Does Working the Night Shift Cause Cancer? Plus, What Are The Other Jobs With High Cancer Risks?

Now, there's more evidence that it's not just a matter of what kind of job you hold, but what shift you pull, when it comes to trying to stay cancer-free.

A new study finds that those who work night shifts can be more susceptible to contracting cancer because DNA cannot readily repair itself as easily when sleep rhythms are disturbed.

The study in the Journal of Pineal Research notes that interfering with the body's normal sleep schedule has not only been linked to increased risk for cancer, but can lead to other health issues, like becoming overweight or developing cardiovascular problems.

To focus on the sleep schedule issue, however, researchers in a controlled laboratory experiment examined leukocytes, or white blood cells, from a group of young adults as part of simulation of three days or nights of work shifts.

"The simulated night shift schedule significantly altered the normal circadian rhythmicity of genes involved in cancer hallmark pathways," the study found.  DNA repair was underway after the simulated day shift schedule, but not the night shift.

"Our results suggest that circadian dysregulation of DNA repair may increase DNA damage." It creates the potential of "elevated cancer risk in night shift workers," the study's abstract states.

The findings buttress the link between sleeping patterns and cancer from earlier studies. The European Society for Medical Oncology, for instance, reported that the International Agency for Research on Cancer, which included 27 scientists from 16 countries, classified certain night shifts as "probably carcinogenic to humans" in 2019.

Of course, there are other ways that working can elevate one's risk to cancer.

Mechanics, plumbers and seafarers are at risk for mesothelioma when they come into contact with asbestos, a long-term study of 45 million people in Nordic countries found.  And skin cancers can befall those who work outdoors. Gardeners, farmers and fishing industry workers, for instance, were most susceptible to lip cancer. Woodworkers and furniture makers face a risk from nasal cancer.

Related: Asbestos Causes Cancer But Now the Federal Government Is Opening the Door to its Comeback

Even though airline crews work entirely indoors in the metal tubes of aircraft fuselages they are also at risk to more ultraviolet and cosmic rays, according to a study published in JAMA Dermatology.

The study, however, didn't show a link to higher incidences of melanoma.

One profession that might, on its face, seem unlikely for contracting cancer, but at big risk for falling off roofs: chimney sweeps.

Despite their fanciful image from classic movies like Mary Poppins, the cancer risk is there.

"Chimney sweeps are exposed to carcinogens such as polycyclic aromatic hydrocarbons from the chimney soot," the Nordic study found.

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