"due to"

     [This is a fast-access FAQ excerpt.]
"Due to" meaning "caused by" is undisputedly correct in contexts
where "due" can be construed as an adjective (e.g., "failure due to
carelessness").  Its use in contexts where "due" is an adverb
("He failed due to carelessness") has been disputed.  Fowler says
that "due to is often used by the illiterate as though it had
passed, like owing to, into a mere compound preposition".  But
Fowler was writing in 1926; what hadn't happened then may well
have happened by now.