De or het worstvergiftiging?

The correct Dutch article is:

de worstvergiftiging

Rule Words ending in -ing: almost always de. See the rule

How to use worstvergiftiging

the worstvergiftigingde worstvergiftiging
this worstvergiftigingdeze worstvergiftiging
that worstvergiftigingdie worstvergiftiging
our worstvergiftigingonze worstvergiftiging
your worstvergiftigingjouw worstvergiftiging
every worstvergiftigingelke worstvergiftiging
which worstvergiftiging?welke worstvergiftiging?
a big worstvergiftiging / the big worstvergiftigingeen grote worstvergiftiging, de grote worstvergiftiging