26784
RESULTS : Although 3 - h hypoxia or 100 mu M of zinc alone did not induce noticeable cytotoxicity , their combination led to a dramatic increase in astrocytic cell death in a zinc - concentration - dependent manner .
 zinc, zinc
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 zinc, zinc