*112359*
*112305*
S. A. Syurin, MD, DrMedSci.
Kola Research
Laboratory for Occupational Health, Kirovsk, Russia
Risks for
occupational pathology in workers engaged in nickel and copper production in
the Kola North
Introduction. At all stages of the process of nickel and copper
production, that is, from the extraction of copper-nickel ores and to the release of
commercial products, industry workers are exposed to hazardous occupational factors that create an
increased risk of occupational diseases [2, 3]. Despite
general similarities, each technology section of the copper-nickel production
has its own characteristic features in the spectrum and mechanism of harmful
factors action [1]. Currently, however, the
literature does not present the results of the comparative evaluation of the
risk of health problems on exposure to harmful factors of the different
sections of copper and nickel production.
The aim of the study was to examine the levels of risk of occupational diseases upon exposure to harmful
factors at the different sections
of the copper-nickel production in the Kola North.
Materials and Methods. An analysis of occupational morbidity of copper-nickel
industry workers was based on the archival data accumulated in Kola Research Laboratory for
Occupational Health (Kirovsk, Murmansk region). Archival materials included all cases of
occupational diseases registered in the
Murmansk region for the period from 1975 to 2010. Assessment of working conditions was conducted in accordance with the results of job place attestation (Guidelines
2.2.2006-05). MicroSoft Excel 2007 and the program 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 when p is less then 0.05.
The results. In the archival
materials there was information on 1103 cases of newly diagnosed occupational diseases among 708 employees of Kola
Mining and Metallurgical Company. Of those 283 workers were occupied in underground and
open extraction
of
nickel-copper ore. Three hundred and sixty-two and 58 workers were employed in
different types of nickel and copper production, respectively. From anong the
362 nickel production employees, 178
people worked in pyrometallurgical, 144 people - in hydrometallurgical and 40 people - in carbonyl shops of the
metallurgical plant. Fifty-two and 6 people were employed in pyrometallurgical and electrolytic copper production, respectively. Occupational diseases (OD) were also detected in 6 auxiliary shop workers, who were only periodically exposed to harmful factors while performing production tasks in the main
metallurgical shops. The prevalence of OD in this group of employees was taken
as the level of control.
Working conditions in the
mines and main metallurgical shops meet requirements of hazard class 3.1-3.4. For miners, such factors as exposure to vibration, the intensity of labor and unfavorable
microclimate parameters in underground and opencast mines are of major hygienic
importance. Water-insoluble
aerosols of nickel compounds and sulfur dioxide are the leading hazards in pyrometallurgical processing of nickel and copper. Water-soluble nickel
compounds and nickel tetrakarbonil are the main hazards in hydrometallurgical and carbonyl productions of nickel, respectively. The largest number of jobs with the most dangerous
working conditions (class 3.3-3.4) were found in the nickel carbonyl shop, and
the smallest - in the copper electrolysis shop. Working conditions of auxiliary
shop employees
corresponded to the class 2 (admissible) in the main workplace and to the classes 3.1-3.2 while carrying out temporary tasks in the
metallurgical shops.
At the time of OD detection there were no significant differences among seven groups of employees with regard to the age and length of
service in the company. The mean age ranged from
48.1 ± 0.9 to 49.9 ± 0.5 years (p> 0,05) and the experience - from 19.7 ±
1.2 to 23.0 ± 3.2 years (p > 0.5). The structure of the OD in the groups of
miners and metallurgists was fundamentally different (Table). In the first group it was dominated by pathology of the
musculoskeletal and nervous systems including vibration disease (78.4%), while
in the second group it was predominantly represented by respiratory diseases (94.9%).
Table
Pattern and prevalence of occupational diseases
(cases and %)
Of the respiratory diseases (figure) chronic bronchitis was the most frequently diagnosed ill-health condition (79.1%). Toxic pneumosclerosis, exogenous fibrosing alveolitis and asthma were significantly less prevalent. There were substantial differences in the structure of the respiratory diseases in different groups of workers. The high prevalence of asthma was characteristic of nickel electrolysis production employees (11.6%) and the high prevalence of toxic pneumosclerosis was typical of nickel carbonyl production workers (37.0%)
Figure. Pattern of
occupational respiratory diseases.
The risk of OD in each of the selected occupational groups was
calculated taking into account the reference level of OD prevalence rate and the average annual
number of employees. The lowest risk of developing OD was in the group of copper electrolysis workers which did not exceed the reference level (RR = 1.38; CI 0.43-4.49;
χ2 = 0.29; p = 0.5888234). In the other groups of
workers the risk of OD was significantly higher than both in auxiliary and
copper electrolysis shop workers. In relation to the
control level, an increase in the risk of OD was noted in the following order of production shops: pyrometallurgical
processing of copper (RR = 5.52; CI 2.38-12.77; χ2 = 20.65; p =
0.0000055), pyrometallurgical processing of nickel (RR= 5.66; CI 2.52 -12.70; χ2 =
23.38; p = 0.0000013), extraction of copper-nickel ores (RR=6.67; CI 2.99-14.91; χ2 =
30,11; p = 0.0000001), electrolysis nickel production (RR=6.78; CI 3.01-15.27;
χ2 = 30.03; p = 0.0000001), nickel carbonyl production (RR =8.24; CI 3.52-19.29;
χ2 = 34.64; p = 0.0000001).
Of the pyrometallurgical
production employees OD
were most
often identified in smelters (32.0% of
all cases), of the
electrolysis
production employees - in elelectrolysis bath
operators
(38.9%), of the carbonyl production employees – in operators of the production equipment of all
specialties (35.0%). Tunnelers and
drilling rig operators were most prone to the formation of OD among
the miners: 45.6% and 16.6% of all cases, respectively. The risk of developing OD in nickel production
smelters was 1.98 (CI 1.51-2.59;
χ2 = 22.73; p = 0.0000019) and in copper production smelters - 2.94 (CI 1.75-4.96; χ2 =
16.54; p = 0.0000512) as compared with workers in other professions.
The risk of OD among electrolysis bath operators was ignificantly higher than that of other
specialties workers engaged in electrolysis nickel production (RR =
1.60; CI 1.16-2.20; χ2 = 8,03; p = 0.0045905). Frequent detection of OD in equipment operators
of the
carbonyl nickel production was related to their size, rather than an increased
risk of occupational etiology of health problems (RR=0.80; CI 0.44-1.44; χ2 =
0/57; p = 0. 4484601).
Discussion. The study showed that
the greatest risk of occupational pathology is observed in nickel carbonyl production workers and it is equally high in technicians
for all
major trades. This fact can be associated with exposure to aerosols of
nickel tetrakarbonil at all technological stages of production. Less harmful working conditions for workers of pyrometallurgical production of
copper and nickel, as well as nickel electrolysis production can explain lower risk of developing OD in these groups
of employees as compared with nickel carbonyl production. However, it was significantly higher then the level of risk
observed among workers of auxiliary facilities. The greater exposure to
harmful factors in tunnelers and operators of drilling rigs, smelters and elelectrolysis bath operators (class 3.3-3.4) increase
the risk of OD formation
compared with other professionals of the corresponding types of production.
Conclusion. It is necessary to introduce a set of measures of
technical and medical nature to reduce the risk of ill health of professional etiology in copper-nickel industry workers. This problem is
particularly relevant for such categories of workers as tunnelers and drilling rig operators in copper-nickel ore mines, smelters in copper and nickel production, nickel
elelectrolysis
bath operators and all employees engaged in the
nickel carbonyl production.
References
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Nikanov A. N., Chashchin V. P. Ekologiya cheloveka [Human Ecology], 2008, no.
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Profilaktika professional'nykh zabolevanii organov dykhaniya i perifericheskoi
nervnoi sistemy u rabotnikov nikelevoi promyshlennosti Severa Rossii: posobie
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nervous systems nickel industry workers in the Russian North]. Sankt-Peterburg,
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