http://reply.papertrans.cn/2/168/16774/16774-31.png
http://reply.papertrans.cn/2/168/16774/16774-32.png
http://reply.papertrans.cn/2/168/16774/16774-33.png
http://reply.papertrans.cn/2/168/16774/16774-34.png
http://reply.papertrans.cn/2/168/16774/16774-35.png
Submitted on: 10 March 2012.
Revised on: 07 June 2012.
Accepted on: 02 July 2012.
___________________Journal of Exposure Science and Environmental Epidemiology