Manganese exposure and sleep quality in iron and steel industry workers

Manganese (Mn) is an essential element crucial for the proper functioning of the human body. However, excessive exposure to manganese can lead to complications, particularly neurotoxicity. Among the health issues associated with exposure to heavy metals, one of the major concerns in the adverse effect on sleep quality. A total of 189 employees from a steel factory were divided into two groups: exposed (149 people) and non-exposed (40 people). Air samples were collected using the NIOSH 7300 method, and blood samples were obtained at the end of each shift. The samples underwent analysis by ICP-OES after preparation using the acid-thermal digestion method. To gather information on sleep quality, the Petersburg Sleep Questionnaire (PSQI) was used. The data collected in this study showed abnormal conditions, leading to the inclusion of medians alongside averages. The participants had an average age of 35 and an average work experience of 6 years. The exposed group had a significantly higher median respiratory exposure to manganese (1.32 mg/m³) compared with the non-exposed group (0.20 mg/m³). The average sleep quality score in the exposed group was significantly worse (score of 7) compared with the non-exposed group (score of 4). In addition, there was a significant relationship between the quality of sleep and the level of manganese in the air, so that the quality of sleep decreases with the increase in the level of manganese in the air (<i>p</i>-value = .005). However, no significant relationship was observed between blood manganese level and air manganese level in the exposed group (<i>p</i>-value = .06).