14896
Male F344 rats were initially administered diethylnitrosamine ( DEN , 200mg / kgi . p . ) ; after a 2 - week non - dosing period , they were given diets containing HEP ( 5 or 25ppm ) , HCB ( 70 or 350ppm ) , or their mixtures ( 5 and 70ppm or 25 and 350ppm ) for 6weeks .
 Chemical: diethylnitrosamine; Chemical: DEN; Chemical: HEP; Chemical: HCB
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: diethylnitrosamine; Chemical: DEN; Chemical: HEP; Chemical: HCB