ , Na + and K + level were measured spectrophotometrically by using ready for use kits, serum Pb level was carried out using Atomic.absorption spectroscopy.

Statistical Analysis
The distribution types of the variables results were examined using Kolmogorov-Smirnov test. The normally distributed parameters were expressed as mean ± standard. deviation. For the comparison. between the patients and control groups, pooled t-test has been used. Pearson's correlation coefficients (r) were calculated to estimate the correlation between parameters. The difference between grOups is considered .as statistically different when

Comparison between FSW and control
The comparison between FSW and control group are cited in Table (1). Recent studies about the relationship. between exposure to petrol products and the trace metal status, liver toxicity in gasoline filling workers reported that liver enzymes and serum levels of Cu, and Zn are increased concluding that long term exposure to petroleum products may increases risk of .liver .toxicity [22].
Chronic low. level exposure to toxic metals is an increasing global problem. The symptoms.
associated with the slow. accumulation of toxic. metal are multiple and rather nondescript, and overt expression of toxic. effects may not appear until later in life [23].

Comparison According to the Exposure Time of FSW
The comparison according to the exposure time of FSW group is cited in Table (2). increases the risk of liver and hematopoietic toxicity [24].Repeated. or prolonged exposure to fuel products is more. reflective of the occupational norm. Studies have shown that repeated dermal exposures to. fuels result in skin irritation [25].
The healthy problems due to the long exposure to fuel derivatives depends on many factors such as concentration of the chemical substance and time of exposure. Contact with fuel.
vapors may be responsible for many diseases such as headache, nausea, and respiratory tract allergy [26] .

Correlation between AHR & Trace Elements
The correlations between AHR and some trace elements in FSW group are cited in Table (3). There is a significantʹʹ negative correlation (p=0.014) between serum Pb and AHR in FSW group ( Figure 2). Other trace elements showed no significant. correlation (p>0.05) with AHR. The present results are agreed with previous results where leadʹʹ is a non-essential metal that isʹʹ toxic to human tissue at very low concentrations [27] and is ranked second most toxic substance in the. hazardous substances list by the Agency for Toxicity. and Disease Registry [28]. The body burden of Pb increases with age, despite efforts to reduce exposure to. the metal. The major sources of Pb are paints, water, food, dust, soil, kitchen utensils, and leaded ʹgasoline. Most cases of Pb poisoning are attributable to oral ingestion and absorption .through the gut [29]. Most of the ingested Pb accumulates in specificʹ.. target tissues including blood, soft tissues, and bone, where it has a very long half-life [30]. Co-contamination with mixtures

Correlation between Serum Metals with Age and Weight
The correlations between serum metals with age and weight in FSW group are cited in (Table 4). A-There is significant negative correlation between serum Cu 2+ and age in FSW group ( Figure   3).

Fig. (3) Correlation between Cu 2+ & Age in FSW.
The present results are agreed with previous results, Cu of the blOod circulation is transpOrted into the brain via the blood-brain barrier (BBB) and blood-cerebrospinal fluid (CSF) barrier [34]. PreviOus studies from those laboratory have demonstrated that the BBB serves as the majOr route for the transport of Cu into the brain parenchyma, while the bloOd-CSF barrier (BCB) mainly contributes to maintain the Cu homeostasis in the brain by expOrting excess Cu from the CSF to the blood [35]. Once entering the brain, the Cu cOntent and spatial distribution are uneven [36]. Age-related increase in brain Cu content was observed in mOuse [37]. Other recent published study using X-ray fluOrescent microscopy reveals an extraordinarily high Cu content in the subventricular zone along the wall of rat brain lateral ventricles, which appears to increase with age [38].
B-There is significant correlation between serum Zn +2 and age in FSW group (Figure 4). The present results are agreed with previous results, the serum concentrations of Cu and Zn are strictly regulated by compensatory mechanisms that act to stabilize them within certain ranges of nutritional intake. However, there are mechanisms that are built to decrease serum concentration of Zn and to increase serum concentration of Cu in the presence Of inflammatOry cOnditiOns, sO that a commons feature of several age-related chronic diseases is an increase of the Cu tO Zn ratio (Cu/Zn) [39]. That during ageing, the intake of Zn decreases, thus cOntributing to frailty, general disability and increased incidence Of age-related degenerative diseases [40].
C-There is significant correlation between serum Mg 2+ and age in FSW group ( Figure 5).  D-There is significant cOrrelatiOn between serum Pb and age in FSW group ( Figure 6).

Fig. (6) Correlation between Pb & Age in FSW.
The present results are agreed with previOus results, Pb is assOciated with a wide range Of toxicity in children acrOss a very brOad band of exposures. These toxic effects extend from acute, clinically Obvious, symptOmatic poisOning at high levels of expOsure and effects at lower levels. Pb pOisoning can affect virtually every Organ system in the body. The affected principal organs are the central nervOus system and the cardiovascular, gastrOintestinal, and renal [46].
Adults who are exposed tO a dangerous amount of Pb can experience anemia, nervOus system dysfunction, weakness, hypertensiOn, kidney problems, decreased fertility, an increased level Of miscarriages, premature deliveries, and a lOw birth weight Of their child [47].
The rOle Of Pb as an OccupatiOnal pollutant stressor for elevated blood pressure cOuld well be cOnfounded by the presumed role of other risk factors such as age [48].