WorkSafe has filed charges against the company under the Health and Safety at Work Act 2015.
Court documents show that Pest Control Research Ltd Partnership is facing six charges including exposing an individual to risk of harm or illness, and failing to have an emergency response plan.
The company is expected to appear at Christchurch District Court on February 23.
At the time of the May 2019 exposure, PCR chief executive Matthew O'Brien said he was unable to comment on the circumstances leading up to, or the causes of, the incident.
"Clearly that will be part of both the independent investigation we have commissioned, and WorkSafe's inquiry," he said.
"We will be able to comment in due course when all the facts are known."
O'Brien said PCR had been operating for many years in Christchurch manufacturing pest control devices and poisons without incident.
"We are very experienced at handling dangerous chemicals and have an excellent safety record," he said.
"Obviously, we are very concerned this incident has occurred and will do everything we can to find out how it happened, why, and what can be done to prevent it from happening again."