Copper and Zinc Levels Among Occupationally Exposed Male Workers to Cement Dust in Benin City, Edo State, Nigeria

41

Adejumo BabatundeIshola Gabriel and Abhulimhen Godwin
Medical Laboratory Science Department, University of Benin, Benin City, Nigeria.

All Correspondences to: babatunde.adejumo@uniben.edu,bigadejumo@yahoo.com

ABSTRACT

Background: There are lots of documentary evidence to showthedeleterious effects occasioned by the inhalation of cement dust on human health. Aim: This work is aimed atevaluating the effects of occupational exposure of cement dust on the level of copper and zinc in selected male subjects exposed to cement dust and compare them with those of the nonexposed group in Benin City.  Methods: A total number of eighty-six (86) malescomprised of 46 exposed subjects and 40 unexposed subjects participated in this study. They were recruited for this study from various construction sites in Benin City. Serum level of zinc and copper were assayed using flame atomic absorption spectrophotometer. Results: Theresult indicates that the level of copper of the exposed group (126.24 µg/dl) was significantly higher than the level of the control group (71.72 µg/dl), (P<0.001). However, this was not the case with the other micronutrient, zinc, although, there was also a statistically significant difference in its level between the exposed group (116 µg/dl) and the control group (145.52 µg/dl) P-value of>0.005. Conclusion: In this study, higher level of copper was recorded among people who are exposed to cement dust compared to the controls. However, the serum level of zinc was lower in the exposed group compared to the controls. The use of hand gloves, face masks, protective foot wear and gowns will help in reducing the entrance of these micro elements into the body. Government should increase advocacy on the need to take micronutrient supplements among this group of people to boost their immunity.
Keywords : copper, zinc, cement dust, Benin city.

INTRODUCTION

Cement is the most widely used building material throughout the world. Unfortunately, cement industry is one of the 17 most polluting industries listed by the central pollution control board. The industry releases huge amounts of cement dust into the atmosphere which settle on the surrounding areas forming a hard crust and causes various adverse impacts (1). However, the destructive effects of exposure to cement dust constituents on human have been documented. Cement constituents include 60 -70%calcium oxide, 17 – 25% silicon oxide, and 3-5% aluminum oxide, with some iron oxide, chromium, potassium, sodium, sulphur and magnesium oxide(2)(3). Exposures to most of these metals have been associated with decreased lung function indicators (4)(5). Lipid peroxidation, oxidative damage, and immunological mechanisms are all pathological conditions cement dusts have induced their toxicities (6)(7). The effects of these toxicities can only be felt when their serum levels are altered from the normal physiological values (8).

Trace elements are inorganic compounds that are needed in minute amounts in our diets, for the performance and maintenance of the normal functions of the body. It has been documented that trace elements may play an important role in the diseases caused by viruses (9) (10). However, deficiency of these trace elements causes severe economic loss due to increased susceptibility to oxidative stress, growth retardation, anemia, decrease in feed efficiency and fertility, enhance the virulence of the infectious agent, and decrease immune system function (11).

Specifically, trace elements such as copper (Cu) and zinc (Zn), are essential in human nutrition and are needed in very small amounts for essential metabolic reactions in the body.  Copper is an essential trace metal which is a component of a wide range of intracellular metalloenzymes, including cytochrome oxide, superoxide dismutase, tyrosine, dopamine hydroxylase and lysyl oxidase; more than 75% of the copper is associated with specific copper binding protein like ceruloplasmin (12), moreover, 60% of copper in the blood is tightly bound to a copper-zinc-dependent enzyme known as superoxide dismutase (CuZnSOD) which is a powerful antioxidant. On the other hand, zinc is the second most abundant trace element in the human body. It is an essential element that is required in many very important biological processes when it is known to function as a cofactor in over 200 enzyme reactions and is known to be essential for the function of numerous transcription factors and nuclear regulatory elements(13). Zinc deficiency depresses the ability of the body to respond to infection, affecting both cell-mediated immune and humouralresponses (14). It has also been revealed that people of cement dust zone are badly affected by reproductive problems, respiratory Copper and Zinc Levels Among Occupationally…

problems, gastro intestinal diseases etc.  (15).In Benin City, Edo state, the exponential increase in demand for cement has resulted in the proliferation of cement factories, distribution outlets, blocks molding industries etc.

There are lots of documentary evidence on deleterious effects of metallic components of cement dust on human in Nigeria (3)(16)(17), but none has singled out the effects of pair of copper and zinc in workers who are exposed to cement dust in Benin City, hence the justification of this work.

2.1 Methodology

A total ofeighty-six(86) males within the ages of 18-60 years participated in this study, 46 are those who were exposed to cement dust, while 40 are control subjects.Participants who were unhealthy or have history of hypertension were excluded.They included cement distributors, bricklayers and block moulders.They were recruited from various construction sites at Ugbowo area ofBenin City. The controls are students and staff of University of Benin, Ugbowo campus who have never been exposed to cement dust.Their consents were sought after explaining the purpose of the research. Structured questionnaire was administered to each participant to obtaintheir demographic information. This study was approved by the ethical committee of Ministry of Health, Edo State and the leaders of all the construction sites.

2.2 Sample collection and processing

Five milliliters of blood was collected and dispensed into a plain container. The non-anticoagulated blood was allowed to clot for 1 hour, and thenspun at 1500rpm for 10minutes and the supernatant serum was separated into a separate sterile tubes. The serum was stored at -200C for up to 2 weeks prior to analysis for copper and zinc using flame atomic absorption spectrophotometer (FAAS).

2.3 Data analysis

Data was expressed as mean and standard deviation. Comparative analysis was done using independent sample t-test and analysis of variance (ANOVA). Statistical significance was set at p < 0.05. All statistics were done using IBM/SPSS software (version 20.0).

RESULTS

Table 1 shows the demographic information of the participants. Table 1 shows that 30(65%) of the exposed participants are single while, 16(35%) are married. However, 20(50%) of the non-exposed are single, while

20(50%) are married. All the participants 86(100%) are Nigerians, with 5(11%), 10(22%), 30(65%), and 1(2%) represent Anambra, Delta, Edo, and other states of Nigeria respectively among the cement dust exposed participants. 10(25%), 29(73%), and 1(3%) are non-exposed from Delta, Edo and other states of Nigeria. 35(76%) of the exposed are frequent smokers while the rest 11(24%) are occasional smokers. However, 35(77%) of the controls are occasional smokers, while only 5(13%), are frequent smokers. 40(87%) and 6(13%) represent those who consume alcohol regularly and those who consume alcohol occasionally among those who are exposed to the cement dust, while 4(10%), consume alcohol frequently and 36(90%) occasionally among the controls. 40(87%), 32(70%), and 20(43%) experience body pains, chest pains, and weakness among the exposed group while none was recorded among the controls as part of their medical history. Also, there was no signs of nasal congestion, cough, and eye irritation in the control group, but, 41(89%), out of 46(100%) of the exposed group were currently experiencing cough, nasal and eye irritations respectively. All 46(100%) of the exposed group used pain relievers regularly, but none 0(0%) of them takes multivitamin supplements.6(13%), 2(4%) and 10(22%) wear face mask, hand gloves and foot wears, protective gowns respectively among the participants that are exposed to the cement dust

Table 2.Shows the mean serum levels of the copper and zinc among the participants. The result indicates that the levels of copper of the exposed group (126.24 ± 63.19 µg/dl) was significantly higher than the controls (71.72 µg/dl), (P<0.001). While serum zinc level is lower (116 ± 42.73 µg/dl) among the exposed group compared to the control group (145.52 ± 51.43 µg/dl), (P- value, >0.005).

Figure 1.Shows the bar chat of duration of exposure and the level of copper and zinc of the exposed group; indicating no statistical significance (P-values >0.05). Data show that the concentrations of zinc and copper rose sharply after first year of exposure. However, the concentrations remain constant between the two metals within 5 years of exposure. Furthermore, within 20 years of exposure, zinc level rose higher than copper. Meanwhile, the concentration of copper surpasses that of zinc after 20 years of exposure.

DISCUSSION

The deleterious effects of exposure to constituents of cement dust on human organs system have been well described. Based on this fact, there is need to investigate the effects of this dust on human total wellbeing. Serum level of copper and zinc of group of young men who were exposed to cement dust were estimated in this study. Table 1 shows the demographic information of the exposed participants, 30(65%) of the participants are single while, 16(35%) are married. However, 20(50%) of the nonexposed aresingle, while 20(50%) are married. All the Copper and Zinc Levels Among Occupationally…

participants 86(100%) are Nigerians, with 5(11%), 10(22%), 30(65%), and 1(2%) represent Anambra, Delta, Edo, and other states of Nigeria respectively among the cement dust exposed participants. 10(25%), 29(73%), and 1(3%) are non-exposed from Delta, Edo and other states of Nigeria. 35(76%) of the exposed are frequent smokers, while the rest 11(24%)  are occasional smokers. However, 35(77%) of the controls are occasional smokers, while only 5(13%), are frequent smokers. 40(87%) and 6(13%) represent those who consume  alcohol regularly and those who consume alcoholoccasionally among those who are exposed to the cement dust, while 4(10%),  consume alcohol frequently and 36(90%) occasionally among the controls. 40(87%), 32(70%), and 20(43%) experience body pains, chest pains, and weakness among the exposed group while none was   recorded among the controls as part of their medical history. Also, there was no signs of nasal congestion,cough, and eye irritation in the control group, but, 41(89%), out of 46(100%) of the exposed group were currently experiencing cough, nasal and eye irritations respectively. All 46(100%) ofthe exposed group used pain relievers regularly, but none 0(0%) of them takes multivitamin supplements.6(13%), 2(4%) and 10(22%) wear face mask, hand gloves and foot wears, protective gowns respectively among the participants that are exposed to the cement dust. This agrees with some workers (18) who reported the association of cement dust and respiratory discomforts such as cough, phlegm, and chest tightness and lung function indicators.

Figure 1 show the duration of exposure to the cement dust by the participants. Serum copper level increases with increasing time of exposure and reach the peak at over 20years of exposure while, highest serum zinc level was recorded after 6- 20 years of exposure. However, both metals recorded their lowest serum level at 2-5years of exposure. It is interesting to note that the serum levels of both metals rose sharply at the beginning of exposure (below 1 year).Continuous and prolong exposure to cement dust has been linked with decreased peak expiratory flow as reported by some authorities(19) (20) (21) (22).

In this study the level of copper was higher among the exposed subjects compared to the controls, while lower serum level of zinc was recorded among the exposed group compared to the controls (Table 2). This agrees with the work of Richard et al., 2016(23) in Mfamosing, Cross river state, Nigeria where they worked on cement factory workers. Increased level of copper has also been reported by other researchers among cement factory workers and the increment has been attributed to their exposure to cement dust (7) (24). The toxic effects of most of these metals depend on the absorption, concentration and continuous persistence at the action site. These metals react with endogenous target organs such as receptors, enzymes, DNA, proteins and lipids and altered their biological functional changes that results in toxic damage (25). Zinc and copper are the components of antioxidant enzyme superoxide dismutase (Cu – Zn SOD).  The lower zinc level among the exposed subjects may be due to low level of awareness on the need to regularly take multivitamin supplements and increased demand on the antioxidant system to buffer the deleterious effect of heavy metals. This may have accounted for lower zinc levels and a compensatory increase in copper level as seen among the exposed group compared to unexposed controls. The body in turn may want to conserve copper to combat heavy antioxidant demands (6).

CONCLUSION

In this study, higher level of copper was recorded among people who are exposed to cement dust compared to the controls. However, the serum value of zinc was lower in the exposed group compared to the controls. The use of hand gloves, face masks, protective foot wear and gowns will help in reducing the entrance of these micro elements into the body, which will in turn reduce organ damage occasioned by the absorption of these metals. Government should also increase level of awareness on the need to take multivitamin supplements among the exposed subjects to boost their immunity.

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