Prostate Cancer May Be Linked to Artificial Light at Night

The Universities of Cincinnati and Haifa, in a joint project, have studied the average levels of artificial light at night in different countries, and related them to the frequency of prostate cancer. Their findings have now been made known in a press release from the University of Haifa. They join those of a similar study showing a link between artificial night light and breast cancer in women and of nearsightedness in children.

Data from 164 countries were obtained from the International Agency for Research on nightly exposure among men to artificial light and cases of prostate, lung, and colorectal cancer. In addition, information on illumination at night was obtained from the US Defense Department's weather satellite project. Data about the population density of each country, along with electricity use, socioeconomic factors, and the percentage of urban residents were used to determine the average amount of artificial light to which the population was exposed at night.

The countries were classified into 3 groups – those with little, medium, and high exposure to lighting at night. The average frequencies of prostate cancer were 67, 87, and157 patients per 100,000 for these 3 groups, respectively.

Possible reasons for this apparent linkage were: suppression of melatonin production by artificial light; suppression of the immune system; and disruption of the body clock due to confusion between night and day. It’s known that the World Health Organization (WHO) considers increasing artificial lighting to be environmental pollution. On the other hand, energy-efficient lighting is often brighter than conventional types. This problem will require resolution before we can consider acting on the new findings.