Background: The aim of this study was to examine the relationship between the provision of safety and health information (PSHI) and occupational injuries. Methods: This study was based on data from the 4th Korean Working Conditions Survey (KWCS) (2014). The sample consisted of data from 24,527 wage workers and was divided into high-risk and low-risk groups, depending on the probability of occupational injury. The high-risk group included subjects who could cause harm to themselves or others due to errors during work. We applied chi-squared tests and logistic regression analyses to examine the relationship between PSHI and occupational injuries. Results: In the high-risk group, workers with no PSHI showed an adjusted odds ratio of 1.81 for occupational injury (95% CI 1.33–2.47). In contrast, there was no statistically significant relationship between PSHI and the incidence of occupational injury in the low-risk group. Conclusions: To prevent occupational injuries, multi-faceted approaches that take different levels of injury risk into account are needed. Among workers with a high risk of occupational injury, more a stringent safety education program is required. Keywords: Safety and health information, Occupational injury, KWCS Background system was designed to report suspected cases of Occupational injuries do not only have serious personal occupationally acute poisoning, as well as to share effects, but they can also result in loss of life and/or case information, conduct field surveys, and undertake property. In the case of industrial accidents in South epidemiologic surveys at regional intervention centers. Korea, direct and indirect economic losses in 2015 were In addition to such follow-up efforts, the prevention of estimated at 20.3 trillion Korean won . This was an injuries and diseases is also important. Many researchers increase of 3.89% from 19.6 trillion won in losses in and policy-makers have recognized that occupational and 2014, indicating an increasing trend despite a decrease non-occupational factors may simultaneously contribute in the industrial accident rate . In order to reduce to worker safety and health [3, 4]. A primary step in the such economic damage related to occupational injuries, prevention of disease not only includes improvement of the Korea Occupational Safety & Health Agency has workers’ health but also identification and elimination of been operating an “Occupational Acute Intoxication and various risk factors for occupational diseases . Several Injury Management System” in Incheon City . That types of health information and data from the behavioral sciences have contributed to reducing mortality and mor- bidity as well as injury- or disease-related complications * Correspondence: firstname.lastname@example.org . Therefore, prevention of occupational injuries and Department of Occupational and Environmental Medicine, Dongguk University Gyeongju Hospital, Gyeongju-si, Gyeongsangbuk-do, Republic of diseases, as well as the provision of safety and health Korea © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Seo et al. Annals of Occupational and Environmental Medicine (2018) 30:36 Page 2 of 13 information (PSHI), are essential for all workers. The General characteristics Korean Occupational Safety and Health (OSH) Act was The subjects’ general characteristics included sex, age, enacted in 1981, and since a revision in 1990, there has education level, and monthly household income. The been promotion of a systematic workplace health manage- educational level was divided into three groups: (1) middle ment project. A number of papers related to occupational school or below, (2) high school, and (3) college or above. health education practices and occupational health care The monthly household income level was categorized as providers have been published, but most have focused on follows: less than 1.5 million Korean won (KRW), 1.5– manufacturing or secondary industries . An interest in 2.49 million KRW, 2.5–3.99 million KRW, and 4 million occupational health has spread to various fields, but the KRW and above. importance of and concern about PSHI have not been sustained . For example, in 2004, only 56.1% of workers received safety and health education as mandatorily Occupational characteristics required by Korean OSH Act . In the KWCS, occupational types were divided into 11 The aim of this study was to clarify the relationship groups according to the 6th Korean Standard Classifica- between PSHI and occupational injuries in a nationally tion of Occupations. In this study, those groups were representative sample of South Korean workers. Prior re-classified into three groups: (1) white-collar (manager, research in Korea has rarely focused on the association professional, technicians and associate professionals, office between the rate of occupational injuries and PSHI, in par- workers), (2) pink-collar (service workers, sales workers), ticular, with respect to the degree of occupational-injury and (3) blue-collar (skilled agricultural and fishery workers, risks. In this study, we examined various influencing craft workers and those of related trades, plant and elements, including general characteristics, occupational machine operators and assemblers, elementary occupa- characteristics, and job-related factors, that are associated tions). Company size was included as an occupational with occupational injuries. characteristic and was defined by the number of employees. The occupational characteristics also included working Methods hours per week, tenure, shift work status, type of employ- Study subjects ment, and the presence of labor unions. Working hours This study analyzed data from the 4th Korea Working were classified according to the South Korean Labor Conditions Survey (KWCS) (2014) . The Occupational Standards Act, with 52 h as the standard, comprised of Safety and Health Research Institute (OSHRI) has been 40 working hours and 12 overtime working hours. conducting the KWCS since 2006 in South Korea. The KWCS emulated the European Working Conditions Survey and the UK Labor Force Survey to identify the overall Job-related factors South Korean work conditions such as employment type, Risk factors were classified into three categories: (1) job stability, occupation, and risk factor exposure. Among physical risk factors (vibrations, noise, high and low temper- households from the 2010 Population and Housing Census atures), (2) biochemical risk factors (breathing in smoke or , the KWCS selected individuals who met the criteria of fumes, breathing in vapors such as solvents and thinners, being an “employee,” who were laborers, 15 years or older, exposure to chemical agents or infectious materials), and (3) and who worked for more than 1 h per week at the time of ergonomic risk factors (tiring or painful positions, lifting or the survey. Trained interviewers visited the subjects’ homes moving people, carrying or moving heavy loads, standing, and conducted one-to-one interviews. Statistics Korea repetitive hand or arm movements). Being exposed to risk determined the KWCS information’s reliability to increase factors was defined as exposure for approximately ≥1/4 of the usage of its data. The survey’s response rate was 33.0%, the work hours. Usage of personal protective equipment the cooperation rate 69.9%, and the refusal rate 14.2% . (PPE) was categorized as those who did not require it Because the characteristics of self-employed and wage (no need), those who required it and always wore it workers are markedly different, this study restricted the (need/wear), and those who required it but did not wear it subjects to wage workers. Out of a total of 50,007 respon- (need/no wear). dents, 30,751 were paid workers, excluding military per- sons. A final sample of 24,527 persons was selected after excluding 6224 persons with missing data or refusals Provision of safety and health information (PSHI) in responding to items necessary for the analyses. We com- A positive PSHI status was present if the subject responded pared the control group with the subjects with missing “Very well informed” or “Well informed” to the question values, and there was no statistically significant difference “Regarding the health and safety risks related to per- in their PSHI and occupational-injury characteristics formance of your job, how well informed would you say (p = 0.791 and 0.357, respectively). you are?” Seo et al. Annals of Occupational and Environmental Medicine (2018) 30:36 Page 3 of 13 Occupational injuries and injury risk assessment exposure, and PPE use, with the significance of the dif- Occupational injuries were assessed by using the question ferences in the last three variables being particularly “Over the last 12 months, did you suffer from any of the pronounced. There were no statistically significant dif- following health problems?” and the sub-question “Injuries ferences between the two groups in the number of (be hurt by accident).” Anyone who answered “Yes” was employees or the presence of labor unions. The overall considered as having had one or more injuries. Those who occupational-injury rate was 1.0%, and the injury rate responded with “Yes” to the question “If there was an differed significantly between the low-risk (0.4%) and injury, was it related with your job?” were defined as high-risk (3.1%) groups (Table 1). having experienced occupational injuries. We also assessed the injury risk at the workplace. Belonging to the high-risk 2. Provision of safety and health information (PSHI) group for occupational injuries was determined if the The overall proportion of the study population with answer was “Always,”“Most of the time,” or “Sometimes” PSHI was 64.2%, and there was a significant difference to the question “If you make mistakes in your work, could in PSHI status between the low-risk group (62.3%) and it cause…” with the sub-question “Physical injury to the high-risk group (70.1%) (Table 1). There were signifi- yourself” or “Physical injury to other people.” If the answer cant differences between all subjects’ characteristics and was “Rarely” or “Never,” the subject was classified as a PSHI status, which depended on the risk of occupational low-risk group member for occupational injuries. injury, but, with regard to age, there was no significant relationship in either risk group. Women had a statistically Statistical analyses significant lower PSHI status than men in both groups. Chi-squared tests were used to determine the relevance The lower the monthly income, the lower the PSHI status, of the subjects’ characteristics to the PSHI status and and the smaller the company (i.e., fewer employees), the occupational injuries. General characteristics, occupational lower the PSHI status (p for trend < 0.001 for both associ- characteristics, job-related factors, and the PSHI were ations). With regard to occupational types, PSHI status independent variables. The main dependent variables was lowest in the pink-collar group, a group that includes included occupational injuries and the PSHI; the latter sales workers and service workers. PSHI status was signifi- used to examine poorly informed groups. Crude (un- cantly lower in the group without unions (61.7%) than in adjusted) and adjusted odds ratios (ORs) were calculated the group with unions (79.7%). Among the job-related via multivariate logistic regression analyses to estimate the factors, the group with the need to wear PPE had a association between PSHI and occupational injuries. The higher PSHI status than the group that did not need to ORs were adjusted for variables which showed a statisti- wear it. In addition, the PSHI was significantly higher cally significant association with occupational injury among in the PPE-wearing group than in those who did not general characteristics (age, sex, education level, monthly wear a PPE (Table 2). household income) (Model I), or occupational characteris- tics (working hours per week, tenure, existence of labor 3. Occupational Injuries unions) and job-related factors (physical risk factors, bio- There were various differences between the low-risk group chemical risk factors, PPE) (Model II). Study subjects were and the high-risk group with regard to occupational injuries. divided into high-risk and low-risk groups, depending on The characteristics that showed statistically significant rela- the probability of occupational injuries. All analyses were tionships with occupational injuries, regardless of risk group, performed by using SPSS ver. 20.0 (SPSS Inc., Chicago, IL, were age, monthly income, working hours per week, USA) after stratifying the data by the risk of occupational physical and chemical risk factors, as well as PPE status. injuries. The statistical significance was set at p <0.05. We In contrast, there were no statistically significant relation- used the original data to show the number (N) of people ships between occupational injuries and sex, the number and applied weighted analyses to display the overall of employees, or the shift work status in either group. In proportions (%) as well as the p-values. the low-risk group, the higher the age and the lower the education level, the higher was the number of occupa- Results tional injuries (p for trend< 0.001), while there were no 1. Characteristics of study subjects depending on the risk significant relationships in the high-risk group. Among of occupational injuries the occupational types, the low-risk group had the highest Of the 24,527 subjects, 74.1% were placed in the low-risk number of occupational injuries in the blue-collar group and 25.9% were placed in the high-risk group. category, whereas it was highest in pink-collar workers Statistically significant differences between the two in the high-risk group. Among all study subjects, the groups were observed for age, sex, education level, occupational injury incidence tended to increase with monthly income, working hours per week, tenure, shift longer working hours per week. With respect to employ- work, type of employment, occupational type, risk factor ment types, there were significantly more occupational Seo et al. Annals of Occupational and Environmental Medicine (2018) 30:36 Page 4 of 13 Table 1 Characteristics of study subjects according to occupational injury risk Variables Total Risk of occupational injury Low-risk High-risk p-value a b a b a b N % N % N % Total 24,527 100 18,177 74.1 6350 25.9 General characteristics Age (years) 15–29 3454 13.6 2746 14.6 708 10.7 < 0.001 30–39 6151 26.3 4811 27.9 1340 21.3 40–49 7092 29.1 5284 29.2 1808 28.8 50–59 4920 19.7 3349 17.9 1571 25.1 ≥ 60 2910 11.3 1987 10.4 923 14.1 Sex Male 12,639 51.8 8640 47.8 3999 64.1 < 0.001 Female 11,888 48.2 9537 52.2 2351 35.9 Education level Middle school or below 2996 11.3 1887 9.4 1109 17.0 < 0.001 High school 9455 36.8 6266 32.4 3189 50.0 College or above 12,076 52.0 10,024 58.2 2052 33.1 Monthly income (KRW 10,000) < 150 7435 27.3 5501 27.1 1934 28.0 < 0.001 150–249 8510 35.0 6198 34.2 2312 37.3 250–399 6467 28.3 4773 28.4 1694 27.9 ≥ 400 2115 9.4 1705 10.3 410 6.7 Occupational characteristics Occupational type White-collar 10,228 44.9 8943 52.5 1285 21.8 < 0.001 Pink-collar 6441 24.2 4865 24.8 1576 22.5 Blue-collar 7858 30.9 4369 22.8 3489 55.7 Number of employees 1–4 5495 20.5 4047 20.3 1448 21.3 0.186 5–49 12,514 52.2 9302 52.3 3212 51.8 50–299 4459 19.1 3317 19.3 1142 18.5 ≥ 300 2059 8.2 1511 8.1 548 8.3 Working hours per a week (hours) < 40 13,301 52.9 10,350 55.5 2951 44.9 < 0.001 41–52 6796 29.3 4955 29.2 1841 29.5 53–60 3087 12.5 2011 10.8 1076 17.6 ≥ 61 1343 5.4 861 4.6 482 7.9 Tenure (years) < 1 3018 11.6 2203 11.3 815 12.5 < 0.001 1–5 8846 37.2 6713 38.1 2133 34.4 ≥ 5 12,663 51.2 9261 50.6 3402 53.1 Shift work Yes 2551 10.0 1643 8.6 908 14.5 < 0.001 No 21,976 90.0 16,534 91.4 5442 85.5 Seo et al. Annals of Occupational and Environmental Medicine (2018) 30:36 Page 5 of 13 Table 1 Characteristics of study subjects according to occupational injury risk (Continued) Variables Total Risk of occupational injury Low-risk High-risk p-value a b a b a b N % N % N % Type of employment Regular 18,188 76.1 13,841 78.1 4347 69.8 < 0.001 Temporary 6339 23.9 4336 21.9 2003 30.2 Labor unions Presence 3441 14.3 2506 14.2 935 14.8 0.219 Absence 21,086 85.7 15,671 85.8 5415 85.2 Job-related factors Physical risk factors Yes 9467 37.4 5243 27.9 4224 66.6 < 0.001 No 15,060 62.6 12,934 72.1 2126 33.4 Biochemical risk factors Yes 6097 24.0 3017 15.8 3080 49.0 < 0.001 No 18,430 76.0 15,160 84.2 3270 51.0 Ergonomic risk factors Yes 20,495 81.8 14,438 77.5 6057 94.9 < 0.001 No 4032 18.2 3739 22.5 293 5.1 Usage of personal protective equipment No need 18,510 76.7 15,468 86.2 3042 47.8 < 0.001 Need/wear 5478 21.2 2440 12.4 3038 47.8 Need/no wear 539 2.2 269 1.4 270 4.4 Provision of safety and health information Yes 15,623 64.2 11,227 62.3 4396 70.1 < 0.001 No 8904 35.8 6950 37.7 1954 29.9 Occupational injuries Yes 276 1.0 82 0.4 194 3.1 < 0.001 No 24,251 99.0 18,095 99.6 6156 96.9 Unweighted case numbers of workers Percentages based on weighted analysis Derived by weighted chi-squared test injuries in the temporary workers in the low-risk group group, the ORs of occupational injuries in the high-risk than for regular workers, but this difference was not group without PSHI were as follows: Crude (unadjusted) statistically significant in the high-risk group. Regard- (OR 1.392, 95% CI 1.055–1.837), Model I (adjusted) (OR less of injury risk status, workers without labor unions 1.454, 95% CI 1.095–1.932), and Model II (adjusted) (OR displayed more occupational injuries, although this was 1.812, 95% CI 1.330–2.468) (Table 4). only statistically significant in the high-risk group. The number of occupational injuries was high in workers Discussion exposed to physical, chemical, and ergonomic risk factors This study was conducted to examine the relationship (Table 3). between PSHI at the workplace and occupational injuries in a large-scale nationally representative sample of South 4. Relationship between PSHI and occupational injuries Korean workers. We hypothesized that the importance of There was no statistically significant difference in the PSHI would differ depending on the risk of occupational low-risk group (p = 0.406) regarding the PSHI; however, in injuries. Therefore, to determine the significance of PSHI the high-risk group, the workers with no PSHI had a high related to occupational injury risk level, and because vari- incidence of occupational injuries (p =0.016) (Table 3). ous characteristics of workers differed depending on their After appointing workers with PSHI as the reference risk of occupational injury, the subjects were divided into Seo et al. Annals of Occupational and Environmental Medicine (2018) 30:36 Page 6 of 13 Table 2 Relationships between characteristics of study subjects and PSHI by injury risk level Variables PSHI (Low-risk group) PSHI (High-risk group) c c Total Yes p-value Total Yes p-value a a b a a b N N % N N % General characteristics Age (years) 15–29 2746 1541 57.6 < 0.001 708 459 67.5 < 0.001 d d 30–39 4811 3053 63.7 0.168 1340 973 72.8 0.039 40–49 5284 3369 63.9 1808 1280 71.6 50–59 3349 2087 62.3 1571 1084 69.8 ≥ 60 1987 1177 60.2 923 600 65.6 Sex Male 8640 5757 66.2 < 0.001 3999 2976 74.4 < 0.001 Female 9537 5470 58.7 2351 1420 62.5 Education level Middle school or below 1887 1064 58.5 < 0.001 1109 708 65.3 < 0.001 d d High school 6266 3512 56.7 < 0.001 3189 2179 69.1 < 0.001 College or above 10,024 6651 66.0 2052 1509 74.1 Monthly income (KRW 10,000) < 150 5501 2872 53.8 < 0.001 1934 1148 61.1 < 0.001 d d 150–249 6198 3816 61.6 < 0.001 2312 1555 67.8 < 0.001 250–399 4773 3261 67.2 1694 1345 78.9 ≥ 400 1705 1278 73.4 410 348 84.2 Occupational characteristics Occupational type White-collar 8943 6050 67.4 < 0.001 1285 1024 79.8 < 0.001 Pink-collar 4865 2465 51.6 1576 905 59.9 Blue-collar 4369 2712 61.9 3489 2467 70.5 Number of employees 1–4 4047 1887 48.5 < 0.001 1448 776 56.3 < 0.001 d d 5–49 9302 5723 61.8 < 0.001 3212 2181 68.5 < 0.001 50–299 3317 2398 71.3 1142 935 80.9 ≥ 300 1511 1219 77.9 548 504 91.4 Working hours per a week (hours) < 40 10,350 6479 63.0 < 0.001 2951 2072 71.7 < 0.001 d d 41–52 4955 3117 63.1 < 0.001 1841 1326 72.1 < 0.001 53–60 2011 1152 58.2 1076 697 66.4 ≥ 61 861 479 57.1 482 301 61.9 Tenure (years) < 1 2203 1132 52.2 < 0.001 815 518 67.2 < 0.001 d d 1–5 6713 3956 59.5 < 0.001 2133 1379 65.0 < 0.001 ≥ 5 9261 6139 66.6 3402 2499 74.1 Shift work Yes 1643 1117 67.0 < 0.001 908 745 80.9 < 0.001 No 16,534 10,110 61.8 5442 3651 68.3 Seo et al. Annals of Occupational and Environmental Medicine (2018) 30:36 Page 7 of 13 Table 2 Relationships between characteristics of study subjects and PSHI by injury risk level (Continued) Variables PSHI (Low-risk group) PSHI (High-risk group) c c Total Yes p-value Total Yes p-value a a b a a b N N % N N % Type of employment Regular 13,841 8997 64.6 < 0.001 4347 3185 73.3 < 0.001 Temporary 4336 2230 53.8 2003 1211 62.7 Labor unions Presence 2506 1978 77.4 < 0.001 935 813 86.1 < 0.001 Absence 15,671 9249 59.8 5415 3583 67.3 Job-related factors Physical risk factors Yes 5243 3452 65.8 < 0.001 4224 3035 72.3 < 0.001 No 12,934 7775 60.9 2126 1361 65.8 Biochemical risk factors Yes 3017 2012 65.7 < 0.001 3080 2255 73.2 < 0.001 No 15,160 9215 61.6 3270 2141 67.1 Ergonomic risk factors Yes 14,438 8794 61.5 < 0.001 6057 4171 69.7 0.004 No 3739 2433 65.1 293 225 77.1 Usage of personal protective equipment No need 15,468 8866 58.3 < 0.001 3042 1612 54.4 < 0.001 Need/wear 2440 2179 89.4 3038 2621 86.5 Need/no wear 269 182 66.3 270 163 62.1 Unweighted case numbers of workers Percentages based on weighted analysis P-value of the weighted chi-squared test results P-value for trend in the weighted analysis two groups based on injury risk. In the high-risk group, studies on the association between organizational and there was a statistically significant relationship between workplace factors with injury rates, an active role of top PSHI and occupational injuries, and the occupational injury management in health and safety was associated with rate of workers without PSHI was up to 1.81 times higher lower injury rates . Thus, safety education and training than the rate in those with PSHI. Therefore, the better the within the workplace function as precautionary measures safety information provided at the workplace, the fewer against occupational diseases, such as hearing and vision work-related injuries occurred, which is consistent with the loss, as well as against occupational injuries [15, 16]. results in previous studies. For example, a study that ana- Statistically significant relationships between workers’ lyzed the characteristics of Korean wage workers during characteristics and PSHI status were detected in almost the 1st KWCS, conducted in 2006, showed that the odds all characteristics analyzed in this study. The presence of ratio of occupational injuries in the group without PSHI PSHI was low when there were few employees and no was 1.29 (95% CI 1.05–1.59) . In another investigation labor unions, which is consistent with prior research . that assessed occupational injuries in Korea with health This is because small companies and those without insurance and industrial accident insurance information, unions are thought to be unable to devote resources to the rate of occupational injuries was higher in those who safety aspects due to fiscal constraints in a highly competi- did not receive accident prevention education at the work- tive environment. As of 2005, the proportion of training place than in those who did (OR 1.62, 95% CI 1.42–1.84) investments in all investments by companies with fewer . In addition, according to Ghosh et al., poor safety than 30 employees (0.2%) was less than one-eighth that of performance by workers was significantly associated with large enterprises (1.64%) with 1000 or more employees; occupational injuries (adjusted OR 3.10, 95% CI 1.45–6.63) on that basis, Kang et al. suggested that organizations pro- . Moreover, in an overview which summarized ten viding technical support to small-scale workplaces should Seo et al. Annals of Occupational and Environmental Medicine (2018) 30:36 Page 8 of 13 Table 3 Relationship between subject characteristics and occupational injuries by injury risk levels Variables Occupational injuries (Low-risk group) Occupational injuries (High-risk group) c c Total Yes p-value Total Yes p-value a a b a a b N N % N N % General characteristics Age (years) 15–29 2746 6 0.2 < 0.001 708 11 1.7 0.012 d d 30–39 4811 16 0.3 < 0.001 1340 45 3.2 0.986 40–49 5284 19 0.3 1808 72 4.3 50–59 3349 21 0.5 1571 44 2.5 ≥ 60 1987 20 0.8 923 22 2.7 Sex Male 8640 38 0.4 0.829 3999 127 3.3 0.466 Female 9537 44 0.4 2351 67 2.7 Education level Middle school or below 1887 24 1.1 < 0.001 1109 31 2.7 0.130 d d High school 6266 31 0.4 < 0.001 3189 111 3.6 0.393 College or above 10,024 27 0.2 2052 52 2.5 Monthly income (KRW 10,000) < 150 5501 37 0.5 0.018 1934 39 1.9 0.006 d d 150–249 6198 19 0.3 0.053 2312 89 3.9 0.056 250–399 4773 17 0.3 1694 55 3.4 ≥ 400 1705 9 0.3 410 11 2.7 Occupational characteristics Occupational type White-collar 8943 25 0.2 < 0.001 1285 28 2.3 0.119 Pink-collar 4865 20 0.3 1576 50 3.5 Blue-collar 4369 37 0.7 3489 116 3.3 Number of employees 1–4 4047 22 0.4 0.599 1448 47 3.1 0.943 d d 5–49 9302 43 0.4 0.216 3212 98 3.3 0.481 50–299 3317 12 0.3 1142 34 3.0 ≥ 300 1511 5 0.2 548 15 2.5 Working hours per a week (hours) < 40 10,350 44 0.3 0.042 2951 54 1.8 < 0.001 d d 41–52 4955 18 0.3 0.021 1841 70 3.7 < 0.001 53–60 2011 11 0.5 1076 53 5.3 ≥ 61 861 9 1.0 482 17 3.5 Tenure (years) < 1 2203 5 0.2 0.168 815 12 1.6 0.019 d d 1–5 6713 36 0.4 0.714 2133 69 3.2 0.012 ≥ 5 9261 41 0.4 3402 113 3.4 Shift work Yes 1643 10 0.5 0.318 908 20 2.2 0.107 No 16,534 72 0.4 5442 174 3.3 Seo et al. Annals of Occupational and Environmental Medicine (2018) 30:36 Page 9 of 13 Table 3 Relationship between subject characteristics and occupational injuries by injury risk levels (Continued) Variables Occupational injuries (Low-risk group) Occupational injuries (High-risk group) c c Total Yes p-value Total Yes p-value a a b a a b N N % N N % Type of employment Regular 13,841 48 0.3 < 0.001 4347 132 3.2 0.899 Temporary 4336 34 0.7 2003 62 3.0 Labor unions Presence 2506 8 0.2 0.289 935 19 1.9 0.049 Absence 15,671 74 0.4 5415 175 3.3 Job-related factors Physical risk factors Yes 5243 55 0.9 < 0.001 4224 161 3.8 < 0.001 No 12,934 27 0.2 2126 33 1.8 Biochemical risk factors Yes 3017 42 1.2 < 0.001 3080 128 4.0 < 0.001 No 15,160 40 0.2 3270 66 2.2 Ergonomic risk factors Yes 14,438 78 0.5 < 0.001 6057 188 3.1 0.305 No 3739 4 0.1 293 6 2.8 Usage of personal protective equipment No need 15,468 54 0.3 < 0.001 3042 66 1.9 < 0.001 Need/wear 2440 24 0.9 3038 118 4.2 Need/no wear 269 4 1.6 270 10 4.5 Provision of safety and health information Yes 11,227 47 0.4 0.406 4396 119 2.8 0.016 No 6950 35 0.4 1954 75 3.8 Unweighted case numbers of workers Percentages based on weighted analysis P-value of the weighted chi-squared test results P-value for trend in the weighted analysis determine the risks in those workplaces and implement In our 2014 study, there was a slightly higher PSHI suitable customized safety education . Women and prevalence (64.2%). In other words, the absence of PSHI the pink-collar group also had low PSHI status, which declined from 43.6 to 35.8% over approximately one decade. mayberelated to therelativelyhigh proportion offemales This may be the result of emphasizing the importance of working in the service sector: In this study, 69.9% of safety and health education, including the revision of the pink-collar workers were women and the occupational OSH Act. However, it seems that the absence of PSHI is still injury incidence was highest for the high-risk group in the high; thus, more rigorous education on the effects of PSHI pink-collar category. This result suggests that PSHI at the is needed. workplace is urgently needed, not only for blue-collar Characteristics associated with occupational injuries workers but also for those in service-type occupations. differ depending on the injury risk: In the low-risk group, The PSHI status was low in the group without a need for the factors that had statistically significant relationships PPE but, in the group that did need it, a high PSHI status with occupational injuries were: old age, low education was observed in the workers wearing the PPE, suggesting level, low monthly income, blue-collar occupation, long that PSHI presence may lead to a high PPE usage rate. working hours per week, being a temporary worker, With regard to PSHI prevalence, a study based on physical, biochemical, and ergonomic, as well as the 2006 KWCS data reported that 4018 out of a total of need for PPE. Many results in the low-risk group were 6998 workers (57.4%) were listed as having a PSHI . consistent with those reported in previous studies. Seo et al. Annals of Occupational and Environmental Medicine (2018) 30:36 Page 10 of 13 Table 4 Odds ratios of occupational injuries associated with PSHI in the high-risk group Variables Occupational injuries (high-risk group) a b Crude Model I Model II OR 95% CI OR 95% CI OR 95% CI Provision of safety and health information (ref. Yes) No 1.392 1.055–1.837 1.454 1.095–1.932 1.812 1.330–2.468 Age (years) (ref. 15–29) 30–39 1.560 0.750–3.242 1.420 0.668–3.018 40–49 0.854 0.481–1.517 0.881 0.495–1.569 50–59 0.661 0.392–1.113 0.678 0.402–1.144 ≥ 60 1.196 0.711–2.013 1.241 0.736–2.093 Sex (ref. Male) Female 0.953 0.688–1.320 1.337 0.944–1.893 Education level (ref. Middle school or below) High school 0.610 0.354–1.050 0.784 0.455–1.352 College or above 0.649 0.464–0.908 0.802 0.571–1.127 Monthly income (KRW 10,000) (ref. <150) 150–249 1.557 0.758–3.198 1.382 0.662–2.888 250–399 0.715 0.385–1.328 0.853 0.452–1.608 ≥ 400 0.808 0.436–1.496 1.013 0.541–1.897 Working hours per a week (hours) (ref. <40) 41–52 1.672 0.982–2.848 53–60 0.934 0.562–1.552 ≥ 61 0.708 0.423–1.185 Tenure (years) (ref. <1) 1–5 1.867 1.045–3.338 ≥ 5 0.998 0.734–1.356 Labor unions (ref. Yes) No 1.704 1.044–2.781 Physical risk factors (ref. No) Yes 1.435 0.978–2.107 Biochemical risk factors (ref. No) Yes 1.230 0.896–1.688 Usage of personal protective equipment (ref. No need) Need/wear 2.030 1.096–3.760 Need/no wear 0.828 0.463–1.480 Adjusted for general characteristics (age, sex, education level, monthly income) Adjusted for general characteristics (age, sex, education level, monthly income), occupational characteristics (working hours per a week, tenure, labor unions), and job-related factors (physical risk factors, biochemical risk factors, personal protective equipment) Reference group Generally, advanced age and high physical demands at PPE use, the proportion of respondents who did not need work have been associated with an increased risk of a PPE was 86.2% in the low-risk group and 47.8% in the musculoskeletal claims , likely leading to occupational high-risk group. PPE status displayed the most significant injuries. Workers with small incomes and low levels of difference among the study characteristics related to the education had high occupational injury rates. A Korean risk of occupational injuries; therefore, the necessity of study that examined different samples during the same wearing a PPE is the most important factor that indirectly year reported that, as workers’ income and educational indicates the risk of occupational injuries. Generally, shift status increased, their occupational injury experiences work is associated with a high occurrence of occupational decreased . A blue-collar status and long working injury. In a study into the first KWCS dataset, the odds hours were associated with a high rate of occupational ratio of occupational injuries for workers in shift work was injuries, and construction workers (i.e., blue-collar) in the 2.40 (95% CI 1.65–3.50)  with similar results reported USA who worked long hours were at high risk of occupa- in overseas investigations [26, 27]. There was a high level tional injury . Temporary workers had a lower PSHI of occupational injuries in workers with shift work in status than that of regular workers, and their incidence the low-risk group, but the result was not statistically of occupational injuries was higher, demonstrating the significant. vulnerability of temporary workers to occupational injury In the high occupational-injury risk group, the factors [21, 22]. In the present study, physical and biochemical showing statistically significant associations with occupa- risk factors at the workplace and PPE use were closely tional injuries were: age, monthly income, working hours related to occupational injuries, which is consistent with per week, tenure, the existence of labor unions, physical, results in previous investigations [23, 24]. With regard to biochemical, PPE usage. Age, monthly income, and Seo et al. Annals of Occupational and Environmental Medicine (2018) 30:36 Page 11 of 13 working hours per week exhibited no significant relation- PPE. This indicates that high-risk workers are more likely ships with injuries in the high-risk group. Whereas long to be affected by factors that are directly work related, such tenure, absence of labor unions, presence of physical and as the exposure to specific risk factors and wearing a PPE, biochemical risk factors, as well as the need for PPE were rather than to more general or indirect factors. Therefore, associated with an increased occurrence of occupational in- PSHI might be more important in the high-risk group. juries. There was a high incidence of occupational injuries This may account for the differences of occurrence of in workers without labor unions, which can possibly be occupational injury between the low-risk group and the explained by the relatively few opportunities for individual high-risk group. workers to improve safety and health at work. Notably, This study has several limitations. First, because the PSHI status was significantly low in the absence of unions. KWCS has a cross-sectional design, the association between Thus, it is necessary to offer options to employees encour- PSHI and occupational injuries maybebi-directionaland, aging regular participation in activities to improve safety therefore, causality cannot be established; however, it is very and health issues at workplaces without labor unions . plausible that PSHI has reduced the occurrence of occupa- Being male, in a small company, and ergonomic risk factors tional injuries. Second, because this study was based on were associated with many occupational injuries in a previ- questionnaires, some limitations, such as a recall bias, may ous study , but, in the present study, those relationships be present in the data. Moreover, a “healthy user bias” could were not statistically significant. also be present; for example, in the case of critical or fatal Generally, the risk of occupational diseases is higher in injuries, the subject would not be able to respond to the smaller companies . This is because workers in questionnaire. Thus, there is a possibility that the incidence small- and medium-sized firms may be exposed to more of occupational injuries was underestimated in this study health-hazard risk factors ; it seems that if an organi- . Nonetheless, there was a statistically significant associ- zation’s size is large, it can provide safety information ation between PSHI and occupational injuries in this study, more effectively and also systematically control worksite suggesting that PSHI has a greater role in preventing occu- exposure to harmful factors . In previous studies, an pational injuries than was expected. Our categorization of a increase in injury risk among those who started a new high risk of occupational injury may not have been job and an inverse relationship between job tenure and sufficiently objective; however, considering that it is injury risk were observed [31, 32]. However, our study difficult to judge injury risk as high or low by only revealed the opposite in the high-risk group with the assessing the existence and degree of harmful factors, lowest occupational-injury rate observed in workers with our measurement approach appears rational. Third, we less than 1 year of job tenure. This difference may be were unable to investigate the details of the occupational due to the particular sampling characteristics or to the injuries such as the nature of the trauma, its severity, control of additional variables in the other investigations. treatment, and sequelae. Alternatively, it could be that the more experienced the In spite of these limitations, one of this study’sstrengths laborers, the higher the likelihood they work in a more is its epidemiological nature, which allowed us to examine dangerous job. Furthermore, as employees become the relationship between PSHI and occupational injuries in accustomed to this level of danger, they may be subject a nationally representative sample of the South Korean to more frequent hazards due to momentary neglect or population. Fabiano et al.  classified the factors influen- distraction during work. cing occupational accident frequency into (1) technical, (2) In the low-risk group, the relationship between PSHI economic, (3) labor organizational, (4) environmental, and and occupational injuries was not statistically significant, (5) human, both individual and inter-individual. The but this does not indicate irrelevance of PSHI for these KWCS includes these various occupational-injury-affecting workers. We assert that groups differing in their risk of factors, and its data were thus appropriate for our investi- occupational injuries need different approaches depend- gation. In addition, since the KWCS is conducted every 3 ing on their likelihood of falling victim to job-related years, follow-up or repeated studies on the associations hazards. The statistically significant differences between between occupational injuries and various characteristics the two risk groups were in occupational type, exposure might be useful in revealing secular trends and may serve to risk factors, and PPE use. In other words, blue-collar as a basis for future studies into injury reduction in the workers with exposure to physical and biochemical risk workplace. factors, as well as in need of PPE, are more susceptible to occupational injuries than other employees. The low-risk Conclusions group results in this study were similar to those in previous To prevent occupational injuries, multi-faceted approaches studies. However, the high-risk group showed significant that consider different types and levels of injury risks are associations; mostly for job-related factors including phys- needed. Workers with no PSHI and in the high-risk group ical, biochemical, and ergonomic risks, and the need for exhibited an elevated incidence of occupational injuries Seo et al. Annals of Occupational and Environmental Medicine (2018) 30:36 Page 12 of 13 compared to that in the low-risk group. In the case of 8. Lee MS, Park KO. Workplace safety education and management factors associated with the organizational safety culture in Korean manufacturing occupational-injury in high-risk workers, the provision of companies. Korean J Occup Environ Med. 2006;32:75–83. Korean more stringent safety education programs is required. 9. OSHRI. 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Annals of Occupational and Environmental Medicine
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Published: Jun 4, 2018