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Polycyclic aromatic hydrocarbons ( PCAHs ) , particularly those with a high molecular weight , have been classified as probable carcinogens to humans .
 Polycyclic aromatic hydrocarbons, PCAHs
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Polycyclic aromatic hydrocarbons, PCAHs