I had the same question a month ago. I got the following recipe from Jim
Manavis:

First neutralize DAB with equal volumes of 0.2M Potassium permanganate
and 2.0M  sulphuric acid. I allow the mixture to stand overnight (fume
hood or laminar flow bench) making sure it is appropriately covered. It is
now non-mutagenic. The following day I decolourize the mixture with
Ascorbic acid (adding powder until colour disappears). Then neutralize
with Sodium Bicarb. and either test with pH paper or meter. You can then
discard the solution down the drain.

The reference for this is Lunn & Sansone.1991. The safe disposal of DAB.
Appl.Occup.Environ.Hyg. Vol 6. pages 49-53.

I have been using the above recipe ever since. Hope this helps.

Nima Farsinejad
Research Specialist
Digestive Diseases
Emory University
Atlanta, Georgia


On Wed, 27 Sep 2000, Jill Songer wrote:

> Date: Wed, 27 Sep 2000 13:01:58 -0400
> From: Jill Songer <jtsonger@vt.edu>
> To: "Decarli, Terri" <TerDec@northarundel.org>,
     "'histonet@pathology.swmed.edu'" <histonet@pathology.swmed.edu>
> Cc: "Decarli, Terri" <TerDec@northarundel.org>
> Subject: Re: DISPOSAL OF DAB
> 
> Terri,
> We have our DAB removed from lab by our University Environmental Health and 
> Safety Dept, but I recall reading about using potassium permanganate to 
> treat. Sorry I can't recall the percent solution, but maybe this will jog 
> someone's memory.
> 
> 
> 
> 
> At 11:12 AM 9/27/2000 -0400, Decarli, Terri wrote:
> >How do you dispose of the chromogen DAB?  Is there a treatment that can be
> >used and then dispose of down the drain.  I read that treating it with
> >bleach is not the answer because the reaction products remain mutagenic.  We
> >are not automated, we are doing IHC manually using the Shandon coverplates.
> >Thank you in advance.
> 
> 
> **************************************************************************
> Jill Songer HT (ASCP)
> Anatomic Pathology Lab Supervisor
> Veterinary Teaching Hospital
> Virginia Tech
> Blacksburg, Virginia 24061
> 
>