Thursday, September 02, 2010
Connection Between Light at Night and Cancer Revealed
A new study from the Center for Interdisciplinary Chronobiological Research at the University of Haifa has found an additional link between Light At Night (LAN) and cancer. This research joins a series of earlier studies carried out at the University of Haifa that also established the correlation. “High power light bulbs contribute more to ‘environmental light pollution’, which the study has shown is a carcinogenic pollution,” notes Prof. Abraham Haim, who headed the study.
Earlier studies in which Prof. Haim has participated at the University of Haifa, have shown that people living in areas that have more night-time illumination are more susceptible to prostate cancer in men and breast cancer in women. The researchers’ hypothesis was that LAN harms production of melatonin, a hormone that is released from the pineal gland during the dark part of the 24h cycle and which is linked to the body’s cyclical night-day activity and seasonality. When this hormone is suppressed, the occurrence of cancer rises.
The current study, in which Dr. Fuad Fares and Adina Yokler, Orna Harel and Hagit Schwimmer also participated, set out to establish or refute this hypothesis. In order to do so, four groups of lab mice injected with cancerous cells were examined: one group was exposed to “long days” of 16 hours of light and 8 hours of darkness, simulating exposure to artificial light beyond the natural number of light hours in a day; a second group was exposed to the same “long days” but were treated with melatonin; a third group was exposed to “short days” of 8 light hours and 16 dark hours; and a fourth group was exposed to the same “short days” but during the dark hours was exposed to a half-hour interval of light.
The results show once again the clear link between LAN and cancer: the cancerous growths in mice exposed to “short days” were smallest (0.85 cubic cm. average), while those mice exposed to the interval of LAN during dark hours had larger growths (1.84 cubic cm. average) and those exposed to “long days” even larger growths (5.92 cubic cm. average).
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