STANFORD (KCBS)– A Stanford graduate student who said it was “a cry for help” admitted putting a lab chemical in classmate’s water bottles.

Several students who drank the water tainted with a chemical similar to formaldehyde said they had adverse reactions, but none was seriously hurt.

READ MORE: Possible Listeria Contamination Forces Recall of 230,000 Pounds of Ham, Pepperoni Products

The school of medicine student, who has since left the university, admitted spiking the water bottles in September and November of last year. The student also admitted tampering with other student’s experiments.

READ MORE: Air District: Weather, Wood Smoke To Bring Moderate Air Quality In Bay Area This Week

The Stanford Daily reports the student admitted to suffering mental breakdown.

MORE NEWS: New York City Announces First-In-The-Nation Vaccine Mandate For Private Companies

Police have conducted an investigation of the incident and sent their findings to the Santa Clara district attorney for possible charging.