12044
The aim of this study was to investigate the induction of cytotoxicity , oxidative stress and apoptosis by SiO ( 2 ) NPs ( size 15 nm ) in human skin epithelial ( A431 ) and human lung epithelial ( A549 ) cells .
 Chemical: SiO ( 2 )
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: SiO ( 2 )