| This is a highly professional question, I doubt it if anyone here has a clue. I looked it up and found these sites
http://www.hsph.harvard.edu/Organizations/DDIL/epi221b.htm
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1118945
http://www2.warwick.ac.uk/fac/med/staff/pubs/?ssn=dJy/xBvzuA8=&inst=WARWICK
http://www.ub.ntnu.no/journals/norepid/2001-1/2001(1)Eggen.pdf
http://epirev.oxfordjournals.org/cgi/reprint/12/1/87.pdf
I am sure there is a lot more research published in medical sites. |