How do employment types and job stressors relate to occupational injury? A cross-sectional investigation of employees in Japan

Objective: This study investigated whether 1) the risk of occupational injury differs among permanent employees and specific types of temporary workers, 2) the risk of occupational injury differs across different employment types depending on the degree of job stressors. Study design: A cross-sectional study design based on self-report survey data. Methods: A total of 36,688 full-time workers (28,868 men and 7820 women; average age =35.4) were surveyed by means of a self-administered questionnaire. Employment types consisted of permanent employment and two forms of temporary employment: direct-hire and temporary work agent (TWA). Job characteristics including job demands, job control, and social support at work were measured. Occupational injury was measured by asking whether the participant had an injury on the job in the past 12 months that required a medical treatment. To investigate the relationships between employment types, job stressors, and occupational injury, hierarchical moderated logistic regression tests were conducted. Results: High job demands (OR = 1.44) and low job control (OR = 1.21) were significantly associated with an increased risk of occupational injury, while controlling for demographic, life style, health, and occupational factors. In addition, direct-hires (OR = 1.85) and temporary agent workers (OR = 3.26) had a higher risk of occupational injury compared with permanent employees. However, the relationship between employment types and the risk of occupational injury depended on the levels of job demands and job control. Specifically, the magnitude of the relationship between job demands and the risk of occupational injury was substantially greater for temporary work agents than for permanent employees when they reported low levels of job control. Such an interaction effect between job demands and job control on the risk of occupational injury was not observed between permanent employees and direct-hire temporary workers. Conclusion: The current study indicated that temporary workers might be more vulnerable to occupational injury than permanent employees. High levels of job demands and low levels of job control might also add to temporary workers' risk of occupational injury, particularly for TWAs. (C) 2013 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.