Apart from their role in reproduction and sexual dimorphism, it is increasingly recognized that sex hormones play a role in common chronic disease, such as hormone-related cancers, cardiovascular disease, and diabetes, which may in turn be promoted by environmental endocrine disruptors. As an initial assessment of this possibility, Dr. Mary Schooling, professor at the City University of New York, compared estrogen levels in young men from the United States (U.S.) and China. Young American men had substantially higher levels of estrogen then Chinese men of the same age. Whether these differences are due to greater adiposity in U.S. than Chinese men, environmental endocrine disruptors or other factors remains to be determined, nevertheless these differences are consistent with the differences in disease patterns between the U.S. and China, and as such emphasize the importance of explicating the role of environmental endocrine disruptors in common chronic diseases.