Wednesday, November 6, 2013

Pilots face increased risk of skin cancer

“I’m referring you to a dermatologist,” the doctor said. “It’s probably nothing, but I don’t like the looks of this mole on your back.”

My employer’s insurance company was requiring employees to get preventive physicals. After the revelation of my mother’s sudden diagnosis with colon cancer a few months earlier, the idea of a physical to get a clean bill of health actually sounded like a good idea. With no health complaints, I didn’t expect any problems to arise. After all, I was seeing an AME twice a year for my first class physical and if there were any serious problems, he would have found them. Right?

I didn’t hurry to the dermatologist. I had a few moles, but didn’t really worry. They weren’t irregular and they didn’t get larger. A couple of months later, I found time to make the appointment.

When the doctor looked at the mole on my back, a mole that my AME had seen at least 12 times, he promptly announced, “We’re going to take that off right now.” He said that the small, black mole could be an early stage of melanoma. Literally before I knew that he had removed it, the mole was gone and I was going home to wait on a biopsy.

As I waited, I learned that there is a strong link between pilots and skin cancer. In 2000, Yahoo News reported on an Occupational and Environmental Medicine study that found that airline pilots have up to 25 times the normal rate of skin cancer. The most common type of cancer among pilots was malignant melanoma. Melanoma represents about ten percent of skin cancers, but accounts for 75-85 percent of skin cancer deaths. The scientists at the University of Reykjavik in Iceland who authored the study found that Iceland Air pilots flying international routes had skin cancer rates 15 times higher than expected. For pilots who typically flew across more than five time zones, such as flying from Iceland to the United States, the rate was 25 times higher than expected.

There have been a number of similar studies, the most recent published in 2009 in Occupational Medicine surveyed members of the Air Line Pilots Association in the United States. Many of these other studies also show an elevated skin cancer risk for pilots, but not as high as the University of Reykjavik study.

It seems to be common sense that pilots would be at an increased risk for skin cancer. Pilots spend a lot of their working lives in the sun. Airports are almost devoid of shade and the sun can beat down mercilessly on a pilot performing a preflight inspection. When pilots are flying, they are above much of the atmosphere that protects surface dwellers from harmful solar rays. Few, if any, airline pilots slather on sunscreen before climbing into the cockpit.

As with the general population, there are other factors that lead to an increased risk of skin cancer. These risks apply to pilots as well. The Skin Cancer Foundation lists five factors that increase the risk of melanoma. First, both blistering sunburns as a child and cumulative exposure to the sun can increase risk. The more moles a person has, the greater the risk of melanoma. Dysplastic nevi, atypical moles, can be precursors to skin cancer. People with fair skin are more prone to skin cancer. A personal or family history of skin cancer also means an increased risk for future cancers. People with weakened immune systems, from chemotherapy or HIV/AIDS for example, also have an increased risk. As with other types of cancer and heart disease, smoking also dramatically increases the risk of skin cancer.

Among pilots, flying at higher altitudes and the higher latitudes near the poles presents the greatest risk. According to the Health Physics Society, the amount of cosmic radiation at the poles can be two to three times greater than the radiation at the equator. This is because the Earth’s electromagnetic field helps to block this radiation. The field is strongest at the equator and gets progressively weaker towards the poles. Science Daily notes that the radiation is on par with an x-ray or CT scan, but frequent exposure by flight crews that fly hundreds of hours each year can lead to increased effects. Solar storms, like the one that diverted flights in 2012, also mean increased dosages of radiation. The ionizing radiation of solar flares cannot be avoided by flying at night or wearing sunscreen.

Robert Barish, a physicist and author of “The Invisible Passenger: Radiation Risks for People Who Fly,” told Science Daily that professional flight crewmembers are exposed to more radiation than any other occupation, even nuclear plant workers. “People who work in the nuclear power industry on an average basis are getting 1.6” [milliSieverts of radiation per year], he said. “There are people who fly in airplanes who are getting 2 or 3 or 4 milliSieverts per year. So they are truly radiation workers.”

The fact that the University of Reykjavik study examined Iceland Air pilots who customarily fly in far northern latitudes may explain the extremely high incidence of cancer among these pilots. Flying at high altitudes near the North Pole for the long time periods associated with oceanic flights, Iceland Air pilots would be subject to all of the highest risk factors associated with skin cancer.

Other factors might be at work as well. Several of the studies indicate that some of the increased risk for pilots may be due in part to disturbed sleep patterns. “The excess of malignant melanoma among those flying over five time zones suggests that the importance of disturbance of the circadian rhythm should be taken into consideration in future studies,'' Dr Vilhjalmur Rafnsson said on Yahoo News. Rafnsson speculated that the disturbance of circadian rhythms could affect the production of melatonin by the body.

The American Cancer Society notes that recent studies have shown that low melatonin is linked to higher risks of some cancers, but that some studies have shown that melatonin supplements were beneficial to cancer patients while others show that it made no difference. Melatonin is available over the counter as a natural sleep aid. According to the FAA website, melatonin “appears to be beneficial in alleviating jet lag” and its use “is not proscribed” but “care should be taken to avoid entering duty status with any residual effects.”

Pilots are not the only people at risk from high altitude radiation. Flight attendants and frequent flyers share the same risk factors. Travelers who fly more than once or twice per week are at the greatest risk according to Science Daily. Occasional airline passengers or general aviation pilots who typically fly at altitudes of less than 6,000 feet do not have an elevated risk.

The risk of radiation is not limited to skin cancer. As far back as 1992, the FAA published a report, “Radiation Exposure of Air Carrier Crewmembers,” that addressed the possibility of genetic defects to a child whose parent had been exposed to high altitude ionizing radiation. The unborn child of a pregnant woman who is part of a flight crew is at the greatest risk of severe health problems ranging from mental retardation to childhood cancers. Women are also at high risk for breast cancer according to WebMD.

To minimize their risk of skin cancer or other radiation-induced problems, pilots should follow the prevention guidelines of the Skin Cancer Foundation. Avoid sunburns by wearing hats and sunglasses and seeking the shade, especially between 10 a.m. and 4 p.m. (Indoor tanning booths are also bad.) Use sunscreen with an SPF of 15 for everyday use. For extended outdoor activity, SPF of 30 or higher should be used. Sunscreen should be applied 30 minutes before going outside and reapplied every two hours (or immediately after swimming or sweating). Self inspections of your skin on a monthly basis and yearly medical checkup are also recommended.

Pilots can also avoid taking heavy doses of solar radiation by flying at lower altitudes or taking more southerly routes (in the northern hemisphere) to remain at lower latitudes. An FAA report, “What Aircrews Should Know About Their Occupational Exposure to Ionizing Radiation,” sets a recommended maximum level of radiation and gives estimated dosages for a number of typical flights.

My dermatologist also recommended Heliocare, an oral over-the-counter sun protection supplement available on Used with sunscreen, Heliocare helps to prevent sunburns and repairs previous sun damage to skin.

In the end, my skin story has a happy ending. The biopsy revealed that the mole was not a melanoma, but an atypical mole. Nevertheless, I will have several smaller moles removed as well and will incorporate routine visits to the dermatologist into my health care routine.


Originally published on Aviation Examiner

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