DrMedSci. Syurin S.A., CandMedSci. Nikanov A.N., Syurina O.A.

Kola Research Laboratory for Occupational Health (Kirovsk, Russia)

SIGNIFICANCE OF BEHAVIORAL RISK FACTORS IN THE DEVELOPMENT OF BRONCHOPULMONARY DISEASES IN NICKEL INDUSTRY WORKERS

Introduction. The nickel production belongs to industries with hazardous working conditions, mainly related to exposure to aerosols of nickel compounds. Their inhalation into the human body results in toxic, allergenic and carcinogenic effects, creating an increased risk of chronic bronchopulmonary diseases (CBPD) [1]. However, not only the harmful working conditions, but also unhealthy lifestyle has a negative impact on the health of workers engaged in the production of nickel [5]. Establishing the significance of harmful behavioral factors in the development of CBPD in exposed workers is essential for improving the effectiveness of their prevention, particularly among persons engaged in the nickel industry.

The aim of the study was to examine the effect of harmful behavioral factors on the development of CBPD in nickel industry workers.

Materials and methods. A comprehensive clinical, functional and laboratory examination included 1216 workers engaged in electrolysis and carbonyl nickel productions at the Kola Mining and Metallurgical Company. In the present study, individuals were considered healthy if they had no clinical, functional and radiographic signs of respiratory pathology. In cases where there were risks of respiratory disease and / or clinical signs insufficient for the diagnosis of any CBPD, the surveyed persons were included in the risk group. The universally accepted diagnostic criteria of chronic bronchitis (CB), chronic obstructive pulmonary disease (COPD), asthma and toxic pulmonary sclerosis (TPS) were applied for determining the nosological forms of respiratory pathology.

Smoking, excessive alcohol consumption and obesity were considered as behavioral risk factors of CBPD. Total exposure to tobacco smoke was assessed by smoking index (SI) [3]. Consumption of alcoholic beverages at least once a week in a total dose equivalent to more than 100 g of 100% alcohol was considered as excessive [5]. Alimentary-constitutional obesity was diagnosed in cases when body mass index was equal to or greater than 30 kg/m². MicroSoft Excel 2007 and Epi Info, v. 6.04d were applied for statistical analysis of the collected data with determination of Student's t-criterion, criterion of consent χ², relative risk (RR) and its 95% confidence interval (CI). Numerical data are presented as mean and standard error (M ± m). Differences are considered reliable at p<0.05.

Results. Among the surveyed employees there were 896 (73.7%) men and 320 (26.3%) women. Their average age was 38.8 ± 0.3 years, and the average length of service at the enterprise amounted to 13.3 ± 0.5 years. As a result of medical examination ,718 (59.0%) employees were found healthy and the risk group included 243 (20.0%) people. Of bronchopulmonary diseases, CB was detected in 131 (10.8%), TPS in 66 (5.4%), COPD in 25 (2.1%), the combination of CB and TPS in 13 (1.1% ), and asthma in 7 (0.6%) patients.

Of the surveyed workers the number of smokers amounted to 634 (52.1%) whose average SI was 11.4 ± 0.4 pack-years. All women and 98.6% of men smoked cigarettes with a filter, and 1.4% of older men used cigarettes without filter (papirosas). None of those surveyed used pipe tobacco regularly. The nature of smoking had significant gender differences. Men, compared with women, initiated regular smoking at an earlier age: 21.3±0.6 and 25.7±1.1 years (p<0.01), respectively. Also, they smoked more cigarettes daily: 15.3±0.2 and 10.4 ± 0.4 cigarettes per day (p<0,001). The length of regular smoking time among men and women did not differ: 14.1±0.4 and 13.0±0.6 years (p<0.1). Due to a more intensive smoking SI (integral indicator of exposure to tobacco smoke) was higher in men than in women: 10.8±0.4 and 6.8±0.6 pack-years, respectively (p<0.0001). The maximum rates of smoking have been reported in persons under the age of 30 years (66.3% in men and 40.8% in women), and the minimum rates were recorded in persons of 50 years and older (51.1% in men and 23.2% in women).

Abuse of alcohol was recognized by 466 (38.3%) workers who were predominantly men (94.0%). Abstinence from alcohol for at least one year was claimed by 26 (2.1%) people (mostly after the successful treatment of alcohol dependence). Unlike smoking, the prevalence of excessive drinking was not dependent on the age of employees: 37.5%, 36.7%, 31.6% and 35.0% in the age groups under 30 years, 30-39 years, 40-49 years 50 years and over, respectively (p> 0.5-0.05). The characters of alcohol consumption and smoking are closely linked. The excessive use of alcohol, compared to its moderate use, was associated with a higher prevalence of smoking (58.2% and 41.9%, p<0.0001) and the more pronounced degree of exposure to tobacco smoke (8.32±0.51and 3.52±0.24 pack-years, p<0.001).

Alimentary-constitutional obesity was detected in 213 (17.5%) employees, which is more likely to occur in women than in men: 137 (15.3%) and 76 (23.8%) workers, respectively (p<0.001). The prevalence of lipid metabolism disorders in workers under the age of 30 years was 6.0% and was significantly (p <0,001) lower than in the age group 30-39 years (18.2%), 40-49 years (23.4% ), 50 years and older (22.6%). There were no significant differences in the prevalence of obesity among persons 30 to 50 years of age and older (p>0.5-0.05).

Given the existence of various harmful factors, there was a need to create five comparative groups of surveyed workers. The first group included workers with no harmful behavioral factors. The second, third and fourth groups consisted of individuals who were exposed to only one of the hazards studied. The fifth group included employees exposed to combined effect of all three factors. The analysis revealed a significant negative effect of smoking on the respiratory health of nickel industry workers (table). Among smokers there were less healthy individuals (p<0.001), more people at higher risk of CBPD (p<0.001) and CB patients (p<0.001) compared with employees who did not have harmful behavioral factors. As expected, smokers demonstrated high risk of developing CB: RR=4.34; CI 2.18-8.65; χ2= 21.1; p=0.0000043). Under the influence of smoking the formation of COPD was noted in 3.8% of workers, whereas in non-smokers (the first, third and fourth groups) not a single case of COPD was diagnosed (p <0,05). In contrast to the CB and COPD, smoking did not influence the development of asthma and TPS.

Table

Impact of behavioral risk factors for the development of CBPD in nickel industry employees (cases)

Clinical group	Without risk factors n=349	Smoking n=266	Excessive use of alcohol n=115	Obesity n=116	Combined impact of three risk factors n=69
Healthy	300 (86.0%)	135 (50.8%)	80 (69.6%)	88 (75.9%)	24 (34.8%)
Risk group	14 (4.0%)	72 (27.1%)	12 (10.4%)	14 (12.1%)	18 (26.1%)
CB patients	10 (2.9%)	32 (12.0%)	6 (5.2%)	6 (5.2%)	13 (18.8%)
COPD patients	-	10 (3.8%)	–	-	6 (8.7%)
Asthma patients	2 (0.6%)	2 (0.8%)	2 (1.7%)	-	1 (1.4%)
TPS patients	23 (6.6%)	16 (6.0%)	10 (8.7%)	8 (6.9%)	7 (10.1%)

The role of excessive use of alcohol and obesity in the development of respiratory health disorders in nickel industry workers was considerably less than smoking. Both factors only led to a decrease in the number of healthy individuals and an increase in the number of people in the risk group (p<0.05-0.01), without affecting the prevalence and degree of risk for developing CB, COPD, TPF and asthma. However, excessive alcohol consumption and obesity in combination with smoking (combined effect of three factors) intensified its negative impact, as compared with a group of workers without hazards, and those exposed to their effect. This was manifested in a significant reduction in the number of healthy individuals (p<0.0001) and an increased risk of CB compared to the first (RR = 7.66; CI 3.53-16.59; χ2 = 34.7; p =0.0000001), the third (RR = 3.86; CI 1.56-9.58; χ2 = 9.87; p=0.0016795) and the forth (RR=4.25; CI 1.71-10.58; χ2 = 11.5; p=0.0006967) groups of surveyed workers. The risk of CB was slightly below a level of statistical significance compared only with smokers: OR = 1.77; CI 0.99-3.13; χ2 = 3.61; p = 0.0574552). With the combined effect of all three hazards COPD prevalence reached 8.7% and the risk of its development was higher than in the group of workers exposed to tobacco smoke: RR = 2.71; CI 1.04-7.10; χ2 = 4.30; p = 0.0381437). The combined impact of the three hazards, as well as smoking alone, had no effect on the formation of asthma and TPS.

Discussion. The results of the study confirm that non-production harmful factors may largely determine the development of chronic respiratory pathology (primarily CB) in nickel industry workers [4, 6]. The most important of them is smoking, which is most common among young people. The lack of smoking effect on the risk of developing asthma confirms the modern idea that the pathogenesis of this disease is mainly associated with internal genetically determined factors. [2] Exposure to tobacco smoke has little effect on the formation of TPS, which is a further evidence of occupational etiology of this disease.

The impact of binge drinking and obesity on the development of chronic respiratory pathology was less pronounced than that of smoking. However, it leads to a decrease in the number of healthy individuals and an increased risk of developing CBPD. The combined effect of smoking, alcohol abuse and obesity on respiratory health of nickel industry workers is much higher than the negative effect of each of these hazardous factors separately. Mechanisms of alcohol-related bronchopulmonary disorders require further study. As an explanation it is possible to consider a direct damaging effect of alcohol on the surfactant system, alveocytes and bronchial epithelium during its partial removal from the body through the respiratory system. It is known that obesity may be a cause of respiratory failure, but its possible association with CB and COPD is not clear.

From a practical point of view it is important that the considered risk factors of CBPD belong to a group of modifiable factors and therefore the influence on them may be an effective way of improving respiratory health of nickel industry workers. Promoting a healthy lifestyle should start as early as possible, given the maximum prevalence of smoking among young people.

Conclusion. Not only harmful working conditions, but also a number of non-production factors have a significant negative impact on the development of CBPD in nickel industry employees. Smoking, excessive alcohol consumption and obesity, typical for an unhealthy lifestyle, reduce the number of people with no signs of respiratory disease and increase the risk of CB and COPD. Of the three harmful behavioral factors smoking is of the most important hygienic value. The combined effect of alcohol abuse and obesity increases the negative effects of smoking on the respiratory system. Taking into account the above, identification and management of modifiable behavioral risk factors for CBPD may be viewed as an efficient and cost-effective means of improving respiratory health of nickel industry workers.

References

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2. Global initiative for asthma. Global strategy for asthma management, and prevention. Update 2009. Available at http://www.ginasthma.org.

3. Global Initiative for Chronic Obstructive Lung Disease (GOLD). Global strategy for diagnosis, management, and prevention of chronic obstructive pulmonary disease. NHLBI/WHO workshop report. Update 2009. Available at: http: //www.goldcopd.com.

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5. Spein A.R. Smoking, alcohol and substance use. In: Health transitions in Arctic Populations /Ed. by T. Kue Young and P. Bjerregaard. University of Toronto Press Incorporated. Toronto, 2008: 205-216.

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