Influence of lifestyle factors on reproductive hormones and micronutrients in workers occupationally exposed to heavy metals

Chikaodili Nwando Obi-Ezeani; Chudi Emmanuel Dioka; Samuel Chukwuemeka Meludu

doi:10.4103/ed.ed_19_20

ORIGINAL ARTICLE

Year : 2021 | Volume : 6 | Issue : 1 | Page : 12-16

Influence of lifestyle factors on reproductive hormones and micronutrients in workers occupationally exposed to heavy metals

Chikaodili Nwando Obi-Ezeani¹, Chudi Emmanuel Dioka², Samuel Chukwuemeka Meludu³
¹ Department of Chemical Pathology, Chukwuemeka Odumegwu Ojukwu University, Awka, Anambra State, Nigeria
² Department of Chemical Pathology, Nnamdi Azikiwe University, Nnewi, Anambra State, Nigeria
³ Department of Human Biochemistry, Nnamdi Azikiwe University, Nnewi, Anambra State, Nigeria

Date of Submission	21-May-2020
Date of Decision	18-Nov-2020
Date of Acceptance	20-Jan-2021
Date of Web Publication	30-Mar-2021

Correspondence Address:
Chikaodili Nwando Obi-Ezeani
Department of Chemical Pathology, Chukwuemeka Odumegwu Ojukwu University, Awka, Anambra State
Nigeria

Source of Support: None, Conflict of Interest: None

Check

DOI: 10.4103/ed.ed_19_20

Abstract

Context: Unhealthy lifestyles or social habits such as smoking and alcohol consumption in addition to heavy metals exposure may enhance alterations in micronutrients and fertility hormones.
Aim: The aim of the study was to examine the influence of smoking and alcohol consumption on reproductive hormones and micronutrients in workers exposed to heavy metals.
Materials and Methods: Fifty workers from auto repair workshops and 44 occupationally unexposed control participants were recruited for the study. The occupationally exposed workers and control were further grouped into alcohol drinking smokers (ADS) and abstainers. The occupationally exposed workers comprised 28 ADS and 22 abstainers, while the control comprised 24 ADS and 20 abstainers. Blood samples were analyzed for lead (Pb), cadmium (Cd), selenium (Se), and zinc (Zn); testosterone (Tt), follicle-stimulating hormone (FSH), and luteinizing hormone (LH); and statistical significance set at P < 0.05.
Results: Pb, Cd, FSH, and LH levels were significantly higher, while Se, Zn, and Tt levels were significantly lower in the occupationally exposed workers compared to the control. Blood Pb and Cd levels in the exposed ADS were significantly higher compared to exposed abstainers and the control groups. Blood Se level was significantly lower in the exposed ADS compared to the exposed abstainers and control groups (P < 0.05). Blood Zn level in the exposed ADS was significantly lower compared to the exposed abstainers and abstainers in the control group. Serum Tt level was significantly lower in the exposed ADS compared to the exposed abstainers and control groups (P < 0.05). The serum FSH and LH were significantly higher in the exposed ADS compared to the control groups (P < 0.05).
Conclusion: Smoking and alcohol consumption may exacerbate the adverse effect of heavy metal exposure on reproductive health and fertility. Hence, these workers should be enlightened on the imminent dangers of such unhealthy habits.

Keywords: Alcohol, heavy metals, occupational exposure, reproductive health, smoking

How to cite this article:
Obi-Ezeani CN, Dioka CE, Meludu SC. Influence of lifestyle factors on reproductive hormones and micronutrients in workers occupationally exposed to heavy metals. Environ Dis 2021;6:12-6

How to cite this URL:
Obi-Ezeani CN, Dioka CE, Meludu SC. Influence of lifestyle factors on reproductive hormones and micronutrients in workers occupationally exposed to heavy metals. Environ Dis [serial online] 2021 [cited 2023 Mar 31];6:12-6. Available from: http://www.environmentmed.org/text.asp?2021/6/1/12/312678

Introduction

Heavy metals may be referred to as elements that have ecotoxicological and toxic effects in humans.^[1] Human exposure to heavy metals has dramatically increased in the past years as a result of increased use of these metals in various industrial and technological processes,^[2] with a good number of them having deleterious effects.^[3] These elements including cadmium (Cd), lead (Pb), mercury (Hg), and arsenic (As) have specific densities of >5 g/cm³, and among these heavy metals, Pb and Cd are considered to be of greater public health importance in Nigeria.^[2]

Exposure to heavy metals is imminent in various occupations including automobile industries and workshops which involve welding, battery manufacturing and recycling, painting, and panel beating. Others include mining, smelting, soldering, and so on. Smoking and alcohol consumption usually comes on the top of the list when it comes to unhealthy lifestyles or social habits and may as well be linked with some adverse health concerns including cancer, hypertension, heart disease, and infertility.^[4] Reproductive hormones and associated micronutrients may be altered by undesirable lifestyles as well as environmental factors,^[4] which may result to fertility issues. Sharma et al.^[5] had earlier suggested a positive or negative impact of stress, diet, drugs, cigarette smoking, alcohol consumption, and environmental and occupational exposures on fertility. As a result of the wide availability of tobacco or cigarettes and alcohol, it has become easier for these substances to be abused. These unhealthy lifestyles are mostly common in lower socioeconomic and education class.^[6] Cigarettes contain nicotine in addition to a host of other chemical compounds and toxic chemicals which are detrimental to health. Smoking is capable of damaging the body organs and systems, leading to leukemia, cancers, increased risk of cardiovascular diseases, and infertility in both men and women. Light drinking may be beneficial to the heart which is acceptable; however, heavy drinking can lead to serious medical issues. According to Chia,^[7] a healthy drinking limit is about 3 units of alcohol (not more than 2 drinks) and 2 units (1 drink) a day for men and women, respectively. The neurochemical mechanisms of nicotine and alcohol actions appear to be jointly reinforcing.^[8] Smoking and alcohol consumption in addition to exposure to heavy metals may therefore simultaneously interfere with synthesis of reproductive hormones as well as the micronutrients required for their synthesis. These micronutrients also known as essential elements are required by the body in small amounts for various biochemical processes, and insufficient or deficient levels may result to impaired biological and biochemical processes.

Few studies have reported adverse effects of smoking or alcohol drinking on reproductive hormones and semen parameters;^[9],[10] however, the combined influence of smoking and alcohol consumption on reproductive hormones and essential elements in workers exposed to heavy metals has not been studied. This study therefore was aimed at examining the influence of smoking and alcohol consumption on reproductive hormones and micronutrients in workers exposed to heavy metals.

Materials And Methods

This study employed a convenience sampling technique, of which a total of 156 males in Destiny Layout, Enugu, were approached. Of the 156 males approached, 33 declined and 29 (1 undergoing fertility treatment, 5 on multivitamin/mineral supplement, and 23 occasional drinkers) were excluded from the study. The remaining 94 participants aged 19–53 years made up of fifty workers from auto repair workshops (occupationally exposed) and 44 occupationally unexposed control participants were recruited for this study after obtaining informed consent from them. The occupationally exposed workers and control participants were further grouped into alcohol drinking smokers (ADS) and abstainers based on their social habits. The occupationally exposed comprised 28 ADS and 22 abstainers, while the control group comprised 24 ADS and 20 abstainers. Participants who consume alcohol and smoke regularly were considered ADS.

Inclusion/exclusion criteria

Apparently healthy consenting male participants between the ages of 19 and 53 years who have worked in the auto repair workshop for 1 year and above were included in the study, whereas occasional drinkers and/or smokers, participants on mineral supplements or fertility drugs were excluded from the study.

Ethical consideration

This study was approved by Nnamdi Azikiwe University Teaching Hospital Research Ethics Committee and conformed to all the ethical requirements of the Helsinki declaration.

Blood sample collection

Blood samples were collected by standard venipuncture, 3 ml was dispensed into K₂EDTA tubes for analysis of lead (Pb), Cd, selenium (Se), and zinc (Zn), 2 ml was dispensed into plain tubes, and sera obtained used for testosterone (Tt), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) analysis. The samples were collected in the morning at places of work or residence.

Biochemical analyses

The Pb, Cd, Se, and Zn concentrations in whole blood were analyzed by atomic absorption spectrophotometer (AAS) according to the American Public Health Association.^[11] For the determination of micronutrients, the blood samples were first digested by adding 1 ml of nitric acid to 1 ml of blood sample, mixed properly, boiled at 100°C for 30 min, made up to 10 ml with deionized water, and the respective micronutrient concentration is measured using Varian AA240 AAS (USA). Serum Tt, FSH, and LH concentrations were analyzed by enzyme-linked immunosorbent assay according to the methods of Tateishi et al.,^[12] Odell and Parlow,^[13] and Kosasa,^[14] respectively.

Quality control

Pooled samples from apparently healthy individuals were used as control; they were placed at intervals and analyzed alongside the other samples during biochemical assay. After each run, the values of the control samples were recorded, from which the means and standard deviations (SD) were obtained for calculation of coefficient of variation (CV = SD/mean × 100) of each biochemical parameter for the determination of precision of biochemical measurements.

Statistical analysis

The Statistical Package for the Social Sciences (SPSS) version 23.0 (SPSS Inc, Chicago, IL, USA) was used for statistical analysis. The variables were expressed as mean ± SD, the independent Student's t-test was used to assess the mean difference between two unrelated, one-way analysis of variance was used to assess the mean difference among variables, and post hoc was used to explore inter group variability. The level of significance was considered at P < 0.05.

Results

The mean levels of blood Pb and Cd, serum FSH, and LH were significantly higher, while the mean levels of blood Se and Zn, and serum Tt were significantly lower in the occupationally exposed workers when compared to the control group (P < 0.05) [Table 1].

Table 1: Lead, cadmium, micronutrients and reproductive hormones of occupationally exposed and control

Click here to view

In [Table 2], the mean blood Pb and Cd levels in the exposed ADS were significantly higher when compared to exposed abstainers as well as the control groups (ADS and abstainers) (P = 0.0001). Blood Pb level was also significantly higher in the exposed abstainers compared to the ADS and abstainers in the control group (P = 0.01 and P = 0.0001, respectively). However, there was no significant difference in the blood Pb level of the control groups (ADS and abstainers) (P = 0.944). The blood Cd level in the exposed abstainers was not significantly different from ADS in the control group (P = 0.183) but was significantly higher in the exposed abstainers and ADS in the control group when compared to the abstainers in the control group (P = 0.009 and P = 0.0001, respectively).

Table 2: Lead, cadmium, and micronutrients in alcohol drinking smokers and abstainers of occupationally exposed and control groups

Click here to view

Blood Se level was significantly lower in the exposed ADS when compared to the exposed abstainers, ADS, and abstainers in the control group (P < 0.05) as well as in the exposed abstainers compared to the control groups (ADS and abstainers) (P = 0.001 and P = 0.0001, respectively). Blood Se level was however not significantly different in both control groups (P = 0.673).

Blood Zn level in the exposed ADS was significantly lower when compared to the exposed abstainers (P = 0.012) and abstainers in the control group (P = 0.047). There was, however, no significant difference in the blood Zn levels of exposed ADS compared to ADS in the control group (P = 0.140), exposed abstainers compared to the ADS, and abstainers in the control group (P = 0.223 and P = 0.925, respectively) as well as between the control groups (ADS and abstainers) (P = 0.350).

In [Table 3], the serum Tt level was significantly lower in the exposed ADS when compared to the exposed abstainers and control groups (P < 0.05). However, there were no significant differences in the serum Tt levels of exposed abstainers when compared to the ADS and abstainers in the control group (P = 0.417 and P = 0.660, respectively) as well as between the control groups (P = 0.708).

Table 3: Testosterone, follicle-stimulating hormone, and luteinizing hormone in alcohol drinking smokers and abstainers of occupationally exposed and control groups

Click here to view

The serum FSH and LH were significantly higher in the exposed ADS when compared to the ADS and abstainers in the control group (P < 0.05) but not significantly different from the exposed abstainers (P > 0.05). There were also no significant differences in the serum levels of FSH and LH in the exposed abstainers when compared to the ADS and abstainers in the control group as well as between the control groups (P > 0.05).

Discussion

This study assessed the influence of smoking and alcohol consumption on reproductive hormones and micronutrients in workers occupationally exposed to heavy metals. In this study, blood lead and Cd concentrations were used as biomarkers of exposure to these metals, which were observed to be higher in these workers. The higher concentrations of these metals is suggestive of higher exposure in these workers than in the occupationally unexposed, possibly from the use of metals or metal containing products as well as from lead and Cd contaminated workplaces.

The concentrations of these metals were also markedly higher in the workers who smoke and drink alcohol than those who do not (abstainers), and this may be attributed to the unhealthy lifestyles of cigarette smoking and alcohol drinking habits. Sciskalska et al.,^[15] had earlier reported elevated blood Cd levels in smoking smelters. Thus, occupational exposure in addition to smoking and drinking may contribute to elevated blood concentrations of these toxic metals. The high contents of these metals in tobacco smoke, the contamination from feedstocks, and water used during production, processing, and canning or packaging alcoholic beverages may have contributed to the elevated blood levels of these metals in these workers.

Toxic metals have been reported to alter sex hormones,^[16] as they are well-known endocrine disruptors. Accordingly, these hormones were significantly altered in the occupationally exposed workers as well as those who smoke and drink alcohol. These alterations were depicted in the lower serum Tt and higher FSH and LH in these workers. The reduction in Tt may be attributed to the increased hepatic metabolism of this hormone or the action of nicotine (one of the toxic substances in cigarette smoke) which has been reported to impair androgen biosynthesis and Leydig cell growth.^[17] In addition, excessive alcohol consumption may damage Leydig cells or impair the hypothalamus pituitary gonadal axis,^[18] possibly resulting to suppressed Tt production with complementary increase in FSH and LH levels. These unhealthy lifestyles or habits may therefore exacerbate the adverse effect of heavy metal exposure on the reproductive health of these workers. The undesirable effects of smoking and alcohol use on sertoli and Leydig cells in the testis results to dysfunction of the male reproductive hormone system which could impair fertility.^[19] Lifestyle factors such as alcohol intake and cigarette smoking have previously been reported to affect male fertility.^[20],[21] Furthermore, the occupationally exposed workers showed reduction in blood Se and Zn levels, and this could be as a result of the ability of toxic metals to displace or interfere with the metabolism of these micronutrients^[22] at different levels which include intestinal absorption, distribution in tissues as well as biological functions.^[23] Lower levels of these micronutrients were further observed in the exposed workers who smoke and drink alcohol than in the abstainers, and this may have resulted from the ability of alcohol as well as some of the toxic substances present in cigarette to interfere with the absorption of micronutrients including Se and Zn. Hence, smoking and alcohol consumption could result to micronutrient deficiency. Isife and Dioka^[24] also observed lower Se and Zn levels in smokers exposed to lead in Coal Camp, Enugu. Interestingly, Se and Zn have been shown to play crucial roles in male reproductive function, while Se enhances Tt production of Leydig cell through enhancing expression of steroid acute regulatory protein and 3ß hydroxysteroid dehydronenase (3ß HSD) genes,^[25] Zn on the other hand is required by 17ß HSD for Tt synthesis. It therefore stands to reason that the lower Tt level in the exposed workers as well as those who smoke and drink alcohol may be linked to the lower Se and Zn levels in these workers.

Conclusion

Smoking and alcohol consumption may therefore exacerbate the adverse effect of heavy metal exposure on reproductive health and fertility. Hence, these workers should be enlightened on the imminent dangers of such unhealthy habits/lifestyles.

Limitation/strength of the study

This study is limited by the small sample size due to the number of participants willing to take part in the study as well as the exclusion criteria which further reduced the sample size. However, the study can serve as a pilot study in the particular study area since this area has not been sampled before.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1.	Duffus JH. Heavy metals – A meaningless term? Pure Appl Chem 2002;74:793-807.
2.	Orisakwe OE. Lead and cadmium in public health in Nigeria: Physicians neglect and pitfall in patient management. N Am J Med Sci 2014;6:61-70.
3.	Mahmood Q, Wang J, Pervez A, Meryem S, Waseem M, Ullah Z. Health risk assessment and oxidative stress in workers exposed to welding fumes. Toxicol Environ Chem 2015;97:634-9.
4.	Barazani Y, Katz BF, Nagler HM, Stember DS. Lifestyle, environment, and male reproductive health. Urol Clin North Am 2014;41:55-66.
5.	Sharma R, Biedenharn KR, Fedor JM, Agarwal A. Lifestyle factors and reproductive health: Taking control of your fertility. Reprod Biol Endocrinol 2013;11:66.
6.	Hart CL, Davey Smith G, Gruer L, Watt GC. The combined effect of smoking tobacco and drinking alcohol on cause-specific mortality: A 30 year cohort study. BMC Public Health 2010;10:789.
7.	Chia S. How Smoking and Drinking Affect the Body; 2017. Available from: https://www.mountelizabeth.com.sg/healthplus/article/how-smoking-and-drinking-affect-the-body. [Last accessed on 2020 Apr 04].
8.	Larsson A, Engel JA. Neurochemical and behavioral studies on ethanol and nicotine interactions. Neurosci Biobehav Rev 2004;27:713-20.
9.	Saleh RA, Agarwal A, Sharma RK, Nelson DR, Thomas AJ Jr. Effect of cigarette smoking on levels of seminal oxidative stress in infertile men: A prospective study. Fertil Steril 2002;78:491-9.
10.	Maneesh M, Jayalekshmi H. Role of reactive oxygen species and antioxidants on pathophysiology of male reproduction. Indian J Clin Biochem 2006;21:80-9.
11.	American Public Health Association. Direct Air-Acetylene Flame Method Standard Methods for the Examination of Metals in Blood. 20^th ed. Washington DC: American Public Health Association; 1995.
12.	Tateishi K, Yamamoto H, Ogihara T, Hayashi C. Enzyme immunoassay of serum testosterone. Steroids 1977;30:25-32.
13.	Odell WD, Parlow AF. Estimation of follicle stimulating hormone test assay. J Clin Invest 1981;47:25-51.
14.	Kosasa TS. Measurement of human luteinizing hormone. J Reprod Med 1981;28:201-6.
15.	Sciskalska M, Zalewska M, Grzelak A, Milnerowicz H. The influence of the occupational exposure to heavy metals and tobacco smoke on the selected oxidative stress markers in smelters. Biol Trace Elem Res 2014;159:59-68.
16.	Obi-Ezeani CN, Dioka CE, Meludu SC, Onuora IJ, Usman SO. Effect of green tea supplementation on blood cadmium and male sex hormone levels in automobile workers in Emene, Enugu State, Nigeria. J Adv Med Med Res 2018;27:1-7.
17.	Funabashi T, Sano A, Mitsushima D, Kimura F. Nicotine inhibits pulsatile luteinizing hormone secretion in human males but not in human females, and tolerance to this nicotine effect is lost within one week of quitting smoking. J Clin Endocrinol Metab 2005;90:3908-13.
18.	Maneesh M, Dutta S, Chakrabarti A, Vasudevan DM. Alcohol abuse-duration dependent decrease in plasma testosterone and antioxidants in males. Indian J Physiol Pharmacol 2006;50:291-6.
19.	La Vignera S, Condorelli RA, Balercia G, Vicari E, Calogero AE. Does alcohol have any effect on male reproductive function? A review of literature. Asian J Androl 2013;15:221-5.
20.	Gaur DS, Talekar MS, Pathak VP. Alcohol intake and cigarette smoking: Impact of two major lifestyle factors on male fertility. Indian J Pathol Microbiol 2010;53:35-40. [PUBMED] [Full text]
21.	Okwara JE, Ezeugwunne IP, Onunkwo SC, Ogbodo EC, Analike RA, Obi-Ezeani CN, et al. Effect of alcohol consumption on testosterone, luteinizing hormone and follicle stimulating hormone levels in males residing in Nnewi Metropolis, Anambra state, Nigeria. Indian J Forensic Community Med 2019;6:13-7.
22.	Matović V, Buha A, Bulat Z, Dukić-Ćosić D. Cadmium toxicity revisited: Focus on oxidative stress induction and interactions with zinc and magnesium. Arh Hig Rada Toksikol 2011;62:65-76.
23.	Al-Fartosy AJ, Shanan SK, Awad NA. Biochemical study of the effects of some heavy metals on oxidant/antioxidant status in gasoline station workers, Basra-Iraq. Int J Sci Res Publ 2017;7:83-93.
24.	Isife CT, Dioka EC. Zinc and selenium levels in smokers exposed to lead and the development implications. Sustain Hum Dev Rev 2010;2:47-60.
25.	Shi L, Song R, Yao X, Duan Y, Ren Y, Zhang C, et al. Effects of maternal dietary selenium (Se-enriched yeast) on testis development, testosterone level and testicular steroidogenesis-related gene expression of their male kids in Taihang Black Goats. Theriogenology 2018;114:95-102.