15863
In this study , an in vitro model of human embryonic stem cell ( hESC ) differentiation into mammary epithelial cells was applied to investigate the effect of low dose BPA on the early stages of mammogenesis .
 Chemical: BPA
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: BPA 
Answer:
 Chemical: BPA