As we talked about in last week’s blog Spooky Season Safety with Dry Ice, there are many safety considerations when working with dry ice including the fact that it can be an explosion hazard. Dry ice is the common term for carbon dioxide (CO2) in the solid phase. At room temperature, dry ice sublimates and turns into CO2 gas. At room temperature, 1 cubic centimeter (1.5 grams) of dry ice expands to 0.8 liters of CO2 gas. That means that a baseball-size chunk of dry ice will turn into 177 liters of gas!
This story is included in Safety Partners’ publication, “Incidents, Accidents, and Near Misses in Laboratory Research (Volume 1).” Unfortunately, the scientist involved found out the hard way that 177 liters of gas is much more than a one-liter sealed plastic container can hold.
It was a cold January afternoon in Cambridge. Kelly, a seasoned biologist, worked in a tissue culture lab at a small biotech company situated near Harvard where she had done her post-doc work. She was conducting cell-based experiments and had a very productive day so far. She was down to the last items on her to do list. Kelly was looking forward to leaving work on time, beating the usual traffic jams at Fresh Pond, and getting home at a decent hour. Her husband Dan had promised to grill salmon on the back porch that night…a special treat on a cold winter’s night.
The Cell Extraction and Freezing Process
Kelly’s tissue culture lab was no different from other tissue culture labs where cells are grown in media. To isolate the desired cells from the growth media, Kelly would place the mix into 1-milliliter microcentrifuge tubes and give them a spin on the centrifuge. Once separated, Kelly would preserve the cell samples by quickly freezing them inside an ice bucket with chunks of dry ice. This flash freezing method preserves the details of the cell membranes for further examination.
In Kelly’s lab, dry ice was stored in the main lab. When she went to get dry ice, she could not find an ice bucket anywhere near the dry ice chest. After a few minutes of searching, she spotted a one-liter plastic container. The container had a wide-mouth opening with a screw top. “That looks like it’ll work as long as I don’t screw the top down too tight,” she thought to herself, scooping up the container and heading back to the lab.
Kelly carefully put the dry ice in the plastic container, rested the lid on top of the container and gave it a slight twist so it wouldn’t slip off. She picked up the container and walked back over to the tissue culture area. As she placed the container down on the lab bench—BAM! The container exploded. Small plastic shards flew around the lab.
Sue, another scientist and friend of Kelly’s, heard the blast and came running. “Are you alright, Kelly?” Sue asked.
Kelly took off her gloves and lab coat and gingerly ran her hands up and down her arms. She felt a small piece of plastic in her right forearm. She touched her face. She found another small piece near her lip. The slightest bit of tears pooled in her eyes.
“Yes. I think so,” Kelly replied. “That shouldn’t have happened. I didn’t screw the top on that tight.” She then noticed another shard of plastic lodged in the drywall near her head. She shook her head in disbelief.
Sue drove Kelly to the local emergency room, fighting the early rush hour traffic. Kelly called her husband Dan from her cellphone to let him know what was happening. At the ER, the medical staff removed the plastic shards and treated Kelly’s cuts. They then used an ultrasound device to make sure there were no other pieces of plastic in her arms or face. Kelly had been wearing her safety glasses and a lab coat, which probably protected her from additional injuries.
Dan arrived at the ER while Kelly was waiting to be discharged. Relieved that it wasn’t worse than it was, Kelly and Dan finally made it home around 8pm. Dan grilled the salmon for dinner as he had promised. They finally sat down to dinner at 9 o’clock.
Kelly was a seasoned biologist with many years of experience working in and around labs. She was known to be conscientious about lab safety and understood the potential hazards of working with dry ice. She knew that if dry ice were stored in an airtight container, pressure would build up quickly as the dry ice turned into gas.
The chain of events leading up to this incident started with the missing dry ice bucket. Either there weren’t enough ice buckets in the lab or someone failed to return one to the right spot. Next in the chain was Kelly’s decision to use the plastic container instead of taking extra time to find an ice bucket. It was handy and looked like it would work. In the moment, she chose expediency over safety.
This dry ice incident and the chain of events leading up to it are uncannily similar to the exploding flask incident reported earlier (“The Stupidest Thing I’ve Ever Done in the Lab”). In both cases, we have experienced scientists; the scientists were in a hurry to finish their processes; the proper containers (the dry ice bucket and the vacuum flask) were nowhere to be found; the scientists grabbed what was expedient and seemingly okay to use; a small explosion occurred due to the build-up of inward or outward pressure; and each scientist escaped with only minor cuts. Both stories serve as a reminder that even the most experienced scientists can get themselves into trouble if, in the moment, they choose expediency over safety.
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