Most researchers have focused on health

Most researchers have focused on health care workers in this field as there is high prevalence of violence in clinical setting. For instance, 13.2% and 10.4–39.1% of nurses had experienced these behaviors in the United States (Nachreiner et al., 2005) and in European countries, respectively (Camerino, Estryn-Behar, Conway, van Der, & Hasselhorn, 2008). Given the high prevalence in clinical setting, studies on employees in other industries such as white-collar workers, e.g., professionals, engineers or clerks, or blue-collar workers, e.g., salespersons, drivers or cleaners, are limited (Camerino et al., 2008; Hogh et al., 2008; Nachreiner et al., 2005; Tolhurst et al., 2003). There are, however, several studies that reported the prevalence rates based on national representative samples of working LY335979 which were carried out in Europe (0.08% in Denmark (Hogh et al., 2003), 0.8% in the UK (Clark et al., 2012) and 7.7% in Turkey (Aytac et al., 2011)). In Asia, there is no other study except for a South Korean study that reported 0.7% of Korean national representative working samples had experienced physical violence at the workplace (Lee, Kim, & Park, 2014), while other studies conducted surveys only among health care workers (Alameddine, Kazzi, El-Jardali, Dimassi, & Maalouf, 2011; Arimatsu et al., 2008; Chen, Hwu, Kung, Chiu, & Wang, 2008; Kamchuchat, Chongsuvivatwong, Oncheunjit, Yip, & Sangthong, 2008). Nevertheless, information on prevalence of physical assaults at work especially in Asian countries are still lacking. On the other hand, it is also important to identify the risk factors for physical assaults in order to prevent employees from being subjected to violence. To the best of our knowledge, there are only two studies that have reported the risk groups and consequences of physical assaults or violence (Aytac et al., 2011; Wieclaw et al., 2006). Among those two studies, one Danish study (Wieclaw et al., 2006) revealed a high prevalence of occupational violence among male workers in personal services and teaching association; female workers in health association, teaching association and personal services. The other study which included workers from various sectors in Turkey (Aytac et al., 2011) revealed that males or security sector workers were usually the victims of physical violence. These studies indicated that workers who are engaged in helping others are more likely to experience physical violence. Meanwhile, researches which focused on socioeconomic status (SES) of the victims are also limited. In recent years, SES (e.g., educational status, income and occupational status) have attracted considerable attention as an important risk factor for violence. For example, recent study showed that low SES were more likely to be exposed to workplace bullying or interpersonal conflicts (Inoue & Kawakami, 2010; Tsuno et al., 2015). Among the minimal researches on work-related physical assaults which focused on SES, high school graduate workers were found to be more exposed to violence compared with university graduate workers (Aytac et al., 2011). Similarly, females with low income were also more vulnerable to violence (Virtanen et al., 2008). These studies indicate that workers of lower SES are at high risk for exposure to physical assaults. In Japan, remuneration is rewarded according to the employee\'s educational status. For example, in 2013, the average lifetime wage of high school graduates is JPY 208.7 million for males and JPY 172.2 million for females but university graduates could earn an average of JPY 261.4 million for males and JPY 212.5 million for females (The Japan Institute of Labour Policy and Training, 2015). Such hierarchical pattern exist even within the same organization, which means educational status cause lower position in the workplace. Low SES is not only at high risk for exposure to physical assaults but also at a high risk for poor mental health; in fact, pelagic zone has a direct relationship with depression and anxiety (Sakurai, Kawakami, Yamaoka, Ishikawa, & Hashimoto, 2010; Virtanen et al., 2008). In the same manner, workers with low SES were more likely to have mental health problems from occupational stress events such as interpersonal conflicts or organizational injustice (Inoue & Kawakami, 2010; Inoue, Kawakami, Tsuno, Tomioka, & Nakanishi, 2013). Therefore, one could hypothesize that the association between exposure to work-related physical assaults and mental health is stronger in low SES individuals than in high SES individuals. However, when investigating separately for males and females, the results are slightly different. For instance, the association of interpersonal conflict with depression was significantly greater among males of high SES than males of a low SES, though this pattern was not observed in females (Inoue & Kawakami, 2010). Although low SES is a risk factor both for exposure to violence and mental illness, the effect of SES on the association between violence and mental health is inconclusive.