Contact with animals and dirty environments may be one reason farm kids are less likely to get allergies, researchers say. iStockphoto.com hide caption

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Isabel Doran, 4, gets a CT scan at Children's National Medical Center with her mom, Veronica Doran. The X-ray radiation in CT scans raises the risks for cancer, including leukemia, a new study shows. Dayna Smith/The Washington Post/Getty Images hide caption

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Kimberly Payton, a teacher at the Small Savers Child Development Center, reads to a group of preschoolers in Washington, D.C., in 2010. Researchers say that teachers who make small changes in how they read to 4-year-olds can improve kids' reading skills later on. Ricky Carioti/The Washington Post/Getty Images hide caption

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A label on a package of Tide laundry detergent packets warns parents to keep them away from children. Nearly 250 cases of illness from such packets have been reported to poison control centers this year. Pat Sullivan/AP hide caption

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