Using fresh human fat tissues in their study, the UC team found that BPA suppresses a key hormone, adiponectin.
Adiponectin is responsible for regulating insulin sensitivity in the body and puts people at a substantially higher risk for metabolic syndrome.
Metabolic syndrome is a combination of risk factors that include lower responsiveness to insulin and higher blood levels of sugar and lipids. If left untreated, the disorder can lead to life-threatening health problems such as coronary artery disease, stroke and type 2 diabetes.
The team, led by Nira Ben-Jonathan, PhD, is the first to report scientific evidence on the health effects of BPA at environmentally relevant doses equal to "average" human exposure. However, earlier studies have primarily focused on animal studies and high doses of BPA.
"People have serious concerns about the potential health effects of BPA. As the scientific evidence continues to mount against the chemical, it should be given serious attention to minimize future harm," said Ben-Jonathan.
She added: "Experimenting with human tissue is the closest we can come to testing the effects of BPA in humans. It's a very exciting breakthrough because epidemiological studies looking at BPA effects on humans are difficult since most people have already been exposed to it."
According to estimates, over 80 percent of people tested have measurable BPA in their bloodstream. But the new study was designed to mimic a realistic human exposure (between 0.1 and 10 nanomolar) in order to get a more direct correlation between human exposure and health effects.
Fior the study, researchers collected fresh fat tissue from Cincinnati patients undergoing several types of breast or abdominal surgery. These samples included three types of fat tissue: breast, subcutaneous and visceral (around the organs).
Immediately, the tissue was taken to the laboratory and incubated with different concentrations of BPA or estrogen for six hours to observe how the varied amounts of BPA affected adiponectin levels.
Then, the effects of BPA were compared to those of estradiol, a natural form of human estrogen.
It was found that exposing human tissues to BPA levels within the range of common human exposure resulted in suppression of a hormone that protects people from metabolic syndrome.
"These results are especially powerful because we didn't use a single patient, a single tissue source or a single occurrence. We used different fat tissues from multiple patients and got the same negative response to BPA," she added.
The findings of the study are reported in the latest online edition of the journal Environmental Health Perspectives.