Manish Arora studies a young boy’s tooth on his computer screen, searching for crucial details about the child’s past. The boy, 10 — we’ll call him Max — lives outside a poor community in Mexico City where lead exposure is a chronic problem. And it shows in the tooth. Max has been around lead from polluted air and water — and even food, because the metal leaches from lead-glazed pottery.
The image on the screen is essentially a color-coded map of the boy’s tooth. It shows Max had a spike in lead exposure just before birth, in the final months of fetal development. After birth, his exposure dropped off to a level common in the local population.
Blood tests can detect lead at any given moment, but they don’t reveal past exposures or time-stamp when they happened. Teeth, Arora has discovered, can do both — not just for lead, but for a growing number of other elements and chemicals, too. That finding holds tremendous potential for environmental health research, like trying to unravel causes of autism spectrum disorder. And it’s why scientists around the world, from Mexico to Sweden to Iraq, have been flocking to Arora, a dentist and exposure biology director at Mount Sinai’s Frank Lautenberg Environmental Health Sciences Laboratory.
He’s turning teeth into time machines.
“Imagine if you measured blood lead level here,” Arora says, pointing to a part of the tooth that had grown after birth. “You’d think there’s less risk. But travel back in time. Just before birth, there’s a huge spike in lead exposure.”
