A new report from the CDC confirms what people in Flint, Michigan, had been saying for a year before state leaders listened to them -- that the city's tap water supply was toxic, filled with lead, and unsafe to drink.
But the main takeaway from the federal agency's comprehensive study of Flint's water crisis was that the whole thing was preventable, especially if officials at several different levels of government did their jobs.
Children who drank tap water in Flint had a 50 percent higher risk of elevated levels of lead in their bloodstreams, a CDC spokesperson told NBC News. The presence of lead in the city's water was a direct result of switching the water source from the Detroit municipal system to water from the nearby Flint River, a move that was intended to save money.
But the water from the Flint River had a different chemical makeup, and stripped away layers of protective coating inside the city's water pipes. With those layers gone, the corrosive water ate away at the pipes, introducing lead into the water supply.
The Flint River should have been treated by state environmental officials before it was used as a drinking water source, according to NBC News, but officials failed to take that precautionary step.
Despite the fact that residents complained for months -- with the city's tap water turning brown, yellow and other colors with contamination -- state government and environmental officials continued to deny the water was unsafe.
The denials continued from 2014 until September of 2015, when pediatric physician Mona Hanna-Attisha of Hurley Medical Center confirmed a steep rise in toxic lead levels among infants and toddlers.
"When pediatricians hear anything about lead, we absolutely freak out," Hanna-Attisha told CNN. "Lead is (an) irreversible, potent neurotoxin."
Lead impacts human cognition and behavior, Hanna-Attisha said, and children younger than six are especially vulnerable because the neurological damage is happening at a critical development point.
"It actually drops your IQ," Hanna-Attisha told CNN. "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 [a] neurosurgeon, and we have all these children who may now need remedial services."
While the CDC report confirmed the elevated lead levels during the time of the water crisis, and confirmed blood levels returned to normal ranges after the drinking water source was restored to the cleaner Detroit municipal system, the study did not measure the scope of the contamination. The CDC reviewed data on 7,000 children.
Despite not knowing the scope of the problem, officials said poor children were disproportionately impacted.
"Most inner city kids and children in other settings have blood lead levels that are detectable in their blood," said Patrick Breysse, director of the CDC's National Center for Environmental Health.