|Year : 2017 | Volume
| Issue : 1 | Page : 92-98
Health-related disorders on occupational exposure to chromium in a leather tanning factory (Menoufia, Egypt)
Gaafar M Abdel Rasoul, Mahmoud E Abou Salem, Heba K Allam, Zeinab A Kasemy, Faten E Younis
Department of Public Health and Community Medicine, Faculty of Medicine, Menoufia University, Menoufia, Egypt
|Date of Submission||28-Sep-2016|
|Date of Acceptance||04-Dec-2016|
|Date of Web Publication||25-Jul-2017|
Faten E Younis
Department of Public Health and Community Medicine, Faculty of Medicine, Menoufia University, Shebin Al-Kom, 232511, Menoufia
Source of Support: None, Conflict of Interest: None
The aim of this study was to study health disorders among workers in a leather tanning industry and its relation with workplace environment in the same factory.
Leather tanning industry wastes pose serious environmental effect on water, land, and air. Leather tanning manufacture processes are also associated with a number of human health risks. Chromium (Cr) is the commonest used tanning agent to stabilize leather against biodegradation. Prolonged exposure to Cr compounds leads to long-term toxic effects in humans.
Participants and methods
A cross-sectional comparative study was conducted on 304 workers in a leather tanning factory and 304 nonoccupationally exposed subjects as control. Air samples for Cr (VI) were carried out. Biological monitoring of Cr in blood and urine of participants was done. Spirometric measurements and hematological investigations were applied.
The mean value of airborne Cr (VI) concentration was higher than the international permissible levels. There were higher serum and urinary Cr levels among exposed workers than controls (P = 0.000). Leather tanning factory workers had a higher significant prevalence of respiratory and skin-related manifestations as well as decreased spirometric measurements and abnormal hematological findings (P = 0.000).
Exposure to high level of Cr is blamed to increase the frequency of skin-related and respiratory manifestations, early spirometric changes, and abnormal hematological findings. Regular wearing of good-quality personal protective equipment, especially masks and gloves, to decrease Cr exposure is highly recommended.
Keywords: chromium, hematological investigations, leather tanning, spirometry
|How to cite this article:|
Abdel Rasoul GM, Abou Salem ME, Allam HK, Kasemy ZA, Younis FE. Health-related disorders on occupational exposure to chromium in a leather tanning factory (Menoufia, Egypt). Menoufia Med J 2017;30:92-8
|How to cite this URL:|
Abdel Rasoul GM, Abou Salem ME, Allam HK, Kasemy ZA, Younis FE. Health-related disorders on occupational exposure to chromium in a leather tanning factory (Menoufia, Egypt). Menoufia Med J [serial online] 2017 [cited 2019 Aug 20];30:92-8. Available from: http://www.mmj.eg.net/text.asp?2017/30/1/92/211508
| Introduction|| |
Tanning leather is the process of treating skins and hides of animals to produce leather, which is more durable and less susceptible to decomposition . The tanning industry forms the backbone of the Egyptian leather industry. Egyptian hides are known for a unique leather texture owing to the moderate climate. Approximately 300 tanneries are located in the 'Old Cairo District' in Cairo city. The labor force comprises ∼250 000 workers .
Chromium (Cr) exits in two stable oxidation states, namely, the trivalent (III) and hexavalent (VI) forms. Hexavalent Cr is more toxic than trivalent Cr owing to its oxidizing ability and high solubility ,. Chrome tanning is the most common technique in leather processing; 90% of tanning industries use basic Cr (III) sulfate instead of other tanning agents to obtain better-quality leather . Hexavalent Cr (VI) is produced industrially when Cr (III) is heated in the presence of mineral bases and atmospheric oxygen . Tannery workers are mainly exposed to Cr in the inorganic or protein-bound form (leather dust) . Occupational exposure to Cr is generally through inhalation and dermal absorption, although ingestion is also possible where there is poor personal hygiene ,,.
Cell toxicity caused by Cr is attributed to oxidants over antioxidants. Cr (VI) enters many types of cells and under physiological conditions can be reduced by hydrogen peroxide (H2O2), glutathione reductase, and glutathione to produce reactive intermediates. Any of these species could attack DNA, proteins, and membrane lipids, thereby disrupting cellular integrity and functions. Many forms of DNA damage can be produced: oxidative DNA lesions such as strand breaks, Cr–DNA adducts, DNA–DNA interstrand cross-links, and DNA–protein cross-links ,.
Dermatological effects of Cr compounds may include ulcerations, dermatitis, and allergic skin reactions ,. Localized erythematous or vesicular lesions at points of contact or generalized eczematous dermatitis should suggest sensitization .
Respiratory effects of Cr compounds can result in ulceration and perforation of the mucous membranes of the nasal septum, irritation of the pharynx and larynx, asthmatic bronchitis, bronchospasms, and edema .
Other health problems caused by Cr are weakened immune systems, kidney and liver damage , alteration of genetic material , and lung cancer ,.
Cr measurements in blood and urine are considered most reliable for detecting elevated level of exposures to Cr . There is a paucity of research studies done in this field among Egyptian workers, so this study is intended to be performed to provide further evidence of the possible adverse effects of Cr in leather tannery workers.
| Participants and Methods|| |
This study took place in a leather tanning factory (in industrial zone, Queisna City, Menoufia Governorate, Egypt), between September 2014 and September 2016. A cross-sectional comparative study was designed to study all occupationally exposed male workers from tanning department in the studied factory (174 workers), and an equal number (174 workers) was chosen randomly (simple random sample) from the preparatory and finishing departments (87 workers from each department). After exclusion of nonresponders, with response rate of 94.3%, and application of exclusion criteria which included worker who had any chest, skin, neurobehavioral, hematological, liver or kidney diseases; diabetes mellitus; and hypertension before employment in the factory, the recruited workers from the studied factory were 304 (152, 79, and 73 workers from tanning, preparatory, and finishing departments, respectively). A control group of 304 male individuals was selected from the relatives of the exposed group, who had never worked at leather tanning factory; they were matched with the exposed group for age, residence, education, and income. Participants were interviewed between 7:00 a.m. and 3:00 p.m.
In the questionnaire interviews, detailed descriptive information was collected, including personal descriptive characteristics, occupational lifestyles, working positions, working environment, and personal hygiene. Direct observations were also made and recorded to confirm the questionnaire results. Also, medical history of respiratory, skin, and hematological diseases and past history of other diseases (e.g., mental and nervous diseases, hypertension, diabetes mellitus, and liver and kidney diseases or use of antipsychotic drugs as well as skin, chest, or eye allergies) were gathered.
Spirometric measurements were taken by using the MIR (Medical International Research) company, Rome, Italy to determine forced vital capacity (FVC%), forced expiratory volume at the first second (FEV1%), forced expiratory ratio (FEV1/FVC%), forced expiratory flow (FEF25–75%), and peak expiratory flow (PEF%). The best value of three technically acceptable maneuvers was recorded. Percentages were reported, and the results were compared with predictive values based on age, sex, and height of the participant.
From each participant, 10 ml of venous blood was taken through a vein puncture using a dry plastic disposable syringe under complete aseptic condition. Of that, 3 ml of blood was kept in a tube, allowed to clot, and then centrifuged to separate the serum for determination of Cr level. Another 3 ml of blood was dispensed in a sterile glass test tube containing potassium EDTA, as an anticoagulant, for the analysis of different hematological parameters (complete blood count). The remaining 4 ml of blood was kept in a tube, allowed to clot, and then centrifuged to separate the serum, and an aliquot of serum samples was stored in a freezer (−20°C) until biochemical analysis [liver function tests including serum glutamic-oxaloacetic transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT); renal functions including blood urea nitrogen (BUN) and creatinine; serum ferritin; and serum iron]. The samples for hematological and biochemical measurements were analyzed at Clinical Pathology Department, Menoufia University Hospital. The air, urinary, and blood Cr samples were analyzed at the National Research Center, Cairo, Egypt.
For each participant, spot urine sample (30 ml) was taken. The urine samples were kept in polypropylene sampling vessels and stored at −20°C before analysis.
Air samples at breathing zone of the workers in different departments of the factory were obtained by the use of atomic absorption spectrophotometry (SOLAAR-UNICAM 989) Perkin Elmer, Jena, Germany at the National Research Center, Cairo, Egypt. Three readings were reported from the factory, where the mean value was recorded for regular work duration of 8 h (The breathing zone is the area immediately surrounding a worker's nose and mouth where the majority of air is drawn into their lungs. This zone is the area monitored during an industrial hygiene survey to aid in determining the presence of airborne contaminants.).
This study was approved by the Menoufia Faculty of Medicine Committee for Medical Research Ethics. All of the participants received a clear explanation of the purpose of this study and agreed to participate using signed consent forms. All personal information about the study participants was kept confidential. Approval from the factory management was obtained.
Analyses were conducted with the statistical package for social sciences, version 22 (SPSS Inc., Chicago, Illinois, USA). Student's t-test was used for comparison between the two means of continuous quantitative parametric variables and Mann–Whitney U-test for nonparametric variables. c2-Test was used for categorical variables and Fisher exact test 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. Multiple linear regressions were applied to detect the relationship between two variables by fitting a linear equation to observed data. A linear regression line had an equation of the form Y = a + bX, where X was the independent (explanatory) variable and Y was the dependent variable. Statistical significance was accepted for P value 0.05 or less for results that were two tailed.
| Results|| |
Overall, 304 male workers in a leather tanning factory and 304 matched controls were included in this study. Exposed group and controls were matched for age, sex, socioeconomic standard, educational level, residence, and marital status (P > 0.05). The environmental measurements recorded that the mean value of Cr concentration was 10.4 ± 0.63 μg/m 3 [Table 1], which was higher than recommended exposure limit set by the National Institute for Occupational Safety and Health and the Occupational Safety and Health Administration. Also, there was significantly higher serum and urine Cr levels among exposed (3.1 ± 2.2 and 2.6 ± 2.5 μg/l, respectively) [Table 1] than controls (0.15 ± 0.08 and 0.38 ± 0.44 μg/l, respectively; P < 0.001).
|Table 1 Mean airborne, blood, and urinary chromium levels among studied groups|
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The present respiratory manifestations including rhinitis, cough, expectoration, wheezes, dyspnea, chest pain, chronic bronchitis, and asthma were significantly more prevalent among exposed group (11.2, 21.7, 9.2, 9.9, 8.6, 4.9, 6.9, and 7.6%, respectively) than controls (3.3, 12.2, 3, 1.6, 0.7, 0.3, 0.0, and 0.0%, respectively; P < 0.001) [Figure 1]. Also, skin manifestations among the exposed workers experienced a significantly higher prevalence of skin redness (8.2%), itching (5.9%), and papules and vesicles (4.6%) than controls (3.3, 2.3, and 1.0%, respectively; P < 0.05) [Figure 1].
The spirometric measurements between exposed workers and controls revealed that there was significantly lower mean values of FVC%, FEV1%, FEV1/FVC%, FEF25–75%, and PEF% in exposed workers (77.4 ± 9.3, 77.9 ± 9.8, 81.9 ± 13.9, 73.9 ± 17.1, and 59.9 ± 22.1, respectively) than controls (83.6 ± 6.7, 85.6 ± 5.6, 90.5 ± 14.2, 86.1 ± 16.5, and 72.9 ± 17.2, respectively; P < 0.001) [Table 2].
On comparing exposed workers and controls regarding the hematological and biochemical findings, there were significant lower mean values of red blood cells (RBCs), hemoglobin (Hb), serum iron, and serum ferritin among exposed (4.6 ± 0.76 × 106/mm 3, 13.6 ± 1.2 g/dl, 67.7 ± 21.5 μg/dl, and 29.8 ± 17.03 ng/ml, respectively) than controls (5.1 ± 0.66 × 106/mm 3, 14.5 ± 1.2 g/dl, 77.7 ± 27.2 μg/dl, and 42.8 ± 21.9 ng/ml, respectively; P < 0.001) [Table 3]. There were significant higher mean values of BUN and creatinine level among exposed group (18.01 ± 5.2 and 0.61 ± 0.26 mg/dl, respectively) than controls (15.5 ± 4.8 and 0.49 ± 0.19 mg/dl, respectively; P < 0.05) [Table 3] but the mean values of SGOT, SGPT, BUN, and creatinine level among exposed workers were still within the reference range (reference values of creatinine and BUN levels are 0.7–1.2 and 7–20 mg/dl, respectively).
|Table 3 Mean hematological and biochemical measurements among studied groups|
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In this study, there were significant positive correlations between urinary as well as serum Cr levels (μg/l) with duration of current employment (years) (r = 0.128, P < 0.05 and r = 0.187, P < 0.001, respectively) [Figure 2] and [Figure 3].
|Figure 2: Spearman correlation between urinary chromium and duration of current employment among exposed group.|
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|Figure 3: Spearman correlation between serum chromium and duration of current employment among exposed group.|
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On application of multiple linear regressions to determine which selected variables were significantly influencing either of the serum or urinary Cr levels after adjusting for all the confounders, there was a significant relationship between serum Cr and either of current employment duration (regression coefficient β = 0.295) or mean concentration of Cr in air (regression coefficient β = 0.339; P < 0.05). Also, there was a significant relationship between urinary Cr and mean concentration of Cr in air (regression coefficient β = 0.435; P < 0.05) [Table 4].
|Table 4 Multiple linear regression model for detecting predictors for serum and urine chromium levels among exposed workers|
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| Discussion|| |
Cr is used as a basic tanning pigment, so it represents an important health risk factor for the tannery workers. The present work was undertaken to provide more information on possible health effects of Cr in tannery workers. Overall, 608 individuals were included in the study, of which 304 were those who worked in this tannery and had occupational hazards of exposure and direct contact with the chemicals used in tanneries, and the other 304 were from the relatives of the studied group, who had no direct exposure or contact.
In the studied factory, environmental measurements recorded that mean value of airborne Cr (VI) level exceeded the accepted 8-h time-weighted average exposure limit of 5 μg of Cr (VI) per cubic meter of air (5 μg/m 3) recommended by Occupational Safety and Health Administration  and 0.2 μg/m 3 recommended by National Institute for Occupational Safety and Health . Previous two studies ,,,,,,,,,,,,,, have reported the levels of Cr in tannery plants in Kenya, which found higher mean Cr levels in breathing zone air of the workers than those of the control group.
The results of the present study showed that the serum and urinary Cr levels of the exposed participants were higher than those in the matched control participants. The mean levels of Cr in serum and urine of general populations were 0.10–0.16 and 0.22 μg/l, respectively . These results of the exposed workers were attributed from increased air levels of Cr at the workplace through inhalation, absorption through the skin, and possibly through ingestion.
Another study among tannery workers in Egypt  reported a significant increase in Cr level in their serum when compared with the control group. Similar studies ,,,,,,,,,,,,,, of different tannery plants in Kenya reported higher mean Cr levels in urine of exposed workers.
This is supported by Zailina et al. , who studied machinists in Malaysia and recorded higher blood Cr level and urine Cr level among them. The printing workers in Southern Thailand  had higher urinary Cr levels and serum Cr levels than the control group. This clarifies that the highest exposure to air Cr level in either tannery, machinists, or printing environment could be blamed for increase in the serum and urinary Cr levels among exposed workers.
In this study, present respiratory manifestations were significantly more prevalent among exposed group than controls. This may be contributed to ventilation errors in the factory environment, added effects of chronic exposure to Cr, and synergistic effect of smoking.
These results agree with those reported by Subodh et al.  and Were et al. , who reported higher prevalence of respiratory manifestations in exposed tannery workers than controls in Kanpur and Kenya, respectively.
The spirometric measurements between exposed workers and controls revealed that there were significantly lower mean values in exposed workers than controls. Also, the spirometric measurements of exposed tannery workers in Kenya  showed significantly lower mean values among them than controls. Overall, 197 male workers  drawn from leather tanneries in Kanpur had significant lower spirometric measurements than controls. Issever et al.  studied respiratory problems in tannery workers in Istanbul and found decreased pulmonary function results than controls.
The use of spirometry is an important tool for assessment of lung function due to exposure of the workers to various metals at different workplaces. This is in agreement with Abdel-Rasoul et al.  who studied workers in a fluorescent lamp factory and found early changes in ventilatory functions in the form of FVC, FEV1, FEV1/FVC%, and FEF25–75% among exposed workers owing to mercury.
In the present work, the skin manifestations among the studied groups showed that the exposed workers experienced a significantly higher prevalence than controls. Cr (VI) when in contact with the skin may trigger inflammatory skin reactions. Also, Cr has the potential to bind with skin proteins of tannery workers to produce complex antigens which lead to hypersensitivity. Similarly, the tannery workers in Kenya  showed a significantly higher prevalence of dermatological symptoms (rashes and itching) compared with the control group. However, 472 workers at two leather factories in Indonesia  were studied, and 7.4% had an occupational contact dermatitis. Of the 197 male workers from 10 tanneries in India, 9% had skin rash, papules, and itching.
In this study, on comparing exposed and controls regarding the hematological and biochemical findings, there were significant lower mean values of RBCs, Hb, serum iron, and serum ferritin among exposed than controls. There were significantly higher mean values of BUN and creatinine level among exposed participants than controls, but the mean values of SGOT, SGPT, BUN, and creatinine level among exposed workers were still within the reference range. The exposed workers had significantly raised Cr levels in their biological fluids that led to adverse health effects owing to enhanced oxidative stress and inflammatory changes. So, the hematological, hepatic, and renal function impairments because of oxidative stress on body systems may act as an indicator of Cr toxicity.
Previous study among Egyptian leather tannery workers  reported significant hematological defects and recorded a significant difference between tannery workers and control group regarding white blood cells, platelet counts, and Hb concentration, but there was no significant difference in RBC count between tannery workers and control group. Similar investigations among tannery workers of Kasur industrial area, Pakistan , found that studied parameters were within the reference range, but SGPT and SGOT showed higher values among factory workers aged from 21 to 40 years and from 41 to 60 years than nonworkers of the same age. On the contrary, Ramzan et al.  found no significant changes in the values of Hb, mean corpuscular volume, and mean corpuscular Hb concentration between tannery workers and control individuals.
This study shows that with increased duration of employment, urinary and serum Cr levels (μg/l) increased. This correlation is supported by the findings of machinists in Malaysia , which recorded that positive correlation was present between blood and urinary Cr levels with employment years.
| Conclusion|| |
This study revealed occupational exposures to Cr and the related health effects among workers in a leather tanning factory, Egypt. It is suggested that a combination of inadequate engineering controls, work practices, and personal hygiene, together with high exposures to Cr in air, resulted in the related health effects among workers. Based on the findings of the study, it is recommended that monitoring and Cr regulation compliance levels in tanneries, along with the relevant training support mechanisms, should therefore be designed and implemented in the tanning industry.
The author thank all the workers and the participants who generously agreed to participate and also the administrators of the factory who facilitated the access to the study group.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4]