Do Marelon white through hulls have a maximum use date?

[Fuss]

Marelon through hulls are meant to be very tough and not suffer from any of the problems underwater like normal nylon. Many metal boats use these ....... but maybe they become brittle and dangerous after a certain time and no one is telling us.
I read on one thread here that they might be good for 50 years.
Anyone know more or have any experiences to share?

[Sailmonkey]

Mounted above the waterline they’re still extremely tough after 42 years in the sun. I replaced one last year and it would not crack or break to remove, it did saw nicely however.