A fringe theory about 49ers injuries has gone viral. Here's what scientists say.

"To help clear up public misconceptions, Woloschak explained that electromagnetic radiation has two general types, one with very high energy and the other with low energy. Human sources of the strong type, called 'ionizing' radiation, include nuclear reactors and weapons. This kind of radiation can indeed break DNA and cause cancer, such as people experienced following the atomic bombings in World War II."

"But the other type, 'non-ionizing' radiation, is extremely weak comparatively. And in modern times, everyone from NFL stars to average fans is surrounded by it. Cellphones, microwave ovens and, of course, power lines emit this more feeble kind of radiation. For Woloschak, the science is clear that power lines do not pose a threat."

"In the huge number of studies that have tried to look at the effects of non-ionizing radiation on cells, there's been no reported damage to DNA, proteins or other molecules that's been identified. Now, there may be one or two loose reports in the literature that you can find that say otherwise, but they've all been refuted."

George Kittle tore his Achilles during a playoff game, and that injury prompted circulation of a theory blaming low-frequency radiation from a nearby electrical substation. Experts in radiation say there is no proof that power lines or substations caused the team's injuries. Electromagnetic radiation includes high-energy ionizing radiation, which can break DNA and cause cancer, and low-energy non-ionizing radiation, which includes cellphones, microwaves and power lines. Numerous studies have examined non-ionizing radiation and have not identified damage to DNA, proteins or other molecules, and isolated contrary reports have been refuted.

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