Formalin fixationa and risk of infection

[darkokoen]

Hi everybody.
I have a question, and could not find a definitive answer.
So I post it here, hoping you can give me an answer.

When tissues are formalin-fixed are they incapable of transmitting viral infection?
i.e. viruses are fixed and inactivated and thereby they are no more harmful.

Apparently everyone says "yes, it's  like this formalin kills everything"... but is real ?

I understand that for prions the question is much more complicated, but is 10% formalin sufficient to incativate HIV; HCV; HBV? I wonder time is an important variable too: 48 hours would it be enough ? Or should we conserve tissues for more time (1 week? 2 weeks?). I suppose that the size of the tissue is important too... Somewhere I've read that for a whoéle brain 2 weeks fixation should be enogh. But for smaller specimens (like 1x1x1 cm)? Last but not least formalin that has been in contact with such tissues... is it "micro-biologically" safe (no infectious diseases transmission...)?

In a lot of laboratories I've seen people quite "relaxed" while handling formalin fixed tissues... where they right ?
And what about paraffin embedded tissues: everybody handle them hands naked...

Hope you can answer,
thank you in advance,
best regards,

darkokoen.

[excalibur]

Yep, formalin and paraffin processing will kill most everything except for prions.

I recall a story of a lab inspector criticizing a histology department for not wearing gloves while enbedding, cutting, etc. After much explanation of the powers of formalin,alcohol, xylene, the superviser of the lab in exasperation took a block and licked it in front of the inspector. End of discussion!

I have worked in histology for over 30 years and only wear gloves when handling UNFIXED tissue! I am working 7 days a week and am rarely ill.

[darkokoen]

thank you very much for your kind answer.

Best regards,
darkokoen.

[Yao]

the formalin can denature or destroy the activity of the enzymes and proteins.although the genome of virus maybe stable, without those RTase or integrase activity, i think everything is OK.