A new MIT study says a chemical called NDMA, which can be found in some medicines and polluted water, may be far more dangerous for kids than for grown‑ups.
When young mice drank water with tiny amounts of NDMA, they showed a lot of DNA damage and many got cancer. Older mice that drank the same water stayed mostly healthy.
The findings help explain earlier research that linked NDMA exposure before birth to more childhood cancers in a town in Massachusetts. The work also shows why scientists need to test chemicals on young animals, not just adults.
“We hope safety tests will start looking at young animals so we can catch bad chemicals early,” said MIT professor Bevin Engelward. “Preventing cancer is far better than trying to treat it later.”
Nature Communications
Where NDMA Comes From
NDMA forms during many industrial processes. It is also in cigarette smoke, processed meats, and some drugs such as valsartan, ranitidine, and metformin. In the 1990s, NDMA was found in drinking water near an old chemical plant in Wilmington, Massachusetts.
A 2021 health report linked that polluted water to a spike in childhood cancer cases in the area. After the contaminated wells were closed in 2003, the number of new cases dropped.
How NDMA Hurts DNA
Most toxin studies use adult mice that are at least four weeks old. In this study, researchers compared 3‑week‑old mice (young) with 6‑month‑old mice (adult). Both groups drank water with a low NDMA level for two weeks.
Inside the body, a liver enzyme called CYP2E1 changes NDMA into harmful pieces that stick tiny methyl groups onto DNA. This creates small lesions called adducts.
Both young and adult mice formed similar amounts of these early lesions. The difference showed up later. Young mice’s cells tried to fix the damage, but the repair process broke both strands of DNA. Those breaks led to mutations that grew into liver cancer.
Adult mice showed almost no double‑strand breaks and far fewer mutations. Their livers stayed healthy even though they had the same initial DNA lesions.
Fast‑Growing Cells Make Kids More Vulnerable
The key factor is how quickly cells divide. Young liver cells are busy growing, so damage turns into permanent mutations faster. Adult liver cells divide slowly, giving them more time to repair.
When adult mice were given a thyroid hormone that forced their liver cells to grow faster, they started to develop mutations at the same rate as the young mice.
Other things that speed up cell division—like infections, a high‑fat diet, or heavy drinking—could also make adults more sensitive to NDMA.
What Comes Next
The researchers are now testing whether a high‑fat diet makes NDMA even more dangerous.
This project was done by several MIT labs and was funded by the National Institute of Environmental Health Sciences and other grants.