18723
Both of these particulate substances lead to severe lung toxicity that might impair oxygen uptake , but testicular toxicity is only observed with GaAs .
 Chemical: oxygen; Chemical: GaAs
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: oxygen, GaAs 
Answer:
 Chemical: oxygen; Chemical: GaAs