1 Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada.
2 School of Public Health, University of Nevada, Reno, Reno, Nevada 89557, United States.
3 Air Quality Research Division, Environment and Climate Change Canada, Toronto, Ontario M3H 5T4, Canada.
4 Department of Chemistry and Biochemistry, Concordia University, Montreal, Quebec H3G 1M8, Canada.

Bisphenol A (BPA) is a common endocrine disruptor widely found in commercial products. Despite negative human health effects, its usage is not fully banned worldwide with ongoing human exposure from sources including dust, aerosol particles, and surfaces. Although attention has been paid to the abundance of alternatives with similar structures that are replacing BPA, uncertainties remain with respect to their chemical transformations and products, toxicity, and environmental fate. We provide the first experimental and modeling assessment of gas-particle multiphase OH oxidation of BPA and six common bisphenol alternatives. We examine the transformation of condensed-phase BPA and its alternatives using an oxidation flow reactor with products monitored by online mass spectrometry. Fourteen products were identified and used to develop a generic mechanism applicable to all bisphenols and to provide inputs into an environmental fate model (PROduction-to-Exposure; PROTEX). Our modeling results highlight the role of heterogeneous surface reactions in determining the indoor retention of these chemicals and their relative environmental persistence indoors and outdoors. All investigated parent molecules yield transformation products predicted to accumulate indoors, with extended indoor persistence if a long chemical lifetime on surfaces (e.g., >100 weeks) is assumed. Evidence of phenoxy radical presence upon oxidation raises a human health risk concern.