Minimum concentration/time of application of bleach to kill all viruses?

[Spirochete]

I am specifically interested in using bleach to kill the plantars wart virus (Verruca plantaris), part of the HPV family. It is a DNA virus. I know bleach will destroy DNA but I'm looking to minimize the concentration used to save money and prevent exposure to concentrated bleach fumes. "Full strength" is 6% sodium hypochlorite. Anyone know how much water I can mix it with to assure full destruction of virus particles on a surface?

 

[CRGreathouse]

A 5% bleach solution (0.25-0.3% sodium hypochlorite) is the weakest that you can generally get away with. But usually destroying the viruses is easier than meeting statutory requirements, so you may need 15% or more depending on the regulations.

I think OSHA requires 10% for many applications. Note, also, that full 5-6% sodium hypochlorite is not good enough for some applications -- high concentrations sometimes don't offgass sufficiently to kill certain viruses! I can't remember, I think Hep-C might be one.

 

[Spirochete]

Strange that OSHA requires around 15%, when even 100% doesn't kill all viruses. What does "offgas" mean out of curiosity?

 

[Andy Resnick]

We decontaminate our flow hood with 10% bleach for 20 minutes. We also put 10% bleach in the waste trap from suctioning off media, etc. I have 15% bleach for DNA/RNA sensitive operations on the bench.

Try a titration-type measurement, see what you get. I'd be curious.

The term "offgas", in my experience, means trapped gases that slowly diffuse out of a solid (infrequently a liquid). As in, formaldehyde offgases from new carpet.

 

[CRGreathouse]

Strange that OSHA requires around 15%, when even 100% doesn't kill all viruses. What does "offgas" mean out of curiosity?

OK, I looked it up, and it actually doesn't need to be anywhere near that strong. OSHA requires 1% to 10% dillution of 5.25% sodium hypochlorite for bloodborne pathogens, so the minimum OSHA concentration of 6% bleach would be something like 1:114. But I wouldn't go that low.

Of course depending on what you need to do you may need a disinfectant from EPA List A, List E, or List D instead.

Offgas may not be the right term, I'm not sure. But you're looking to create chlorine gas from the breakdown of the sodium hypochlorite if you want to kill certain viruses, rather than direct contact with the sodium hypochlorite itself.