16665
RATIONALE : Both the acute and chronic consumption of ethanol have been reported to modify several molecular events in the central nervous system , and the endogenous mu - opioid receptor system is involved in the reinforcing / rewarding effects of ethanol .
 Chemical: ethanol; Chemical: ethanol
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: ethanol; Chemical: ethanol