Molds and Viruses

[Jeff Grossman]

Visited my favorite cheese-monger today. He was all excited to have received several Quadrello di Bufala - he described it as a taleggio made of 100% buffalo milk. (He has some other similar cheese but it is cow's milk blend.)

Anyway, he's hefting this large, heavy block around, and says that it just came in from Bergamo.

My snap judgment was to avoid it. Does that seem reasonable to you?

 

[Christian Miller (CMM)]

originally posted by Jeff Grossman:
Molds and VirusesVisited my favorite cheese-monger today. He was all excited to have received several Quadrello di Bufala - he described it as a taleggio made of 100% buffalo milk. (He has some other similar cheese but it is cow's milk blend.)

Anyway, he's hefting this large, heavy block around, and says that it just came in from Bergamo.

My snap judgment was to avoid it. Does that seem reasonable to you?

Haven't seen any info on how long the virus lasts on cheese rind (where are those researchers' priorities?) On cardboard it's 24 hours per a new study from NIH. Was it flown or shipped in? My instinct is that cheese is a competitive and often hostile environment for many "uncheesy" bacteria, but no idea if that applies in this case.

 

[Oswaldo Costa]

There is no way to know, of course, whether there are live viruses on the rind, but since current estimates are that it can live for up to nine days in non-extreme temperatures, you should be safe if you keep it in your fridge (or even freeze it) for ten days.

 

[georg lauer]

originally posted by Jeff Grossman:
My snap judgment was to avoid it. Does that seem reasonable to you?

Reasonable, if eating it would have made you uncomfortable.

Necessary, most certainly not. Infectious virus from a cheese rind after several days if not weeks from leaving Italy is rather implausible.

 

[Oswaldo Costa]

Just found this in the nytimes: The virus lives longest on plastic and steel, surviving for up to 72 hours. But the amount of viable virus decreases sharply over this time. It also does poorly on copper, surviving four hours. On cardboard, it survives up to 24 hours, which suggests packages that arrive in the mail should chave only low levels of the virus — unless the delivery person has coughed or sneezed on it or has handled it with contaminated hands.

 

[Pavel Tchichikov]

now Cosmo Castorini can say, about copper - it costs money because it saves lives

 

[VLM]

This is from NIAID:

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www.niaid.nih.gov

The scientists found that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was detectable in aerosols for up to three hours, up to four hours on copper, up to 24 hours on cardboard and up to two to three days on plastic and stainless steel.

Here is the paper:

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www.nejm.org

Here is the relevant text:

Both viruses had an exponential decay in virus titer across all experimental conditions, as indicated by a linear decrease in the log10TCID50 per liter of air or milliliter of medium over time (Figure 1B). The half-lives of SARS-CoV-2 and SARS-CoV-1 were similar in aerosols, with median estimates of approximately 1.1 to 1.2 hours and 95% credible intervals of 0.64 to 2.64 for SARS-CoV-2 and 0.78 to 2.43 for SARS-CoV-1 (Figure 1C, and Table S1 in the Supplementary Appendix). The half-lives of the two viruses were also similar on copper. On cardboard, the half-life of SARS-CoV-2 was longer than that of SARS-CoV-1. The longest viability of both viruses was on stainless steel and plastic; the estimated median half-life of SARS-CoV-2 was approximately 5.6 hours on stainless steel and 6.8 hours on plastic (Figure 1C). Estimated differences in the half-lives of the two viruses were small except for those on cardboard (Figure 1C). Individual replicate data were noticeably “noisier” (i.e., there was more variation in the experiment, resulting in a larger standard error) for cardboard than for other surfaces (Fig. S1 through S5), so we advise caution in interpreting this result.

 

[mark e]

originally posted by VLM:
This is from NIAID:

Loading…

www.niaid.nih.gov

The scientists found that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was detectable in aerosols for up to three hours, up to four hours on copper, up to 24 hours on cardboard and up to two to three days on plastic and stainless steel.

Here is the paper:

Loading…

www.nejm.org

Here is the relevant text:

Both viruses had an exponential decay in virus titer across all experimental conditions, as indicated by a linear decrease in the log10TCID50 per liter of air or milliliter of medium over time (Figure 1B). The half-lives of SARS-CoV-2 and SARS-CoV-1 were similar in aerosols, with median estimates of approximately 1.1 to 1.2 hours and 95% credible intervals of 0.64 to 2.64 for SARS-CoV-2 and 0.78 to 2.43 for SARS-CoV-1 (Figure 1C, and Table S1 in the Supplementary Appendix). The half-lives of the two viruses were also similar on copper. On cardboard, the half-life of SARS-CoV-2 was longer than that of SARS-CoV-1. The longest viability of both viruses was on stainless steel and plastic; the estimated median half-life of SARS-CoV-2 was approximately 5.6 hours on stainless steel and 6.8 hours on plastic (Figure 1C). Estimated differences in the half-lives of the two viruses were small except for those on cardboard (Figure 1C). Individual replicate data were noticeably “noisier” (i.e., there was more variation in the experiment, resulting in a larger standard error) for cardboard than for other surfaces (Fig. S1 through S5), so we advise caution in interpreting this result.

I can only imagine that "replicate data were noticeably “noisier” (i.e., there was more variation in the experiment, resulting in a larger standard error)" is not beautiful music to a statistician's ears.

 

[Christian Miller (CMM)]

originally posted by mark e:
I can only imagine that "replicate data were noticeably “noisier” (i.e., there was more variation in the experiment, resulting in a larger standard error)" is not beautiful music to a statistician's ears.

No. It's driving me nuts to see all these numbers and % floating around without standard deviation or confidence intervals or even just sample size. Said cardboard a good example.

Back to the original topic, I read somewhere that aluminum foil was a pretty hostile environment, but can't find original source. The stainless steel finding surprised me, as I always think of it as unfriendly to bacteria.

 

[mark e]

originally posted by Christian Miller (CMM):

originally posted by mark e:
I can only imagine that "replicate data were noticeably “noisier” (i.e., there was more variation in the experiment, resulting in a larger standard error)" is not beautiful music to a statistician's ears.

The stainless steel finding surprised me, as I always think of it as unfriendly to bacteria.

Stainless can harbor microorganisms, while copper is bacteriostatic.

 

[georg lauer]

originally posted by Christian Miller (CMM):
Back to the original topic, I read somewhere that aluminum foil was a pretty hostile environment, but can't find original source. The stainless steel finding surprised me, as I always think of it as unfriendly to bacteria.

(Bacteria yes, viruses less so.)
Edited: Neither unfriendly to bacteria nor viruses was the right answer.

 

[MLipton]

Stainless steel is so because of a protective outer layer of chromium oxide. Metallic copper OTOH oxideizes slowly and so is present as elemental copper (and sulfide salts thereof). It is possible that this latter disrupts the viral envelope. Just speculation, mind you.

Mark Lipton

 

[Jeff Grossman]

Brass also presents a hostile environment for germs. Brass doorknobs have contributed to public health for quite some time; I think the Victorians knew about its effects.

 

[Christian Miller (CMM)]

originally posted by MLipton:
Stainless steel is so because of a protective outer layer of chromium oxide. Metallic copper OTOH oxideizes slowly and so is present as elemental copper (and sulfide salts thereof). It is possible that this latter disrupts the viral envelope. Just speculation, mind you.

Mark Lipton

So in essence, stainless steel is favored for sanitation because it cleans very well, not due to being a more difficult environment for bacteria?

 

[MLipton]

originally posted by Christian Miller (CMM):

originally posted by MLipton:
Stainless steel is so because of a protective outer layer of chromium oxide. Metallic copper OTOH oxideizes slowly and so is present as elemental copper (and sulfide salts thereof). It is possible that this latter disrupts the viral envelope. Just speculation, mind you.

Mark Lipton

So in essence, stainless steel is favored for sanitation because it cleans very well, not due to being a more difficult environment for bacteria?

I suppose. I think it’s probably because it retains its shine and not much more.

Mark Lipton

 

[Jeff Grossman]

originally posted by MLipton:

originally posted by Christian Miller (CMM):
So in essence, stainless steel is favored for sanitation because it cleans very well, not due to being a more difficult environment for bacteria?

I suppose. I think it’s probably because it retains its shine and not much more.

Just to unpack that a little: stainless steel is very hard and very resistant to reaction -- of which 'corrosion' is a reaction of special interest -- but it also does not wear away if you wipe it with strong surfactants, it does not deform if you scrub it with rough sponges, etc..

 

[Christian Miller (CMM)]

originally posted by Jeff Grossman:

originally posted by MLipton:

originally posted by Christian Miller (CMM):
So in essence, stainless steel is favored for sanitation because it cleans very well, not due to being a more difficult environment for bacteria?

I suppose. I think it’s probably because it retains its shine and not much more.

Just to unpack that a little: stainless steel is very hard and very resistant to reaction -- of which 'corrosion' is a reaction of special interest -- but it also does not wear away if you wipe it with strong surfactants, it does not deform if you scrub it with rough sponges, etc..

This makes sense, because in industrial food/beverage production the cleaning is incessant.

 

[Brian C]

originally posted by Jeff Grossman:
Molds and VirusesVisited my favorite cheese-monger today. He was all excited to have received several Quadrello di Bufala - he described it as a taleggio made of 100% buffalo milk. (He has some other similar cheese but it is cow's milk blend.)

Anyway, he's hefting this large, heavy block around, and says that it just came in from Bergamo.

My snap judgment was to avoid it. Does that seem reasonable to you?

No, Personally, I'd think a visit to the store and being around other customers poses more risk than anything product you'd buy there.