Beta-mercaptoethanol spill – Lessons Learned

In April, EH&S received an on-call related to a beta-mercaptoethanol spill in a laboratory building on campus. Approximately 50 mL of undiluted beta-mercaptoethanol was accidently spilled onto the floor of a laboratory. The lab PI and staff immediately cleaned up the spill in accordance with the SDS for the product. Despite the timely clean-up, the odor of the chemical persisted in the lab and could also be smelled in the adjacent hallway. At this point, the concerned PI reached out to EH&S for assistance and advised the lab group to not enter the space until cleared.

Beta-mercaptoethanol (BME) is a reducing agent often used in biochemistry applications for protein denaturing. Because this chemical is ubiquitous, its toxicological effects are sometimes forgotten. BME is a poison if ingested, causes irritation in the mucous membranes, and can be absorbed dermally. Chronic exposure to BME is linked to heart and liver damage. As with other thiols, BME is characteristic in having a pungent odor. In fact, the odor threshold of BME is so low that often the smell of the chemical becomes obvious before the levels are high enough to cause any health effects.

Upon the investigation, EH&S verified that the spill was effectively cleaned up and there appeared no further means of exposure to the lab staff. Since BME is fairly volatile, EH&S surmised that the lingering odor was related to a small amount that had vaporized; however, the odor was also present down the hallway, approximately 30 feet from the lab. EH&S contacted Facilities Management (FM) to aid in the investigation of the ventilation system in the lab. FM quickly evaluated the space for pressure differential and noticed that somehow the air pressure in the lab had become slightly positive with respect to the hall. This meant that the air was being pushed out from the lab through the gaps in the door and was likely the cause of the odor observed in the hallway. Labs should always be maintained at a negative pressure to prevent chemical contaminants from escaping into shared spaces and exposing occupants.

The PI made the correct decision by quickly contacting EH&S so that the fugitive odor could be further investigated. This quick thinking allowed for changes to be made to the lab ventilation controls such that occupants located in the area, and those passing through the hallway, were not inconvenienced by the odor. It should be noted that ventilation systems in labs are not always perfect. If your lab is a part of the annual lab safety review program, you may notice your lab safety professional checking the air pressure in your lab. But checking once a year is not enough, so it is important that staff periodically ensure that the air pressure in their lab remains negative with respect to hallways and common spaces, so that other staff and students in the vicinity are not exposed to chemicals used within lab spaces. Lab pressure differential can be easily checked by placing a small piece of tissue paper flat against the outside edge of the lab door frame and verifying that the air is flowing into the lab space, drawing the tissue into the lab.

Any concerns related to lab ventilation should always be reported to FM through the work order system. EH&S relies on researchers, staff and students for playing their part in keeping our campus safe and we appreciate all your help!