In August 2015, Dr. Mona Hanna-Attisha was having a glass of wine in her kitchen with two friends, when one friend, a water expert, asked if she was aware of what was happening to the water in Flint, Mich.

Hanna-Attisha, a pediatrician in Flint, knew that the city had changed its water source the previous year. Instead of channeling water from the Great Lakes, residents were now drinking water from the nearby Flint River. She had been aware of some problems with bacteria after the switch, but she thought everything had been cleared up.

Her friend warned otherwise: "She said, 'Mona, the water isn't being treated properly. It's missing something called corrosion control. ... Without that corrosion control, there is going to be lead,' " Hanna-Attisha remembers.

The possibility that the city's drinking water had been tainted by lead raised alarms in Hanna-Attisha; exposure to lead can result in long-term cognitive and behavioral problems, especially in children.

As Hanna-Attisha began reviewing her patients' medical record, she noticed that the percentage of children with elevated lead levels had increased after the water switch. But when she shared her data at a hospital press conference, government officials tried to discredit her.

"The state said that I was an unfortunate researcher, that I was causing near-hysteria, that I was splicing and dicing numbers," Hanna-Attisha says. "It's very difficult when you are presenting science and facts and numbers to have the state say that you are wrong."

But Hanna-Attisha refused to give up. Instead, she spearheaded efforts to publicize and address the water crisis in Flint. She writes about her experiences in the book What the Eyes Don't See.

"This is a story of resistance, of activism, of citizen action, of waking up and opening your eyes and making a difference in our community," she says. "I wrote this book to share the terrible lessons that happened in Flint, but more importantly, I wrote this book to share the incredible work that we did, hand in hand with our community, to make our community care about our children."

On how the Flint water crisis began

Flint was in a near-bankruptcy state, really suffering from crisis for years, if not decades before this water crisis. In Michigan, if you're in financial dire straits, the state can come in and really usurp democracy. So in 2011 Flint became under the control of state-appointed financial emergency management, and that emergency manager's job was austerity. It was ostensibly save money no matter what the cost.

They decided that the water that we had been getting for half a century from the Great Lakes — fresh pretreated Lake Huron water that we had been buying from Detroit — was too expensive. We would start drawing water from the local Flint River until a new pipeline to the Great Lakes was to be built. So the move to the Flint River was to be a temporary move. ...

The greatest irony is that the treatment chemical, the corrosion control, would only have cost $80 to $100 a day. That's all it would've cost to properly treat this water.

Mona Hanna-Attisha

This was all done to save money, to cut costs, with no, no regard for public health or children's health. The folks who grew up in Flint know the history of the Flint River. We are a legacy industrial community. The Flint River has actually caught on fire twice in the past. The corrosion or the impact of the water crisis was not the Flint River's fault. The Flint River probably would have been OK, not ideal, if it was treated properly. The greatest irony is that the treatment chemical, the corrosion control, would only have cost $80 to $100 a day. That's all it would've cost to properly treat this water. Yet that was never put in this water. The pump to install that treatment was actually never installed, so there never even was an intent to treat this water properly.

On how lead is a "silent pediatric epidemic"

The consequences of lead exposure is something we don't readily see. It impacts, at a population level, cognition, so actually drops the IQ of a population of children, shifting that IQ curve to the left where you have more children who need special education services, less gifted kids. It impacts behavior — increasing the likelihood of things like attention deficit disorder. It has been linked to impulsivity. It has been linked to violence and even to criminality. So lead exposure has these lifelong cognitive and behavioral consequences that you do not see right away.

On her approach to treating children exposed to lead

Our response in Flint has been very proactive and preventative, because we cannot ethically wait to see the consequences of lead poisoning, of lead exposure, so we have put into place multiple, multiple interventions that we know that will promote children's brain development and limit the impact of this crisis. We can't take away lead — I wish I could I prescribe a magic pill or an antidote to take away lead poisoning; there is no such thing. But we can do a lot to limit children's exposure to mitigate the impact of this crisis.

On whether the people of Flint can safely bathe in the water

A lot of people had concerns, especially early on, with bathing and showering. We had bacteria in the water, then we had a lot of chlorine in the water, which irritated people's skin and eyes. People had rashes and hair loss and they'd take a bath and up to the water line their kids would break out in rashes. We didn't really know why people had these rashes. Lead per se does not cause skin issues. The [Centers for Disease Control and Prevention] actually came in and did a huge rash investigation and what they noted was that yeah, people had more skin issues, but we don't know why. There was a lot of stuff in this water that could have irritated people's skin. So that is a case-by-case basis, deciding if you can bathe, if you can shower. For some people, it's fine; for some people it still causes irritation.

On the quality of Flint's water today

Flint is still in a state of public health emergency. The people of Flint are still recommended to drink filtered water or bottled water. Our water quality has dramatically improved since the onset of this crisis; however, Flint is embarking on something that no other city is doing: We are replacing our damaged lead pipes. We were on this corrosive untreated water for 18 months and that ate up our infrastructure. So those pipes are being replaced and that takes time. We've replaced about 6,000 of those damaged lead pipes, but there's about 9,000 of those pipes that still need to be replaced. Until then, if the people have not had their pipes replaced, they need to be [drinking] filtered or bottled water. ...

[Flint is] one of the poorest cities in the country. Until recently the state was paying for bottled water, and that ended a few weeks ago, so now it's being supported by churches and nonprofits like the United Way.

On how the Flint water crisis exacerbates the "toxic stress" the city's residents already face

Growing up in poverty is a toxic stress. Being exposed to violence, lack of nutrition, unsafe places to play — all of these are toxic stresses. And now recently, with the incredible science of brain development, we've learned that all this repetitive stress and trauma for children impacts their entire life course trajectory in a very graded and predictable way.

The more of these adversities you have — especially really early in life during this period of critical brain development, this prenatal or preschool period — the more of these toxicities you have, be it lead exposure or be it poverty or family separation, the more likely that you are going to grow up to be unhealthy and have more chronic diseases.

In the original study on [adverse childhood experiences], it actually showed an impact on mortality. If you had six or more of these ACEs, these adverse childhood experiences, your mortality dropped 20 years. Your life expectancy dropped 20 years. Our kids in Flint already had a decreased life expectancy. Their life expectancy in the Flint ZIP code is 15 years less than the life expectancy of an adjacent ZIP code. So we were a community that was already rattled with these toxic stresses.

Sam Briger and Mooj Zadie produced and edited the audio of this interview. Bridget Bentz, Molly Seavy-Nesper and Scott Hensley adapted it for the Web.

Copyright NPR 2018.