[Histonet] Fw: Waste paraffin and edge effect

[Jeffrey Silverman]

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Hello everyone, 
 
Our system's  hazardous chemical waste consultants changed our method of disposal- we had been solidifying the paraffin in a hood and then red bagging it, ie treating it as regulated medical (biohazard) waste. 
 
But, due to it's contamination with xylene, the very reason for our disposing of it, the paraffin is really hazardous chemical waste. Believe it or not, EPA regs prohibit most hospitals from treating their chemical waste and the consultants worried that solidifying it under the hood was considered "treating" the waste.  Yeah right!!   Anyway, the blocks of solidified paraffin are now dumped in it's own specially labelled drum and has become a part of our hazardous waste stream, manifested like the xylene and dye waste. I'd be careful about putting hazardous chemicals into regulated medical waste. 
 
Interestingly, our system recently inquired if formalin in discarded surgicals needs to be decanted before disposal- many hospitals are doing just that, but most of those, but not all, recycle formalin (yuk!). Our disposal facility informed us that as long as the containers are plastic, ie are flammamble, they can be incinerated with the formalin and there is no need to decant.  Glory be!! 
 
In IHC slides, edge effect, or more intense, sometimes nonspecific, staining at the periphery of the tissue, can be caused  by more intense fixation of a block at the periphery, drying out of the edges of a block before fiation,  and/or by some degree of drying of antibodies and detection chemistry reagents during staining- this cause is more common in manually stained slides rather than those stained on automated stainers.  
 
Also electrocautery used during the excision can also cause intense staining at the edges of specimens. 
 
Jeffrey S. Silverman HT HTL QIHC (ASCP)
Southside Hospital- NSLIJ Health System
Pathologists' Assistant and Laboratory Safety Officer