About 150 years ago, people figured out that lead pipes could kill them. In 1861, fifty prisoners in King County Jail in Brooklyn started vomiting uncontrollably, until a doctor realized that the water supply was contaminated with lead. Seven years later, a New York City woman named Elizabeth Galler was accused of poisoning her husband to death, until the coroner concluded that the lead in his body came not from one big dose, but rather from many small doses over a long time. The New York Herald ran an editorial demanding an investigation into the city’s lead pipes. We now know that the lead level in New York tap water back then was over 100 times more toxic than the EPA’s current standard.

The economic historian Werner Troesken tells these stories in his 2006 book The Great Lead Water Pipe Disaster to make a point: This is an old problem. But sadly it is not one that has gone away. This is one lesson to take from the events unfolding in Flint, Michigan, where an entire town has been drinking contaminated water since March 2014. The stories of nauseating brown water and blasé state officials paint a shockingly distressing picture of mismanagement and neglect. 

Unfortunately, in America, the lead problem is not limited to Michigan. Instead, it extends far beyond Michigan. If 4 percent is too many kids to have high lead concentrations in Flint—and it undoubtedly is—then what does it say that it’s 12.9 percent in Milwaukee and 17.6 percent Cleveland? Or, can you believe it, 40 percent in Claiborne Parish, Louisiana, and 58.3 percent in Houston County, Alabama?

To be fair, tremendous progress has been made on the public health front, and much of this progress has been in the area of healthy homes.  For example, the number of people living in substandard housing has fallen by almost half since 1978, and we now have less than 1 million units in this condition, with many of these units in rural areas.

We have even made considerable progress where lead exposure is concerned.  Between 1976 and 2006, the incidence of lead in blood among children under 5 fell dramatically, from 13.5 million to 174,000. So we are a long way from the days when 85 percent of big cities used lead pipes and 10 percent of Massachusetts residents suffered from lead poisoning.

But 174,000 kids exposed to lead is still far too many, so our work continues in programs across the country actively working to minimize lead exposure. In Milwaukee, researchers have been tracking children’s blood lead levels and found them improving from the city’s lead hazard control program. In Rochester, the city’s housing inspection law has made thousands of homes safer from lead paint. In Boston, the National Center for Healthy Housing has reduced outdoor lead contamination with low-cost soil interventions. Throughout the nation, the Department of Housing and Urban Development has issued grants that reduced lead contamination in homes and improved children’s health.

This is all good news.

But a second lesson I am reminded of from the Flint case is that poor people often bear the burdens of environmental degradation.  Companies have a long history of locating their most pollution-intensive plants closest to the poorest neighborhoods, making life harder for the Americans for which it is already the hardest.  Experience shows that maintaining reduced lead exposure in such at-risk communities is especially hard. The HUD intervention, for example, cleaned out the lead dust in the short run, but a year later, it piled up again. Home maintenance requires constant vigilance.

One look at Flint is all it takes to see how communities deteriorate without sustained investment. Cost-cutting becomes a dangerous temptation. In Flint’s case, they had to cede power to a state-appointed “emergency manager” who made the ill-fated switch to a cheaper water system. As one Flint resident pointed out, there’s no mystery why they got stuck with this penny-pinching czar: “Almost every city that got one was a poor, African-American-majority city devastated by a shrinking industrial sector: Flint, Pontiac, Detroit, Highland Park, Benton Harbor, and so on.”

What does all of this say? It says that healthy housing matters. It says that healthy neighborhoods matter. And it says that for all our progress—let’s not forget that those percentages have fallen significantly in recent decades—we are still allowing too many American kids to be poisoned. Usually, of course, it’s the kids who are already starting at a disadvantage, coming from poor homes and segregated neighborhoods.

It’s definitely progress that Flint shocks us. In Elizabeth Galler’s day, there was no outrage over the lead pipes that killed her husband. We have come to expect more from our cities because our cities have shown that they can overcome these threats to our health.

Our homes, above all else, should not be threats. They should be the one place where we—and our children—can feel safe. But safety does not come free. It requires a commitment by all of us to invest in the programs and policies that can condemn known, predictable threats like lead exposure permanently to the past where they belong.