Lessons Learned: Incompatible Chemicals Generate Chlorine Gas

Lessons Learned: Incompatible Chemicals Generate Chlorine Gas

Incident Description

A researcher was finishing up their work and added their remaining Qiagen RNA kit reagents to their waste container. The waste container had been used for tissue processing waste and contained bleach. The mixture immediately produced a strong-smelling gas. This caught the researcher off guard and they poured the waste container contents down the sink and started running the water. The smell dissipated quickly. The researcher alerted the other researchers in the area, as well as their Departmental Safety Coordinator (DSC). The DSC advised the researcher to open the fume hoods all the way and contacted EH&S for additional support. EH&S advised the lab to continue to run the water for an additional 30 minutes, and indicated that if any lab members were feeling ill/dizzy/etc to go to the ER (since by this time it was close to 6pm on Friday).

Following up with the researcher, the initial odor that was detected was described as being extremely pungent (similar to bleach) and that the kit reagents included guanidine hydrochloride. This led to the conclusion that chlorine gas was produced when the kit reagents were mixed with the bleach waste.

What went right?

The researcher alerted their colleagues and their DSC immediately after the incident, and continued to work with their DSC and EH&S to help determine what gas had been produced.

What should have been done differently?

Researchers should always read the kit directions before working with proprietary kits, and pay particular attention to safety reminders. The kit directions clearly state to not mix certain reagents (which contain guanidine hydrochloride) with bleach.

Researchers at this facility have access to a ventilation shut off switch that should have been used in this situation: when activated it shuts off supply air and increases exhaust. As a result the room becomes increasingly negative to allow for quick exhaust of any unwanted contaminants in the air and prevents escape into adjacent spaces. 

Waste containing guanidine hydrochloride should always be disposed of as a chemical waste.

How to prevent this in the future?

Always read the product information or handbook before using a kit, paying careful attention to any safety information and waste handling instructions. In addition, it is key to understand the available controls in the workspace and when to exercise any emergency controls that might be available to the workspace.

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