This study finds an important increase in depression symptom severity associated with exposure to temporary work at any point in time in the two preceding years (including concurrently). Most importantly, these results were obtained through propensity score matching on a number of covariates affecting the likelihood of temporary work status, including, most notably, prior depressive symptoms. Moreover, the exposed group was limited to workers who reported temporary employment status, and did not include those with perceived job insecurity or alternative contractual arrangements (Bernhard-Oettel, Sverke, & De Witte, 2005
; P Virtanen, Vahtera, Kivimaki, Pentti, & Ferrie, 2002
). These findings are consistent with a previous meta-analysis, but remain a novel contribution using US data (M. Virtanen, et al., 2005
). Models with different lag periods of two and four years between the most recent possible exposure and the outcome were not conclusive however, as the models’ assumptions of covariate balance were not met.
Our results contributed to the literature by examining these processes among a US population, with longitudinal controls for factors that may predict entry into temporary work. Yet, other selective factors that may have an influence on the likelihood of being a temporary worker were not included in the models here, and could consist of introducing confounding, such as region and employer (demand-side), variables (Belman & Golden, 2000
; Coleman & McLaughlin). Region may also be an indicator for mobility, or opportunity for employment - in this case, exposure to temporary employment. Moreover, these analyses did not consider the industry, which may have provided additional predictive power (but would have proved difficult to balance due to the large number of empty cells it would have created). Dimensions of inadequate employment not addressed here include: skill mismatch; status discord; inadequate hours, or involuntary part-time work, or the work conditions of jobs performed by temporary workers (Friedland & Price, 2003
The fact that the lagged models did not meet the propensity scores assumptions could be due to the small number of workers in temporary positions, though the very significant results of Model 1, achieved with similar numbers of respondents, would tend to discredit this hypothesis. Another likely explanation is that temporary work is for the most part a transitory status in this population: among the 940 respondents having experienced at least one temporary job from 1992 to 1998, 80% experienced only one such job, 18% two, and 2% three temporary jobs. Therefore, the lagged models assume that temporary work has long-lasting effects on mental health, while this may not be the case in the face of changing, and potentially improving, situations. Thus, while the “scarring” effects of a similarly insecure situation such as job displacement have been found in Sweden (Eliasson & Storrie, 2006
), we did not find evidence of this effect for temporary work in the US.
An important limitation of our analyses is that it is assumed here that temporary workers would prefer a permanent position if it were available. Yet, a study of female temps in New Zealand reported the positive aspects of being in a non-committal work relationship: as a lifestyle choice, an escape from an unsatisfactory conventional job or a self-defined transitional period (Casey & Alach, 2004
). In this sample, it is possible that the composition of temporary jobs and expectations of temporary workers was not representative of all sectors. As a result, despite the specific definition of temporary work exposure, a mixture of low-income, skill mismatched, status discordant work and preferred work conditions were likely found.
Previous studies may shed some light on the possible mechanisms through which temporary work affects mental health, such as the insecurity that characterizes these positions. Indeed, previous studies have argued that there may be a need among employees for the availability, or perception of the availability, of a long-term, continuing relationship with one’s employer, based on the need for job and/or income security, as a crucial factor in determining emotional well-being and depression risk (Barnes, 1980
). In particular, our results are comparable with the findings of Ferrie and colleagues, who estimated the effect of chronic job insecurity over a 2.5 year period among Whitehall II participants (2002), and found that workers who were in chronically insecure positions had higher mean depression scores (1.84, 95% CI: 1.28; 2.40).
Policy implications on the demand-side, suggest a need for increasing the awareness of employers of the long-term or global health impact of relying on a temporary work force, to meet current demands, and in planning future employment needs. From a governmental perspective, temporary workers could be protected by organizational structures involving certification of occupational skills, as in Germany, where an institutionalized transition pathway, linked to a strong occupational segment of the workforce, appears to be more resistant to the increasing flexibility in work patterns in the organization of labour (Heinz, 2003
In conclusion, our results suggest that the proximate effect of temporary work appears to be significantly associated with greater depressive symptoms. This effect is not trivial, as it constitutes an increase by more than 50% in depressive symptoms compared to the average of the population. Moreover, it is likely that the health effects of job insecurity are mediated by the availability of other opportunities in the labour market, which makes these results all the more pressing in these times of economic crisis (Polanyi, Tompa, & J., 2004
). Finally, our results suggest that the expectation that temporary workforces increase productivity may be perversely affected by increases in depressive symptoms: indeed, the WHO found that, in many developed countries, anywhere between a third to almost half of the cases of absenteeism from work are due to mental health problems (World Health Organization, 2003
), and even when employees are present at work, productivity at work may be impaired (World Health Organization, 2005
). Our results suggest then that it could be profitable for both employers and employees to consider employee mental health effects when responding to labour demands in the context of an increasingly competitive globalized economy.