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To determine the effects of different cord serum levels of Zn and Se on neurobehavioral development in neonates and to explore possible threshold level of Zn and Se based on fetal neurodevelopment , we conducted this epidemiological research .
 Chemical: Zn; Chemical: Se; Chemical: Zn; Chemical: Se
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: Zn; Chemical: Se; Chemical: Zn; Chemical: Se