Industrialization, electromagnetic fields, and breast cancer risk

The disparity between the rates of breast cancer in industrialized and less -industrialized regions has led to many hypotheses, including the theory th at exposure to light-at-night and/or electromagnetic fields (EMF) may suppr ess melatonin and that reduced melatonin may increase the risk of breast ca ncer. in this comprehensive review we consider strengths and weaknesses of more than 35 residential and occupational epidemiologic studies that invest igated the association between EMF and breast cancer. Although most of the epidemiologic data do not provide strong support for an association between EMF and breast cancer, because of the limited statistical power as well as the possibility of misclassification and bias present in much of the exist ing data, it is not possible to rule out a relationship between EMF and bre ast cancer. We make several specific recommendations for future studies car efully designed to test the melatonin-breast cancer and EMF-breast cancer h ypotheses. Future study designs should have sufficient statistical power to detect small to moderate associations; include comprehensive exposure asse ssments that estimate residential and occupational exposures, including shi ft work; focus on a relevant rime period; control for known breast cancer r isks; and pay careful attention to menopausal and estrogen receptor status.