Increasing concern that “light pollution” caused by artificial lighting that
reduces the production of the hormone melatonin by the brain’s pineal gland can
cause cancer and other diseases has led to new research into which types of
electric bulbs cause less potential risk.
Now a University of Haifa
researcher and his colleagues who are participating in an international study of
the subject have found that nighttime exposure to white-light-emitting diode
bulbs – which are actually blue light on the spectrum – commonly used both in
outdoor and some indoor lighting suppresses the beneficial hormone’s production
five times more than does high-pressure sodium bulbs that emit an orange-yellow
Prof. Abraham Haim, with scientists from Italy and the US, just
published findings on the subject in the Journal of Environmental Management
an article titled “Limiting the impact of light pollution on human health,
environment and stellar visibility.”
Sent the paper by The Jerusalem
, Health Ministry public health chief Prof. Itamar Grotto said on Sunday
that it will discuss the recommendations with other factors including the
Standards Institution and other regulatory bodies.
The researchers said
that since civilization is obviously unwilling to return to the caveman era and
live in darkness when the sun goes down, efforts can be made to minimize
exposure at night to types of illumination that reduce melatonin
“Just as there are regulations and standards for ‘classic’
pollutants, there should also be regulations and rules for pollution stemming
from artificial light at night,” said Haim, head of the University of Haifa’s
Center for Interdisciplinary Chronobiological Research and the Israeli partner
in the research.
The Israeli government has, like others abroad, been in
recent years encouraging the public to purchase and use other types of bulbs
that use significantly less electricity and last longer than the old-style
incandescent bulbs based on filaments; increasingly, they are not sold in
LED bulbs are found on thousands of products from cellular phones
and computer monitors to toothbrushes, operating room equipment and bright tiny
bulbs in indoor lighting fixtures.
The new research included a comparison
between HPS bulbs, which emit orange-yellow light and are often used for street
and road lighting, to other bulbs.
From this comparison, it became clear
that the metal halide bulb, which gives off a white light and is used for
stadium lighting and many other uses, suppresses melatonin at a rate more than
three times greater than the HPS bulb, while the LED bulb, which also gives off
a white light, suppresses melatonin at a rate more than five times higher than
the HPS bulb.
“The current migration from the now widely-used sodium
lamps to white lamps will increase melatonin suppression in humans and animals,”
the researchers say. Melatonin, a compound that adjusts our biological clock and
is known for its antioxidant and anti-cancerous properties, is sold freely in
the US and other countries, especially to relieve ‘jet lag,’ but the Health
Ministry in Jerusalem allows its sale only by doctor’s prescription, arguing
that it is a drug that must be controlled.
“White” artificial light is
emitted at wavelengths of between 440 and 500 nanometers, according to the
international team of astronomers, physicists and biologists from ISTIL - Light
Pollution Science and Technology Institute in Italy, the US National Geophysical
Data Center in Boulder, Colorado, and the University of Haifa.
research was the first to examine differences in melatonin suppression in a
various types of light bulbs, primarily those used for outdoor illumination,
such as streetlights, road lighting and mall lighting.
receptors in the retina of the eye affect melatonin production but are
independent of the visual system, meaning that we don’t ‘see’ with
The team calculated wavelength and energy output of bulbs that are
generally used for outdoor lighting and then compared that information with
existing research regarding melatonin suppression to determine how much each
type of bulb used at night suppresses melatonin production.
researchers offered some concrete suggestions that could reduce nighttime
suppression of melatonin production – to limit the use of “white” light to those
instances where it is absolutely necessary; adjust lampposts so that their light
is not directed beyond the horizon, thus significantly reducing light pollution;
using only the amount of light needed for a task; and turning off the lights
when not in use.
They stressed that there is no harm using artificial
light during the day, as the pineal gland does not produce much melatonin
“Unless legislation is updated soon, with the current trend toward
sources as white LEDs, which emit a huge amount of blue light, we will enter a
period of elevated negative effects of light at night on human health and
environment. Lamp manufacturers cannot claim that they don’t know about the
consequences of artificial light at night,” says Dr. Fabio Falchi of
“As a first step in Israel, for example, the Standards Institution
of Israel should obligate bulb importers to state clearly on their packaging
what wavelengths are produced by each bulb. If wavelength indeed influences
melatonin production, this is information that needs to be brought to the
public’s attention, so consumers can decide whether to buy this lighting or
not,” Haim added.
The University of Haifa researcher declared in 2008
that exposure to light at night is the most powerful factor in breast cancer
besides genetic defects.
Other studies have implicated it in prostate
cancer and the development of nearsightedness in children, eyestrain, headaches
and sleep disorders.