Better wake up. Host employers have an obligation to provide safe working conditions to anybody working at their facility, even the employees of some other employer. In response to this problem, OSHA established a rule which basically imposed responsibility on any employer who had control of the site. Not too long ago, this rule made its way into non-construction industries, such as manufacturing plants. As you might expect, several of these cases have landed in court and, although some citations were eventually vacated, the courts' decisions are very narrow and don't preclude further liability for host employers.
Current efforts are underway to clarify the law.
But don't hold your breath. It appears the bill won't be acted on in the near future. If you have outside contractors working at your facility, make certain your agreement clearly sets forth the contractor's safety responsibilities. It's also a good idea to adopt a specific outside contractor safety program. We can review your current contracts with outside contractors and help you design a program that fits your specific situation.