A graduate student was in critical but stable condition at Lawrence Memorial Hospital Thursday after he was admitted with life-threatening injuries. University officials and police said he accidentally ingested a chemical while working in a lab at Malott Hall Wednesday night.

University officials said the student, who was not named, ingested sodium azide about 10 p.m. He left campus and became ill at home about 11 p.m.

University police and Environment Health and Safety officials evacuated Malott Hall and also Haworth Hall, which is connected to Mallott by a skywalk, shortly after learning about the student’s condition at 2:30 a.m. The Department of Environment, Health and Safety declared the buildings safe about 5 a.m.

Chris Keary, assistant chief at the KU Public Safety office, said that the investigation was ongoing, but that they did not think foul play was involved.

Mike Russell, director of environment, health and safety, said the department did two sweeps of the building in the early-morning hours, including one with the Lawrence Fire Department, and determined there weren’t any hazardous materials that would threaten building occupants.

“We did not find any evidence of any chemical release, spill of any type, as far as any exposure concerns go,” Russell said, “so we were able to let areas of the building become open and available for use within.”

Sodium azide is used as a chemical preservative in hospitals, laboratories, automobile air bags and agriculture pest control, according to the Centers for Disease Control and Prevention. Russell said the chemical was a common chemical in different areas of research such as molecular bioscience, medicinal chemistry and pharmacy. He said the substance was a white crystalline powder, similar to table salt, and odorless. He said the chemical had acute toxicity, which means adverse effects could happen within a short time period of exposure.

“Contact is a big concern with this material. Getting it on your skin, ingestion, that kind of aspect,” Russell said. “It doesn’t take a lot of this material to cause adverse health reactions.”

The University sent a text message alert at 7:01 a.m. Thursday to students and faculty who signed up for the service. Lynn Bretz, director of University Communications, said the University wanted to make sure students knew the buildings were safe.

“This involved a life-threatening situation for a student who at one point had been on campus before he went to the hospital,” Bretz said. “Also, we do listen to our students, and they have been very clear in the last year or two since we’ve had the system that when something happens to a student ­— on campus especially — they would like to know.”

The University has activated about five text messages since it implemented the system two years ago, mostly for weather closures. Jill Jess, associate director for news and media relations, said about 17,000 people had signed up for the alerts. Students, faculty and staff can sign up for alerts at alerts.ku.edu.

— Edited by Jonathan Hermes