An average of 4.5mg of nicotine is absorbed from 7.9g of chewing tobacco and an average of 3.6mg of nicotine is absorbed from 2.5g moist snuff.
Severson, H.H. "What Have We Learned From 20 Years of Research on Smokeless Tobacco Cessation?" American Journal of Medical Sciences. 326(4). Oct. 2003: 206-211. Web.http://wohfkidsconnect.com/site_i/PDF/20-Years.pdf