Our research goal was to examine cognitive functions parameters in dynamics among workers employed at an oil extracting facility depending on their work experience under exposure to adverse occupational factors. We estimated cognitive functions in 292 oil and gas extraction operators who were exposed to adverse occupational factors (aromatic hydrocarbons, hydrogen sulphide, occupational noise, labor hardness, and adverse microclimate). The reference group consisted of 65 administrative workers employed at the same enterprise. All the examined people were males aged 20–65; they were divided into several sub-groups depending on their work experience: the 1st subgroup, work experience shorter than 10 years; the 2nd subgroup, 10–20 years; the 3rd sub-group, longer than 20 years. All the subgroups were comparable as per average age (р>0.05). Nervous systems diseases that caused cognitive deficiency were a criterion for exclusion from the research groups. We performed neural-psychological examination using «NS-Psychotest» computer complex («Concept exclusion», short term memory tests for pictures and figures, square number test). To analyze dependence between cognitive disorders and work experience duration in the test and reference groups, we calculated relative risk and its 95% confidence interval (results are given as RR (95% CI)). We also performed one-factor linear regression analysis of dependence on work experience separately for each parameter of examined cognitive functions. Oil and gas extraction operators tended to have 1.3–1.6 times lower cognitive flexibility, picture and number memory, and attention than people who worked under permissible working conditions at their work places. Oil and gas extraction operators with their work experience being equal or exceeding 10 years ran more than 5 times higher risk of cognitive disorders; memory, attention, and analytical activity parameters were lower among them 2–3 times more frequently. Basing on relative risk calculation and one-factor linear regression analysis, we established a correlation between cognitive disorders development and work experience duration. Periodical medical examinations provided for oil and gas extraction operators should include neural-psychological tests that assess memory, attention, and cognitive flexibility since it will allow diagnosing cognitive dysfunction at an early (pre-dementia) stage and revealing people with its minimal signs for further profound examination, prevention activities, and occupational examination.
Relationship between Soil and Vegetation in an Oil and Gas Polluted Environment as Revealed by Regression Analysis
