A new study reveals that chemicals used during hydraulic fracturing or fracking are not only dangerous to the environment but can also have a negative impact in reproductive system and development.

Fracking , along with directional drilling, is used during unconventional oil and gas (UOG) operations to release natural gas from underground rock. Previous studies have shown that fracking is not good for the environment because chemicals used during the operations could leak out and contaminate ground water, posing a threat to wildlife near the fracking site.

The study, published in the journal Endocrinology, showed that chemical released during fracking can have adverse reproductive and developmental outcomes in mouse models, suggesting that exposure to such chemicals could also pose a threat to human development.

"Evidence from this study indicates that developmental exposure to fracking and drilling chemicals may pose a threat to fertility in animals and potentially people," explained Susan C. Nagel, Nagel, an associate professor of obstetrics, gynecology and women's health in the School of Medicine at University of Missouri-Columbia, in a statement. "Negative outcomes were observed even in mice exposed to the lowest dose of chemicals, which was lower than the concentrations found in groundwater at some locations with past oil and gas wastewater spills."

For the study, the researchers concocted 23 oil and gas chemicals in four different concentrations, ranging from those found in drinking water and groundwater to concentrations found in industry wastewater. The mixture was then added in the drinking water of pregnant mice in the laboratory until they gave birth.

The researchers found out that the offspring of the mice given with the mixture during their pregnancy have lower levels key hormones related to reproductive health compared to a control group that were not exposed to the chemical mixtures.

Exposed female mice also showed signs of reduced fertility, including alterations in the development of the ovarian follicles, pituitary and reproductive hormone concentrations. Researchers believe that their findings are not only limited to female mice, but can also occur in people and other animals exposed to chemicals used during gas and oil drilling activities.