Larry Milstein

Yale officials have identified sodium azide, a toxic chemical used in laboratories as an antibacterial agent, as the cause of an incident on Feb. 28 in which four people became ill after drinking coffee from an office coffee machine at the Yale School of Medicine.

A coalition of organizations spearheaded by the Yale Police Department, including law enforcement agencies at the local, state and federal levels, is investigating how the coffee machine became contaminated and whether sodium azide was deposited in the office accidentally or intentionally, among other details, according to YPD Chief Ronnell Higgins.

The presence of the compound was confirmed by an independent laboratory, which tested items taken from the office area, Yale School of Medicine Dean Robert Alpern said in an email to the medical school community on Tuesday night. Upon discovering the reported illnesses, the YPD immediately contacted local and state law enforcement agencies, including the New Haven Police Department and the Connecticut Department of Energy and Environmental Protection, University Vice President for Communications Eileen O’Connor said.

“It’s not unusual [for the YPD] to collaborate with different levels of law enforcement agencies,” Higgins said. “The YPD is fully engaged in the investigation with our partners.”

O’Connor emphasized that the case concerned a single coffee machine in one particular location that is completely disconnected from the central water line and any campus dining halls. She refused to speculate about whether the incident was accidental or intentional while the results of the joint investigation are pending.

The four individuals who reported feeling unwell last week have since returned to work, Alpern said in the email.

Alpern also said the incident has prompted a review of Yale’s safety and security protocols in collaboration with the University’s public safety team. He advised students to contact Yale Health Acute Care if they experience the symptoms of sodium azide exposure, which include dizziness, headache, nausea and vomiting, rapid breathing and rapid heart rate.

O’Connor declined to comment on the symptoms of the four affected individuals, noting that the Health Insurance Portability and Accountability Act stipulates that medical information be kept confidential.

A similar incident occurred at Harvard Medical School in 2009, in which employees also ingested sodium azide from a contaminated coffee machine. According to O’Connor, administrators at Harvard conducted interviews after the incident, but they never disclosed the results of the investigation.

The Harvard incident led Yale to include sodium azide in a list of chemical substances that require safety training in labs, O’Connor added.

In his email, Alpern did not include a timeline for the joint investigation.

“We will keep you updated but caution that gathering complete information will take some time,” he wrote.