-
- LONDON (Reuters) - Airline
pilots have up to 25 times the normal rate of skin cancer and it could
be due partly to disturbed sleep patterns, scientists in Iceland said in
a report published Wednesday.
-
- Cosmic radiation and lifestyle factors, such as more
frequent sunbathing, could also be involved, but scientists at the University
of Reykjavik said pilots who flew over five or more time zones had 25 times
as many cases of malignant melanoma as the general population.
-
- Malignant melanoma is the most serious form of skin cancer.
-
- ``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 told Reuters.
-
- Circadian rhythms regulate sleep patterns and the hormone
melatonin, a chemical naturally released by the brain to induce sleep.
-
- ``Melatonin is something that inhibits the growth of
cancer cells in experimental models. It has recently been tried in the
treatment of malignant melanoma,'' Rafnsson said in a telephone interview.
-
- He stressed that the role of melatonin in the high incidence
of the disease among the long-haul pilots was just speculation and more
research still needs to be done.
-
- ``It could be a combination of bad habits (such as sunbathing)
and melatonin. The next thing to do is to study larger groups of pilots
and whether they are sunbathing all the time,'' he said.
-
- Rafnsson and his colleagues looked at the skin cancer
rates of 265 pilots who worked for Icelandic airlines and compared them
with rates expected to develop in the general population based on data
from the national cancer registry of people of the same age.
-
- Their research is published in the journal Occupational
and Environmental Medicine.
-
- The pilots had higher rates of malignant melanoma than
any other cancer. Rates for pilots flying international routes were 15
times higher than expected and 25 times higher for pilots flying routinely
from Iceland to the United States.
-
- The pilots' estimated dose of annual radiation was well
within accepted levels for occupational exposure.
-
- Melanoma accounts for about 10 percent of all skin cancers
but causes 75-85 percent of skin cancer deaths. Excessive exposure to harmful
sun rays can increase the risk of the disease.
-
- Previous research by Danish scientists showed that long-serving
pilots and cabin crew also had a higher risk of leukemia, which scientists
believe could be due to increased exposure to cosmic radiation.
-
- _____
-
- Beta Carotene Does Not Protect Against Skin Cancer
-
- 2-17-00
-
- NEW YORK (Reuters Health) -- Beta carotene does not protect
humans from developing nonmelanoma skin cancer, report US researchers.
-
- Previous study findings suggested that beta carotene
supplements did protect against basal cell and squamous cell skin carcinomas
in mice. But a report in the February issue of the Archives of Dermatology
shows that men who took beta carotene supplements for 12 years had the
same risk of such skin cancers as men who did not take the supplements.
-
- Researchers led by Dr. Uta M. Frieling of Harvard Medical
School in Boston, Massachusetts, evaluated the effect of taking beta carotene
every other day on the development of nonmelanoma skin cancer among more
than 22,000 male physicians, taking part in the Physicians' Health Study,
which began in 1982 and ended in 1995.
-
- The men were randomly assigned to take either 50 milligrams
of beta carotene or (an inactive) placebo every other day, and to take
either 325 milligrams of aspirin or placebo on alternate days.
-
- A total of 3,607 of these men developed nonmelanoma skin
cancer, 1,786 in the beta carotene group and 1,821 in the placebo group.
Taking the antioxidant supplement did not make any difference in the risk
of these skin cancers, nor did it cause any harmful side effects. The authors
also report that smoking status did not affect the development of these
skin cancers.
-
- Frieling and colleagues offer several explanations for
why beta carotene did not protect participants in their study from skin
cancer. They note, for example, that some studies have found that the supplement
gives more protection to those who have lower blood levels of it to start
with. The current study did not look at baseline levels of beta carotene,
so they can't test this hypothesis.
-
- The researchers conclude that people should not count
on nutritional supplements to protect them against cancers caused by exposure
to the sun. Instead, they need to reduce their risk by limiting their exposure.
-
- In an accompanying editorial, Dr. John A. Baron of the
Dartmouth-Hitchcock Medical Center in Lebanon, New Hampshire, notes that
although animal studies and epidemiological surveys suggested that beta
carotene offers protection against skin cancer, clinical trials have failed
to show any effect.
-
- ``Results from randomized trials of beta carotene for
cancer prevention should raise troubling issues for scientists who wish
to base health recommendations on epidemiological or laboratory data,''
Baron concludes. He states that animal studies can help us understand disease
processes, but the relevance of these studies to the prevention of human
cancer ``remains doubtful.'' Instead, recommendations for humans must come
from carefully structured clinical trials. SOURCE: Archives of Dermatology
2000;136:179-184, 245-246.
-
- ---
-
- Comment
-
-
- From Dallas <dalas@hol.gr
- 2-19-00
-
- Hello Jeff Rense,
-
- I wrote to you recently in praise of you and your website
and I see that you're still maintaining the high quality of articles and
guests.
-
- I just wanted to throw in my two cents about the article
from Iceland about pilots and skin cancer. I am a private pilot and have
been an Airline Mechanic (Eastern Air Lines & Pan American) for 12
years. What the scientists always forget about Airline flight (33,000
ft.) is that it takes you above the heavier lower atmosphere that general
aviation (5,000 ft.) and corporate aviation (22,000 ft.) usually fly through.
The little acknowledged studies point to high energy cosmic and gamma
radiation penetrating the fuselage. Also soft x-rays and high energy ultraviolet
B.
-
- As a mechanic I know what's behind the plastic liners
inside the plane and there is nothing but fiberglass in aluminum blankets
to keep the heat in. The Iceland study about pilots having 25 times more
skin cancer because they cross many time zones really means that the pilots
are in the air for a longer period of time! It is not from sleep disorder.
The government would have us not smoke in planes for people's health but
a pregnant woman on a long distance flight may harm the baby more from
radiation,just by being there, then any amount of smoke from passengers.
-
- As you well know, there are a lot of things that the
government is aware of. It just doesn't tell us.
-
- Chris Dadalias
- Athens, Greece
-
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