I emailed every manufacturer listed HERE (except Trojan -- could not find an email contact method on their site) the email found HERE. I received one bounced email, one instruction to actually call the company (which I didn't really feel like doing), but I just got a written response today that I think is quite helpful!
The email is from a Regulatory Affairs / Quality Assurance Manager at Global Protection Corporation. Now, I don't actually know which brand uses this company -- they appear to be a manufacturer and perhaps they are re-branded and sold under one of the more common names at the link above. In any case, here was the response:
Dear Mr. _,
Condoms are a medical device regulated by the United States Food and Drug Administration (FDA), Health Canada and other regulatory bodies. Guidelines are provided that outline labeling and language requirements, storage, and testing.
Physical testing is performed on each lot of condoms and includes:
- Dimensional Testing for length, width and thickness
- Air Inflation Testing for volume and pressure at burst
- Leakage Testing
- Visible Defects
- Freedom From Holes testing
- Package Integrity Testing
- Colour fastness (for color condoms only)
Please note that every condom is electronically tested for reliability and safety.
Prior to receiving approval to sell condoms in the United States or International Markets, biological testing is required to assure the safety of the materials. Additionally, stability studies have been conducted and demonstrate the shelf-life of condoms to be 5 years.
Storage of condoms in a wallet is not recommended as damage to the product could occur. Short-term storage in a wallet is less of a concern than longer-term storage. Degradation will occur at higher temperatures, and continued pressure or folding of the condoms can weaken the latex. There is no study that I am aware of that specifically tests condoms in wallets. The warning comes from general knowledge that
- Higher temperatures for extended periods degrades latex and
- Pressure on the condom for extended periods can degrade the latex.
It is recommended that condoms be stored in a cool, dry place (below 100° F) and avoid exposure to direct sunlight.
Please let me know if you have any additional questions.
So, my takeaway is that the recommendation is due to materials science factors and degredation of the latex. I don't know that I buy the "pinholes from rubbing" explanation, though I suppose these could come about -- we'd need to know what failure mechanism latex degredation leads to. Pinholes might be it, but it could simply be breakage once the condom is actually used vs. a failure before hand. Not sure!
I'll update the answer if I hear back from any other manufacturers I emailed!