2559
OBJECTIVES : The present study aimed to be the largest to date in sample size and 5HT - related behaviors ; the first to compare present ecstasy users with past users after an abstinence of 4 or more years , and the first to include robust controls for other recreational substances .
 Chemical: ecstasy
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: ecstasy