A significant new study on the link between bisphenol and cancer wasn't released in time for Sunday's GreenSpace column about the ubiquitous chemical, also referred to as BPA.

This morning, the University of Michigan School of Public Health announced the completion of "one of the first studies to show a significant association between BPA and cancer development."

They found liver tumors in mice exposed to BPA via their mothers during gestation and nursing.

"We found that 27 percent of the mice exposed to one of three different doses of BPA through their mother's diet developed liver tumors and some precancerous lesions. The higher the dosage, the more likely they were to present with tumors," said Caren Weinhouse, a doctoral student in the school's Department of Environmental Health Sciences, in a press release.

She is lead author of the study, published online this morning the the journal, Environmental Health Perspectives.

What does it mean for humans? So far, that's unclear.

"This current study … says let's take another look at BPA and cancer in humans," said Weinhouse. The next step, she said, will be to look for biomarkers in the mouse genes that would indicate a higher risk for cancer, and then see if humans have something similar.

One of the study's collaborators, Dana Dolinoy, the John G. Searle Assistant Professor of Environmental Health Sciences, said in the same press release that the study is the first statistically significant finding of clinically evident tumors in any organ.

Dolinoy said another interesting finding is that gender didn't matter. Generally, females are at lower risk of liver cancer, she said, but "that distinction was erased in this study, with both males and females showing tumors."

Also, in most studies involving small animals, the animal is directly exposed to BPA. In this study, the mothers were exposed, and the only exposure of the offspring was as a fetus or a nursing pup.

"A previous study that exposed adult mice to much higher doses of BPA did not show the same link to cancer development," Dolinoy said. "This tells us the timing of exposure and the dosage are extremely critical in evaluating study outcomes."

Other authors included David Vandenbergh, Joseph Gyekis, Marc Dingman and Jingyun Yang from Pennsylvania State University.

The current research was supported by the Michigan Nutrition Research Obesity Center, National Institutes of Health, National Institute of Environmental Health Sciences Core Center of Excellence, Children's Environmental Health Formative Center and an NIEHS Institutional Training Grant.