(Undated) -- Warnings about the potential hazards of radiation from WiFi in school classrooms are on the rise. But those who are concerned about the health effects of Radio-Frequency Radiation – RFR, as it’s known – are finding it can be hard to make headway. Sheri Calarco of Wilmette says her youngest son started getting headaches and rapid heart rates, only when he was in school. After a lengthy process of elimination, WiFi remained the likely culprit. The Calarcos found another school, less dependent on wireless computing, for both their sons, and they want parents to know what they know now. In Rhode Island, high school teacher Shelley McDonald says she has been warned her job is in danger if she continues to raise concern about WiFi in her school. Studies show links to fatigue, neurological disorders, and cardiac irregularities, among other symptoms.