- More than 80,000 chemicals are registered for use in everyday items in the U.S.
- Chemical compounds like BHT, PFOA and TBT added to breakfast cereals and other products disrupt hormones and promotes obesity in people
- Innovative stem-cell testing system can evaluate the health effects of chemicals used and can prevent obesity
Growing evidence from animal experiments shows that chemicals that are added to breakfast cereals and other products used in everyday life make people obese, reveals a new study. However, scientists have faced formidable obstacles in confirming these findings in humans, until now.
A novel platform and protocol has been developed for testing the effects of chemicals on humans known as endocrine disruptors. The study was published by Cedars-Sinai investigators in Nature Communications
In this study, the three chemicals
tested are found abundantly in modern life.
- Butylhydroxytoluene (BHT), an antioxidant is commonly added to the breakfast cereals and other foods, to help protect the nutrients and keep fats from becoming rancid.
- Perfluorooctanoic acid (PFOA), a man-made chemical is a polymer found in some cookware, carpeting and other products.
- Tributyltin (TBT), a compound present in paints can make its way into water and gathers in seafood.
Hormone-producing tissues grown from human stem cells were used by the research team to demonstrate how chronic exposure to these three chemicals can interfere with signals in the body, that are sent from the digestive system to the brain, which would help people know when they are "full" during meals.
People may often continue eating, when this signaling system breaks down causing them to put on weight.
The hormones that communicate between the gut and the brain were found to be damaged due to these chemicals, reveal Dhruv Sareen, PhD, an assistant professor of Biomedical Sciences and director of the Induced Pluripotent Stem Cell Core Facility at the Cedars-Sinai Board of Governors Regenerative Medicine Institute.
He said that when these three were tested together, the combined stress was found to be more vigorous.
Sareen said that among the three chemicals tested, some of the strongest detrimental effects were produced by BHT .
Innovative Stem-Cell Testing System
Previous studies have also shown that these compounds can disrupt hormone systems in the laboratory animals.
However, this study is the first to use human pluripotent stem cells and tissues. The research team has documented how these chemical compounds could disrupt hormones, which are important in gut-to-brain signaling and in preventing obesity in people, said Sareen.
Clive Svendsen, PhD, director of the institute and the Kerry and Simone Vickar Family Foundation Distinguished Chair in Regenerative Medicine. More than one-third of U.S. adults are considered to be obese, according to federal statistics said: "This is a landmark study that substantially improves our understanding of how endocrine disruptors may damage human hormonal systems and contribute to the obesity epidemic in the U.S."
In this study, the research team has developed a new testing system, which is very essential, safe and is a cost-effective method. This system evaluates the health effects of thousands of existing chemicals and also the upcoming chemicals present in the environment.
Sareen and his team first obtained blood samples for their experiments from adults. Then introduced the reprogramming genes, which converted the cells into induced pluripotent stem cells.
The research team then used these stem cells to grow human epithelium tissues that line the gut and neuronal tissues of the brain's hypothalamus region, which helps in regulating appetite and metabolism. These tissues were then exposed to BHT, PFOA and TBT one by one and then were exposed in combination.
The research team observed as to what was happening inside these cells and found that these chemical compounds disrupted the networks that prepare the signaling hormones to maintain their structure and to be transported out of the cells, which makes them ineffective. These chemical compounds damaged the mitochondria, the cellular structures that help in converting both food and oxygen into energy and drives the body's metabolism.
Disrupted Hormone System Promotes Obesity
The findings of this study suggest that a defective hormone system can impact a pregnant mother and her fetus in the womb due to the chemical damage that occurred in the early-stage "young" cells, said Sareen.
In previous animal studies, scientists have found that the effects of endocrine disruptors can be passed down to future generations.
However, this process is not yet proved in humans, explained Sareen.
In the U.S, more than 80,000 chemicals have been registered for use in everyday items like foods, personal care products, lawn-care products and household cleaners, reveals the National Toxicology Program of the U.S. Department of Health and Human Services.
While the program states on its website that relatively few chemicals are thought to pose a significant risk to human health, it also states: "We do not know the effects of many of these chemicals on our health."
There were limitations in this study, to test the safety of many chemicals the cost and ethical issues like the health risks of exposing human subjects to harmful substances were among the barriers. As a result, various compounds that are used remained unevaluated in humans due to their health effects, particularly to the hormone system.
Sareen said that by testing these chemical compounds on human tissues in the laboratory can potentially make this analysis easier and more cost-effective.
- Dhruv Sareen, et al. Endocrine disrupters: potentially harmful chemicals for human hormones.Nature Communications(2017). DOI: 10.1038/10.1038/s41467-017-00254-8