The recent lead contamination crisis in Flint, Michigan has brought the dangers of lead exposure back to the forefront of national discussion. But the really scary part is that almost everyone is regularly exposed to small amounts of lead — a silent pandemic. And there is no safe level of lead exposure.
Dr. David Bellinger, Professor of Neurology at Harvard University (you may remember him from Episode #58, covering neurotoxins in general) explains the dangers of lead, why lead removal is expensive but worth it, and how to treat lead exposure.
Why is Lead Exposure Dangerous?
Lead is an equal opportunity neurotoxicant — it damages your brain on multiple levels. But it’s most damaging for children, whose brains are still developing, and who will carry lead damage with them for the rest of their lives.
Lead damages neurotransmitter function. This is particularly devastating in children since in young brains, neurotransmitters don’t just regulate communication, but also brain development, helping to establish brain circuits that will be relied on as an adult.
It seems to reduce overall neuroplasticity when lead exposure happens early in life. In experiments, rodents exposed to lead early in life recover less rapidly from later brain injuries. So it’s a double whammy: brain damage in the moment and a brain that is less able to recover from future damage.
It lowers IQ at all levels of exposure, and the rate of IQ decrease actually increases at lower levels of exposure.
Treating Lead Exposure
The bad news is that we don’t have many treatments for lead that are backed by science.
For people with very high blood levels of lead — more than 45 micrograms of lead per deciliter of blood (μg/dL) — chelation therapy is one option. During chelation, a synthetic solution is injected into the bloodstream to remove heavy metals or minerals from the body.
Chelation can bring down levels of lead quickly, but even though the lead is removed, the damage to neurocognition is already done.
There is another, non-medical, approach to treatment. Studies have shown that children and young animals exposed to an enriched environment consisting of social interaction and visual, tactile, and auditory stimulation, end up with more neuroplastic brains. Their brains become more resistant to future brain damage. Enriched environments may be an effective therapy for children to counter the effects of lead exposure.
What Should We Do About Lead?
Once someone has been exposed to lead, the damage is already done. That’s why we can’t rely on treatment; we need to prevent exposure in the first place.
Unfortunately, lead remediation is very expensive — just removing all lead pipes in the US would cost about $300 billion. But if you do a cost-benefit analysis for lead abatement, it’s actually better value for money than vaccinations.
That value is realized in the future, however, when millions of children enter the workforce with higher IQs and more resilient brains.
A lot of lead has already been removed from our environment: the mean level of lead in preschoolers has decreased from 15 micrograms per deciliter to less than 1. But as we realize that even small amounts of lead are damaging, what seems like a public health success (and is, to a certain extent) doesn’t look like a complete solution anymore.
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