Various types of plastic resins are used to package and serve food and beverages. Polyethylene terephthalate, or PET, is used in 20-ounce water and soda bottles. Polyvinyl chloride (PVC) is used in plastic wrap and deli food containers.
Bisphenol A, or BPA, is one of many chemicals contained in plastic resins that are used to make reusable water bottles and children’s sippy cups.
But in 2011, California passed a law to ban BPA from bottles or cups designed for children under three years old. The compound is estrogenic: its chemical effects mimic those of estrogen, the hormone that regulates female sexual development.
However, a pair of studies commissioned by the Center for Environmental Health (CEH) revealed that resins in some BPA-free plastic sippy cups may contain greater amounts of estrogenic chemicals than cups that contain BPA.
The studies tested 35 different sippy cups that were purchased between October 2011 and March of 2013. Nine of the cups yielded significant estrogenic activity, or estrogenicity.
According to CEH, sippy cups that contained color-changing plastic had the highest levels of estrogenicity.
An important question remains: can these chemicals be leached, or dissolved, in sufficient quantities to cause adverse health effects in human beings?
High enough concentrations of estrogenic chemicals have negatively impacted the health of test animals. Estrogen can also promote the growth of breast cancer tumors.
Yet according to Mike Denison, a professor of environmental toxicology at University of California, Davis who took part in one of the studies, the wider impacts on human health are “still pretty controversial,” adding that he himself uses plastic food containers.
Still, the scientist cautions, “If you clearly know there are chemicals, and those chemicals are impacting hormone systems, then it’s, I think, naive to ignore it and say ‘well, it’s not gonna do anything.’ “