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The High-risk Groups According to the Trends and Characteristics of Fatal Occupational Injuries in Korean Workers Aged 50 Years and Above

Background Due to an increasing number of workers aged 50 years and above, the number of those employed is also on the rise, and those workers aged 50 and over has exceeded 50% of the total fatal occupational injuries. Therefore, it is necessary to implement the selection and concentration by identifying the characteristics of high-risk groups necessary for an effective prevention against and reduction of fatal occupational injuries. Methods This study analyzed the characteristics of high-risk groups and the occupational injury fatality rate per 10,000 workers among the workers aged 50 and over through a multi-dimensional analysis by sex, employment status of workers, industry and occupation by targeting 4,079 persons who died in fatal occupational injuries from January 2007 to December 12. Results The share of the workers aged 50 years and above is increasing every year in the total fatal occupational injuries occurrence, and the high-risk groups include 'male workers' by sex, ‘daily workers’ by worker’s status, ‘craft and related-trades workers’ by occupation, and ‘mining’ by industry. Conclusion The most frequent causal objects of fatal occupational injuries of the workers aged 50 years and above are found out to be ‘installment and dismantlement of temporary equipment and material on work platforms including scaffold’ in the construction industry and ‘mobile crane, conveyor belt and fork lifts’ in the manufacturing industry.


Introduction
The world population of people aged 65 years and above is estimated to increase from 8.2% in 2015 to 17.6% in 2060, and the median age increases from 29.6 years to 37.3 years, while the number of Korean people aged 65 years and above is presumed to surge from 13.1% to 40.1%, and the median age increases from 40.8 years to 57.9 years. Also, the average global fertility rate is 2.56 persons, and fertility rate in advanced countries is 1.64 persons, is 2.35 persons in Asia, and is 1.50 persons in Europe. Korea's old age dependency ratio is lower than that of the advanced countries but is estimated to surpass after 2030 [1]. Among the working age population (15e64 years old), those aged 30e49 years, who are the most active age group, accounted for 49% in 2005 but are estimated to decline continuously to 42% in 2020 and 37% in 2050. The ratio of the workers aged 50 years and above took up 25% in 2010 and is projected to exceed 33% in 2020, accelerating the aging of the workforce [1e3]. According to the economically active population trends, those aged below and above 50 years showed a higher increase rate as it moved from 2000 to 2014, and those aged 60 years and above also resumed an increase [3,4].
Also, if one examines elderly workers aged 50 years and above by employment status, the self-employed had the highest rate in 2013, followed by the regular workers, temporary workers, daily workers, and unpaid family business workers. By industry, the agriculture had the highest percentage, followed by forestry, fishery, whole and retail sale manufacturing, accommodation and food service activities, and construction. By occupation type, the elementary workers had the highest employment percentage, followed by the skilled agriculture, forestry and fishery workers, the sales workers, and the service workers [4,5]. Such aging of workforce can not only increase occupational illnesses, accidents, and deaths due to the degenerating physical, mental, and physiological functions caused by a lack of sensory function, balance function, and motor control ability but can also lead to a deterioration in the quality of work ability [6e9]. In addition, among the total occupational injuries, the index values of workers aged 45 years and above showed a trend of steady increase from 2001 to 2010 every year [10], and among the total fatal occupational injuries, the number of the workers aged 50 years and above is very high [11]. Therefore, the prevention of the fatal occupational injuries among elderly workers aged 50 years and above requires an accurate understanding of the characteristics and attributes of the age group, the identification of high-risk groups which need the focus of prevention efforts, and the optimization of intervention time when the resources and capacities need to be strengthened to reduce the fatal occupational injuries.

Materials and methods
To faithfully fulfill its purpose, this study used the administration information sources including the Korea Workers' Compensation and Welfare Service's industrial accident compensation applications and industrial accident surveys and the Korea Occupational Safety and Health Agency's major industrial accident investigation reports. Based on these reports, the study established a database of 7,993 persons who died from occupational incidents caused by material agencies from January 1, 2007 to December 31, 2013 by classifying their variable attributes into 25 subgroups including individual and occupational characteristics, accident types, material agencies, unsafe acts, or unsafe conditions. To calculate the rate of occupational injury fatality per 10,000 workers by personal and occupational characteristics, the data of economic activity population survey of the National Statistical Office were reworked and used as the parameter value.
It used the final analysis data of 4,079 persons or 51% of the total fatal occupational injuries, who are elderly workers aged 50 years and above, who fulfilled the purpose of the study. The first analysis content included the demographic and occupational characteristics analysis; the second was the in-depth analysis of fatal accident causes and the trend of occupational injury fatality rates per 10,000 workers; and the third was the detailed characteristics of high-risk groups for prevention of fatal occupational injury accidents and the policy proposals. In 2007, the workers aged 50 years and above took up 42.1% of the total annual fatal occupational injuries, and the percentage of the workers aged 50 years and above in comparison to that of the total occupational injury workers showed an increasing tendency Table 1.
From the results of analysis of the fatal occupational injuries of the male workers aged 50 years and above based on the database of fatal occupational injuries accumulated for a period of 7 years from 2007 to 2013, the causal object for 40.7% of fatal occupational injuries is building, structure, and surface, followed by the equipment and machinery (23.3%) and transportation (19.3%). In female workers aged 50 years and above, causal objects for 28.7% of fatal occupational injuries are the equipment and machinery and building, structure, and surface, followed by transportation (23.9%). All in all, there was a statistically significant relation between sex and causal object ðc 2 value ¼ 27:420; p ¼ 0:001Þ.
Based on the type of accident, in the male elderly workers aged 50 years and above, "fall of persons" accounted for the highest percentage (38.7%), followed by "struck against objects" (18.8%) and "buried and rolled over by objects and tripping of persons" (9.9%). In the female elderly workers aged 50 years and above, "struck by objects" had the highest percentage (30.3%), followed by "buried and rolled over by objects and tripping of persons" (20.2%) and "fall of persons" (15.4%). A statistically significant relation between sex and type of accidents was observed (c 2 value ¼ 80.587, p ¼ 0.000).
In the analysis of unsafe behaviors at the time of a fatal occupational accidents of the male workers aged 50 years and above, "negligent job performance and noncompliance of procedure" accounted for the highest percentage of the total fatal occupational injuries of the group at 24.9%, followed by "neglect of and failure to identify dangerous structures" (24.1%) and "inappropriate use of protective clothing and gear" (17.6%). In case of the female workers aged 50 years and above, "negligent job performance and noncompliance of procedure" took up the highest percentage of the total fatal occupational injury of the group at 26.2%, followed by "neglect of and failure to identify dangerous structures" (25.7%), "negligence during job performance" (17.6%), and "inappropriate use and maintenance of facility, machinery and materials" (17.5%). All in all, a statistically significant relation between sex and unsafe behaviors was observed (c 2 value ¼ 29.137, p ¼ 0.000). Table 1 The distribution of victims of fatal occupational injuries and fatality rates per 10,000 Korean workers aged 50 years and above.

Division
Number of employees aged above 50 y In the results based on the employment status of the fatal occupational injuries of the male workers aged 50 years and above, "struck against objects" accounted for the highest percentage of the fatal occupational injuries of regular workers at 25.6% and "equipment$and machinery" took up the highest percentage at 33.2% among the material agencies of injuries. The most frequent cause of accidents among the daily workers was found out to be "fall of persons" with the highest percentage at 50.6%, and the most common material agency of their fatal injuries was "building, structure, and surface" with the highest percentage at 56.4%. In the case of the temporary workers aged 50 years and above, the most frequent cause of accidents turned out to be "fall of persons" with the highest percentage at 36.9%, and the most common material agency of their fatal injuries was "building, structure, and surface" with the highest percentage at 41.0%. In the case of the part-time workers aged 50 years and above, the most frequent cause of accidents turned out to be "stuck and caught in objects" with the highest percentage at 37.5%, and the most common material agency of their fatal injuries was "equipment and machinery" with the highest percentage at 37.5%. All in all, by the employment status, a statistically significant relation between accident type and causal object was observed (c 2 value ¼ 490.330, p ¼ 0.000; c 2 value ¼ 540.609, p ¼ 0.000, respectively). In addition, looking at types of works at the time of fatal occupational accidents, "transportation, loading and unloading, and operation works" took up the highest percentage of fatal occupation injuries among all status of workers groups including regular workers, daily workers, temporary workers, and part-time workers. The percentage of the fatal occupational injuries caused by unsafe behaviors showed variations in the rankings by employment status; the regular workers had the highest percentage at 25.7% in the category of "negligent job performance and noncompliance of procedure"; the daily workers showed the highest percentage at 29.8 in "neglect of and failure to identify dangerous structures". In the case of temporary workers, "neglect of and failure to identify dangerous structures" took up the highest percentage at 24.5%, followed by "inappropriate use of protective clothing and gear" (23.9%). In the case of part-time workers, "inappropriate use of protective clothing and gear" took up the highest percentage at 37.5% (c 2 value ¼ 377.438, p ¼ 0.000).
According to the results of the cross analysis between occupation, industry, and causal object by sex, the male workers aged 50 years and above showed the highest percentage of fatal occupational injuries at 47.1% in the category of "craft and related trade workers". In contrast, the female workers aged 50 years and above revealed the highest percentage of fatal occupational injuries at 58.0% in the category of "elementary workers". Considering this, a statistically significant relation between sex and occupation was observed (c 2 value ¼ 148.313, p ¼ 0.000). Also, in the fatal occupational injuries of the male workers aged 50 years and above by industry and causal object, the construction industry showed the highest percentage at 48.9%, and "building, structure, and surface" was the most frequent causal object of fatal occupational injuries with the highest rate at 40.7%. In the case of the female workers aged 50 years and above, the manufacturing industry showed the highest percentage at 27.7%, followed by the construction industry (22.3%). In terms of the causal object of injuries, both "equipment, structure, and surface" and "building, structure, and surface" accounted for the highest percentage at 28.7%. Statistically significant relations between sex and industry and between sex and causal object were observed (c 2 value ¼ 218.019, p ¼ 0.000 and c 2 value ¼ 27.420, p ¼ 0.000, respectively). The most frequent accident type of fatal occupational injuries among the male workers aged 50 years and above was "fall of persons" with the highest percentage at 38.7%, equivalent to about four workers out of every 10 persons. In the case of the female counterparts, the most common accident type of fatal occupational injuries was "struck against objects" with the highest percentage at 30.3%, equivalent to about three workers out of every 10 persons. In addition, looking at types of works at the time of fatal occupational accidents, both male and female workers aged 50 years and above showed the highest percentages at 35.8% and 46.0%, respectively, in the category of "transportation, loading and unloading, and operation works". A statistically significant relations between sex and accident type of fatal industrial accidents were observed (c 2 value ¼ 97.028, p ¼ 0.000). Also, in the fatal occupational injuries by unsafe behaviors, the male workers aged 50 years and above showed the highest percentage at 24.9% in the category of "negligent job performance and noncompliance of procedure", followed by "neglect of and failure to identify dangerous structures" (24.1%). In contrast, their female counterparts showed the highest percentage at 26.2% in the category of "negligent job performance and noncompliance of procedure", followed by "negligence during job performance" (25.7%). All in all, a statistically significant relation between sex and unsafe behaviors was observed (c 2 value ¼ 29.137, p ¼ 0.000).

Trend of occupational injury fatality rates per 10,000 workers by sex, employment status, occupation, and industry
In the occupational injury fatality rates per 10,000 workers by sex, the male occupational injury fatality rates per 10,000 workers stood at 1.16& in 2007, which gradually increased to 1.32& in 2011 before it dropped again to 1.12& in 2013. In contrast, the female occupational injury fatality rates per 10,000 was recorded at a  relatively lower 0.09& and remained at a standstill until 2011, but after that, it showed a slow declining tendency [ Fig. 1]. In the employment status, the daily workers showed the highest occupational injury fatality rate per 10,000 workers and especially at as much as 4.70&, equivalent to 4.7 workers per 10,000 persons in 2011. In contrast, the temporary workers had the lowest occupational injury fatality rate per 10,000 workers at approximately 0.17& every year [ Fig. 2].
By occupation, the craft and related trade workers had the highest fatal occupational injury rate, followed by equipment$and machine operating and assembling workers and elementary workers, and the other occupation groups showed the fatal occupational injury rate of less than 1.00 & [Fig. 3]. If one examines the occupational injury fatality rates per 10,000 workers by industry, the mining and quarrying industry experienced the repeated fluctuations and showed the highest occupational injury fatality rate at 23.1& in 2002, equivalent to 23 workers per 10,000 workers. And the second highest fatal occupational injury fatality rate per 10,000 workers was recorded in 2009 by the sewerage, waste management, materials recovery, and remediation activities industry, which showed an increasing tendency until 2009 but showed a declining tendency afterward [ Fig. 4].

Trend of occupational injury fatality rates per 10,000 workers by sex*industry and sex*occupation
In the cross-sectional analysis by sex and industry, the mining and quarrying industry showed the highest occupational injury fatality rate per 10,000 workers among the male workers aged 50 years and above, followed by the sewerage, waste management, materials recovery, and remediation activities industry and the construction industry. In case of the female workers aged 50 years and above, the sewerage, waste management, materials recovery, and remediation activities industry showed the highest occupational injury fatality rate per 10,000 workers, followed by construction industry, and was 15.4& in 2009 [ Fig. 5].
According to the results of the cross analysis between sex and occupation, the craft and related trades workers had the highest occupational injury fatality rate per 10,000 workers among the male workers aged 50 years and above. In contrast, the equipment•and machine operating and assembling workers had the highest occupational injury fatality rate per 10,000 workers among the female workers aged 50 years and above [ Fig 6].

Trend of occupational injury fatality rates per 10,000 workers by employment status* industry and employment status*occupation
The results of the cross-sectional analysis by employment status and industry and occupation on the occupational injury fatality rates per 10,000 workers of the elderly workers aged 50 years and above are as follows: At first, in regular workers aged 50 years and above, the mining and quarrying industry showed the highest occupational injury fatality rate per 10,000 workers, followed by the sewerage, waste management, materials recovery, and remediation activities industry and construction industry. The top three industries had occupational fatality rates per 10,000 workers of over 5.00&. In the daily workers aged 50 years and above, the sewerage, waste management, materials recovery, and remediation activities industry had the highest fatal occupational injury rate, followed by construction industry. Especially, the occupational injury fatality rates per 10,000 workers in the sewerage, waste management, materials recovery, and remediation activities  industry were extremely very high after 2009. Also in the temporary workers, the construction had the highest fatal occupational injury rate, followed by the sewerage, waste management, materials recovery, and remediation activities industry [ Fig. 7].
In the results of the occupational injury fatality rates per 10,000 workers of the regular workers aged 50 years and above by occupation, the skilled agriculture,•forestry, and fishery workers showed the highest occupational injury fatality rate per 10,000 workers, followed by the craft and related trades workers, the equipment$and machine operating and assembling workers, and the elementary workers. By occupation, in daily workers aged 50 years and above, the professionals and related workers displayed the highest occupational injury fatality rate per 10,000 workers, followed by the craft and related trades workers, the equipment$and machine operating and assembling workers, and the skilled agriculture, forestry, and fishery workers. Especially, the occupational injury fatality rates per 10,000 workers among the skilled agriculture, forestry, and fishery workers showed an overall increasing tendency after repeated increases and decreases, and among the temporary workers, the craft and related trades workers showed the highest occupational injury fatality rate per 10,000 workers but had an extremely wide fluctuation (or variation) every year [ Fig. 8].

Discussion
Among the total number of 7,993 victims of fatal occupational injures for 7 years from 2007 to 2013, the workers aged 50 years and above accounted for 51% or 4,079 victims. The percentage of the workers aged 50 years and above against the total annual fatal occupational injures stood at 42.1% in 2007 and showed an increasing trend every year. In 2012, it surpassed the half of the  total fatal occupational injuries with a percentage of 57.5%. This can be ascribed to the fact that when those aged 50 years and above reenter the labor market [4], the middle-aged and senior workers have relatively weakened motor, sensory, and cognitive functions due to rapid physical aging [7,9]. Among the 4,079 workers aged 50 years and above, who were the victims of fatal industrial accidents, the male high-risk groups with the highest occupational fatality rates were "construction" among the industry subcategories, "craft and related trades workers" among the occupation subcategories, "fall of persons" among the type of accident subcategories, "building, structure, and surface" among the causal object subcategories, "transportation, loading and unloading, and operation works" by the subcategories of the content of work at the time of accident, and "negligent job performance and noncompliance of procedure" among the unsafe behavior subcategories. In contrast, the female high-risk groups include "manufacturing" and "construction" by industry, "elementary workers" by employment status of worker, "struck against objects" by cause of accident, and "equipment and machinery" by causal object (Tables 2e4).
In the characteristics of the high-risk groups of the workers aged 50 years, by the employment status of worker, the "equipment and machine operating and assembling workers" in the manufacturing industry were the highest risk group among the regular workers, and the craft and related trades workers in the construction were the highest risk group among the daily workers and temporary workers. Also, the craft and related trades workers in the "membership organizations, repair, and other personal services" were the highest risk group among the part-time workers. According to the analysis results of causal objects and causes of fatal occupation accidents, "equipment and machinery", "struck by objects", and "stuck and caught in objects" took up the highest percentage of fatal occupational injuries among the regular workers and parttime workers, and "building, structure, and surface" and "fall of persons" took up the highest percentage of fatal occupational injuries among the daily workers and part-time workers. And the fatal industrial accidents occur most frequently among regular workers, daily workers, temporary workers, and part-time workers, when they engage in the transportation, loading and unloading, and operation works. Other articles reported that those workers aged 50 years and above were exposed to the highest risk when they installed or dismantled the work platform including scaffold and temporary structures in the construction industry [11e14]. In addition, they reported that "fall of persons" were the most frequent material agency of fatal industrial accidents in the Table 2 Victims and share of fatal occupational injuries of the workers aged 50 years and above by causal objects.