19417
Case report : A male worker in a chemical plant was accidentally exposed to the mixture of high - concentrated ethenone and crotonaldehyde for 5 min in an open space and worked continuously in the polluted area for approximately 12 h .
 ethenone, crotonaldehyde
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 ethenone, crotonaldehyde