Collocations for irresponsible - adj.

be, seem
become
consider sb/sth

extremely, fairly, very, etc.
deeply, grossly, highly
Their actions were highly irresponsible.

criminally
these extreme and criminally irresponsible policies

completely, totally, utterly (esp. BrE), wholly (BrE)
He's fun, but totally irresponsible.

a little, slightly, etc.
socially
It is socially irresponsible to refuse young people advice on sexual matters.

fiscally (AmE)