NMU and tobacco

[ynakao at kean.ucs.mun.ca]

Dear Netters
     Would you please tell me the relationship between tobacco smoke and N-
nitrosomethylurea (NMU)? Though tobacco smoke contains many kinds of 
nitrosoamines, NMU is not in the list of them. I know NMU is used anti 
cancer drug and not amines but ureas. How about the possibility that a 
nitrosomamine becomes NMU after metabolism? If you know any refernces of 
the origin of NMU and NMU as a metabolite of nitrosoamine containied
tobacco smoke, please send me a Email. 
(I suppose NMU does not relate with tobacco specific nitrosoamines...
.. However, I am not sure.)
                               Thanks in advance
                                                 Yoshifumi Nakao
                                                 ynakao at kean.ucs.mun.ca