1481
The aim of this study was to determine the effect of tobacco smoke exposure , and AKR1A1 * 2 and AKR1C3 * 2 polymorphisms , on AKR1A1 and AKR1C1 - AKR1C3 messenger RNA ( mRNA ) levels in PBLs from smokers .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities:  
Answer:
 None