Researchers at the National Institute of Environmental Health Sciences (NIEHS) recently reported that arsenic exposure during embryonic development is linked to an early puberty and adult obesity in mice. The study was published in the journal Environmental Health Perspectives and is entitled “Effects of in Utero Exposure to Arsenic during the Second Half of Gestation on Reproductive End Points and Metabolic Parameters in Female CD-1 Mice.”
Arsenic is a chemical element used for strengthening mixtures of metals, for instance in car batteries. Arsenic is also used in electronic devices due to its semi-conductive properties, and is employed in the production of pesticides, herbicides and insecticides. Arsenic contamination of groundwater is a major problem that affects millions of people worldwide.
It has been previously reported that mice exposed to high arsenic levels in utero (still inside the mother’s womb) are more susceptible to develop tumors when they reach adulthood. However, the impact of in utero arsenic exposure on the animal’s general physiological functions including metabolism and reproduction are poorly elucidated.
In the study, researchers divided pregnant mice into three different groups. One group received arsenic in the drinking water at 10 parts per billion (which is the current U.S. Environmental Protection Agency maximum allowed for arsenic in drinking water), another group received 42.5 parts per million of arsenic (which is known to have detrimental effects and induce tumors in mice), and the third group was a control that was not exposed to arsenic. Mice were exposed to arsenic, except the control group, during the gestational day 10 up to birth. The team then assessed the effects of in utero exposure to arsenic on reproductive and metabolic features when the exposed female mice reached adulthood.
Researchers found that arsenic-exposed females had an early onset of vaginal opening, a sign of sexual maturity. In terms of fertility, females exposed to arsenic at 10 parts per billion dose were not affected, whereas females exposed to 42.5 parts per million had a reduced number of litters. Interestingly, in both arsenic dose groups, the team observed that exposed females had a significantly higher body fat content, body weight gain and glucose intolerance.
“We unexpectedly found that exposure to arsenic before birth had a profound effect on onset of puberty and incidence of obesity later in life,” said the study’s senior author Dr. Humphrey Yao in a news release. “Although these mice were exposed to arsenic only during fetal life, the impacts lingered through adulthood.” Male mice exposed to arsenic in utero were also found to exhibit an increased weight gain with age.
The research team concluded that female mice exposed in utero to arsenic at relevant doses for humans exhibited signs of early puberty and obesity in adulthood. The authors believe that this study supports the idea of further research into the possible effects of arsenic exposure in health outcomes in humans.
“It’s very important to study both high doses and low doses,” added the director of NIEHS Dr. Linda Birnbaum. “Although the health effects from low doses were not as great as with the extremely high doses, the low-dose effects may have been missed if only high doses were studied.” The authors emphasize that more research is required to determine the long-term impact of what mothers eat, drink and even breathe during pregnancy on the well-being of the offspring.