If you look at the bottom of your plastic water bottle, chances are you’ll find the words “BPA-free” imprinted underneath. This marking refers to the compound Bisphenol A, which has proven harmful to certain animals. Though BPA-free products no longer contain this seemingly dangerous chemical, they still contain alternatives to BPA which are structurally similar. A recent study published by Patricia Hunt, a professor at Washington State University, found that substitutes for BPA caused adverse health effects in lab animals, suggesting that these BPA alternatives may be harmful for humans as well.
First, what is BPA, and how is it harmful? It is a compound that has been used in the manufacturing of plastics and resins since the 1960s. The chemical helps to harden plastic products and make them shatter-resistant. It is also found in cash register receipts and can be absorbed through the skin.
In 2008, the U.S. Food and Drug Administration (FDA) expressed concern about the harmful effects of BPA on fetuses and young children, citing adverse health effects observed in animal studies. The chemical structure of BPA was thought to mimic the effects of the hormone estrogen, resulting in harmful changes to the reproductive and endocrine systems.
Despite a vast amount of research, conclusions about the dangerous nature of BPA remain controversial even today. Some studies conducted on lab animals have not resulted in behavioral or reproductive issues, while other reports suggest that even low levels of BPA exposure in humans could lead to breast cancer, diabetes and behavioral problems.
Currently, the FDA has banned the use of BPA in baby bottles, sippy cups and infant formula packaging. A number of states, including Connecticut, Maryland and Vermont, have enacted laws to restrict the sales of products containing BPA. Other states, like Massachusetts, have only banned the sale of children’s containers made with BPA.
In order to continue producing plastics, manufacturing companies have been using alternatives such as bisphenol S (BPS) and diphenyl sulfone, which are similar in chemical structure to BPA, but whose effects have not been studied carefully.
Hunt, who has done extensive research on BPA, discovered the adverse effects of BPA alternatives nearly by accident. During her studies on BPA, Hunt noticed odd results in her control mice housed in cages made of polysulfone. After further investigations, she and her colleagues discovered that the polysulfone in the cage was degrading into BPS, a compound commonly used as an alternative to BPA.
As a result of this discovery, Hunt chose to focus her research directly on testing BPA alternatives to determine whether they too produced health defects in lab animals. In their investigation, Hunt and her colleagues fed pregnant female mice low amounts of either BPA, BPS, diphenyl sulfone or a placebo. In comparison to control females, the mothers and fetuses exposed to BPA and its substitutes were characterized by reproductive and chromosomal abnormalities, particularly during meiosis, which is the process of cell division that produces sperm and eggs. Furthermore, genetic defects persisted for two generations of mice that were not directly exposed to BPA and its replacements.
Though this study may be alarming, researchers are still skeptical of the effects of BPA and its substitutes on humans, particularly at normal levels of exposure.
“Nobody has ever proven it causes harm at the levels to which people are normally exposed to it,” said Australian chemist Oliver Jones, as reported in Science magazine.
Though research remains inconclusive, Hunt and colleagues give reason to be wary of plastic products that are labeled as BPA-free. For those concerned about consuming BPA-free products, healthcare providers suggest using containers made of non-plastic materials, such as glass, porcelain and stainless steel.
The study also highlights that plastic containers and objects advertised as BPA-free may contain other compounds, such as BPS, that may also produce harmful effects.
Studies on BPA are steadily evolving. Scientists continue to gather data regarding the effects of BPA in humans, as well as the levels at which this compound can prove toxic to the body.