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Artificial
light at night: Higher risk of Prostate
Cancer
Newswise — A new study at the University of
Haifa discovered: Worldwide, countries with
the highest levels of artificial light at
night also have the highest rates of
prostate cancer
*This discovery joins the findings of a
previous study by the same researchers that
found a connection between exposure to
artificial light at night and the incidence
of breast cancer.*
Countries in which nighttime artificial
lighting is used more intensively tend to
have a higher risk of prostate cancer in
men, concludes a new study that was carried
out at the University of Haifa.
This joins a previous finding that was
published in Chronobiology International in
2008, that exposure to artificial lighting
at night increases the incidence of breast
cancer in women.
The study, carried out by Prof. Abraham Haim,
Prof. Boris A. Portnov, and Itai Kloog of
the University of Haifa together with Prof.
Richard Stevens of the University of
Connecticut, USA, was intended to examine
the influence of various factors - including
the amount of artificial light at night - on
the incidence of three types of cancer:
prostate, lung, and of the large intestine,
in men around the world.
Data was collected from a database of the
International Agency for Research on Cancer,
on the incidence of these types of cancer in
men in 164 countries.
Data on the levels of lighting at night were
gathered from DMSP (Defense Meteorological
Satellite Program) satellite images.
The nighttime illumination data were
adjusted by the geographic distribution of
the population of the country, in order to
reach an accurate measure of "the amount of
artificial light per night per person."
The researchers also examined additional
factors, such as electricity consumption,
percentage of urban population,
socioeconomic status, and other variables.
At the very first stage of the study, it
already became clear that there is a marked
link between the incidence of prostate
cancer and levels of nighttime artificial
illumination and electricity consumption.
Several different methods of statistical
analysis were used to arrive at this
conclusion.
Next the researchers isolated the "amount of
artificial light at night per person"
variable in order to examine its particular
effect.
The countries were divided into three groups
for this stage of the study: those with
little exposure to lighting at night; those
with medium exposure; and those with high
exposure.
The
results demonstrated that the incidence of
prostate cancer in those countries with low
exposure was 66.77 prostate cancer patients
to 100,000 inhabitants.
An increase of 30% was found in those
countries with medium exposure: 87.11
patients per 100,000 inhabitants.
The countries with the highest level of
exposure to artificial light at night
demonstrated a jump of 80%: 157 patients per
100,000 inhabitants.
According to the researchers, there are a
number of theories that could explain the
increased incidence of prostate cancer due
to exposure to lighting at night, such as
suppression of melatonin production,
suppression of the immune system, and an
effect on the body's biological clock
because of confusion between night and day.
Whatever the cause, there is a definite link
between the two. "This does not mean that we
have to go back to the Middle Ages and turn
the lights out on the country.
What it means is that this link should be
taken into account in planning the country's
energy policies," the researchers pointed
out.
The researchers added that an increased use
of artificial lighting is considered by the
World Health Organization as a source of
environmental pollution.
As such, the appeal made by Israel's
Ministry of Environmental Protection to use
energy-efficient lighting is problematic, as
this type of lighting is also much brighter.
The country ought to encourage energy saving
in lighting as well as limiting the
pollution level.
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