And what they cost in workers' comp

According to the Liberty Mutual Research Institute for Safety Workplace Safety Index, overexertion ranked first as the leading cause of disabling injury in the workplace.

The overexertion category, which includes injuries related to lifting, pushing, pulling, holding, carrying, or throwing, cost U.S. businesses $15.1 billion and accounted for more than one quarter of the top 10 disabling injury causes in 2012, the most recent year for which data are available. All told, the listed injury causes amounted to nearly $60 billion in total U.S. workers compensation costs or more than $1 billion dollars a week spent by businesses on disabling injuries.

The Workplace Safety Index is developed annually by Liberty Mutual researchers based on information from the company's workers compensation claims, the U.S. Bureau of Labor Statistics (BLS), and the National Academy of Social Insurance. Using BLS injury event coding, researchers determined which injuries caused an employee to miss six or more days of work and then ranked those events by total workers compensation costs.

10 Leading Causes and Direct Costs of Workplace Injuries in 2012

  1. Overexertion: $15.1B: 25.3%
  2. Falls on same level: $9.19B: 15.4%
  3. Struck by object or equipment: $5.3B: 8.9%
  4. Falls to lower level: $5.12B: 8.6%
  5. Other exertions or bodily reactions: $4.27B: 7.2%
  6. Roadway incidents involving motorized land vehicle: $3.18B: 5.3%
  7. Slip or trip without fall: $2.17B: 3.6%
  8. Caught in/compressed by equipment or objects: $2.1B: 3.5%
  9. Repetitive motions involving micro-tasks: $1.84B: 3.1%
  10. Struck against object or equipment: $1.76B: 2.9%

The top five injury causes accounted for 65.4% of the total 2012 workplace injury cost burden, based on Liberty Mutual data. The leading "overexertion" category and the two "falls" categories among the top five combined to generate more than 50% of the leading causes of disabling workplace injuries.