Synthetic and natural chemicals that manage to fit into the flexible binding site of estrogen receptors—compounds called xenoestrogens—can potentially interfere with a spectrum of physiological processes mediated by estrogen sex hormones, such as estradiol. In searching for xenoestrogens among food additives, a research team led by Pietro Cozzini of the University of Parma, in Italy, analyzed an international database of 1,500 commonly used food additives and identified 13 potential xenoestrogens (Chem. Res. Toxicol., DOI: 10.1021/tx800048m). The researchers used a virtual screening process to evaluate the size and shape of the molecules for their ability to bind to estrogen receptors. Of the 13 potentially problematic compounds, four were already known to exhibit estrogenic activity. The team then used binding studies and in vitro assays to test the remaining nine compounds. Two of the compounds, propyl gallate, which is used as an antioxidant, and 4-hexylresorcinol, which is an antiseptic, are potent xenoestrogens, the researchers report. They now caution against using these two compounds as food additives. The researchers plan to run in vivo tests and develop fluorescence-based chemosensors to further monitor food additives, Cozzini says.