Below are the off-list responses I received to my inquiry on Wednesday about liquid nitrogen use. Note the difference in experience in two different, but adjacent, states. It sounds like technique plays a role as well... Thanks for everyone who responded. - Ralph From: "Dewinkle, Gary M"
Date: August 22, 2007 6:52:41 PM EDT Subject: RE: [DCHAS-L] LN2 for tissue storage Have you checked for information related to bovine semen storage? - it is my understanding that it is stored in the liquid phase. Gary De Winkle, CIH, CSP EMSL Safety & Health Representative IOPS Program Manager EMSL/2393 509-372-2931 (Office) or 509-539-8099 (Cell) Mail Stop K8-80 ~~~~~~~~~~~~~~~~~~ From: "Erik A. Talley" Date: August 22, 2007 10:05:43 PM EDT Subject: RE: [DCHAS-L] LN2 for tissue storage Ralph, There are some serious safety concerns with storing in the liquid phase. Many of the containers that are used for cryo storage will hold the LN2 when stored in the liquid phase and then explode when taken out. This isn't theoretical...it has happened 3 times here, which is why we created an Update on the issue. We have only found one recommended solution which involves sealing them in a bag. The EHS Update at http://www.med.cornell.edu/ehs/updates/ln2.htm details the issue. Jim Crandall in my office did the leg work on the issue and can provide additional details if needed. Regards, Erik ~~~~~~~~~~~~~~~~~~ From: "Hadden, Susan [PRDUS]" Date: August 23, 2007 7:58:20 AM EDT Subject: RE: [DCHAS-L] LN2 for tissue storage Our PPE for handling liquid N2 includes: safety glasses AND face shield, cryogloves and liquid impermeable apron over a lab coat. If the cryounit will be stored in space with limited air exchange, an O2 sensor with alarm is a must have. (You should do the math to calculate the N2 gas release if there should be a containment failure.) ~~~~~~~~~~~~~~~~~~ From: "Wawzyniecki Jr, Stefan" Date: August 23, 2007 9:52:23 AM EDT Subject: Re: [DCHAS-L] LN2 for tissue storage Here are 2 comments from our researchers... "I have been storing samples in liquid nitrogen for many years. The manufacturers of cryovials say that they can explode if stored in the liquid phase (i.e., when trapped liquid expands on warming), but in 25 years of doing just this, I have never seen it happen. I usually leave the vial lids slightly loose to allow escape of gas, but some people I know punch tiny holes in the lids as a precaution. I generally wear nitrile gloves (usually double gloves) to remove cryovials and canes from the storage dewar, and transfer canes to low styrofoam containers filled with liquid nitrogen to manipulate or sort samples. Hemostates work well for grabbing vials and lids to unscrew. In all these years I have occasionally had minor frostbite on my fingertips, but nothing worse." ~~~~~~~~~~~~~~~~ "We routinely store cells in the liquid phase of LN2. PPE includes a face shield and the cryo gloves sold by Fisher and others (easily found in the LN2 sections of the Fisher catalogue), as well as a lab coat. Vials are stored in racks, which we let drain when we pull them out of the liquid phase of LN2. Any remaining liquid will evaporate rapidly when at air temperature." ~~~~~~~~~~~~~~~~~~ From: "Hunt, Chris (NIH/NIEHS) [E]" Date: August 23, 2007 7:11:36 PM EDT Subject: RE: [DCHAS-L] LN2 for tissue storage This link may provide some useful information. http://www.wfcc.info/tis/info4.html Chris Hunt, Jr.,CIH Safety Officer Health and Safety Branch
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