Peggy,
	Interesting question. We use liquid nitrogen here all the time
and to be honest with you I have never considered the disposal issue. We
just let it evaporate. We are freezing animal tissue that may or may not
be infected with virual constructs that are non pathogenic in humans.

Cynthia Favara
Rocky Mountain Laboratories
903 S 4th Street
Hamilton, MT 59840
ph: 406-363-9317
FAX: 406-363-9286
e-mail: cfavara@nih.gov


> ----------
> From: 	lpwenk@netquest.com[SMTP:lpwenk@netquest.com]
> Sent: 	Monday, December 07, 1998 4:44 PM
> To: 	histonet@pathology.swmed.edu
> Subject: 	LIQUID NITROGEN DISPOSAL
>
> Someone asked me a question about how to dispose of liquid
> nitrogen. That got me thinking about how it is used, and about
> whether is should be considered biohazardous.
>
> If fresh tissue is frozen in the liquid nitrogen, could
> some of the bacteria/fungi/viruses from the tissue be frozen
> and floating free in the liquid nitrogen? Would these
> frozen micro-organisms then be still viable when thawed out,
> such as when the liquid nitrogen is thrown on the floor
> or outside under a bush?
>
> This concerns not only tissues quickly frozen in liquid
> nitrogen, but also tissues in long term storage in
> liquid nitrogen.
>
> If the dumping/evaporating of the liquid N2 is done indoors,
> is there a chance that the microorganisms become
> airborn? If dumped outside on the ground, what happens to
> the microorganisms? Does air and sunlight kill them? Would
> it be better to let the liquid N2 evaporate in the hood?
>
> I don't know of any way to dispose of liquid N2, other than
> dumping/evaporating. Obviously, pouring liquid Chlorox into
> the liquid N2 isn't going to work.
>
> Any and all (useful) suggestions will be appreciated and
> passed along.
>
> --
> Peggy A. Wenk, HTL (ASCP)
> Anatomic Pathology
> Wm. Beaumont Hospital
> 3601 W. 13 Mile Rd.
> Royal Oak, MI 48073-6769
>