21710
In all water samples , concentration of Ni was expressed as nanogram per milliliter ( ng / mL ) and found to be higher than Pb and Cd levels .
 Chemical: Ni; Chemical: Pb; Chemical: Cd
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: Ni; Chemical: Pb; Chemical: Cd