致使 (zhìshǐ) is a formal, written verb meaning 'to cause, to lead to' — it always implies a negative outcome and is common in official reports or legal language. It is more formal than 导致 (dǎozhì) and narrower than 引起 (yǐnqǐ), which can also be used for positive results. As a conjunction, it means 'so that, as a result', introducing a consequence clause, unlike 以便 (yǐbiàn) which introduces a purpose.