17958
Earthworms exposed to quantum dots showed significant bioaccumulation of cadmium and selenium ( 5 . 3 - and 1 . 5 - fold higher concentration over negative controls , respectively ) after 4 wk .
 Chemical: cadmium; Chemical: selenium
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: cadmium; Chemical: selenium