You would be better off with the Wounding or Poisoner's legendary effect over the Irradiated one. Those two effects apply to every enemy except Robots. Wounding gets you, Targets bleed for 25 points of additional damage. Poisoner's does, Target is poisoned for 10 seconds. (3 points poison damage per second). Those would be ideal for a silenced 10mm.
If you know your going to be going up against Humans then Irradiated does a nice job. I use it on a fully upgraded Laser pistol when clearing Raider/Gunner camps/buildings. So I burn them on the outside with the Lasers flame effect and cook them on the inside with the radiation dose from Irradiated.
Another legendary effect I love to use is Explosive. Your bullets explode when they hit your target or another solid object. I love it since it will damage your target but it also does damage to any enemy NPC around your target. It also works when your target is hiding behind a wall. Your shot might miss but the explosion still wounds your target through the wall.
There is a draw back to Explosive though. It will kill friendly NPC's like the traveling merchants and their guards. I found this out when I took out Cricket, her Brahmin, and all her guards when shooting at a bear at the camp outside Vault 81. It will also put your companion down until they heal up again or you hit them with a Stimpack. So Explosive is best for solo play and when your know there are no friendly NPC's any where in the area.