16645
The aim of the study was to investigate the association of blood lead levels , urinary uric acid ( UA ) and N - acetyl - beta - d - glucosaminidase ( NAG ) in chronic occupational lead - exposed workers , and to study whether the association was influenced by MT1A gene polymorphisms .
 Chemical: uric acid; Chemical: N - acetyl
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: uric acid; Chemical: N - acetyl