Women especially vulnerable: Study
Rotating and night shift workers have a higher risk of work injury, with women being a particularly vulnerable group, according to a study from the University of British Columbia (UBC) in Vancouver.
For the years 1996 to 2006, the proportion of injuries among daytime workers (2.9 per cent) was considerably less than those in night (5.9 per cent), rotating (3.9 per cent) and other (3.1 per cent) shifts, found the study, which looked at the annual Survey of Labour and Income Dynamics by Statistics Canada (which tracks workers who received workers’ compensation). Most of the daytime workers were employed in non-manual labour while non-daytime workers were primarily in mixed and manual labour.
“It’s more than just working at night, (shift work is) actually having some health effects and safety issues that need to be considered,” said Jan Chappel, a senior technical specialist at Canada’s National Centre for Occupational Health and Safety. “People in general don’t give it a lot of consideration — they’re not thinking that it might have an effect.”
The odds ratio (OR) of injury was 2.65 among night shift workers and 1.73 among rotating shift workers compared to regular daytime workers, found the study.
“This result, in conjunction with our finding that there is steady growth of workers in this category, suggests that the burden of injury associated with night shift work may be increasing,” said “Shift work trends and risk of work injury among Canadian workers,” which appeared in the Scandinavian Journal of Work, Environment and Health.
“Both men and women working night shift schedules have almost twice the risk of injury than those in regular daytime schedules.”
The primary driver for the increased risk is likely sleep deprivation or sleepiness, said Imelda Wong, a PhD candidate at UBC’s School of Environmental Health and co-author of the study.
“People that work at night may have disrupted sleep or not as good quality sleep, and so they carry this over and when they’re working, they may not be quite as alert, which puts them at a higher risk for injury,” she said.
“Work conditions at night actually might be different than work conditions during the day — generally there may be less supervision or workers at night might not have as high seniority or as long of work experience as people who work during the day.”
If a job requires more manual labour, that also increases the risk, along with educational level and longer hours, found the study.
“Generally speaking, people who work shift work might not have as many years of education as people who work daytime work,” said Wong. “The number of hours feeds into the theory that the more you work, the more tired you become, the higher the risk of injury can be. People with lesser education might work in riskier occupations which put them at higher risk of injury, which ties into occupational physical demands.”
Jobs not unsafe
One of the main concerns of the study was whether the differences with shift work were because the jobs and occupations people have in shift work are just inherently hazardous, said Chris McLeod, a faculty associate at UBC’s Centre for Health Services and Policy Research and co-author of the study. However, the study did account for differences in occupations, physical demands on the job, and still found a two-fold increase in night shift injuries.
“I don’t believe that these risks are inherent in the work, I think they are risks that can be mediated,” he said, adding the study does not identify key drivers.
From 1996 to 2006, the number of reported worker injuries overall decreased from 415,000 to 356,300, a decline of 27.9 per cent from 4.2 to three injuries per 100 workers. However, the injury rate among night shift workers remained stable during this period, found the UBC study.
That is a concern, said McLeod, and it could mean we just haven’t been as effective in remediating or focusing on the hazards that take place at work during night shifts.
“That could be a combination of workers being fatigued but it also could be — and this is a hypothesis — due to (the fact) that work is qualitatively different at night, so mainly that there’s less supervision, it may mean there’s less workers around, it may mean the type of steps we’ve taken in the industry to remediate hazards have been more effective in daylight hours than they have at night. Those are things we need to look at.”
Women more vulnerable
From 1996 to 2006, almost one-half of the growth of Canada’s labour was in non-regular daytime shift work and the number of women in rotating and night shift work increased by 94.5 per cent while for men it was 50 per cent, found the study.
Among men, the risk for night shift workers was significant (OR 1.91) but not for rotating shifts. For women, the risk was more robust among regular night shifts (OR 2.04) and rotating shifts (OR 2.29).
“To actually see there was such an excess risk between men and women was a little bit surprising for me,” said Wong.
However, studies show women, on average, spend nine hours more per week than men on household duties and women are generally the primary caregivers at home, so daily tasks centre around child care or household tasks, she said.
“Frequent rotation between day and night shifts may have a detrimental effect on work-life imbalance for women, perhaps causing a less stable environment for regular child-care duties,” said the study. “This may lead to fatigue and increased chance of injury at work.”
What employers can do
In 2006, there were 2.7 million lost-time injury compensation claims in Canada. Of these, 107,000 of men’s claims and 200,000 of women’s could be attributed to higher risk of injury associated with shift work, said the UBC study. The average reported injury compensation awarded to non-regular daytime workers in 2006 was $165, which totals more than $50.5 million in lost-time claims.
For shift work, it’s largely about awareness and realizing it might be a little different at night than during the day, said Chappel.
That means when employers are doing risk assessments or safety checks, they should remember to check each actual shift because there may be different things happening at different times of the day that are not accounted for.
“And maybe because it’s the night shift, there aren’t people around to do their safety checks and risk assessments, they’re just not giving it consideration that they might need to do extra things or that they’re doing extra things and they’re not accounted for because the day people aren’t there to check up,” she said. “(It means) treating it as a hazard itself that needs to be looked at and what happens at that time versus three (o’clock) in the afternoon.”
