6401
Furthermore , the rate at which Elodea reduced malathion ' s toxicity in the water column increased with macrophyte density .
 Chemical: malathion
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: malathion 
Answer:
 Chemical: malathion