Night Shift Work May Cause Cancer
Press Release / HealthPartners Research 30nov2007
Hazards of painting, firefighting also examined by international research committee
BLOOMINGTON, Minn — A study by the World Health Organization has found that night shift work increases the risk of cancer in humans. The study found that after prolonged exposure to night shift work, women are at a higher risk to develop breast and colon cancer. Men who work the night shift are more likely to experience prostate cancer.
"Shift work that interferes with regular nighttime sleep disrupts circadian rhythms, our body's natural clock," said Dr. Erhard Haus of HealthPartners Research Foundation who chaired a subgroup of the study. "This impedes biologic function by suppressing the immune system, reducing melatonin production and may damage genes leading to the production of abnormal cells."
Dr. Haus was part of a team of 24 scientists from ten countries who met at the International Agency for Research on Cancer in Lyon, France, to assess the potential carcinogenicity of shift work, painting, and firefighting. The workgroup analyzed several epidemiologic studies and animal experiments. In addition to their findings on shift work, they determined that overall, occupational exposure as a painter is carcinogenic to humans. They also classified occupational exposure as a firefighter as possibly carcinogenic to humans.
A preliminary report of the WHO International Agency for Research on Cancer (IARC) will appear in Lancet Oncology, December 7, 2007.
Between 15 and 20 percent of the working population in the U.S. and Europe are engaged in shift work, which is most prevalent in the health care, transportation, communication, leisure and hospitality sectors.
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HealthPartners family of care includes HealthPartners Research Foundation (http://www.hprf.org). Conducting about 250 research projects each year, the Foundation is dedicated to advancing scientific knowledge through research to improve the health of our members and the community. Founded in 1957, HealthPartners (http://www.healthpartners.com) serves more than one million medical and dental health plan members nationwide and is the largest consumer-governed, nonprofit health care organization in the nation, providing care, coverage, research and education to improve the health of members, patients and the community.
Shift Work Increases Cancer Risk:
JEREMY BARKER / National Post (Canada) 30nov2007
If you've ever felt that your job is killing you, you may be right.
Shiftwork can be so detrimental to your body that a World Health Organization study says it should probably be classified as carcinogenic. The report from International Agency for Research on Cancer, WHO's cancer agency, says shift workers have a higher risk of cancer than the general population.
"Shiftwork that involves circadian disruption is probably carcinogenic to humans," the IARC reported Friday, referring to the body's internal clock that tells cells when to produce various hormones. The lack of natural light and darkness is fingered by the agency as the most likeliest cancer risk.
"Nearly 20% of the working population in Europe and North America is engaged in shiftwork. Shiftwork is most prevalent in the health care, industrial, transportation, communications and hospitality sectors. Among the many different patterns of shiftwork, those that include nightwork are most disruptive to the circadian system."
This report hits close to home to those of us working at nationalpost.com, but it is the kind of death-defying risk we are willing to make to ensure you are entertained and in the know. No need to thank us, that's just the way we are.
Shift Work Can Cause Cancer, World Agency Says
MAGGIE FOX / Reuters 30nov2007
WASHINGTON -- Shift workers and firefighters have a higher risk of cancer than the general population and such work should probably be classified as carcinogenic, the International Agency for Research on Cancer said Friday.
A team of 24 scientists who sifted through the evidence said more studies must confirm the link, but found that shift work that disturbs the body's internal clock appears to have cancer-causing effects, too.
This internal clock regulates circadian rhythms, a complex system that signals cells to produce various hormones at various times.
"Shiftwork that involves circadian disruption is probably carcinogenic to humans," the IARC, the cancer agency of the World Health Organization, said in a statement.
The finding could affect a significant number of people.
"Nearly 20% of the working population in Europe and North America is engaged in shiftwork. Shiftwork is most prevalent in the health-care, industrial, transportation, communications, and hospitality sectors," the IARC said.
"Among the many different patterns of shiftwork, those that include nightwork are most disruptive to the circadian system ... Occupational exposure as a firefighter is possibly carcinogenic to humans," it added.
A full report will be published in the December issue of The Lancet Oncology medical journal, but the conclusions are based on years of published research.
In 2001, a team at the Fred Hutchison Cancer Research Center in Seattle found that women who work night shifts may have a 60 percent greater risk of breast cancer.
Another study in 2004 suggested that night lights may raise the risk of childhood leukemia. And several tests in mice show that circadian clock genes are disrupted in tumor cells.
In 2006, Japanese researchers reported that people who work a mix of day and night shifts may face a greater risk of dying from heart disease.
Other studies provide evidence that firefighters, who breathe in smoke, chemicals and dust and who also work shifts, have a higher risk of cancer and heart disease.
The shift work findings may all have to do with the body's response to light, and that could explain why shift work might affect cancer risk.
The brain's pineal gland produces the hormone melatonin after the body is exposed to a certain amount either sunlight or artificial light. It is stimulated by darkness, and so production is disrupted when people are up at night with the lights on.
A reduction in melatonin is linked to an increased risk of certain cancers. Melatonin acts as an antioxidant protecting DNA from the type of damage that leads to cancer and heart disease.