Researchers at the University of Rochester found that exposing very young mouse pups to low levels of bishphenol-A or BPA, a chemical compound that gives plastics their sturdy nature, can impair their brains’ adaptability. BPA is very prolific and can be found in everything from medical respirators to construction hard hats, but the products of most concern are those involved in food packaging, like metal cans and plastic containers.
In the study, published in the journal Frontiers of Neuroanatomy, mouse pups were exposed to a dose of BPA that is half the acceptable exposure level set by the Environmental Protection Agency. The exposure took place early in development, during a period of rapid growth of nerve cells. One week after BPA exposure ended, mice underwent a technique in which one eye was deprived of sight to assess the adaptability of the areas of the brain that process vision. Usually, when mice lose vision in one eye during development, they exhibit a reorganization of brain circuitry, but BPA exposed animals did not show this reorganization.
The researchers think that when BPA was present it threw off the balance between the production and thinning of dendritic spines, the appendages on nerve cells that communicate with other nerve cells. That imbalance is what led to the higher density of dendritic spines in BPA treated mice and caused the impairment in adaptability. Though the imbalance only occurred when BPA was present, it persisted beyond the end of BPA exposure, suggesting that low levels of BPA may cause long-lasting impairment of adaptability of brain circuitry.
Though the EPA and FDA have deemed the current estimated BPA exposure levels in the U.S. to be safe, study authors say that their study and others showing negative effects on mammalian reproductive and nervous systems suggest that the current acceptable daily exposure level may need to be reassessed.
Emily Kelly, Ph.D. and Ania Majewska, Ph.D., of the Department of Neurobiology and Anatomy and Lisa Opanashuk, Ph.D., of the Department of Environmental Medicine conducted the study, which was funded by the NIH. They say that more research is needed to understand the full impact BPA may have in human systems.