Study: Nighttime LED light increases risk of cancer

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September 13, 2011 03:29

University of Haifa research shows "light pollution" suppresses melatonin, said to be beneficial against cancer.

4 minute read.



A light post

light fixture 311. (photo credit:Courtesy)

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 light.

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Prof. Abraham Haim, with scientists from Italy and the US, just published findings on the subject in the Journal of Environmental Management in an article titled “Limiting the impact of light pollution on human health, environment and stellar visibility.”

Sent the paper by The Jerusalem Post, 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 production.

“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 stores.

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.

Their 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.

“Blue light” receptors in the retina of the eye affect melatonin production but are independent of the visual system, meaning that we don’t ‘see’ with them.

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.

The 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 then.

“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 ISTIL.

“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.

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