I just got killed by radiation and I don't know what I could've done to remove the effect. Once I got it it just kept ticking for a very very very long time until I died. I tried rolling, jumping off the cliff. Didn't help. Also the first time I played I saw one of those purple grass barriers and rolled into it, I got trapped inside and had to restart.
The Radiation debuff is definitely a bit too punishing right now when applied to the player, there will be a tweak to it in the next update. The only way it can apply to you is if one of your own bullets with radiation is reflected back at you, so if you collect that ammo mod just try to be careful when firing at Holoshields or barriers for now.
Also I'm not sure where you are describing with "purple grass barriers", my best guess is you meant the Solus quill areas with the purple sacks littered around. If one of the quill gates blocked you, usually there is a Quill Nest nearby that needs to be destroyed to open the gate. It's possible you rolled behind a loot gate though and it didn't lower to let you out after skipping it. If you get stuck again try to take a screenshot where it was and it will be easier for us to locate and fix it.
This is a similar barrier: In this barrier I can walk through the red-lined areas and I can make it all the way to the bottom. I can't roll/dodge through the bottom because I get 1/2 the way through the collision area and then get pushed back up but on the barrier I encountered earlier I was able to roll through an upper-left part and was not able to roll back. I know I can make these barriers come down, and all I'm saying is that I rolled against one and it trapped me inside it.
Also I think I had no mods at the time since it was the first time I played.