Can temporary workers be sued individually for negligence

Yes, although there are often good reasons not to do so but to only sue the employer, since the worker (a) may not be able to pay any judgment; (b) may be difficult to locate; and (c) may be more likely to be a truthful witness if they are not being sued personally.  There could also bevquestions about whether an individual worker, who you are not paying, has violated a duty to you.