Radiation has the green damage melting on the target. This is a green cloud on the target. There is no DOT on the target at all and I have damage numbers turned on so I'd see.
If you want when I rip the clip mod back out of the Shotgun I got I'll take a screen shot of it. Was called something like "Toxic Ammo Modifier" or something like that. Here's the icon in my inventory:
http://steamcommunity.com/profiles/7.../?appid=224600
The 20% damage increase is pretty insane and I use it a lot when in groups to help out the team do more damage.



