1. A security system for use in a process plant having a process control system that performs product manufacturing related control functions and a safety system that performs safety related control functions with respect to the process plant, comprising: a computer having a processor and a memory; a process controller communicatively coupled to the computer and adapted to perform process control functionality using one or more process control field devices; a safety system controller communicatively coupled to the computer and adapted to perform safety system functionality using one or more safety system field devices; a security database adapted to store access privileges related to both the process control functionality and the safety system functionality; one or more user applications stored in the memory of the computer and adapted to be executed on the processor to communicate process control system messages to or from the process controller and to communicate safety system messages to or from the safety controller; and an integrated security application stored on the memory of the computer and adapted to be executed on the processor to use the security database to enable a user of the one or more user applications to access both the process controller and the safety system controller via the process control system messages and the safety system messages based on access privileges for the user stored in the security database.