[Histonet] Bleaching in the histo lab

Lee & Peggy Wenk lpwenk <@t> sbcglobal.net
Wed Feb 1 17:03:21 CST 2012

Several questions and comments, in no particular order:

1. What percent of bleach?
- 10% is all that is needed for biohazards. If you are concerned about the 
smell, it might be too high a percent.

2. How good is your ventilation? How long do you continue to smell the 
- If you continue to smell it hours later, or even the next day, have your 
safety officer and maintenance people check out the ventilation.

3. After wiping down with 10% bleach, are you wiping down the counter with 
- Need to clean off the corrosive bleach off the surfaces. That would also 
help with the smell. But takes more time.

3. What locations in the lab are you cleaning with dilute bleach?
- The only areas that need to be cleaned with a disinfectant are those areas 
that have fresh or not completely fixed tissue, so around the grossing 
stations and the cryostat. Maybe where specimens are received into the lab.
- The areas where you process tissue, embed, microtome, do staining, file 
slides and blocks should not need to be disinfected with bleach. The tissue 
has been fixed in formalin, and gone through alcohol, xylene (or 
substitute), and placed in 60 degree C (140 degree F) paraffin. That should 
kill almost all microorganisms. Therefore, should not need to clean up with 
anything beyond soap and water. If you have a very underprocessed tissue 
block, and it's oozing and weeping all over the counter and microtome, you 
may want to disinfect the area. (If it's a CJD case, you are going to need 
strong solutions than 10% bleach, but that's a whole new conversation.)
- So talk with your safety officer, about how there are no biohazards in the 
other parts of the lab. They may be thinking more of the clinical pathology 
labs, with blood tubes and petri dishes, needing to be disinfected with 
bleach every day/shift.

4. Chemical incompatibility:
Bleach is incompatible with ammonia (makes chlorine gas - deadly)
Bleach is incompatible with acids
Bleach is an oxidizer, and formaldehyde is supposed to be kept away from 
So, yes, I would be a little worried about chemical interaction. However, 
wiping down the area first with water, to remove other chemicals, before the 
bleach, would take care of this problems.

5. What does Epidemiology suggest for disinfectant?
Our epidemiology is suggesting other cleaning solutions for disinfecting, 
rather than bleach, in many cases.
- not as corrosive
- less obnoxious fumes
- more "green"
- better disinfectant and faster, than bleach

Peggy Wenk, HTL(ASCP)SLS
Beaumont Health Systems
Royal Oak, MI 48073
(Comments reflect my opinions, not that of my hospital)

-----Original Message----- 
From: angela smith
Sent: Wednesday, February 01, 2012 8:57 AM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] Bleaching in the histo lab

I have been told by our safety officer that it is standard practice too 
clean the lab at the end of the day with diluted bleach. I have noticed a 
chemical reaction (smell) when cleaning the main area of the lab. I have 
concerns that this is not a good practice due to chemical reactions as we 
use so many chemicals in histology. What do other people do?  Also I believe 
it is unsafe to use bleach with anything formalin related.
Please let me know if you have a "standard" practice or mandated cleaning 
from your facility.
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