Elegran
Not sure of the percentage in the UK but 50% of items used in hospitals are sterilised this way in the US. The big uproar was not about the items sterilised but repeated gas leaks in the vicinity of the places doing the sterilisation. Pollution in the neighbouring areas. There's lots written about this online. There will eventually be an alternative.
Mainly (I understand) it's used for plastics and resins, items with hard-to reach places (such as catheters), things in layers (eg sterile wound dressings) or in packaging with paper instructions.
Heart stents are also sterilised this way - and the sort of catheter specially made to go up from the groin for heart surgery.
It's still the only method that works for lots of things and is widely used for "everyday" hospital items.
Other methods are things like radiation, steam, heat, hydrogen peroxide, chlorine gas... I know there's more.
Just how much taxpayers money have the Tories wasted
Water Pollution -“ A National Disgrace”? A case for renationalisation?
How much do you spend on yourself?