19653
Our aims were to assess exposure by the extent of ZnO - NP penetration into the viable epidermis and hazard by changes in the viable epidermal redox state for a number of topical products .
 ZnO
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 ZnO