There's a reason why your chips and breakfast cereal keep their crunch for so long after you open the package, and that reason is the presence of BHT, a widely used food preservative that helps packaged food stay fresh. Less fortunately, however, the chemical may also act as a trigger for obesity.

Researchers at Cedars-Sinai Medical Center tested three chemicals known to interfere with the action of hormones in the body. The chemicals, known as endocrine disruptors, were BHT (butylhydroxytoluene), an antioxidant added to many packaged foods to prevent fats from becoming rancid and to protect other nutrients; PFOA (perfluorooctanoic acid), found in cookware and other household products; and TBT (tributylin), an ingredient in paint that can find its way into water systems and build up in seafood.

There are over 80,000 chemicals registered for use in the U.S., yet only about two percent have been tested for safety.

Using stem cells from human study participants, the researchers grew epithelial tissues like the ones that line the digestive tract and nerve tissues in the area of the brain that regulate appetite and metabolism. They tested how the chemicals interfere with signals from the brain that tell the stomach it is full, a concept known as satiety. Interference with this signaling system can cause people to continue eating past that point, which can cause weight gain.

BHT had the most harmful effect when the chemicals were tested separately, but the combined effect of all three chemicals was even stronger, according to author Dhruv Sareen. The chemical damage occurred in “young” cells, suggesting that pregnant women and their babies could be particularly vulnerable.

There are over 80,000 chemicals registered for use in the U.S., yet only about two percent have been tested for safety. They are found in everything from foods to personal care products to household cleaners and lawn-care products. Many of the effects of these chemicals on human health are not known, and factors like cost and the ethics of exposing people to what are potentially harmful substances have prevented a full examination of their potential adverse consequences.

The ability to grow human tissue in a lab will make it possible for scientists to examine the effects of new and existing chemicals on human health in a precise and risk-free way. The outcome could be a better understanding of the role these substances may play in the development of diseases like type 2 diabetes and obesity.

The study is published in Nature Communications.