Three Mile Island engineers William Behrle (from left0, Michael Benson, Sam Griffith and Martin Cooper enter the containment building from the personal airlock in Middletown, Pa., on Aug. 15, 1980. AP hide caption

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Police officers wear gas masks while on patrol in a vehicle at the Fukushima nuclear power plant on March 12. Experts are concerned about the safety of the nuclear workers, but they say that so far, there's no risk for others in Japan or in the U.S. Kaname Yoneyama/AP hide caption

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Technicians at the Three Mile Island plant enter the outer airlock door leading into the containment building housing the disabled nuclear reactor at the Three Mile Island nuclear plan in February 1982. The accident at the Harrisburg, Pa., plant began on March 28, 1979. AP hide caption

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Makers of water bottles, including Camelback, now sell products that don't contain BPA, a chemical that can mimic the sex hormone estrogen. But a new study says that even if they don't contain BPA, most plastic products release estrogenic chemicals. David McNew/Getty Images hide caption

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A new study finds that radio waves from a cell phone can affect the metabolism of brain cells, though there is no evidence that the effect is harmful. Here, a pedestrian talks on her phone on a street in San Francisco. Justin Sullivan/Getty Images hide caption

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Malcom Brown (left) is hit by Jake Smith on a kickoff return during a high school state championship game in Arlington, Texas, in December. Sports medicine professionals and the NFL are calling for tougher regulations on head injuries sustained by young athletes. Matt Strasen/AP hide caption

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A hormone that impacts memory in rats likely does the same thing in other animals, like humans. S. Ugur Okcu/ hide caption

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Modern bedbugs are increasingly resistant to pesticides. Some populations, in fact, can survive 1,000 times the amount of pesticide that would be needed to kill a traditional bug. Orkin LLC/AP hide caption

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People with autism have impaired feelings of trust and empathy, and early studies show that the hormone oxytocin could help. Steven van Soldt/ hide caption

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Fear The Prius? A Toyota Prius hybrid model car waits for customers at a Toyota dealer in Hollywood, Calif., on March 10. Concerns about the cars suddenly accelerating dogged the company earlier this year. Mark Ralston/AFP/Getty Images hide caption

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Residents of Times Beach, Mo., were forced to leave their town in December 1982 because the chemical dioxin was found in the soil. Thirty years later, the Environmental Protection Agency can't decide how dangerous the chemical is. Bill Pierce/Time & Life Pictures/Getty Images hide caption

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