When it comes to lead exposure in America, we still dont have a clear picture of how many children are being exposed to the neurotoxin and where they are. This leaves hundreds of thousands of children vulnerable to the dangers of lead, and compounds inequality in the form of cognitive and behavioral deficits that can hamper communities for generations.

Experts say that its possible to eradicate lead from American infrastructure, but that we dont prioritize it.

We are currently doing things backwards [by] using childrens blood as detectors of environmental contamination, said Dr Mona Hanna-Attisha, the pediatrician who famously uncovered elevated levels of lead in her pediatric patients and linked it to a new water source in Flint, Michigan. The screening that needs to happen is in the environment before children are ever exposed.

Why lead is so dangerous

Lead is a naturally occuring heavy metal valued for both its affordability and malleability. People have used lead to make cosmetics, drinking and eating vessels, aqueducts and more since the days of Ancient Rome (the word plumbing comes from the Latin word for lead, plumbum).

People from the ancient world also knew that coming into direct contact with large amounts of lead was harmful, and linked to forgetfulness, melancholy and insanity. But this didnt stop manufacturers in America and other countries from using lead compounds in pipes, paint, food cans and gasoline at the turn of the 20th century.

All of these industrial uses put lead particles in the air, in homes and in food and water. In Europe, France, Belgium and Austria were among the first countries to ban it in interior paints in 1909.

By 1924, independent American scientists understood that lead in gasoline posed a lethal hazard to the workers making gas, as well as a more subtle but chronic danger for people breathing in car exhaust and factory emissions.

But it wasnt until the early 1970s that Congress overcame intense industry opposition and began slowly banning the use of lead-based paint in federal housing, removing lead from gasoline and setting limits on the element in drinking water. It was a long process; lead wasnt completely banned from gasoline until 1996.

The US is still grappling with how to remove lingering lead from the environment. Last Friday, the Environmental Protection Agency finalized new regulations that would drastically cut the levels of acceptable lead in dust in public housing, hospitals and schools built before 1978.

By 1976, the blood lead level of the average American child between one to five years old was estimated at 15 micrograms per one-tenth litre of blood , or what is now three times the CDCs current intervention threshold.

Scientists would eventually discover that lead exposure during childhood can destroy brain cells, disrupt communication between neurons and shrink the prefrontal cortex, which is the part of the brain that helps with complex decision making, emotion and aggression regulation and impulse control.

Nationally, chronic lead exposure in the US has been linked to everything from a significant loss of IQ points to a rise in violent crime to billions of dollars lost in future earnings and tax revenue. There is no safe level of lead, and its effects are irreversible. The only treatment that doctors have at their disposal, chelation, is not used except in extreme poisoning cases.

Young American children nowadays have an average blood lead level of about one microgram per one-tenth liter of blood (1 g/dL). We know this because every year, a small but representative sample of about 5,000 Americans are picked randomly to answer surveys and undergo physical exams that will give health officials an overall picture of the nations health including how much lead is in peoples blood. This sample is known as the CDCs National Health and Nutrition Examination Survey (NHANES).

But this national average tells a deceptive story about the risks that environmental lead still pose to children.

The CDC estimates that there are more than half a million children in the US like Catholdi-Dows son who have blood lead levels at or above the CDCs reference value for intervention. They are concentrated mostly in low-income communities throughout the country because they are the ones who are most likely to live in substandard housing. An estimated 23m housing units in the US have at least one lead-based paint hazard 3.6m of which are homes for children under six years old.

Making matters even worse is that the US does not have a robust surveillance system that can find these at-risk children and track potential emergencies like the 2014 one in Flint, Michigan, said Eric Roberts, a research scientist specializing in lead exposure at Public Health Institute, a not-for-profit health research organization.

Indeed, the Flint, Michigan lead exposure crisis was uncovered by concerned citizens, local pediatricians like Hanna-Attisha and independent scientists.

This is because not all states require pediatricians to measure blood lead levels in children or report them to county or state health departments. These results, in turn, may or may not get reported to the CDC. That means that the CDCs most up-to-date local data cant be used to identify short-term trends or make generalizations about childhood lead exposure at the local, state or national level.

It took a 2016 Reuters investigation to identify and map out more than 3,800 neighborhoods throughout the US with lead exposure rates double those found in Flint, Michigan, after their water became contaminated. Reuters maps are based on local public health data that had not been published.

The Centers for Medicare and Medicaid Services require all children enrolled in Medicaid be tested for lead at ages one and two years old. But this kind of universal screening has never been achieved.

In fact, Roberts estimates that less than 20% of all young children are tested for lead, no matter what kind of insurance they have, and this screening only identifies about 60% of children with elevated blood lead levels in the US. This estimate, which is the only comprehensive analysis on the subject, is based on numbers from the previous decade.

I know that in the public health establishment were very pious about our belief that lead exposure is bad and protecting kids is good, Roberts said. But I dont see us making an honest effort to make sure that all the kids are lead free.

What would it cost to rid the US of lead hazards permanently?

If the US is serious about bringing down blood lead levels, officials need to both strengthen blood testing regulations and set their sights on remediating lead in homes, water infrastructure and soil, public health officials and advocates say.

Well never medically test our way out of this, said David Jacobs, chief scientist at the National Center for Healthy Housing and a former director in charge of lead hazard control at the US Department of Housing and Urban Development. Weve got to test the houses, not only the children who have already been exposed.

The CDC also agrees that getting rid of lead in the environment is the best way to prevent lead exposure.

Primary prevention the removal of lead hazards from the environment before a child is exposed is the most effective way to ensure that children do not experience harmful long-term effects of lead exposure, said Dr Adrienne Ettinger, chief of the CDC Childhood Lead Poisoning Prevention Program.

The issue is cost about $400bn over a 10-year period, according to a calculation by Voxs Matt Yglesias.

But the investment is worth it. Removing leaded drinking water lines, remediating lead paint hazards, eliminating lead from plane fuel and other eradication efforts to protect just the children born in 2018 alone could result in as much as $84bn in future benefits, according to a 2017 analysis from the Pew Charitable Trusts. This money would be in the form of increased revenue and savings to the healthcare, education and criminal justice systems. While the report didnt put a figure on the total cost of these repairs, it estimated that it would cost $2bn to replace lead service lines and $18.7bn to deal with lead paint hazards in homes for the 2018 babies.

The federal government is the obvious main funder for this kind of initiative, but Jacobs says that the money should also come from private sources specifically, the paint and gasoline companies that put all the lead in the environment in the first place. Companies who caused this problem have to be part of the solution, Jacobs said. Everyone else has paid for it except them.

Lawsuits

This concept has antecedents in settlements like the Tobacco Master Settlement Agreement, which set up a perpetual pot of money funded by Americas largest cigarette companies to help states pay for tobacco-related healthcare.

California is the first state to pursue and win this kind of judgment against former lead paint manufacturers. In 2017, the California court of appeals upheld the Santa Clara county superior court decision to hold Sherwin-Williams Company, NL Industries, Inc, and ConAgra Grocery Products responsible for finding and remediating homes with lead paint hazards built before 1951. The US supreme court declined to hear the paint manufacturers appeal, and the lead abatement fund is now set at $409m, according to the county of Santa Clara.

While this may seem like a lot of money, its nothing compared to what paint companies might have to pay if more jurisdictions begin allowing people with documented lead poisoning to pursue these lawsuits individually.

In May, a federal jury awarded three Milwaukee men $2m each for lead paint poisoning they suffered as toddlers, to be paid by the paint companies Sherwin-Williams, Armstrong Container Corp and DuPont. The verdict is the first of its kind, and the plaintiffs lawyer told the Milwaukee Journal Sentinel that he hopes that the decision is just the beginning of a wave of lawsuits.

In Cleveland, Ohio, city officials are under renewed pressure to reduce high levels of lead exposure in homes, particularly in its almost 50,000 one- or two-unit rental homes, where a majority of children who are poisoned live, because of grassroots advocacy on the issue.

Educating landlords, contractors, parents

After Catholdi-Dows son was hospitalized, he endured six months of chelation therapy, which involved swallowing a medicine that both tastes and smells like rotten eggs twice a day.

He is now six years old, and his blood lead levels have decreased significantly. When he entered elementary school, Catholdi-Dow struggled with whether or not to disclose his former diagnosis and current blood lead level, which is now at 12 microgram per one-tenth liter of blood (g/dL).

I was very nervous to share it with his teachers because I didnt want him to be written off as someone who had brain damage and wouldnt be able to learn, she said.

Catholdi-Dow knows that the effects of acute lead exposure will become more obvious as he gets older, when school becomes more demanding. Currently, her son is mostly non-verbal unless hes repeating songs or TV shows that he likes. And while its difficult to disentangle the effects of lead poisoning from his autism diagnosis, she and his doctors feel that his hyperactivity may be one consequence of the exposure.

Thankfully, Catholdi-Dow has nothing but praise for the teachers at her sons school. His special education class maintains a one-to-one ratio of teachers to students, and she says that his teachers see his potential and teach to his strengths.

Another thing shes thankful for: her youngest child, a daughter one year younger than her son, has no detectable lead in her blood. Were very lucky that it wasnt a dust situation, and [the lead exposure] was more from him biting.

Because of everything she and her family have experienced, Catholdi-Dow decided to join the Childhood Lead Action Project, a Rhode Island organization dedicated to eliminating lead exposure in children.

She helps educate landlords, contractors and parents about the potential hazards of both lead paint and lead paint removal. If not done correctly, power sanding, open flame burning and other paint removal techniques can actually produce lead dust, making the problem even worse.

Catholdi-Dow thinks one thing that could prevent lead exposure in future children would be to make lead testing and education a standard part of prenatal care and preparation for a new baby. And if youre buying a home, definitely get it checked for lead before purchasing it, especially if its a home built before 1978, she said.