222384
NNK and its metabolite 4 - ( methylnitrosamino ) -1 - ( 3-pyridyl ) -1 - butanol ( NNAL ) are potent systemic lung carcinogens in rats .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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