Health risks and occupational pathology in the extraction of fuel and energy minerals in the Russian Arctic (en)

Introduction Huge mineral resources of the Arctic zone of Russia have led to creation of the largest manufacturing facilities in the country in this area with extreme natural and climatic conditions. These include enterprises engaged in extraction of fuel and energy minerals. The largest oil and gas production enterprises are located in the Yamal-Nenets and Nenets Autonomous Okrugs.  Oil and gas are produced to a lesser extent in the Taymyrsky Dolgano-Nenetsky District of Krasnoyarsk Krai and the Chukotka Autonomous Okrug. Coal is mainly mined in Vorkuta and in lesser amounts in the Chukotka Autonomous Okrug and the Taymyrsky Dolgano-Nenetsky District [1, 2, 3, 4].

It is known that the combination of severe natural and climatic conditions of the Arctic regions with harmful working conditions accelerate formation and aggravate progression of many occupational diseases (PD) [5, 6, 7]. Fibrogenic aerosols [8, 9, 10, 11] are considered to be a specific harmful production factor in coal mining, and sulphur-containing compounds (hydrogen sulphide, mercaptans, carbon disulphide, sulphur anhydrite, sulphuric acid anhydride, sulfuric dust), which belong to the substances of the 2nd - 4rth hazard classes [12, 13, 14, 15], are considered to be specific harmful production factors in coal mining. Diseases arising as a result of extraction of minerals, primarily musculoskeletal and nervous systems, respiratory organs, sensorineural hearing loss (noise effects of the inner ear) are the main reason for premature occupational capacity decrement or loss [16, 17, 18, 19].
At the same time, the highest level of occupational morbidity in Russia is observed in coal mining, which in 2017 amounted to 103.11 cases per 10,000 workers [20]. Under conditions of limited human resources, premature termination of employment by qualified specialists is a serious obstacle to the social and economic development of the Arctic region [21].

The “Fundamentals of the state policy of the Russian Federation in the Arctic for the period up to 2020 and long term” [22] has set the task to achieve reliable operation of life support systems and production activities in this important region. Part of this task is to develop a set of measures aimed at preservation of the health and work capacity of the Arctic population.

The purpose of the study was to compare the working conditions and occupational pathology of workers involved in oil, gas and coal production in the Arctic zone of Russia.

Materials and methods. The data of social and hygienic monitoring “Working conditions and occupational morbidity” of the population of the Arctic zone of Russia in 2007-2017 were studied.  Information has been delivered by the Federal Hygiene and Epidemiology Centre of the the Federal Service for Supervision of Consumer Rights Protection and Human Well-Being, Moscow. They included data on the annual number of initially diagnosed patients with occupational diseases and their nosological form, the number of persons in contact with the harmful production factors and their nature, the types of economic activities of the diseased, and the type of economic facilities controlled by Rospotrebnadzor. 

The research results were processed using Microsoft Excel2010 software and Epi Info, v. 6.04d. The Student's t-test for independent samples, approval criterion, relative risk (RR) and 95% confidence interval (CI) were determined. Numerical data are presented in the form of arithmetic mean and standard error (M±m). Differences in indicators were considered significant at p<0.05.

  Results of the study. The data of 1,891 employees, who during the period of 2007-2017 were diagnosed with 2339 occupational diseases for the first time, were studied. Among them, 1,851 persons were employed in coal mining, including 1,777 in Vorkuta, 73 in the Chukotka Autonomous Okrug and 1 in the Taymyrsky Dolgano-Nenetsky District of the Krasnoyarsk Krai. There were 40 people employed in the oil and gas industry, including 34 in the Yamal-Nenets Autonomous Okrug, 4 in the Nenets Autonomous Okrug and 2 in the Taimyr Dolgano-Nenets district. The average age and length of service of the coal mining industry workers were less than that of the oil and gas industry workers, amounting to 50.9±0.1 and 54.2±0.8 years (p<0.001) and 24.5±0.1 and 26.9±1.2 years (p<0.05), respectively. Among the coal miners there were 56 (3.0%) women, while all the employees of oil and gas enterprises were men.

Working conditions in the mining industry were compared based on the average annual number of jobs at the facilities of various supervision groups of sanitary and epidemiological welfare in 2007-2017. It has been established that in coal mining there are no facilities of the first supervision group of sanitary and epidemiological welfare (jobs with satisfactory working conditions), and more than 90% of miners are employed in the facilities of the third supervision group (with extremely unfavourable working conditions). In contrast to miners, more than half of the oil and gas workers were employed in the facilities of first supervision group with satisfactory working conditions, and only 4% of them were employed at the enterprises of the third group of sanitary and epidemiological welfare with extremely unfavourable working conditions. For the number of workers present in each of the three supervised groups, the differences between coal miners and persons employed in the oil and gas companies were statistically significant. In general, there were almost 9 times as many oil and gas workers in the Arctic zone of Russia as there were miners of coal mining companies (Table 1).                                                                                                                                      

 Table 1. Average annual number of employees (absolute, %) at the facilities of supervision groups engaged in coal, gas and oil production in the Arctic in 2007-2017

 Table 2. Average annual number of employees (absolute, %) exposed to harmful production factors during coal, oil and gas production in the Arctic in 2007-2017 

Coal miners are more likely to have occupational diseases under working conditions of hazard classes 3.3 and 3.4. Harmful production factors determining development of occupational diseases are mainly severity of work, strongly fibrogenic aerosols and local vibration. All other factors account for only 13.4% of occupational diseases. In the vast majority of cases (92.6%), the reasons for harmful production factors are structural defects of machines, mechanisms and other equipment, as well as imperfection of workplaces. 

Oil and gas industry employees are more likely to be diagnosed with occupational diseases when working under hazard class 3.1 conditions.  In comparison with miners, occupational pathology is mainly developed because of exposure to noise and general vibration. A common risk factor for occupational diseases in both groups of workers is severity of work. In the oil and gas industry, 80.6% of cases of exposure to harmful production factors is related to imperfection of technological processes and workplaces (tab. 3).

Table 3.  The number of occupational diseases arising from various working conditions in coal, oil and gas production in the Arctic in 2007-2017 (absolute, %). 

The number of occupational diseases per miner was higher than an oil and gas worker had: 1.24±0.01 and 1.08±0.04 cases respectively (p<0.001). The nature of health disorders in the two groups of employees compared had significant differences (Table 4). Thus, within the structure of occupational pathology of miners, disorders of musculoskeletal system, respiratory organs and nervous system had a more significant proportion, and within the structure of pathology of workers of oil and gas enterprises, the most common were diseases of the ear and mastoid process, as well as injuries, intoxication and some other consequences of external causes. Miners had radiculopathy, chronic bronchitis and mono-polineuropathy among the three most common nosological units of occupational diseases.  Sensorineural hearing loss (inner ear noise effects), radiculopathy and vibration disease were the most common diagnoses of those engaged in gas and oil extraction.

Mineworkers were more likely to be diagnosed with occupational pathologies through periodic medical examinations (56.7%), while oil and gas production personnel were more likely to be diagnosed through self-administration due to health problems (62.8%). 

Table 4. Nosological structure of occupational pathology of employees in coal, oil and gas production in the Arctic in 2007-2017 (abs., %).

     In the Arctic zone of Russia, the annual number of coal miners who had their first occupational diseases, ranged from 108 (2007) to 223 (2013). The level of occupational diseases over the course of eleven years had a significant tendency to increase. All the years it was significantly higher than in oil and gas production in the Arctic zone of Russia, as well as in all types of economic activities in the Arctic zone of Russia and in Russia as a whole (Fig.). In 2017, the level of occupational diseases in coal mining in the Arctic was 2.82 times higher than the same national indicator (103.11 per 10,000 employees). The risk of occupational diseases in coal mining in Vorkuta and the Chukotka Autonomous Okrug did not differ significantly (RR=1.12; CI 0.90-1.40; χ2=1.11; p=0.2919).

The annual number of oil and gas production workers who first were diagnosed with occupational diseases varied from 0 to 7 people. The level of occupational morbidity in oil and gas production during the whole period of observation was lower than in coal production, as well as in all types of economic activities in the Arctic zone of Russia and nationwide. In 2017, these differences were 240.1 times, 9.28 times and 1.08 times, respectively (Fig.). In 2017, the level of occupational diseases in oil and gas production in the Arctic was 1.75 times lower than the same national indicator (2.12 per 10,000 employees). Employees of the main oil and gas producing regions - the Yamal-Nenets Autonomous Okrug and the Nenets Autonomous Okrug - did not have any significant differences in their health risks: RR=2.50; CI 0.89-7.05; χ2=3.23; =0.0724.

Comparison of probability of occupational pathology in the process of extraction of various fuel and energy minerals has shown that it is higher than that of oil and gas in the process of extraction of coal (RR=331.1; CI 242.2-452.5; χ2=1637.8; p<0.001), all economic activities in the Arctic (RR=15.1; CI 15.0-16.5; χ2=20009.5; p<0.001) and nationwide (OP=224.6; CI 195.8-257.5; χ2=44275.4; p<0.001). In oil and gas production, the risk of occupational diseases development was lower than in all economic activities in the Arctic (RR=0.05; CI 0.03-0.06; χ2=767.0; p<0.001) and was close to the nationwide level of occupational diseases (RR=1.08; CI 0.52-2.27; χ2=0.04; p=0.8334).

Conclusion:  In 2007-2017, there was no significant improvement in working conditions at coal mining enterprises in the Arctic zone of Russia. The level of occupational morbidity of Arctic miners is 2.82 times higher than the national figures for coal mining and has no tendency to decrease. Compared to miners, oil and gas workers have significantly less harmful working conditions and a low level of occupational diseases. In view of the above, comprehensive measures to protect the health of coal miners in the Arctic are a priority area of work for occupational safety and medicine professionals. 

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