This study was conducted to examine the relationship between PSHI at the workplace and occupational injuries in a large-scale nationally representative sample of South Korean workers. We hypothesized that the importance of PSHI would differ depending on the risk of occupational injuries. Therefore, to determine the significance of PSHI related to occupational injury risk level, and because various characteristics of workers differed depending on their risk of occupational injury, the subjects were divided into two groups based on injury risk. In the high-risk group, there was a statistically significant relationship between PSHI and occupational injuries, and the occupational injury rate of workers without PSHI was up to 1.81 times higher than the rate in those with PSHI. Therefore, the better the safety information provided at the workplace, the fewer work-related injuries occurred, which is consistent with the results in previous studies. For example, a study that analyzed the characteristics of Korean wage workers during the 1st KWCS, conducted in 2006, showed that the odds ratio of occupational injuries in the group without PSHI was 1.29 (95% CI 1.05–1.59) [7]. In another investigation that assessed occupational injuries in Korea with health insurance and industrial accident insurance information, the rate of occupational injuries was higher in those who did not receive accident prevention education at the workplace than in those who did (OR 1.62, 95% CI 1.42–1.84) [12]. In addition, according to Ghosh et al., poor safety performance by workers was significantly associated with occupational injuries (adjusted OR 3.10, 95% CI 1.45–6.63) [13]. Moreover, in an overview which summarized ten studies on the association between organizational and workplace factors with injury rates, an active role of top management in health and safety was associated with lower injury rates [14]. Thus, safety education and training within the workplace function as precautionary measures against occupational diseases, such as hearing and vision loss, as well as against occupational injuries [15, 16].
Statistically significant relationships between workers’ characteristics and PSHI status were detected in almost all characteristics analyzed in this study. The presence of PSHI was low when there were few employees and no labor unions, which is consistent with prior research [7]. This is because small companies and those without unions are thought to be unable to devote resources to safety aspects due to fiscal constraints in a highly competitive environment. As of 2005, the proportion of training investments in all investments by companies with fewer than 30 employees (0.2%) was less than one-eighth that of large enterprises (1.64%) with 1000 or more employees; on that basis, Kang et al. suggested that organizations providing technical support to small-scale workplaces should determine the risks in those workplaces and implement suitable customized safety education [17]. Women and the pink-collar group also had low PSHI status, which may be related to the relatively high proportion of females working in the service sector: In this study, 69.9% of pink-collar workers were women and the occupational injury incidence was highest for the high-risk group in the pink-collar category. This result suggests that PSHI at the workplace is urgently needed, not only for blue-collar workers but also for those in service-type occupations. The PSHI status was low in the group without a need for PPE but, in the group that did need it, a high PSHI status was observed in the workers wearing the PPE, suggesting that PSHI presence may lead to a high PPE usage rate.
With regard to PSHI prevalence, a study based on 2006 KWCS data reported that 4018 out of a total of 6998 workers (57.4%) were listed as having a PSHI [7]. In our 2014 study, there was a slightly higher PSHI prevalence (64.2%). In other words, the absence of PSHI declined from 43.6 to 35.8% over approximately one decade. This may be the result of emphasizing the importance of safety and health education, including the revision of the OSH Act. However, it seems that the absence of PSHI is still high; thus, more rigorous education on the effects of PSHI is needed.
Characteristics associated with occupational injuries differ depending on the injury risk: In the low-risk group, the factors that had statistically significant relationships with occupational injuries were: old age, low education level, low monthly income, blue-collar occupation, long working hours per week, being a temporary worker, physical, biochemical, and ergonomic, as well as the need for PPE. Many results in the low-risk group were consistent with those reported in previous studies. Generally, advanced age and high physical demands at work have been associated with an increased risk of musculoskeletal claims [18], likely leading to occupational injuries. Workers with small incomes and low levels of education had high occupational injury rates. A Korean study that examined different samples during the same year reported that, as workers’ income and educational status increased, their occupational injury experiences decreased [19]. A blue-collar status and long working hours were associated with a high rate of occupational injuries, and construction workers (i.e., blue-collar) in the USA who worked long hours were at high risk of occupational injury [20]. Temporary workers had a lower PSHI status than that of regular workers, and their incidence of occupational injuries was higher, demonstrating the vulnerability of temporary workers to occupational injury [21, 22]. In the present study, physical and biochemical risk factors at the workplace and PPE use were closely related to occupational injuries, which is consistent with results in previous investigations [23, 24]. With regard to PPE use, the proportion of respondents who did not need a PPE was 86.2% in the low-risk group and 47.8% in the high-risk group. PPE status displayed the most significant difference among the study characteristics related to the risk of occupational injuries; therefore, the necessity of wearing a PPE is the most important factor that indirectly indicates the risk of occupational injuries. Generally, shift work is associated with a high occurrence of occupational injury. In a study into the first KWCS dataset, the odds ratio of occupational injuries for workers in shift work was 2.40 (95% CI 1.65–3.50) [25] with similar results reported in overseas investigations [26, 27]. There was a high level of occupational injuries in workers with shift work in the low-risk group, but the result was not statistically significant.
In the high occupational-injury risk group, the factors showing statistically significant associations with occupational injuries were: age, monthly income, working hours per week, tenure, the existence of labor unions, physical, biochemical, PPE usage. Age, monthly income, and working hours per week exhibited no significant relationships with injuries in the high-risk group. Whereas long tenure, absence of labor unions, presence of physical and biochemical risk factors, as well as the need for PPE were associated with an increased occurrence of occupational injuries. There was a high incidence of occupational injuries in workers without labor unions, which can possibly be explained by the relatively few opportunities for individual workers to improve safety and health at work. Notably, PSHI status was significantly low in the absence of unions. Thus, it is necessary to offer options to employees encouraging regular participation in activities to improve safety and health issues at workplaces without labor unions [12]. Being male, in a small company, and ergonomic risk factors were associated with many occupational injuries in a previous study [28], but, in the present study, those relationships were not statistically significant.
Generally, the risk of occupational diseases is higher in smaller companies [29]. This is because workers in small- and medium-sized firms may be exposed to more health-hazard risk factors [30]; it seems that if an organization’s size is large, it can provide safety information more effectively and also systematically control worksite exposure to harmful factors [12]. In previous studies, an increase in injury risk among those who started a new job and an inverse relationship between job tenure and injury risk were observed [31, 32]. However, our study revealed the opposite in the high-risk group with the lowest occupational-injury rate observed in workers with less than 1 year of job tenure. This difference may be due to the particular sampling characteristics or to the control of additional variables in the other investigations. Alternatively, it could be that the more experienced the laborers, the higher the likelihood they work in a more dangerous job. Furthermore, as employees become accustomed to this level of danger, they may be subject to more frequent hazards due to momentary neglect or distraction during work.
In the low-risk group, the relationship between PSHI and occupational injuries was not statistically significant, but this does not indicate irrelevance of PSHI for these workers. We assert that groups differing in their risk of occupational injuries need different approaches depending on their likelihood of falling victim to job-related hazards. The statistically significant differences between the two risk groups were in occupational type, exposure to risk factors, and PPE use. In other words, blue-collar workers with exposure to physical and biochemical risk factors, as well as in need of PPE, are more susceptible to occupational injuries than other employees. The low-risk group results in this study were similar to those in previous studies. However, the high-risk group showed significant associations; mostly for job-related factors including physical, biochemical, and ergonomic risks, and the need for PPE. This indicates that high-risk workers are more likely to be affected by factors that are directly work related, such as the exposure to specific risk factors and wearing a PPE, rather than to more general or indirect factors. Therefore, PSHI might be more important in the high-risk group. This may account for the differences of occurrence of occupational injury between the low-risk group and the high-risk group.
This study has several limitations. First, because the KWCS has a cross-sectional design, the association between PSHI and occupational injuries may be bi-directional and, therefore, causality cannot be established; however, it is very plausible that PSHI has reduced the occurrence of occupational injuries. Second, because this study was based on questionnaires, some limitations, such as a recall bias, may be present in the data. Moreover, a “healthy user bias” could also be present; for example, in the case of critical or fatal injuries, the subject would not be able to respond to the questionnaire. Thus, there is a possibility that the incidence of occupational injuries was underestimated in this study [33]. Nonetheless, there was a statistically significant association between PSHI and occupational injuries in this study, suggesting that PSHI has a greater role in preventing occupational injuries than was expected. Our categorization of a high risk of occupational injury may not have been sufficiently objective; however, considering that it is difficult to judge injury risk as high or low by only assessing the existence and degree of harmful factors, our measurement approach appears rational. Third, we were unable to investigate the details of the occupational injuries such as the nature of the trauma, its severity, treatment, and sequelae.
In spite of these limitations, one of this study’s strengths is its epidemiological nature, which allowed us to examine the relationship between PSHI and occupational injuries in a nationally representative sample of the South Korean population. Fabiano et al. [34] classified the factors influencing occupational accident frequency into (1) technical, (2) economic, (3) labor organizational, (4) environmental, and (5) human, both individual and inter-individual. The KWCS includes these various occupational-injury-affecting factors, and its data were thus appropriate for our investigation. In addition, since the KWCS is conducted every 3 years, follow-up or repeated studies on the associations between occupational injuries and various characteristics might be useful in revealing secular trends and may serve as a basis for future studies into injury reduction in the workplace.
