Syurin S.A., DrMedSci.

Kola Research Laboratory for Occupational Health (Kirovsk, Russia)

OCCUPATIONAL PATHOLOGY IN APATITE ORE MINERS OF THE KOLA HIGH NORTH

Introduction. Most apatite ore miners of the Far North have unhealthy working conditions due to cooling workplace microclimate, vibration, noise, physical overload, work in forced and awkward positions, dust and gas mixtures [1, 2]. Adverse impact of the above production factors significantly increases the risk for developing disorders of musculoskeletal, nervous, cardiovascular and respiratory systems, hearing and visual impairment [4].

The aim of the study was to examine the prevalence, structure and features of formation of occupational diseases in the Kola High North apatite ore miners.

Materials and methods. Data on occupational diseases of Kola High North apatite ore miners for the years 1964-2012 were obtained from archival documents stored at Kola Research Laboratory for Occupational Health (Kirovsk, Murmansk region). The character of miners' working conditions was determined by the results of workplace certification based on their severity and intensity, the parameters of the microclimate, physical, chemical and dust factors. 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, Pearson´s correlation coefficient (r), 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.

The results. We found information on 1150 cases of occupational diseases newly diagnosed during the period 1964-2012 in 663 apatite miners (1.73 ± 0.05 cases per employee). Among them there were 662 men (99.8%) and one woman (0.2%) with an average age 45.9 ± 0.4 years and the experience of work at the enterprise 20.1 ± 0.3 years. In recent years there has been a steady upward trend in the detection of occupational diseases in apatite ore miners (employees of JSC “Apatite"). Thus, 67 patients were identified in 2001-2003, 80 patients – in 2004-2006, 113 patients - in 2007-2009 and 115 patients - in 2010-2012.

The ratio of underground and surface mine workers among patients with occupational health disorders was 3.9:1 (529 and 134 patients), whereas the average ratio of miners employed under and above the ground was only 2.2:1. Occupational diseases were most frequently diagnosed in tunnellers, drillers and blasters. They were much less prevalent in drivers of various vehicles (heavy trucks, excavators, electric locomotives, scoop trams), timber-men and workers in other professions (see Figure).

Figure. The incidence of occupational diseases among workers of different

professions (number of cases).

According to the hygienic assessment of working environment factors, working conditions of tunnellers (hand and mechanized excavation), hole drillers and drilling rig operators were defined as harmful of third - fourth degree (3.3 - 3.4). Working conditions of blusters, timber-men, breakage face workers, drivers and operators of various cargo-hauling vehicles and mechanisms are rated as harmful of first - second degree (3.1-3.2).

The structure of occupational pathology of apatite ore miners was dominated by diseases of the musculoskeletal and peripheral nervous systems, vibration disease and neurosensory hearing loss. Together, they accounted for 95% of all cases (Table 1). The shortest length of service prior to the development of occupational pathology was observed in tunnellers and drillers and it was shorter (p<0.05-0.001) than that of heavy truck drivers, timber-men and cargo-hauling vehicle operators.

Table 1

Structure of occupational pathology in apatite ore miners

№	Type of health disorders	Structure
		Number of cases	%
1	Diseases of musculoskeletal system	384	33.4
1.1	Humeroscapular periarthrosis	136	11.8
1.2	Deforming osteoarthrosis	96	8.3
1.3	Humeral epicondylitis(osis)	64	5.6
1.4	Antebrachial myofibrosis (pathosis)	65	5.7
1.5	Myofascitis	20	1.7
1.6	Other diseases	3	0.3
2	Vibration disease	225	1.6
2.1	Vibration disease (first stage)	89	7.7
2.2	Vibration disease (first – second stage)	61	5.3
2.3	Vibration disease (second stage)	75	6.5
3	Diseases of nervous system	271	23.6
3.1	Chronic radiculopathy (cervical-thoracic and lumbosacral levels)	102	8.9
3.2	Angioneurosis (angiotrophoneurosis) of upper limbs	53	4.6
3.3	Reflex syndromes of the cervical and lumbar levels	89	7.7
3.4	Vegetative (autonomic-sensory) polyneuropathy	24	2.1
3.5	Other diseases	3	0.3
4	Neurosensory hearing loss	212	18.4
5	Cataract	24	2.1
6	Diseases of respiratory system	25	2.2
6.1	Chronic brochitis	16	1.4
6.2	Pneumoconiosis	4	0.3
6.3	Bronchial asthma	3	0,3
6.4	Diseases of upper respiratory tract	2	0,2
7	Diseases of other organs and systems	9	0,8

The greatest number of diseases diagnosed in one worker was registered in timber-men and underground mine workers, which was higher than that of loading and haul equipment operators (p<0.05), heavy truck drivers (p<0.02), tunnellers (p<0.01 ) and blusters (p<0.05) (Table 2). The highest risk of health problems was observed in tunnellers and drillers, which include, respectively, 38.6% and 16.0% of all patients.

Table 2

Specific features of occupational pathology in apatite ore miners

Group of workers	Length of service	Number of cases per worker	Health disorders ( % )
			Musculo-skeletal system	Nervous system	Vibration disease	Hearing loss	Others
Tunnellers	16.7±0.4	1.46±0.05	31.1	12.7	42.0	13.0	1.2
Drillers	17,7±0.7	1.81±0.09	44.1	24.7	15.9	12.9	2.4
Blusters	19.8±1.1	1.57±0.10	38.5	15.6	1.0	19.8	25.0
Timber-men	23.2±1.1	1.94±0.14	58.8	13.2	7.3	19.1	1.5
Cargo-hauling vehicle operators	22.3±0.8	1.59±0.07	26.9	27.5	9.0	32.9	3.8
Heavy truck drivers	24.0±1.4	1.53±0.08	17.2	44.8	6.9	27.6	3.4

The nature of occupational diseases of apatite ore miners was largely determined by the peculiarities of their professional activity. Vibration disease was the most frequent health disorder in tunnellers (42.0%) with the risk of its development being higher than that in all other miners (RR = 4.69; CI 3.46-6.36; χ2 = 135.8; p = 0.0000001), including drillers with similar working conditions (RR = 2.33, CI 1.73-2.86; χ2 = 35.6; p = 0.0000001). The timber-men and underground mine workers are at higher risk of developing diseases of the musculoskeletal system (RR = 2.25; CI 1.69-2.99; χ2 = 17.9; p = 0.00002). The heavy truck driver are most likely to suffer from disorders of peripheral nervous system, primarily chronic lumbosacral radiculopathy (RR = 3.36; CI 2.68-4.20; χ2 = 53.4; p = 0.0000001) as compared to other miners.

Neurosensory hearing loss was most common among cargo-hauling vehicle operators and heavy truck drivers (p<0.05-0.02) with high risk of development in comparison with all other workers of the mine (RR = 3.36; CI 2.68-4.20, χ2 = 53.4; p = 0.0000001). Cataract developed almost exclusively (23 of 24 cases) in the blusters due to the impact of toxic components of explosive materials.

Severity of occupational health problems of miners increases with length of service. At a length of up to 10 years, one employee was diagnosed to have 1.21 ± 0.07 cases of occupational diseases. At the experience of 10-19 years, their number increased to 1.55 ± 0.05 cases (p<0.02), and at the experience of 20 years and more reached the highest level of 1.77 ± 0.06 cases per worker (p<0.05). The severity of symptoms of vibration disease intensified with increasing duration of exposure to harmful factors: the first degree of the disease was diagnosed at the experience of 15.1 ± 0.6 years, and the second – 20.6 ± 0.9 years (p<0.001). There was a direct correlation of pathological changes in vibration disease with the length of service (r = +0.25, p<0.01).

Discussion. The current conditions in the extraction of apatite ores in the Far North predominantly contribute to the development of diseases of musculoskeletal and peripheral nervous systems, vibration disease and neurosensory hearing loss. The above health disorders are more prevalent among employees of underground mines as compared to workers employed at open pit mines. The formation of work-related health problems is mainly determined by the influence of physical factors: vibration, cooling microclimate, noise, adverse ergometric parameters. Toxic chemical substances and dust which may cause cataract and respiratory diseases are of much less importance. The risk of developing pathological conditions in apatite ore miners and their severity are directly related to an increase in length of service.

The structure of identified occupational pathology in general is consistent with previous studies [3, 4]. In recent years, there has been a steady trend towards increased prevalence of occupational diseases among apatite ore miners of the Kola High North. In all probability, this fact can not be explained by the deterioration of miners´ health but can be attributed to more qualified periodic medical examinations.

Conclusions. The findings suggest the need to improve working conditions of apatite miners and, above all, those of tunnellers and drilling rig operators. Special attention should be paid to the development of more effective prevention of locomotor system disorders, vibration disease and hearing loss.

References

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2. Skripal B.A., Nikanov N.A. The role of professional and industrial risk factors in the formation of morbidity rates in underground miners in the Kola North. Ekologiya cheloveka. 2005; 5: 10-13 [in Russian].

3. Skripal B.A. Occupational morbidity, its features on enterprises of mining and chemical complex in Kola Polar region. Ekologiya cheloveka. 2008; 10: 26-30 [in Russian].

4. Syurin S.A., Rocheva I.I., Burakova O.A. General and occupational morbidity in apatite ore miners in Kola Polar region. Zdravookhranenie Zapolyariya. 2010; 1: 34-38 [in Russian].