Here’s one more update for anyone interested. I received a reply from IRH regarding whether they recommend routine helmet replacement after 5 years:
[I]What you have heard about 5 year replacement for helmets had been started by another helmet company to get consumers to purchase new helmets.
It is just a marketing ploy and IRH will not be a part of miss leading our customers. There is absolutely no scientific date to back these lies.
I am one of the original founding members back in 1985 that help develop the current ASTM F1163 standard and I am still active in committee activities.
I have attached a study for you reference concerning these false and miss leading statement about the expected life span of any safety helmet.
Sincerely yours,
IRH
Frank Plastino
President[/I]
He did attach a document regarding a study on bicycle helmets (summary here; abstract from peer-reviewed journal here).
I’m no expert so I don’t know if bicycle and riding helmets are similar enough that that applies. I’m also unwilling to take a risk with my brain, plus the lack of packaging was reason enough to return it IMO. But the article is interesting anyway.