27820
In human populations , there is a well - defined sequence of involvement in drugs of abuse , in which the use of nicotine or alcohol precedes the use of marijuana , which in turn , precedes the use of cocaine .
 nicotine, alcohol, cocaine
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 nicotine, alcohol, cocaine