Electromagnetic fields: the jury´s still out. 1. Biological effects

Concerns that electromagnetic (EM) fields may cause cancer and endocrine and nervous system disorders are discussed. The focus is on 60 Hz fields, where the mechanism of interaction probably involves the cell membrane, is nonlinear, and may act by causing some cooperative phenomena among the components of the cell membrane. Two basic epidemiological study designs have been used in work on cancer caused by EM fields. The first, retrospective case-control studies, compare an existing population of cases with a control group without the disease that is selected to be similar in all other characteristics. The second type computes the proportional mortality (or incidence) ratio, which compares the mortality from (or incidence of) disease in the sample population to that in general public. Selected studies that have looked for a link between exposure to power-frequency fields and cancer are summarized. Results have been mixed, but many studies do suggest a connection. One possibility is that EM fields act as a promoter of cancer. Also discussed are studies on birth defects and circadian rhythm, and cell and organ studies. Some experiments suggest that mediation by the cell membrane and/or large proteins that float in it is the mechanism by which fields couple to the cell.<>