First, children living near power lines were at risk for leukemia. Then, cell phones were going to fry our brains. Now, wireless networks are harmful too? Three families have sued a Cook County, Ill., school district, claiming that wireless local area networks installed in the district\u2019s 10 schools, which allow students to access the network from anywhere in a classroom, are subjecting their kids to prolonged exposure to low-level, high-frequency electromagnetic radiation, presenting substantial and serious risks to their health.Just how harmful are wireless local area networks? According to the Federal Communications Commission, evidence of the harmful biological effects of low-level radio frequency radiation has been "ambiguous." However, the FCC does admit that prolonged exposure to high levels of this radiation can result in the heating of human tissue and an increase in body temperature. This, in a nutshell, is how microwaves cook food.Wi-Fi experts argue that while wireless networks do, in fact, produce low levels of electromagnetic radiation, they emit no more than household gadgets do. If wireless networks are hazardous to your health, they say, so then is nuking a slice of pizza. Microwave ovens and many cordless phones actually operate at the same 2.4GHz frequency used by a 802.11b wireless network. Even those wireless speakers you can buy at RadioShack emit similar radiation levels. "At this point, we have no reason to believe there is any harm in wireless networks," says Wi-Fi Alliance Managing Director Frank Hanzlik. The school district in question, Oak Park Elementary School District #97, is standing behind its decision to use wireless technology. In a statement, representatives said they spent two years researching the issue and listening to expert testimony. The district believes the technology, the same as that used in buildings around the world, is safe.But plaintiffs in the Oak Park Elementary School District lawsuit claim they have more than 400 scientific articles outlining the health risks of low-intensity radio frequency radiation exposure. In their lawsuit they assert that "responsible scientists have reported that prolonged exposure to low-intensity radio frequency radiation can break down DNA strands, cause chromosome aberrations and break down the blood-brain barrier, thereby permitting toxic proteins to invade the brain."They are scheduled to get their day in court this month.