16107
The results indicate there is only a marginal risk for these metal - based nanomaterials in surface water ( 0 . 7 % risk for nano - Ag and < 0 . 1 % for nano - TiO2 ) and some risk in sewage treatment plant effluents ( nano - Ag 39 . 7 % , nano - TiO2 18 . 7 % , and nano - ZnO 1 . 1 % ) .
 Chemical: Ag; Chemical: TiO2; Chemical: Ag; Chemical: TiO2; Chemical: ZnO
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: Ag; Chemical: TiO2; Chemical: Ag; Chemical: TiO2; Chemical: ZnO