Although federal Medicaid rules require blood-lead tests for children at 1 and 2 years old, state records show that more than 54 percent of Ohio children on Medicaid were not tested in 2006. That's 86,500 children. Officials with the Ohio Department of Job and Family Services, which oversees the state's Medicaid program, say they are working to improve testing rates. But they also say there is little they can do to force parents and doctors to perform the tests. "It requires parents to understand the importance of lead testing and what the harmful effects are," said Mary Haller, chief of stakeholder relations at the agency. "The (doctors) themselves may just not be accustomed to looking for that or including that in a regular visit." Environmental health advocates say there is no excuse. "That system left a lot of children falling through the cracks," said Jane Houlihan, vice president of research for the Environmental Working Group, based in Washington. The group released a study of lead-poisoning issues in Ohio in 2004. The study estimated that more than 13,300 children, including those with private insurance coverage, had lead poisoning but were not tested. The problem isn't limited to Ohio. A 2000 study by the Centers for Disease Control estimated that 79 percent of 1- and 2-year-olds covered by Medicaid were not being tested. The same study found that, nationwide, 535,000 children covered by Medicaid had high blood-lead levels. About one-third that number of children also had lead poisoning but were not covered by Medicaid, showing that it's a problem that can affect children of all socioeconomic backgrounds. Houlihan said accountability is one of the main problems. Federal rules don't penalize states if they don't meet the testing requirements. Other states have tougher policies or are proposing them. New York requires all doctors to screen every 1- and 2-year-old for lead poisoning. Vermont legislators are considering mandatory screenings as well. Ohio's efforts include sending letters to doctors and parents that say the tests are required. In Ohio, state records show that, in 2006, 59 percent of 1-year-old children covered by Medicaid were tested. The number dropped to 33 percent of 2-year-olds. Haller blamed the drop on fewer doctor visits after a child turns 1. There also are big differences in testing rates among counties. State records show that 86 percent of eligible 1-year-olds and 57 percent of 2-year-olds in Franklin County were tested in 2006, compared with 23 percent of 1-year-olds and 13 percent of 2-year-olds in Fayette County. Haller said testing rates can rise and fall depending on a doctor's ability to perform the tests. She said some doctors, who don't have the equipment needed, refer patients to other doctors or labs, which means making another trip. Funding often makes a difference. Since 1996, Columbus Public Health has spent more than $4 million and tested more than 72,500 children, largely by sending workers to Head Start classes citywide. The tests over 11 years have found 3,034 children with high lead levels, said Jose Rodriguez, a health department spokesman. "It lets us get to children who are in at-risk neighborhoods and ages." Dispatch reporter Mark Ferenchik contributed to this story.