DOI: 10.7910/dvn/essr7a
title: Replication Data for: The Relationship Between Respiratory Complaints and Urine Aluminum Levels in Aluminum Factory Workers

description: ABSTRACT

Background: It is known that foundry asthma and pneumoconiosis occur as a result of occupational exposure to aluminum. It is important to investigate the exposure conditions and duration in field studies. 

Aim: The study aimed to investigate the forms and conditions of respiratory effects in workers working in an Aluminum Profile Factory. 

Study Design: Prospective case-control study

Method and materials: All male (42 persons, mean age: 32.2 ± 6.9) workers working in an Aluminum Profile Factory in Adapazarı were compared with 33 control subjects who were not exposed to aluminum. The urinary aluminum levels of the workers (10.7 ± 8.8 mcg/lt) were significantly higher than the control group (2.2 ± 0.8) (p&lt;0.001). 
Complaints of cough (52.4%), sputum (59.5%), shortness of breath (40.5%) and wheezing (40.5%) were statistically significantly higher than the control subjects. In aluminum workers, those with dyspnea had a significantly higher urinary Al level than those without dyspnea (13.5 µgr/lt vs 8.7 µgr/lt, p=0.048).
 
Discussion: It is thought that primary and secondary prevention are both important in the workplaces with aluminum exposure. Urinary aluminum level monitoring could be key to protecting the respiratory health of the workers. 

Key Words: Respiratory functions, Urine Aluminum level, Aluminosis, Aluminum foundry, Aluminum workers 

INTRODUCTION
Aluminum is a metal that finds widespread use in industry due to its lightness, flexibility and formability. Occupational exposure to dusts containing aluminium, aluminum oxides or hydroxides, in the metal industry (during welding, grinding and polishing during the production or processing of Al powder); foundries (melting, casting, cleaning, spraying); and factories handling certain materials (such as spray-on metals) are observed during work or when covering surfaces1. In the production of Al powder, as well as in Al foundries and the welding and crushing of Al-containing material, high concentrations of respirable Al are released into the environment.

Due to the low solubility of aluminum-containing powders, aluminum oxide and aluminum hydroxide dust particles can accumulate in and disrupt the clearance of the lung, causing inflammation in the surrounding tissue and eventually fibrosis. Occupational exposure to aluminum has been reported to be related to the development of pneumoconiosis (Aluminosis), asthma, alveolar proteinosis, lung cancer, granulomatous disease, chronic bronchitis, acute tracheobronchitis, and pneumonia 2, 3.

In studies evaluating aluminum exposure by measuring plasma and urinary Al levels, clear data on whether there is a correlation is unavailable. However, in some studies conducted in Al powder production and in welders, blood and urine Al concentrations were in a linear relationship 4, 5.

For individuals without occupational exposure, urinary Al levels are generally &lt; 15 μg/l. Occupational exposure studies have reported that 1000 μg/l of Al was excreted in the urine and 500 μg/l of Al in welders after inhalation of Al powder 6, 7.

Our study aimed to compare the employees of a factory producing Al profile with controls working in the same workplace in terms of working conditions, respiratory complaints, pulmonary function tests and urine Al levels. In addition, we aimed to evaluate respiratory effects related to Al in terms of its relation with urinary Al levels. 

MATERIALS AND METHODS

The study was conducted between 01.11.2015 and 31.04.2016.
All male (42 persons, mean age: 32.2 ± 6.9) workers working in the Aluminum Profile Factory in Adapazarı were compared with 33 control subjects (mean age: 30.0 ± 7.9) who were not exposed to aluminum.

At the aluminum facility in Sakarya, where the study was conducted, approximately 480 workers work in production, mostly in the hot extrusion and press sections, and in the electrostatic paint shop and anodized coating departments. In addition to these workers, about 50 people work in the transportation division and offices. A working group was formed from 42 volunteers working in production, while a control group was formed from 33 volunteers working in office and transport.
Patients were informed about the study in advance, and those who wanted to participate in the study filled out a voluntary consent form. Exposure History form and ATS-DLD 78 respiratory questionnaire were completed by all volunteers. The control and study groups were transported to the health center in groups, and examinations were performed.

Pulmonary Function Tests

Spirometric pulmonary function tests and carbon monoxide diffusion test (DLCO) were performed using a CareFusion Hoechberg / Germany (model MASTERSCREEN™ PFT) in all cases at the Düzce University Faculty of Medicine, Department of Chest Diseases Pulmonary Function Test Laboratory.
At the beginning of pulmonary function evaluation, Forced Vital Capacity (FVC) and Forced Expiratory Volume in One Second (FEV1) measurements were done 8. The single-breath carbon monoxide technique was used for diffusion measurement. The DLCO maneuver was initiated by the patient's non-forced expiration up to the residual volume (RV) level. Inspiration was performed rapidly from the RV level to the patient's total lung capacity (TLC). The volume reached during this inspiration should be 85% of the patient's maximal vital capacity (VC). The inspiratory time should also be less than 4 seconds. Then, each patient was asked to hold his breath for 10 ± 2 seconds at TLC level 9.

Manufacturing Process in the Aluminum Factory

The stages of Al profile production include melting, molding, extrusion with high heat, coating and painting. 

Determination of Aluminum in Urine

Principle: Urine was mixed with Vortex. It was incubated for 15 minutes at room temperature, read at 522 nm against the blank in the DR 6000 HACHLANGE spectrophotometer. Urine aluminum level was first read in terms of µg/L on the spectrophotometer. This value was then calculated in terms of µg/24-hour urine. The normal level in 24-hour urine is 0-20 µg/24 hours. The following reagents were used: Hach Lange Permachem Reagent GmbH Düsseldorf –Germany 1. Ascorbic Acid Cat. 14577-99 Pk/100 2. AluVer 3 Aluminum Reagent Cat. 14290-99 Pk/100 3. Biaching 3 Reagent Cat. 14294-49 Pk/100 4. Standard 100 ± 1 mg/L Cat. 14174-42

Statistics

The SPSS-21 package program was used for statistical evaluations. Appropriate descriptive statistics (mean, standard deviation) were applied according to the types of all data included in the study. Independent Samples t-test was used for the intergroup comparison of the variables that met the parametric test assumptions, and the Mann-Whitney U test was used for the intergroup comparison of the variables that did not. Fisher Exact and Pearson Chi-square tests were used to compare categorical variables. In logistic regression analysis, covariants with independent effects on qualitative parameters were investigated. A value of p&lt;0.05 was considered statistically significant.

RESULTS

A total of 42 workers working in the Aluminum Profile Factory and 33 control group workers were compared. All aluminum workers and the control group both consisted entirely of men. While the mean age of the workers was 32.2 (min:21, max:53), the mean age of the individuals in the control group was 30.1 (min:18, max:46). While the mean body mass index (BMI) of the workers was 26.3 (min: 20, max: 36), the mean BMI of the individuals in the control group was 24.8 (min: 17.7, max: 31). The working period of the workers was 4.8 years (min:2, max:8), which was significantly shorter than the control group (10.1 years, min:1,max:22) (p&lt;0.001).
The mean urinary Al level of the Aluminum Profile Factory workers was 10.7 ± 8.8 µgr/lt, and that of the individuals in the control group was 2.2 ± 0.8 µgr/lt (p&lt;0.001).
The workplace and working conditions of workers and controls are shown in Table 1.

Workers at foundries have reported exposure to dust, chemicals and fumes in the workplace environment. Preventive measures in workplaces are not sufficient. Absence from work for more than one day due to work-related reasons was observed at a rate of 40%. The rate of job change due to health problems was low (7.1%).
Respiratory complaints of the workers and controls and the relationship of the complaints with the workplace are shown in Table 2.

The rates of cough, sputum, sputum production for more than 3 months a year, dyspnea, wheezing and smoking were significantly higher in the foundry workers. Complaints were also more likely to worsen at work and improve during holidays and weekends.
The mean percentage expected FVC value of the workers (93.4% to 101.4%, p=0.019) was significantly lower than the controls (Pulmonary function data was not shown). 
Urine Al values according to the presence of basic respiratory complaints in aluminum workers were compared in Table 3.

In aluminum workers, those with dyspnea had significantly higher urinary Al levels than those without dyspnea (13.5 µgr/lt vs 8.7 µgr/lt, p=0.048).
In the linear regression analysis, when age and smoking cofactors were taken into account, the presence of dyspnea was found to be independently effective on urinary Al levels (p=0.012, B=0.095, Exp (B)= 1.100, 95% C.I. for EXP (B)= 1.021-1.186).
Workers with dyspnea had a lower mean expected FVC than those without (84.1% vs 99.5%, p=0.004). The mean expected FEV1 of workers with dyspnea was lower than those without (79.8% vs. 97.8%, p=0.005).
There was no significant correlation between urinary Al levels of aluminum workers and respiratory function values. There were no significant differences in pulmonary function between smokers and non-smokers (results not shown).

DISCUSSION

In sectors in which Al is processed in different ways, the diseases and disorders caused by the Al dusts and the fumes containing Al in the respiratory system have been widely reported in the literature. However, in a small number of studies investigating the relationship between respiratory function disorders caused by occupational exposure to Al and Al levels in body fluids, it was observed that respiratory functions did not deteriorate despite high Al levels in the urine of workers 10, 11. In our study, the urine Al levels of the workers working in profile making with Al and working in casting process, heating and sanding of Al-containing material were higher and the mean % expected FVC values were significantly lower than the control group. Urinary Al levels were also significantly higher in workers with dyspnea, and the presence of dyspnea had an independent effect on urinary Al levels. Since urine Al level measurement is a noninvasive examination, more studies should be done examining its usage in monitoring work areas exposed to Al.
Studies reporting respiratory effects from occupational exposure to Al have also reported that complaints increased as the duration of the study increased. Chan-Yeung, in a study in Canada involving 1510 workers, found the frequency of coughing in the foundry to be 22.6% among those with heavy exposure and 14% among those with low exposure, while the frequency of wheezing was 17.1% and 10.5%, respectively. Researchers found no cases of asthma . Søyseth reported that longer working time led to 2 to 4 times more wheezing and chest pressure complaints among aluminum casting workers than in non-exposure groups 12. VanRooy et al., in their study of 182 Al casting workers, found the average daily respirable dust, metals, hydrogen fluoride, fluoride salts, sulfur dioxide values below the reference values in the workplace. However, intermittent CL gas was also observed in the workplace due to disruptions in the production process. Recurrent dyspnea (1.8%), wheezing (1.4%), asthma attacks (2.8%), and physician-diagnosed asthma (2.6%) were observed at different rates in workers 13. In our study, cough was observed in 52.4%, sputum 59.5%, wheezing 40.5% and dyspnea complaints in 40.5% of the workers. Respiratory complaints, which were more than 40% in our study group compared to the controls, and the fact that the symptoms were higher despite the short working time made us think that the protective measures in the relevant workplace were not sufficient. 
Chan-Yeung, in their study examining Al smelters, found that the FEV1 and MMEF values adjusted for age, height and smoking factors were significantly reduced in the comparison of heavily exposed smelters with controls. Although the respiratory functions of the workers with moderate exposure were lower than the controls, the difference was not significant. In this study, ambient dust and gas measurements were within normal ranges. 14. 
In a study by Choupani in Al smelters, Al exposure was evaluated by comparing urine Al levels and ambient Al measurements. Mean urine Al levels among workers in foundries in two different departments were 45.8 and 47.02 µgr/lt, and were significantly higher than the controls. However, there was no significant correlation between ambient Al particles and urine Al levels 15. In our study, while the average urinary Al level of the workers of the Aluminum Profile Factory was 10.7, it was 2.2 µgr/lt in the individuals in the control group. However, since the workers in our study were not only from the casting department, but also from the surface coating, hot forming, molding and paint shop departments, it may be that Al exposure may be generally lower than those observed in the study by Choupani. However, a limitation of our study was that ambient Al and other dust measurements were not performed, meaning that exposure has been evaluated only by measuring urine Al levels.

CONCLUSION

Urinary Al levels were high and FVC was low in workers of a factory producing aluminum profiles when compared to controls. There were no significant correlations between respiratory function and urinary Al level. Urinary Al levels were significantly higher among workers with dyspnea. It is suggested that the use of urinary Al levels for monitoring be evaluated by further studies as a noninvasive exposure monitoring method.

Acknowledge: This study is an extended version of the study titled “Pulmonary functions, respiratory complaints and radiographic findings in aluminum foundry workers” presented at the European-Respiratory-Society (ERS) International Congress 2017. DOI: 10.1183/1393003.congress-2017.PA4786

Thanks: Sakarya University, Faculty of Medicine, Department of Biochemistry, studying aluminum levels in urine. We would like to thank Prof. Dr. Mehmet Akdoğan for his efforts.

Ethics Committee Approval: The study was approved by Düzce University Faculty of Medicine Ethics Committee (ethics committee file no.: 2015/60 dated 06.10.2015)
Data Sharing Statement: The data that support the findings of this study are available from the corresponding author upon reasonable request

Authors’ Contribution: CB and PA conceived, designed and performed statistical analysis and editing of the manuscript. CB, PA, EGB, ANA & ÖB performed data collection and wrote the manuscript. PA and CB performed the review and gave final approval.

Grant Support & Financial Disclosures: None

Conflict of Interest: No conflict of interest was declared by the authors

Funding: The authors declared that this study received no financial support