In a 2013 report, The Incidence of Accepted Workers Compensation Claims for Mental Stress in Australia, Safe Work Australia compiled statistics on mental disorders and included information from other reports and research. 

A large number of workers are estimated to be impacted by mental health disorders, and there are known prevention options which can be used in the workplace.

According to the Australian Safety and Compensation Council  2008 (precursor to Safe Work Australia), the development of a mental disorder is recognised in the Australian workers’ compensation system as a potential outcome of experiencing mental stress in the course of work. Mental stress accounts for an average of 95% of mental disorder claims across the last ten years. 

Leka et al (2003) describe workplace mental stress as “the adverse reaction experienced by workers when workplace demands and responsibilities are greater than the worker can comfortably manage or are beyond the worker's capabilities.”

The research conducted by Safe Work Australia was based on workers’ compensation data from accepted workers’ compensation claims. It does not include information on unsuccessful claims, people not covered by compensation, or details of the number of people who are suffering but do not make a claim. It also does not include the Police in WA, Defence Force Personnel or the self-employed. The data is skewed towards workers who are more likely to claim based on their occupation, age, industry of the employer, and where they have secure employment. The data does not describe the actual prevalence of work-related mental stress.

The report aims to explore what mental stress is, what causes it, and how it can affect the health and wellbeing of workers.

The mental stress subcategories used as the source in the report are:

• Work pressure – mental stress disorders which arise from work responsibilities and workloads, deadlines, organisational restructures, workplace interpersonal conflicts and workplace performance or promotion issues.
• Exposure to workplace or occupational violence – this may include being the victim of an assault by a person who may or may not be a work colleague, or they may also be a victim of or witness to a bank robbery, hold up or other violent event.
• Exposure to a traumatic event – these disorders arise from witnessing a fatal or other incident.
• Suicide or attempted suicide – this includes all suicides regardless of circumstances of death and all attempted suicide.
• Other mental stress factors – this may include dietary and deficiency diseases (such as bulimia or anorexia).
• Work-related harassment and/or workplace bullying – this may be repetitive assault and/or threatened assault by one or more work colleagues, repetitive verbal harassment, threats, and abuse from one or more work colleagues. 
• Other harassment – this might include being the victim of sexual or racial harassment.

Although work-related mental stress is a state of mind and body rather than an illness as such, if experienced over a long period of time, stress can contribute to the development of serious physical and mental illnesses. In addition to causing distress and illness, it reduces organisational productivity and can be a burden on the health and welfare services. 

Two significant studies have found that work-related mental stress workers’ compensation claims are the most expensive form of workers’ compensation because they frequently involve long periods of absence from work.

Trends in mental stress

The report acknowledges that while there has been a reduction in the number of physical injuries and fatalities in the workplace last three decades, mental disorders arising from work-related mental stress have become increasingly important.

The report note that research indicates that the number of compensation claims for mental disorders which are launched substantially underestimates the size of the problem, particularly in lower socio-economic jobs (LaMontagne et al 2010).

The Australian Bureau of Statistics 2009–2010 found that workers who reported mental stress were less likely to claim workers’ compensation than workers with other injuries. 70% of workers who said that they experienced work-related stress did not apply for workers’ compensation. The ABS statistics in 2005–06 and 2009–10 showed that the exposure to mental stress remained stable, accounting for 5% of all work-related injuries for both surveys.

In North America, it was noted that employees deferred claiming compensation as they feared losing their job. This may also apply to Australian employees who have experienced job insecurity due to their precarious work status. Around one in five Australian employees do not have leave entitlements or permanent job security. The ABS Work-Related Injuries Survey 2009–2010 found that casual employees were less likely than permanent employees to apply for workers’ compensation, even though they reported higher injury rates. Some of the reasons given included: 

• They didn't know they were covered or eligible
• It was too inconvenient or too much trouble
• The injury was minor or claim unnecessary
• They thought would have a negative impact on their current or future employment 

The financial impact of mental stress is considerable, across workplaces and the broader economy. A 2008 Medibank Private commissioned study found that in 2007, the total cost of work-related mental stress on the Australian economy was $14.81 billion. The direct cost to employers alone in stress-related presenteeism and absenteeism was $10.11 billion. These figures did not include the hidden costs of re-staffing and retraining as a result of the high staff turnover. Stress is also known to contribute to a number of other health conditions.