The student and her roommate were being treated for potential exposure to the poison, although neither has exhibited symptoms, said Dr. Theresa Spalding of UT Student Health Services.
The student told university police she found the chunky powder Thursday as she was doing her laundry at the Moore-Hill dormitory, Spalding said. Preliminary tests for ricin came back positive Friday.
¿We were very concerned as soon as we heard about the positive testing late this evening,¿ Spalding said. She said the quarters had been in the students' dorm room for several months.
Ricin is extracted from castor beans and can be added to food or water, injected or sprayed as an aerosol. It can be in the form of a powder, mist, pellet, or it can be dissolved in water or weak acid.
Symptoms can include anything from difficulty breathing, fever, cough, nausea and sweating to severe vomiting and dehydration.
The dorm was sanitized and inspected, and students were cleared to return, the university said.