In the 1970s, pediatrician Herbert Needleman and colleagues collected and analyzed the baby teeth of schoolchildren across Boston and Philadelphia in return for small rewards.
But their so-called tooth fairy project confirmed a dark reality.
Many kids had been exposed to lead.
Lead is a metallic element that's distributed across Earth's crust.
When it enters the human body, it can disrupt many critical processes that span various systems, producing a diverse set of symptoms.
This is because the body tends to falsely recognize lead as similarly charged metallic elements like calcium, iron and zinc and use it in their place for essential reactions, wreaking whole-body havoc.
For example, lead can disrupt the synthesis of hemoglobin, an essential protein to the body's oxygen-transporting red blood cells, and it can compete with iron to be absorbed in the intestines.
Both things can lead to anemia and fatigue.
Lead can also cross the blood-brain barrier, damaging neurons and interfering with the activity of neurotransmitters like serotonin and dopamine.
This can spur cognitive and behavioral changes, including hyperactivity and aggression.
And because of negative effects in other areas.
Lead exposure can also cause high blood pressure headaches, pregnancy complications and abdominal joint and muscle pain.
Mimicking calcium lead may also get stored in teeth and bone, then released back into the bloodstream later in life.
And because children's bodies are smaller and still developing, they're especially sensitive.
Lead exposure can lead to developmental delays, cognitive and behavioral issues and, at high enough concentrations seizures, coma and death.
No level of lead exposure is considered safe, no matter how small the amount.
So, lead is obviously a serious health concern, and people actually made that link early on.
Circa 20 BCE.
Roman architect Vitruvius noted lead workers' pallor and health issues, and one 18th century Italian physician similarly attributed the frailty and abdominal pains of potters to lead.
Yet, despite the long-known health risks, lead became incredibly popular during the 19th and 20th centuries.
Its malleability made it appealing for molding into things like pipes, coins, and pans.
And its opacity meant it was an effective pigment in paints and cosmetics.
Sounds pretty great. if you were to overlook or obscure lead's toxicity.
And unfortunately, certain people were set on doing just that.
By the early 20th century, there were widespread reports of brain damage, convulsions and death among children who inhaled or ingested lead, most often from paint.
In 1921, the League of Nations passed lead paint restrictions, which were enacted in many countries.
But the US never joined the League of Nations and the American lead industry aggressively promoted lead products as safe and advocated for leaded gasoline.
Through the 1960s, activist groups like the Young Lords and Black Panthers brought attention to lead poisoning.
The lead industry, in turn, attempted to blame the issue on lower-income parents.
Their claim?
That the parents didn't prevent their kids from crawling around and putting their hands in their mouths typical behavior among children.
But evidence about lead's harms were accumulating.
When Edelman's team compared the lead levels in the baby teeth they'd collected, they realized that children with the highest amounts performed worse on cognitive and behavioral assessments findings the lead industry attempted to undermine and obfuscate.
Gradually.
The US introduced laws against lead paint in the 1970s, lead water pipes in the 80s and leaded gasoline in on-road vehicles in the 90s.
But none of this undid the damage of decades of aggressive lead implementation.
And the process of removing lead is dangerous, time-consuming and costly.
As of 2024, lead paint still coats walls and contaminates soil and water worldwide.
Tens of millions of people in the U.S. alone drink water from lead pipes.
The lead industry made billions following the same denial and disinformation playbook the oil and tobacco industries used, sometimes even relying on the same consulting firm.
But there have been some steps towards justice.
In California in 2019, lead manufacturers were ordered to finance over 300 million worth of lead paint replacement a glint of levity in a history leaden with industrial greed.
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