Exposure to low levels of arsenic through drinking water in utero resulted in signs of early puberty and obesity as adults in female mice, according to recent findings.

“We unexpectedly found that exposure to arsenic before birth had a profound effect on onset of puberty and incidence of obesity later in life,” Humphrey Yao, PhD, a reproductive biologist at the National Institute of Environmental Health Sciences (NIEHS), said in the release. “Although these mice were exposed to arsenic only during fetal life, the impacts lingered through adulthood.”

Currently, the Environmental Protection Agency states that the maximum allowable amount for arsenic in drinking water is 10 parts per billion.

The researchers divided female mice into three groups: control (no exposure), standard exposure (current EPA guideline) or high level (42.5 parts per billion). Exposure occurred during gestation, between 10 days after fertilization and birth corresponding to the middle of the first trimester and birth in humans.

The researchers found that both the high and low doses resulted in weight gain as well as onset of puberty.

“It’s very important to study both high doses and low doses,” Linda Birnbaum, PhD, director of NIEHS and the National Toxicology program, said in the release. “Although the health effects from low doses were not as great as with extremely high doses, the low-dose effects may have been missed it only high doses were studied.”