Update (3/3/14): After this story went to press, the US Food and Drug Administration published a paper finding that BPA was safe in low doses. However, due to laboratory contamination, all of the animals-including the control group-were exposed to this chemical. Academic scientists say this raises serious questions about the study’s credibility. Stay tuned for more in-depth reporting on the FDA’s most recent study.

Each night at dinnertime, a familiar ritual played out in Michael Green’s home: He’d slide a stainless steel sippy cup across the table to his two-year-old daughter, Juliette, and she’d howl for the pink plastic one. Often, Green gave in. But he had a nagging feeling. As an environmental-health advocate, he had fought to rid sippy cups and baby bottles of the common plastic additive bisphenol A (BPA), which mimics the hormone estrogen and has been linked to a long list of serious health problems. Juliette’s sippy cup was made from a new generation of BPA-free plastics, but Green, who runs the Oakland, California-based Center for Environmental Health, had come across research suggesting some of these contained synthetic estrogens, too.

He pondered these findings as the center prepared for its anniversary celebration in October 2011. That evening, Green, […]