The public exposé of severe lead contamination in the tap water of Flint, Mich., has prompted national soul-searching, legal battles, some of which are ongoing, and beefed-up state rules governing lead in drinking water. The Environmental Protection Agency is expected to propose an update to the federal Lead and Copper Rule soon, a long-overdue step in strengthening federal regulation of drinking water.

But a troubling campaign is afoot to launder the history of Flint’s water crisis and to recast the episode there as a blip in an overall downward trend in U.S. children’s lead exposure in the past half-century. Some researchers have reproached advocates and other members of the scientific community for stridently sounding alarms over the threat posed by lead in water. Such pushback may encourage the EPA to suggest only modest updates to the Lead and Copper Rule, allowing millions of water-bearing lead service lines to remain in place.

We cannot let this happen. That the enormous toll of lead poisoning on public health was unknown or tolerated in the past does not now render tolerable the reality that many children today are exposed to high levels of lead in water, paint and soil, even if those levels represent an improvement from the mid-20th century. Federal law should not greenlight weak standards for lead in water. The Lead and Copper Rule needs bold and far-reaching change.

Flint’s crisis captured our attention because of how extreme it was. The lead levels in Flint’s water were among the highest recorded in recent years in a large water system, as measured by independent testing. While such mammoth levels are unusual among large water systems, lead in drinking water crops up quite often in smaller systems, albeit at lower levels: About 5.5 million people were served by community water systems that exceeded EPA standards between January 2015 and March 2018.

Lead is a powerful neurotoxin that can damage nearly every organ and system in the human body. Exposure to lead, even at low doses, can harm the developing brains and nervous systems of babies and young children. Lead exposure can also trigger miscarriages and stillbirths in pregnant women and cause kidney and cardiovascular damage, cognitive impairment and fertility troubles in adults. When ingested, lead is gradually transferred from the bloodstream to organs and stored in bones and teeth, making bones brittle. Women’s bones sometimes release stockpiled lead into the bloodstream during pregnancy, affecting the fetus.

The EPA’s current 15-parts-per-billion “action level,” which triggers action to abate water-lead levels, is far too high. Most utilities are not required to take remedial action unless 10 percent of water samples exceed 15 parts per billion when tested over the course of a lead-monitoring cycle.

But scientific studies have repeatedly demonstrated a link between rising water-lead levels and higher blood-lead levels in exposed children. Several studies have shown that this association holds true even for water-lead levels as low as 5 parts per billion, well below the EPA’s 15 parts-per-billion standard. Federal agencies, intergovernmental organizations and professional associations — including the Centers for Disease Control and Prevention, the World Health Organization and the American Academy of Pediatrics — now agree that no level of lead exposure is safe. A health-protective regulatory standard for lead in water should fall below 5 parts per billion, accounting for the limited capacity of utilities to reliably reduce water-lead levels.

Federal regulations must also require the full replacement of lead service lines adjoining water mains to people’s homes — which deliver water to millions of Americans — regardless of lead levels in water. Even when utilities have a maximally effective program to control lead corrosion, lead service lines can still release lead into drinking water. When a system’s water chemistry changes, heavy trucks drive over pipes or nearby construction occurs, the protective coating or “scale” on the interior of the lead lines can erode or be dislodged, causing lead to be released into the water. To protect the public, federal law should require all water utilities to count the number of lead service lines in their distribution systems and to dig up and replace them with safer materials.

Utilities will probably protest, insisting that they do not own the portion of the lead service line running under private property. Don’t fall for it. City codes and water utility guidelines have routinely approved, encouraged and in some cases mandated the installation of lead service lines.

No doubt, such an infrastructure project will be costly — probably about $30 billion. But the burden of lead protection also does not have to fall on the poor. The costs of fully replacing lead service lines can be built into utility rate structures, and the federal government should give funding assistance to low-income communities to take on the project.

Such an investment is worth the price tag, if it means protecting our communities from toxic drinking water.