23101
In this study , submerged macrophyte Ceratophyllum demersum ( C . demersum ) was adopted to examine the effects of anatoxin - a on morphological ( growth ) , physiological ( photosynthetic pigment contents ) and biochemical ( hydrogen peroxide level , biotransformation and antioxidative enzymes ) responses in the aquatic plant at environmentally relevant concentrations ( 0 . 005 , 0 . 05 , 0 . 5 , 5 and 50 mu g / L ) .
 Chemical: anatoxin - a; Chemical: hydrogen peroxide
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: anatoxin - a; Chemical: hydrogen peroxide