|Year : 2017 | Volume
| Issue : 4 | Page : 1103-1109
Neurobehavioral and hematological health disorders among fuel supply station workers
Gaafar M Abdel Rasoul, Eman A Salem, Heba K Allam, Yasser A Shehata, Mahmoud E Abu-Salem, Asmaa F El-Sayed Zagloul
Department of Public Health and Community Medicine, Faculty of Medicine, Menoufia University, Menoufia, Egypt
|Date of Submission||08-Apr-2017|
|Date of Acceptance||09-May-2017|
|Date of Web Publication||04-Apr-2018|
Asmaa F El-Sayed Zagloul
Department of Public Health and Community Medicine, Faculty of Medicine, Menoufia University, Shebin El-Kom, Menoufia
Source of Support: None, Conflict of Interest: None
This study aimed to study neurobehavioral and hematological health disorders among fuel supply station workers and its relation to the workplace environment.
Gasoline and its constituents are one of the most hazardous chemicals to the nervous and hematological systems.
Patients and methods
A case–control nested cross-sectional study was carried out on 92 workers in all licensed fuel supply stations in Shebin El-Kom district, Menoufia governorate, and 92 nonoccupationally exposed matched participants matched for age and sex were selected as a nonexposed group. Environmental studies for light-chain aromatic hydrocarbons [benzene, toluene, ethyl benzene, and xylene (BTEX components)] were carried out. Neurobehavioral test battery and complete blood picture were applied.
The mean values of BTEX levels (3.69 ± 1.88, 120.59 ± 1.17, 133.70 ± 7.20, and 114.35 ± 6.86 ppm, respectively) were higher than the threshold limit value of the American Conference of Governmental and Industrial Hygienists (0.5, 100, 100, and 100 ppm for BTEX, respectively). Fuel supply station workers had significantly lower performance on the neurobehavioral test battery than nonexposed participants (P < 0.001). Hematological findings including hemoglobin% and platelet count were significantly lower among the exposed workers (13.73 ± 1.13 and 247.36 ± 57.69, respectively) than the nonexposed participants (14.18 ± 0.94 and 268.46 ± 46.83, respectively) (P = 0.004 and 0.007, respectively).
Exposure to BTEX concentrations higher than permissible levels resulted in deteriorated performance on the neurobehavioral test battery and abnormal hematological findings in exposed workers. Regular use of good-quality personal protective equipment especially masks and gloves and periodic medical examination is highly recommended.
Keywords: BTEX components, gasoline, hematological hazards, neurobehavioral test battery
|How to cite this article:|
Abdel Rasoul GM, Salem EA, Allam HK, Shehata YA, Abu-Salem ME, El-Sayed Zagloul AF. Neurobehavioral and hematological health disorders among fuel supply station workers. Menoufia Med J 2017;30:1103-9
|How to cite this URL:|
Abdel Rasoul GM, Salem EA, Allam HK, Shehata YA, Abu-Salem ME, El-Sayed Zagloul AF. Neurobehavioral and hematological health disorders among fuel supply station workers. Menoufia Med J [serial online] 2017 [cited 2018 Sep 19];30:1103-9. Available from: http://www.mmj.eg.net/text.asp?2017/30/4/1103/229212
| Introduction|| |
Gasoline (benzene) is a complex, volatile, and inflammable liquid. It contains over 500 hydrocarbons that occur naturally in petroleum and become more concentrated after refining of petroleum to produce gasoline.
Exposure to gasoline can be environmental or occupational. Occupational exposure occurs in petrochemical and petroleum refining industries. Also, workers in fuel supply stations are constantly exposed to high levels of gasoline and its constituents.
Benzene, toluene, xylene, and oxygenates are the most frequently added additives to gasoline to improve octane number and decrease exhaust of the engine, enabling more efficient fuel combustion after reduction of lead content in gasoline since 1995 and use of unleaded gasoline in Egypt by 1998. The commonly used oxygenates include ethyl tertiary butyl ether, methyl tertiary butyl ether, ethanol, and methanol.
Excessive exposure to benzene has been known to cause harm to the bone marrow, which causes a decrease in the number of circulating blood cells, anemia, thrombocytopenia, leukopenia, and aplastic anemia. Development of one or more types of leukemia is an alternative consequence of benzene exposure.
Exposure to toluene and xylene may cause neuropsychological symptoms including headache, fatigue, insomnia, depression, sleepiness, anxiety, drunken feelings, difficulty in concentrating or memorizing, and other cognitive disorders.
Few researches have been carried out in this field among Egyptian fuel supply station workers; thus, this study was carried out to study neurobehavioral and hematological health disorders among fuel supply station workers and its relation to the workplace environment.
| Patients and Methods|| |
This was a case–control nested cross-sectional study carried out from the beginning of December 2015 to the end of January 2017 at all licensed fuel supply stations in Shebin El-Kom district, Menoufia governorate, Egypt.
Of 98 workers at the stations studied, 92 participated in this study as they fulfilled the exclusion criteria, with a response rate of 95.9%. An equal number of nonexposed participants were recruited from among the workers' relatives; they had no history of occupational exposure to similar hazards. They were matched with exposed workers for age, sex, and socioeconomic standard. Participants were interviewed between 7:00 a.m. and 3:00 p.m.
All the study participants were subjected to the following.
An interview was done at the station administration using a pre-designed questionnaire. The questionnaire was developed after a review of the related literature and was tested for content validity by a board of specialists in the field. Cronbach's α was calculated and it was 0.82. Unclear and uncertain words were revised. A pilot study was carried out on 10 workers who were excluded from the study sample to test the feasibility and applicability of the tools and modifications were made accordingly.
The questionnaire included demographic data (age, sex, etc.), special habits (smoking, alcohol, etc.), and occupational histories (working hours/day, years of exposure, use of personal protective equipment, etc.). Also, medical history of neurological and hematological manifestation, and previous history of diseases (e.g., neurological, psychiatric, blood, renal, hepatic disorders, diabetes mellitus, hypertension, etc.) were assessed.
Neurobehavioral assessment using the neurobehavioral test battery
The test battery was selected from the Wechsler intelligence scale for adults including; the trail-making test (parts 1 and 2) was used to measure attention, visual conception, and psychomotor function; the similarities test that was used to measure concentration, abstract thinking, and intelligence; the Benton visual retention test was used to assess visual perception, visual memory, and visuoconstructive abilities, the block design test was used to assess the ability of perception and analysis of objects, visual level of abstraction, visual motor coordination, and psychomotor function; the Santa Ana dexterity test was used to assess visual perception and hand dexterity; and the Beery visuomotor imitation test was used to assess the extent to which individuals can integrate their visual and motor abilities. Better performance was evaluated by higher scores obtained on tests of similarities, the Benton visual retention test, the block design test, the Santa Ana dexterity test, and the Beery visuomotor imitation test; by contrast, lower scores or time to complete the trail-making test (parts 1 and 2) were indicators of better performance.
Complete blood count
Two milliliters of blood was withdrawn by venipuncture using a sterile plastic syringe; then, the needle was detached and the required amount of blood was placed into a sterile plastic tube containing disodium ethylene diamine tetra acetate as an anticoagulant. The blood samples were then placed in an automatized counter (Sysmex K-1000, Ramsey, Minnesota, USA), which directly yielded the hemoglobin concentration, red blood cells (RBCs), white blood cells, and platelets counts.
Environmental measurement (monitoring of BTEX in ambient air by gas chromatography)
The exposure to benzene, toluene, ethyl benzene, and xylene (BTEX) in ambient air was monitored continuously during work shifts of 8 h. Ambient air samples were collected at 1.5 m above the ground about 2–3 m from the fuel pump by active sampling at a flow rate 100 ml/min using an SKC battery-operated air sampling pump model PCXR4. Activated charcoal cartridges were used to collect the samples. At each station, two to three samples were collected at several time intervals (a total of 40 samples).
After sampling, the contents of each cartridge were placed in a separate vial, which was sealed and placed in a cooled path for 20 min and was then left for 1 h at 10°C. The samples were extracted with carbon disulfide, and then the sample solution was analyzed by gas chromatography.
The BTEX calibration was performed using a standard solution (Supelco EPA TO-1 Mix 1A, 2017 Merck KGaA, Darmstadt, Germany). Solutions with concentrations ranging from 0.1 to 4.0 ng/PL were used to construct the calibration curve. The correlation coefficients always were above 0.99. The quantification limit calculated for each BTEX was 20 pg/PL, in relation to a concentration of 1.0 pg/m 3 in the atmosphere. All these steps were carried out under the supervision of a qualified professor from the air pollution department at the National Research Center, Cairo, Egypt.
The cumulative exposure index (CEI) of BTEX was calculated by multiplication of summation of the hazard quotient (HQ) of BTEX by working years:
Ci is the Time Weighted Average of the chemical and TLV is the threshold limit value of the same chemical.
This study was approved by the Menoufia Faculty of Medicine Committee for Medical Research Ethics. A formal consent was obtained from all participants of the study after an explanation of the study objectives was provided. All personal information about the study participants were kept confidential. Approval from the station mangers was also obtained.
Data were collected, tabulated, and statistically analyzed by an IBM personal computer and statistical package SPSS (version 22; SPSS Inc., Chicago, Illinois, USA). Two types of statistics were calculated: descriptive statistics: for example, percentage, mean, SD, and analytic statistics: e.g., Student's t-test was used for comparison of the means of continuous quantitative parametric variables and the Mann–Whitney U- test for nonparametric variables. χ2 was used for categorical variables and the Fisher exact test was used for categorical variables when the expected value was less than 5. Spearman correlation coefficient (r) was used to measure the association between two quantitative variables. Statistical significance was accepted for P value less than 0.05 for results that were two-tailed.
| Results|| |
Ambient concentrations of BTEX were 3.69 ± 1.88, 120.59 ± 1.17, 133.70 ± 7.20, and 114.35 ± 6.86 ppm, respectively, which exceeded the corresponding local and international safety guidelines for these elements.
Fuel supply station workers and nonexposed participants were matched in terms of their age, sex, residence, education levels, and smoking habits. The mean value of work duration of the exposed workers was 8.65 ± 9.69 years and the mean value of working hours per day was 10.63 ± 1.56. Most workers were included in night shifts 10.45 ± 3.63 times per month. Most of the fuel supply station workers did not use personal protective equipment (87%) [Table 1].
|Table 1: Characteristics of fuel supply station workers and nonexposed participants|
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The prevalence of neurological manifestations (headache, blurring of vision, nervousness, insomnia, inattention, lack of concentration, paresthesia, weakness, and spasm) was significantly higher among fuel supply station workers (34.7, 30.4, 39.1, 38, 33.6, 28.3, 14.1, 41.3, and 14.1%, respectively) than nonexposed participants (6.11, 12.47, 9.68, 5.09, 6.52, 6.63, 5.54, 18.37, and 3.2%, respectively, with P = 0.01, <0.001, <0.001, 0.01, 0.01, and 0.01 [Figure 1].
Fuel supply station workers had significantly lower performance in all the studied neurobehavioral tests used to assess attention, visual conception, and psychomotor functions (trail-making test parts 1 and 2) (82.26 ± 31.65 and 158.81 ± 52.67, respectively) than nonexposed participants (63.51 ± 16.86 and 125.01 ± 29.32, respectively) (P< 0.001), concentration, abstract thinking, and intelligence (similarities test) (13.31 ± 2.78) than nonexposed participants (17.28 ± 1.66) (P< 0.001), visual perception, visual perception, and memory (Benton visual retention test) (6.97 ± 3.12) than nonexposed participants (8.076 ± 0.96) (P = 0.002), intellectual function (block design test) (27.49 ± 5.26) than nonexposed participants (33.00 ± 3.28) (P< 0.001) and hand dexterity (Santa Ana dexterity tests dominant and nondominant hands) (40.85 ± 7.22 and 36.77 ± 6.97, respectively) than nonexposed participants (47.93 ± 5.61 and 42.88 ± 4.03, respectively) (P< 0.001) [Table 2].
|Table 2: Scores on the neurobehavioral test battery for the groups studied|
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Attention test [trail-making test (parts 1 and 2)] scores were significantly positively correlated with the CEI (BTEX) (P< 0.001 and = 0.007, respectively). However, visuomotor integration test (Beery visuomotor imitation test) scores were significantly negatively correlated with the CEI (BTEX) (P< 0.001) [Table 3].
|Table 3: Pearson's correlation between the cumulative exposure index (BTEX) and scores of the neurobehavioral test battery among the exposed group (n=92)|
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On comparing fuel supply station workers and nonexposed participants on the complete blood count elements, there were significantly lower mean values of hemoglobin%, RBC count, total leukocytic count (TLC). and platelet count among fuel supply station workers (13.73 ± 1.13, 4.94 ± 0.51, 7.54 ± 2.16, and 247.36 ± 57.69, respectively) than nonexposed participants (14.18 ± 0.94, 5.14 ± 0.41, 8.31 ± 1.88, and 268.46 ± 46.83, respectively), with (P = 0.004, 0.004, 0.01, and 0.007, respectively) [Table 4].
|Table 4: Complete blood count elements among fuel supply station workers and nonexposed participants|
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There were significant negative correlations between the CEI (BTEX) with RBCs and TLC (P = 0.021 and 0.033, respectively), whereas there were significant positive correlations between the CEI (BTEX) and both mean corpuscular volume and mean corpuscular hemoglobin among fuel supply station workers (P = 0.002 and 0.001, respectively) [Table 5].
|Table 5: Pearson correlation between the cumulative exposure index (BTEX) and complete blood count elements among fuel supply station workers|
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| Discussion|| |
Several toxicological effects linked to exposure to gasoline in fuel supply stations can be attributed to the existence of a specific mixture of aromatic hydrocarbons including BTEX components. These chemicals are immune, blood, and nervous system toxicants, as well as proven or suspected agents of carcinogenicity.
In the present study, fuel supply station workers were exposed to higher levels of benzene than the permissible levels of The Egyptian Ministry of Trade and Industry, Law 4 Decree 1095 (1.56 ppm). In addition, the exposed levels of BTEX were higher than the corresponding TLVS of American Conference of Governmental and Industrial Hygienist (0.5, 100, 100, and 100 ppm for BTEX, respectively). Therefore, neurobehavioral and hematological health disorders that were found among workers among these fuel supply stations could be attributed to occupational exposure to these high levels of BTEX components. The higher levels of BTEX exposure in gasoline stations have also been reported in previous studies from Brazil and northern India.
Fuel supply station workers in this study had significantly higher prevalence of neurological manifestations than nonexposed participants. This might be because of neurological hazards in the fuel supply station environment including high levels of BTEX components, with the added effects of poor ventilation and improper use of personal protective equipment. These results are in agreement with those of El-Kafas et al., who reported that the prevalence of depression, anxiety, headache, tremors, dementia, and insomnia was significantly higher among petroleum refinery workers exposed to BTEX components compared with nonexposed individuals.
A significantly lower performance on neurobehavioral tests was found among fuel supply station workers compared with the nonexposed participants in the present study. Also, Abbate et al. found a significant difference in the response to neurobehavioral tests and behavioral tendencies toward anxiety and depression among workers exposed to hydrocarbons in a large refinery. Moreover, Kang et al. found poor neurobehavioral performance among workers exposed to aromatic hydrocarbons.
Duration and level of exposure were important determinants of disorders developed from exposure to BTEX components in this study as indicated by significant correlations between the CEI of BTEX, with impaired performance in tests of attention and visuomotor integration in exposed workers. These results are in agreement with Ithnin et al., who reported a significant correlation between neurobehavioral performance and duration of employment of workers exposed to pollutant diesel fuels in a locomotive depot.
This study also examined the consequences of exposure to BTEX components on the hematological system. On comparing fuel supply station workers and nonexposed participants in terms of the complete blood count elements, there were significantly lower mean values of hemoglobin%, RBCs count, TLC, and platelet count among fuel supply station workers than nonexposed participants. Moreover, the levels of RBCs and TLC were significantly negatively correlated with CEI of BTEX components among the exposed workers. This could reflect the causal relationship of exposure to BTEX components, especially benzene, and these hematological findings.
These results were in agreement with Aleemuddin et al., who found that the mean values of hemoglobin%, RBC count, and TLC were significantly decreased among attendants working in different petrol pumps compared with nonexposed individuals. Also, an Egyptian study carried out by Abou-El Wafa et al. reported significantly lower levels of hemoglobin and RBCs among petrol station attendants than those of the control group, whereas there were no significant differences between both groups in white blood cells and platelet counts.
The strength of this study is that this is the first study carried out in Egypt assessing the neurobehavioral disorders among fuel supply station workers. However, this study has the limitation of lack of biological monitoring of BTEX among fuel supply station workers as it was unavailable.
| Conclusion|| |
Exposure to BTEX concentrations higher than permissible levels resulted in deteriorated performance on the neurobehavioral test battery and abnormal hematological findings among fuel supply station workers. Regular use of good-quality personal protective equipment, especially masks and gloves and periodic medical examination, is highly recommended.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]