The municipal water crisis in Flint, Michigan has brought new attention to the dangers of lead in drinking water. Scientists have known for a long time that even low levels of lead can cause loss of IQ points and behavioral problems in children. But a recent study out of Wayne State University suggests lead exposure can also cause changes to DNA that might affect several generations.

“When a mother drinks leaded water, like what happened in Flint, she’s exposing her fetus, so that’s going to directly affect brain development of her baby,” says Doug Ruden, co-author of the study and Director of Epigenomics at Wayne State’s Institute of Environmental Health Sciences. “What most people don’t realize is that you’re also expressing the germ line cells, and that can affect the grandchildren, and even potentially beyond that.”

Ruden’s study looked at blood lead levels in 35 mothers and their babies in Detroit. They observed a correlation between elevated blood lead levels in the mothers and changes in DNA.

“If the mothers had high blood lead levels when they were born, then their grandchildren have changes in their DNA,” he says. “And the changes in the DNA we were looking at weren’t permanent changes. They’re what we call epigenetic mutations.”

LISTEN: “How Lead Impacts Our DNA”

Ruden says these sorts of changes control gene expression. And this is how lead is thought to cause neurobehavioral defects.

Ruden says they don’t know if these changes in DNA are good, bad or neutral. He says they need to do more studies to learn what this could mean. They’re studying how exposures in pregnancy can affect not just the baby a mom is carrying, but also her grandchildren.

“The way you think about it is—if a mother is pregnant with a baby, she’s also carrying the baby’s children too,” he says. “Because it’s like a Russian doll. All of the eggs that a person has in life are actually developed in the fetus, during the fetal period, and all the sperm progenitor cells in the boy babies, the boy fetuses, are also present in the fetus,” he says.

One important caveat here: this study is small. Ruden says it will need to be repeated on larger scales and in different populations.

“It is well established in animal models, though—like in mice and rats—that environmental exposures to compounds such as lead can have effects for many generations,” he says. “So this isn’t entirely surprising.”

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This story comes from our partners at Michigan Radio’s Environment Report, a program exploring the relationship between the natural world and the everyday lives of people in Michigan.