The residents of Flint, Michigan, continue to face an unprecedented crisis over lead in water. A new report from the Centers for Disease Control and Prevention makes clear how much damage was done."When the source of the water supply was switched to the Flint River, without appropriate corrosion control measures, young children who drank the water had blood lead levels that were significantly higher than when the source of water was the Detroit water system," according to the report. "After the switch back to the Detroit water system, the percentage of children under 6 years with elevated blood lead levels returned to levels seen before the water switch took place." While the city relied on the Flint River for water, children younger than 6 had a 46 percent higher chance of testing at or above 5 micrograms of lead per deciliter of blood, the CDC's level of concern. The CDC reviewed blood lead level tests for more than 7,000 children 6 and younger. The tests were done before the water supply was switched from the Detroit water system to the Flint River, after the switch but before a water advisory was issued, after the advisory was issued and after the water supply was switched back. "This crisis was entirely preventable, and a startling reminder of the critical need to eliminate all sources of lead from our children's environment," Patrick Breysse, director of the CDC's National Center for Environmental Health, said in a news release. Children under 6 are particularly vulnerable to lead poisoning, according to the Mayo Clinic, and it can severely impact mental and physical development. "When pediatricians hear anything about lead, we absolutely freak out," Dr. Mona Hanna-Attisha told CNN's Dr. Sanjay Gupta in January. "Lead is (an) irreversible, potent neurotoxin." This week, the American Academy of Pediatrics released a new policy statement urging new legal requirements to remove lead from housing, child care facilities and school water fountains because there is no safe level of blood lead concentrations. "We care about (lead) so much because it impacts your cognition and your behavior," said Hanna-Attisha, the doctor who first sounded the alarm about Flint's lead crisis. "It actually drops your IQ. Imagine what we've done to an entire population. We've shifted that IQ curve down. We've lost our high achievers, the next kid who's going to be neurosurgeon, and we have all these children who may now need remedial services." In order to reduce a water fund shortfall, the city switched water sources in 2014. While a new pipeline connecting Flint with Lake Huron was under construction, the city turned to the Flint River as a water source during the two-year transition. According to a class-action lawsuit, the state Department of Environmental Quality was not treating the Flint River water with an anti-corrosive agent, in violation of federal law. Since the water wasn't properly treated, lead from aging service lines to homes began leaching into the Flint water supply after the city tapped into the Flint River as its main water source. The CDC is urging Flint residents to continue to use recommended filters for any water they will be drinking or using to cook or to brush their teeth. The agency said it's OK to use unfiltered water for showering and bathing because lead isn't absorbed into the skin but cautioned parents to be vigilant about their children drinking bath water. In the report, the CDC stressed the continued importance of blood lead level screenings for children younger than age 6 living in Flint. Most doctors recommend that children's lead levels be tested during routine wellness exams. The test is covered by Medicaid and most private health insurance. At a minimum, the American Academy of Pediatrics recommends (PDF) that children be tested at ages 1 and 2. "We have ... expanded Medicaid and strongly urge parents to enroll their children and schedule appointments for them to be seen by a health provider, who can follow their health as they grow and develop," Dr. Nicole Lurie, U.S. Department of Health and Human Services' assistant secretary for preparedness and response, said in a news release about the CDC report. Hanna-Attisha noted that there's no antidote for lead, but there are ways to mitigate exposure. Nutrition, for one, plays a huge role. Some foods can help limit the absorption of lead: foods high in calcium, such as milk, yogurt, cheese and leafy green vegetables; iron, including lead red meats, beans, peanut butter and cereals; and vitamin C, such as oranges, green and red peppers and juice. "When (lead) gets into your body ... it can get excreted or it can get absorbed in your bones," said Hanna-Attisha. "That's where calcium plays a role. If you're fully loaded with these vitamins, it will limit the absorption of lead into your body."