23954
The seemingly disparate areas of oxygen toxicity , radiation exposure , and aging are now recognized to share a common feature - the aberrant production and / or removal of biologically derived free radicals and other reactive oxygen and nitrogen species ( ROS / RNS ) .
 Chemical: oxygen; Chemical: oxygen; Chemical: nitrogen
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: oxygen; Chemical: oxygen; Chemical: nitrogen