Long hours increase risk of illness and injury

Affects both safe and risky professions

Workdays longer than 12 hours put workers at increased risk of injury and illness, regardless of how hazardous the job is or how long their commute is to and from work.

That's what a study by the University of Massachusetts (UMass) Medical School Center for Health Policy and Research found. More than half of the 5,100 injuries and illnesses found in the 11,000 people surveyed occurred during extended working hours or overtime. After adjusting for age, gender, type of industry, and job, employees working overtime were 61% more likely to sustain a work-related injury or illness than employees who did not work overtime, according to Allard E. Dembe, ScD, co-director of the doctoral program in occupational health services research at UMass and Harvard in Boston.

Further analysis indicated that the increased risks were not merely the result of demanding work schedules being concentrated in inherently "riskier" industries or jobs, Dembe says.

The principal findings of the study, Dembe says, include:

• Working in jobs with schedules that routinely involve overtime work or extended hours increases the risk of suffering an occupational injury or illness.

• Overtime schedules had the greatest relative risk of occupational injury or illness, followed by schedules with extended (>12) hours per day and extended (>60) hours per week.

• The risk of injury was found to increase with the increasing length of the work schedule, even after controlling for the entire amount of working time spent "at risk" for injury.

• Multivariate analyses indicated that the increased injury risks are not merely the result of the demanding work schedules being concentrated in riskier occupations or industries.

• Results are consistent with the hypothesis that long working hours indirectly precipitate workplace accidents by inducing fatigue or stress in affected workers.

The authors say their findings back up the theory that long working hours indirectly precipitate workplace accidents by inducing fatigue and stress. And they support government initiatives, such as those espoused by the European Union, to cut working hours.

"Strategies for preventing workplace injuries and illnesses should include changes in work organization and job design, addressing the length of work schedules and the performance of overtime work," says Dembe.

The report on the UMass study, "The impact of overtime and long work hours occupational injuries and illnesses: new evidence from the United States," appears in the August 2005 issue of Occupational and Environmental Medicine and is available at http://press.psprings.co.uk/oem/september/588_om16667.pdf.