The following sites may have useful information:

The Image Permanence Institute of The Rochester Institute of
Technology
http://www.imagepermanenceinstitute.org

The American Institute for the Conservation of Historic and
Artistic Works at: http://aic.stanford.edu/

Conservation On Line site at:
http://palimpsest.stanford.edu

Also, if you are in the USA call Kodak's customer service
number 1 800 242 2424 and ask for extension 19, the
professional group. They might be able to guide you to Kodak
sources and possibly other sources. There are many other
sources but these should get you started.

  There is a very large body of literature on the
permanence of photographic color materials. The motion
picture industry especially has been very interested in this
for years. You are probably going to have to do some
old-fashioned research at a good university library in
addition to the web stuff. A good source for motion picture
oriented articles is:
_The Journal of the Society of Motion Picture and Television
Engineers_.

This is totally unscientific, but yesterday I was looking through some
of my father's slides from 1959-1961, vacations and parties and such.
Most of the Ektachromes have turned into something almost like
monochrome, varying intensities of reddish-brown.  A few rolls of
Ektachrome have held up better and one can still guess at the original
colors... not sure why those particular rolls held up better than the
rest.  All the Kodachromes still look great, bright natural colors.  All
of these were shot on commercially available 35mm amateur film (on a
Kodak Retina Reflex if anyone cares), processed by Kodak (probably at
Fair Lawn, NJ), and have been stored in identical plastic pages away
from light at "typical" household temperature and humidity.  I don't
know which Ektachrome process was in use at that time.

Adam