Tuesday, March 17, 2009

Night shift "probable" risk for breast cancer

March 16, 2009

Did you know working at night is considered a risk factor for breast cancer?

In October 2007, The International Agency for Research on Cancer (IARC), part of the World Health Organization, concluded that night work is "probable" cancer risk and classified it as a Group 2A risk.

It is felt to be due to the disruption in light-dark cycle. Melatonin is produced in the dark cycle and is an anti-oxidant that scavenges for dangerous chemicals that may lead to illness. So if one is awake during the dark cycle, melatonin levels are lower and there is a potential for harmful chemicals to wreck havoc.

All hypothesis at this point.

The American Cancer Society hasn't officially classified it as a risk, though night shift workers are at increased risk for obesity, cardiovascular disease, diabetes, gastrointestinal problems, sleep and mood disorders as well as occupational injuries.

Most affected are folks who shift between shifts, instead of working just one or the other, like nurses.

In Denmark, 38 women with breast cancer have received compensation via their employers' insurance companies. To qualify, they had to have worked at least 1 night shift a week for 20-30 years. Breast cancer was identified because they had been studying women and flight attendants .

There is a suggestion that there may also be an increased risk of prostate cancer.

Sources: CNN, eCancerMedicalScience, Independent

For the curious, here are some of the things on the IARC List.

Group 1: Carcinogenic to humans (105)

Arsenic, asbestos, benzene, Epstein-Barr virus, estrogen therapy, ethanol (drinking alcohol), Hepatitis B/C, HIV 1, solar radiation, X and gamma rays, Japanese salted fish, wood dust, chewing tobacco, first and second hand smoke, chimneysweep, paving, roofing and rubber industry.

Group 2A: Probably carcinogenic to humans (66)

Chemotherapy (Adriamycin & Cisplatin), inorganic lead compounds, Kaposi's sarcoma, nitrogen mustard gas, ultraviolet rays A-C, sunbeds/sunlamps, diesel exhaust, hairdresser, barber, shiftwork involving circadian disruption and emissions from high-temperature frying.

Group 2B: Possibly carcinogenic to humans (248)

Antimony, cobalt, DDT, isoprene, lead, magnetic fields, naphthalene (mothballs), nickel, phenobarbital, styrene, pickled vegetables, welding fumes, carpentry, firefighter, printing processes and textiles manufacturing.

Group 3: Not classifiable as to carcinogenicity to humans (515)

para-Aminobenzoic acid (PABA), acrylic fibers, Ampicillin, caffeine, carrageenan, chlorinated water, coal dust, fluorescent lighting, malathion, polyvinyl chlorine (PVC), prednisone, tannic acid, Vitamin K, crude oil, jet fuel, petroleum jelly and glass, leather, lumber and paper manufacturing.

Group 4: Probably not carcinogenic to humans (1)

Caprolactam

Why just one?

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