Actually it's anthrax and swim is going to drown if he uses it.
There is no way we can know this so there isn't anything we can say here. If you want, you can look into reagent testing but I can't imagine you're going to go through the effort for some resin on an old pipe so please just clean it or discard the pipe. You don't know what it is or how old it is or anything and it's not worth the risk.
Also, as thizz said, please don't use swim here. Take a look at the forum guidelines and drop me a PM if you have any questions