1491
MATERIALS AND METHODS : Three groups , comprised of 21 cocaine naive participants ( CN ) , 30 occasional cocaine ( OC ) , and 48 regular recreational cocaine ( RC ) users , were compared .
 Chemical: cocaine; Chemical: cocaine; Chemical: cocaine
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Chemical: cocaine; Chemical: cocaine; Chemical: cocaine