Breast Cancer Linked to Light Pollution

A recent study published in

Chronobiology International supports the hypothesis of a link between nighttime exposure to light and breast cancer. (This hypothesis originated from studies of shift-workers, which led to the International Agency for Research on Cancer to classify night-shift work as a probable human carcinogen.) Researchers examined nighttime ambient light levels and breast cancer rates in 147 cities and towns in Israel and found that the incidence of breast cancer was 73% higher in the most highly illuminated communities than in the least-lit communities.

Multiple regression analysis was used to screen out demographic variables such as ethnicity and income. While the study did not attempt to explain the correlation between higher light levels and breast cancer, other research has pointed to a cause involving the reduction of melatonin secretion.