06 feb 2009-- Men who live in countries with the highest levels of artificial light at night appear more likely to develop prostate cancer, according to American and Israeli researchers.
They looked at the incidence of prostate cancer among men in 164 countries and also studied data on nighttime lighting.
The incidence of prostate cancer in countries with low nighttime lighting exposure was 66.77 per 100,000, compared with 87.11 per 100,000 among men with medium exposure (30 percent greater risk), and 157 per 100,000 among men with high exposure (80 percent greater risk).
The University of Cincinnati and University of Haifa researchers said a number of theories could explain the apparent link between nighttime lighting and increased prostate cancer risk, including: suppression of melatonin production; suppression of the immune system; and disruption of the body clock due to confusion between night and day.
"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 said in a news release.
In a previous study, the same team of researchers found an association between nighttime light and the incidence of breast cancer.