1.  An employee must be in pay status (roughly "on the job" although it can get complicated) at the time of an injury or exposure, or Workers' Compensation does not cover the expenses.

2.  Graduate students who are Purdue employees but who are injured/exposed doing research for which they are not paid are not in pay status.  Graduate Student Accident Insurance is carried -- by the University, not by the grad student -- to cover grad students who are injured or made ill while performing activities associated with their enrollment in their department's 599 or 699 course.  From the Grad Student Employment Manual: 

"The coverage provides accidental death, dismemberment, disability income, and medical expense for those hazards to which an insured person may be exposed while engaged in class work, research, course-related activities, or in approved field work or travel for University activities related to research or coursework."

There is a little more, see Rick Management Programs section on page 24, part D, of the the Graduate Student Employment Manual.