The toxicity of endocrine disruptors depends on the synergistic interactions of biological, environmental, and behavioral factors. The specific effects of diet, consumer product use, and behaviors, however, are debated in the literature, particularly with regard to endocrine disruptors found in breast milk. This study aimed to measure the levels of phthalate metabolites, bisphenol A, parabens, and triclosan in breast milk and to investigate their associations with various lifestyle factors. The breast milk samples as well as surveys were collected from 221 first-time mothers throughout South Korea and each sample was analyzed for the presence of 15 endocrine disruptors. Phthalate metabolites were detected in 5.4-83.3% of the samples, with median concentrations of 0.08-1.72 μg/L, while bisphenol A, parabens, and triclosan were detected in 25.8-88.2% of the samples, with median concentrations of 0.12-1.47 μg/L. High levels of endocrine disruptors were associated with frequent consumption of fish and cup noodles; the use of plastic and disposable food containers; the use of air fresheners, lotions and make-up; the purchase of new furniture; and socioeconomic status. We also observed the potential role of moderate walking activity on the reduction of these chemicals in breast milk. Our data provide evidence of the potential effects of diet, consumer products, and behavior on the presence of phthalate metabolites, bisphenol A, parabens, and triclosan in breast milk. Future studies should include community or regional impact on a mothers' exposure to endocrine disruptors, to assess the joint contribution of both individual and neighborhood factors.