Gov. Jerry Brown announced Tuesday that he signed a law banning the chemical bisphenol A, more commonly known as BPA, from baby bottles and sippy cups.
Baby bottles and sippy cups that have a BPA level of more than 0.1 parts per billion are now banned from being manufactured, sold and distributed in California, effective next July.
A scientist studying birth defects in lab mice first announced the potential dangers of BPA in 1998. Patricia Hunt concluded the chemical was emulating estrogen, leading to birth defects in as many as 40 percent of newborn mice.
Since then, seven states have banned the chemical outright: Connecticut, Washington, Maryland, Wisconsin, Minnesota, New York and Vermont.
However, no government study has ever concluded BPA is harmful, according to science writer Jon Entine.
A government study has shown that BPA appears in the urine of 90 percent of U.S. adults and children.
But the U.S. Food and Drug Administration said in 2010 the chemical "is not proven to harm children or adults."
The World Health Organization came to a similar conclusion last year.