OK, but what do they mean in practical sense? If HDPE has a value of 2900 for O2, it passes 2900 cm^2/m^2.... Does that mean death to developers or is that an acceptable value? I have been storing mine in HDPE bottles and it is fine for all practical sense for over 6 months period. (so for my purpose, it's perfectly fine....)

For comparison purpose, do you have such data for Polypropylene which I did notice some color change.