But I ran across a new variable yesterday that still surprises me: sex. As in sexual differences and the associated body chemistry differences, and how that may lead to differences in degradation inside of the body.
The FDA has a group studying the issue:
"...The team objectives are to develop scientific understanding and test methods related to degradation mechanism of polymers and the impact of known sex-based physiological differences on the molecular mechanisms of degradation in polymeric systems. The candidate...will synthesize target polymers for degradation studies and fabricate different material systems that emulate the various components of diseased coronary arteries ...The best part is that they even have an open postdoc.
Personally I am surprised that male/female internal chemistry can vary enough to change degradation mechanisms that much, but that is not an area in which I have much experience. [*] Regardless, someone seems to think that it is an important issue and I think it would be a really cool area of study.
[*] My only experience with internal body chemistry was when I was working for a medical device company making an implantable hearing aid suffering from corrosion problems. We looked at the body as 0.9wt% NaCl at 37 C and nothing else, and definitely didn't consider sexual differences.