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 Table of Contents  
Year : 2016  |  Volume : 19  |  Issue : 2  |  Page : 124-127

Study of haematological parameters of lubricating engine oil factory workers and controls in Nnewi, South-East Nigeria

1 Department of Medical Laboratory Science, College of Health Sciences, Nnamdi Azikiwe University, Nnewi, Anambra, Nigeria
2 Department of Haematology, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Anambra, Nigeria

Date of Web Publication5-Jul-2016

Correspondence Address:
John C Aneke
Department of Haematology, Nnamdi Azikiwe University Teaching Hospital, PMB 5025, Nnewi, Anambra State
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DOI: 10.4103/1119-0388.185435

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Background: Products of crude oil, including benzene and its derivatives, exert adverse cytotoxic and suppressive effects on blood cells, particularly the hematopoietic precursors in the bone marrow. Objective: To determine the effect of exposure to lubricating oil on hematological parameters and how these are influenced by alcohol consumption in factory workers in Nnewi, South-East Nigeria. Subjects and Methods: A total of 50 nonsmoking lubricating oil factory workers and 50 apparently healthy nonoil factory workers were recruited for this study. A volume of 3 ml of venous blood was collected from each participant for full blood count, using automated hematology analyzer (PE-6800, Prokan; ). Data were analyzed using the Statistical Package for Social Sciences version 16.0 (SPSS Inc., Chicago IL, USA). The level of statistical significance was P < 0.05. Results: The mean ages of study subjects and controls were 29.00 ± 6.06 and 30.55 ± 5.47 years, respectively (P = 0.37). The means of red blood cell count, hemoglobin concentration, hematocrit, red cell indices and white cell and differential counts were significantly lower in the study subjects than controls (P values all < 0.05). There were no significant differences in parameters at different durations of exposure and between test subjects who consumed alcohol and those who did not. Conclusion: Occupational exposure to lubricating oils appears to suppress hematopoiesis, in a manner that may be independent of the duration of exposure.

Keywords: Hematological parameters, lubricating engine oils, occupational exposure

How to cite this article:
Ibeh NC, Aneke JC, Okocha CE, Ogenyi SI. Study of haematological parameters of lubricating engine oil factory workers and controls in Nnewi, South-East Nigeria. Trop J Med Res 2016;19:124-7

How to cite this URL:
Ibeh NC, Aneke JC, Okocha CE, Ogenyi SI. Study of haematological parameters of lubricating engine oil factory workers and controls in Nnewi, South-East Nigeria. Trop J Med Res [serial online] 2016 [cited 2020 Aug 8];19:124-7. Available from: http://www.tjmrjournal.org/text.asp?2016/19/2/124/185435

  Introduction Top

Lubricating engine oils are nonvolatile, viscous substances derived from crude oil through the process of fractional distillation; its main components include mixtures of base oils (such as paraffinic, naphthenic, and aromatic oils) and numbers of performance enhancing additives (PEAs). [1] The base oil determines the physical characteristics of the oil, such as the viscosity index, volatility as well as its additive response, while the PEAs control solubility, oxidation status, among other things. [1]

Earlier evidence has shown that occupational exposure to a number of crude oil-derivatives is associated with increased morbidity and mortality from organ tissue damage, especially of the respiratory and urinary systems. [2],[3] The factor implicated in disease etiology is the polycyclic aromatic hydrocarbons (PAHs), which are found in significant amounts in lubricating engine oils. [3] PAHs (include nitrobenzene, aniline, benzo(a)pyrene, and oxalene) are direct derivatives of the aromatic hydrocarbon benzene. [4]

Occupational exposure to PAH occur mainly through inhalation of fumes and dermal uptake, less frequently, ingestion could occur, especially when factory workers eat or drink without proper hand washing. [5] The metabolism of PAH leads to the formation of free radicals which cause organ/tissue dysfunction, through damage of cell membrane and DNA, these are implicated in the pathogenesis of a number of hematological disorders such as hemolytic anemia and malignancies. [6],[7],[8]

This study was to determine the effect of occupational exposure to lubricating engine oils on hematological parameters and how this may be influenced by social habits, such as alcohol consumption.

  Subjects and Methods Top

Study subjects

These comprised 50 consenting volunteer lubricating oil factory workers (30 males and 20 females) and an equal number of apparently healthy nonfactory workers as controls. Inclusion criteria for controls included age between 18 and 45 years, no evidence of ill health or chronic medication use, no blood transfusion in the last 6 months or blood donation in the last 3 months.

Study site

The study was carried out in Nnewi town of Anambra State, South-East Nigeria.

Study design

This was a cross-sectional descriptive study; participants were selected using simple random sampling. Information was obtained using questionnaire.

Sample analysis

Each participant had 3 ml of venous blood collected into ethylene diamine tetra acid specimen bottles, following standard protocol for venesection, for full blood count estimation which was carried out using automated 3-part hematology analyzer (PE-6800, Prokan® ).

Ethical clearance

Ethics clearance for this research was sought and obtained from the ethics committee of the Nnamdi Azikiwe University, Nnewi Campus and each participant gave informed written consent.

Data analysis

Data were analyzed using the Statistical Package for Social Sciences, version 16.0 computer software (SPSS Inc., Chicago IL, USA,). Results were expressed as means and standard deviations, while comparison of indices between groups was carried out using the Student's t-test. Level of statistical significance was set at P < 0.05.

  Results Top

There were 30 males and 20 females; M:F ratio = 1.5:1) with mean age of 29.00 ± 6.06 years and 50 controls, mean age of 30.55 ± 5.47 years (P = 0.37).

The means of red blood cell count (RBC), hematocrit, hemoglobin concentration, and mean cell volume were significantly lower in study subjects compared with controls [4.81 ± 0.86 × 10 12 /L vs. 5.66 ± 1.15 × 10 12 /L; 39.18 ± 8.82 L/L vs. 44.65 ± 9.23 L/L; 11.8 ± 2.88 g/dl vs. 13.27 ± 3.27 g/dl and 73.63 ± 9.65 fl vs. 78.95 ± 6.01 fl, respectively, P values all < 0.05, [Table 1]. Correspondingly, the means of mean cell hemoglobin (MCH), MCH concentration, neutrophil, white cell and lymphocyte counts were significantly lower in study subjects compared with controls [21.59 ± 3.55 pg vs. 23.38 ± 2.10 pg; 28.28 ± 9.01 g/dl vs. 31.57 ± 9.70 g/dl; 2.40 ± 0.68 × 10 9 /L vs. 2.56 ± 1.01 × 10 9 /L; 5.05 ± 1.05 × 10 9 /L vs. 5.33 ± 1.51 × 10 9 /L; 2.58 ± 0.50 × 10 9 /L vs. 2.66 ± 0.70 × 10 9 /L, respectively, P values all <0.05, [Table 1]. There were no statistically significant differences in the means of platelet count and mean platelet volume in study subjects and controls [P values all >0.05, [Table 1].
Table 1: Comparison of means of hematological parameters in subjects and controls

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There were no significant differences in the means of all hematological parameters in study subjects at different durations of exposure [P values all >0.05, [Table 2].
Table 2: Hematological parameters of test subjects according to duration of exposure

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There were no significant differences in the means of all hematological parameters between study subjects that consumed alcohol and those who did not [P values all >0.05, [Table 3].
Table 3: Comparison of hematological parameters in study subjects by history of alcohol consumption

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  Discussion Top

A number of seminal studies had earlier investigated the effects of products of crude oil in humans and experimental animals with very interesting results. [9],[10],[11],[12],[13],[14],[15] There seems to be a consensus that products of crude oil exert a suppressive effect on erythropoiesis, evidenced by reduced red cell count, hemoglobin and red cell indices. There are a number of hypotheses that tried to explain the pathogenesis of erythropoiesis suppression by products of crude oil. Ita and Shakirov surmised that increased oxidative damage, coupled with inhibition of critical enzymes in the RBC adenyl and mono oxygenase enzyme systems (leading to interference with the haem biosynthetic pathway) by lead in crude oil may be an important pathogenetic pathway. [16],[17] Other researchers however attributed the erythropoietic dysfunction to the effect of the element benzene and argued that it induces hematopoietic stem cell dysfunction and bone marrow micro-environment abnormalities, which could potentially progress to bone marrow failure. [11],[12] Indeed these studies consistently linked the pathogenesis of aplastic anemia, leukemia, and myelodysplastic syndrome to exposure to benzene. [11],[12]

In this study, all the indices that reflect normal erythropoiesis (red cell count, hemoglobin concentration and the red cell indices) were significantly lower in test subjects compared with controls [Table 1] Our observation is in support of these earlier reports which indicated that products of crude oil suppress erythroid activity, this therefore adds further credence to the recommendation that handlers of crude products, particularly in the occupational setting should routinely use personal protective equipments (PPEs) to shield them from these hazards.

This study also observed that the total white and differential counts were significantly lower in test subjects compared to controls [Table 1]. It may thus appear that lubricating oil also has a suppressant effect on leukopoiesis. While this may be the case in this study, there appears to be no general consensus on this. While some experimental studies agree with our observation, attributing this to an inhibitory effect of crude (and its products) on white cell production, others reported that exposure to substances found in crude oil was associated with stress and inflammatory response, resulting in increased white cell and differential counts. [14],[15],[18],[19]

Interestingly, this study did not show any significant differences in cell counts in subjects at increasing work (exposure) duration [Table 2]. This appears to suggest that our observations may not necessarily be as a result of a cumulative (prolonged) effect of lubricating oil exposure on the hematopoietic system and could imply that any protective protocol for staff at the work place must include protection from the first time of exposure and not deferred till sometime later. Our finding is however in contradiction with earlier reports by Ibeh and Udonwa among auto mechanics and petrol station attendants/auto mechanics in Nnewi (South-East Nigeria) and Calabar (South-South Nigeria) respectively, in which adverse effects on hematological parameters in subjects were reported to worsen with increasing duration of exposure. [4],[10] Even though, the reason(s) for this discrepancy was not entirely clear from this report, we suspect that the dose and nature (configuration) of PAHs may actually be different in lubricating oil and premium motor spirit (PMS). We studied workers that were exposed to lubricating engine oils, whereas the 2 earlier reports studied workers exposed to PMS.

Some social habits such as alcohol consumption have an adverse effect on blood counts which could be potentially exacerbated by exposure to benzene and its derivatives in the occupational setting. [20] More so consumption of alcohol could impair judgment and may potentially hamper the ability to observe adequate hygienic measures that could reduce the degree of workplace exposure to benzene and its derivatives. Although this study did not actually quantify the amount of alcohol that was consumed by each respondent, we did not observe any significant difference in hematological parameters between subjects that consumed alcohol and those that did not [Table 3]. This may thus either mean that alcohol intake does not have any significant additive effect on hematological dysfunction in our population, or the volume of alcohol consumed by our subjects was too small to induce any significant additive effect.

Further line of research

It will be interesting to evaluate cytogenetic chromosomal abnormalities in this study population along with the volume of alcohol consumed by each respondent. The presence of cytogenetic chromosomal abnormalities may be a pointer to the possibility of developing malignant hematological conditions such as leukemia and myelodysplasia.

  Conclusion Top

Occupational exposure to lubricating oil is associated with depression in red and white cell production. These changes do not appear be cumulative and most probably occur early following exposure. We therefore re-iterate the call for the provision of PPEs to all groups whose job description expose them to crude oil and its derivatives, particularly lubricating oil workers.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Smolenski D. Component Performance in Formulating Engine Oils. Society of Tribologists and Lubrication Engineers; October, 2013. Available from: http://www.stle.org. [Last accessed on 2015 Oct 25].  Back to cited text no. 1
Dolin PJ, Cook-Mozaffari P. Occupation and bladder cancer: A death-certificate study. Br J Cancer 1992;66:568-78.  Back to cited text no. 2
Mastrangelo G, Fadda E, Marzia V. Polycyclic aromatic hydrocarbons and cancer in man. Environ Health Perspect 1996;104:1166-70.  Back to cited text no. 3
Udonwa NE, Uko EK, Ikpeme BM. Ibanga IA, Okon BO. Exposure of petrol station attendants and automobile mechanics to premium motor spirit in Calabar, Nigeria. J Environ Public Health. 2009;2009:1-5.  Back to cited text no. 4
Becher G, Bjørseth A. Determination of occupational exposure to PAH by analysis of body fluids. In: Bjørseth A, Ramdahl T, editors. Handbook of Polycyclic Aromatic Hydrocarbons. New York: Marcel Dekker; 1985. p. 237-52.  Back to cited text no. 5
Tanabe M, Tamura H, Taketani T, Okada M, Lee L, Tamura I, et al. Melatonin protects the integrity of granulosa cells by reducing oxidative stress in nuclei, mitochondria, and plasma membranes in mice. J Reprod Dev 2015;61:35-41.  Back to cited text no. 6
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Skyberg K, Hansteen IL, Jelmert O, Rønneberg A. A cytogenetic and haematological investigation of oil exposed workers in a Norwegian cable manufacturing company. Br J Ind Med 1989;46:791-8.  Back to cited text no. 8
Ezejiofor TI, Ezejiofor AN, Orisakwe OE, Nwigwe HC, Osuala FO, Iwuala MO. Anicteric hepatoxicity: A potential health risk of occupational exposures in Nigerian petroleum oil refining and distribution industry. J Occup Med Toxicol 2014;9:3.  Back to cited text no. 9
Ibeh N, Aneke J, Okocha C, Nkwazema A. Hematological indices in automotive technicians in Nnewi, South-East Nigeria. Niger J Med 2015;24:256-60.  Back to cited text no. 10
Das M, Chaudhuri S, Law S. Benzene exposure - An experimental machinery for induction of myelodysplastic syndrome: Stem cell and stem cell niche analysis in the bone marrow. J Stem Cells 2012;7:43-59.  Back to cited text no. 11
Snyder R. Leukemia and benzene. Int J Environ Res Public Health 2012;9:2875-93.  Back to cited text no. 12
Kamal A, Malik RN, Martellini T, Cincinelli A. PAH exposure biomarkers are associated with clinico-chemical changes in the brick kiln workers in Pakistan. Sci Total Environ 2014;490:521-7.  Back to cited text no. 13
Orisakwe OE, Akumka DD, Njan AA, Afonne OJ, Okechi OO. Hepatotoxic and haematological effects of Nigerian bonny light crude oil in male albino rats. Toxicol Environ Chem 2005;87:215-21.  Back to cited text no. 14
Akporhuarho PO. Effect of crude oil polluted water on the haematology of cockerel reared under intensive system. Int J Poult Sci 2011;10:287-9.  Back to cited text no. 15
Ita SO, Udofia UA. Comparative study of some haematological parameters in rats following ingestion of crude oil (Nigerian Bonny Light), petrol, kerosene and diesel. Asian J Biol Sci 2011;4:498-505.  Back to cited text no. 16
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Dongre NN, Suryakar AN, Patil AJ, Ambekar JG, Rathi DB. Biochemical effects of lead exposure on systolic and diastolic blood pressure, heme biosynthesis and hematological parameters in automobile workers of north Karnataka (India). Indian J Clin Biochem 2011;26:400-6.  Back to cited text no. 18
Okoye JO, Ngokere AA, Okeke CO. Biochemical, haematological and histological effects following Escravos crude oil ingestion by Chinchilla rabbits. Int J Med Med Sci 2014;6:63-8.  Back to cited text no. 19
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  [Table 1], [Table 2], [Table 3]


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