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Author: Subject: possibly dumb question: Food safety of unknown glassware
GammaFunction
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possibly dumb question: Food safety of unknown glassware

I bought a lot of glass, supposedly from the estate of a medical doctor. It includes a few really nice Pyrex bottles, with stainless stopper clamps (to keep rubber stoppers from popping out).

One of the bottles had some residue; the other was pretty clean. I washed both by cooking them in several rounds of hypochlorite bleach, and then hydrogen peroxide (generic OxyClean). To get rid of metals, I suppose I could do a dilute nitric acid soak.

I'd like to use these bottles for small test-batch home brewing (wines, meads, ciders), when a whole carboy is too much. But I'm not sure if mystery glass can ever be made reliably safe.

On the one hand, conventional wisdom is that you never, ever mix lab glass with edibles. And people cite particularly toxic substances that are used in the lab.

But sometimes standard wisdom is a bit paranoid, like MSDSs for sand and scandals about pouring hydroxylic acid down the drain. You always find ppm and ppb traces of stuff, everywhere. And we cook in chromium and copper and other toxic elements all the time. And a glass seller once told me that you can never really contaminate glass (barring visible residues, I guess).

What are the experts' thoughts? Can one clean mystery glass and use it for potables, or is it forever a risk?
DraconicAcid
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You probably can, but I wouldn't. Just because.
GammaFunction
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 Quote: Originally posted by DraconicAcid You probably can, but I wouldn't. Just because.

And that's why I asked for opinions from experts.
Simbani
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no problem IMHO. In our daily world there are much more toxic substances in much higher concentrations in our food and everywhere around us. What do you think how many carcinogenic substances are in our food? dozens. We just don´t know about them or they are perfectly natural and were in there for ages. And what about all the other daily deadly risks we undertake, just by driving to work? Not to mentoin smoking or other drugs or the background radiation. Everything paranoia in my opinion. Just live your life and be happy, you´ll die anyway.
If you want, you could wash the stuff with 50°C warm H2SO4/H2O2, that will destroy everything organic. Be sure to wear goggles

Endimion17
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Glass can be contaminated so that the substance can leech into the whatever you store in the vessel, but the amount of the contaminants would be very, very small on a smooth glass surface. Therefore only the worst of the worst simple ionic poisons (fucked up heavy metals like mercury, thallium and transuranics come to mind) and lots of exposure would be considered alarming.

Since it's from a medical doctor and it was probably used to store things like ethanol, distilled water, piss and physiological solution, boiling concentrated nitric acid in it for 10 minutes would be a desireable overkill.
... unless it's old, damaged and porous. Then just use it to store dry chemicals or plant a flower in it, I don't know.

Hydrochloric acid bath for the CaCO3 deposits, lye-alcohol bath to smooth the surface and hydroxylate the shit out of it, then concentrated HCl or HNO3 boiling inside for a while to remove the -OH from the surface and destroy anything left inside.
Distilled water rinsing at the end.

GammaFunction
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 Quote: Originally posted by Endimion17 Hydrochloric acid bath for the CaCO3 deposits, lye-alcohol bath to smooth the surface and hydroxylate the shit out of it, then concentrated HCl or HNO3 boiling inside for a while to remove the -OH from the surface and destroy anything left inside. Distilled water rinsing at the end.

Thanks for the detailed answer. I should have mentioned that they had two hole stoppers.

Things like Hg and Tl have hazardous doses at the 10 mg level I think, which wouldn't be anywhere close to present. That would be a pretty visible residue, that would need to dissolve all at once, after repeated soakings failed to dislodge it.

Do the acids and bases have to be concentrated, or would a long dilute soak be as good? With large amounts of concentrated acids, it becomes uneconomical, and the flower pot idea starts to look good.

[Edited on 5-2-2013 by GammaFunction]

[Edited on 5-2-2013 by GammaFunction]
GammaFunction
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 Quote: Originally posted by Simbani If you want, you could wash the stuff with 50°C warm H2SO4/H2O2, that will destroy everything organic. Be sure to wear goggles

The expense and absolutely goddawful risk of this would far exceed the benefit of acquiring two spiffy brewing bottles
Random
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 Quote: Originally posted by Simbani no problem IMHO. In our daily world there are much more toxic substances in much higher concentrations in our food and everywhere around us. What do you think how many carcinogenic substances are in our food? dozens. We just don´t know about them or they are perfectly natural and were in there for ages. And what about all the other daily deadly risks we undertake, just by driving to work? Not to mentoin smoking or other drugs or the background radiation. Everything paranoia in my opinion. Just live your life and be happy, you´ll die anyway. If you want, you could wash the stuff with 50°C warm H2SO4/H2O2, that will destroy everything organic. Be sure to wear goggles

I still wouldn't drink from a glass no matter how much you clean it if it had PCBs in it.

Now they probably weren't inside but what do you know?
GammaFunction
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 Quote: Originally posted by Random I still wouldn't drink from a glass no matter how much you clean it if it had PCBs in it. Now they probably weren't inside but what do you know?

Devil's advocate: the FDA limit for PCBs in normal food is 3 ppm, and for plastic-packaged food it is 10ppm. Source

5 liters contains 5 million milligrams, so that there would have to be 50 mg of PCBs on the glass after washing to exceed FDA limits.

Or, in other words, if one worries about PCB residues on glass, perhaps one should absolutely panic about PCBs (probably manufacturing by-products) that can be found on plastic.

[Edited on 5-2-2013 by GammaFunction]
bahamuth
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Buy brand new glassware if you want to use it for foodstuff, that is the unwritten rules. Never use used glassware for food, never.
I admit you might most certainly get it clean but do you want to cross that line?

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Endimion17
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 Quote: Originally posted by GammaFunction Thanks for the detailed answer. I should have mentioned that they had two hole stoppers. Things like Hg and Tl have hazardous doses at the 10 mg level I think, which wouldn't be anywhere close to present. That would be a pretty visible residue, that would need to dissolve all at once, after repeated soakings failed to dislodge it. Do the acids and bases have to be concentrated, or would a long dilute soak be as good? With large amounts of concentrated acids, it becomes uneconomical, and the flower pot idea starts to look good. [Edited on 5-2-2013 by GammaFunction] [Edited on 5-2-2013 by GammaFunction]

Stoppers with two holes? Then the bottles might have been used as humidifiers for air/oxygen stream.

Pyrex, right? Wasting lots of concentrated acid is futile. You can put few mililitres of the acid inside, mount a reflux and heat them over a mat, so their inside surface will be in a continuous flux of corrosive shit.

After such treatment, there's no way something could remain inside. The classic rule "don't use laboratory vessels for foods and drinks" applies when people rinse stuff with tap water. Highly corrosive, hot treatment is not something normal people do.

BJ68
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 Quote: Originally posted by Endimion17 [The classic rule "don't use laboratory vessels for foods and drinks" applies when people rinse stuff with tap water. Highly corrosive, hot treatment is not something normal people do.

And I think in addition to this the rule is more for avoiding confusion for you and other persons.

Bj68

woelen

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I would wash them very well and have them filled with dilute hydrochloric acid (e.g. 10%) for a few days and then rinsed. Any toxic metals which can leach out of the glass then will have leached into the hydrochloric acid. Hydrochloric acid itself is not toxic (at least the remains of it, being simply chloride ions). In order to save some acid you can use the acid from one piece of glassware in the next one.

All the paranoia about toxicity of glassware is somewhat annoying to my opinion. If the glass looks clean and has no frosty inside layer, then it IS clean. If you fill the tank of your car you breathe more toxins, if you eat fruit or vegetables which are not grown locally in your own garden then you get all kinds of toxins in low quantities. Even if a piece of glassware were used for experiments with solutions containing arsenic, then I would not have a problem to drink from them after thorough rinsing and soaking in acid solutions.

There is, however, one thing which you must take care of. NEVER mix the glassware with other lab glassware which is not cleaned thoroughly. If e.g. you use similar glassware at the same location or even sometimes bring similar glassware to the same location, then there is a risk of exchanging things and of course that can lead to nasty situations. So, in practice I am somewhat reluctant to using lab glassware for food purposes, but this is not because of fear for toxins in the glass, but because of the risk of using the wrong piece of glassware for food.

[Edited on 5-2-13 by woelen]

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GammaFunction
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 Quote: Originally posted by bahamuth Buy brand new glassware if you want to use it for foodstuff, that is the unwritten rules. Never use used glassware for food, never. I admit you might most certainly get it clean but do you want to cross that line?

I guess what I'm trying to do is to separate taboos from rational reasons. What is written above is basically a taboo. A rational reason might be, for example, some ability of heavy metals to permeate the glass and leach out slowly.

Would you rather have you child drink water from a well-washed lab bottle that contained pure Bisphenol-A, or a plastic piece of Tupperware made with Bisphenol-A? From a rational perspective, I'd choose the glass bottle.
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I am not sure what one would view as contamination.
Certainly when I boil beer in mainly stainless steel vessels with some copper fittings the copper is brighter after the boil and the stainless changes colour as well.
The wort pH is about 5.5 to 6.5 and it boils for 60 - 90 minutes.
I use food grade polyethylene tanks for fermentation.
Commercially wine was fermented in concrete tanks in France, these have now mainly been replaced with fibreglass resin tanks.
I guess that these are not chemically neutral.
I have also got comprehensive analyses on the water I use. It does contain some nitrate but it is a lot less than the nitrate that comes from the hops and the total nitrate in a couple of litres is a lot less than that contained in a lettuce.
I use new lab glass in the brewery for testing purposes, yeast cultures, etc.
I do not view the glass as a significant source of metals, nitrate, etc compared with the brewing ingredients and the boiling and fermentation vessels.
On a closing note, if you stew rhubarb in an aluminium pan, how much aluminium does it dissolve?
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The lab legend at my UG school was that someone heated a beverage in a clean beaker and died. he had been working with organoarsenic cmpds. It's your life, you decide. I dedicated a 1L beaker to heating soup. (My wife wanted the office microwave).

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GammaFunction
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 Quote: Originally posted by chemrox The lab legend at my UG school was that someone heated a beverage in a clean beaker and died. he had been working with organoarsenic cmpds. It's your life, you decide. I dedicated a 1L beaker to heating soup. (My wife wanted the office microwave).

LD50 of arsenic is about 145mg/kg in a mouse and 760 in a rat. Taking the lower value, it would take about 5 grams of arsenic to kill a human. I don't see that coming out of a clean beaker.

However, it seems organoarsenic compounds like Lewisite (a chemical warfare agent) have other modes of toxicity, and 2 ml on the skin can kill you. Let's divide by 10 for ingestion. Still a heck of lot more than in a clean beaker.

So I'm inclined to call urban legend on this.
ScienceSquirrel
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Used lab glass from schools, dairies, doctor's surgeries etc is unlikely to have been exposed to organic mercury, arsenic, cadmium, etc.
You would not have to drink out of a beaker contaminated with dimethyl mercury, just handing it would be a death sentence.
GammaFunction
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 Quote: Originally posted by ScienceSquirrel Used lab glass from schools, dairies, doctor's surgeries etc is unlikely to have been exposed to organic mercury, arsenic, cadmium, etc. You would not have to drink out of a beaker contaminated with dimethyl mercury, just handing it would be a death sentence.

Yes, things like dimethyl mercury are a nightmare. But it is very volatile (so it won't stay on glass), and the deadly dose is about 100mg (roughly on par with the usual yardstick of 10mg of absorbed mercury being a hazard). 100 mg of residue is a huge amount. So even this ghastly substance would be washed off glassware. Again playing devil's advocate, one could safely drink from dimethyl mercury contaminated glass after a good washing.
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Yes, I agree with you, hence my remark about drinking from glass in which have been solutions of arsenic compounds. If glass absorbs chemicals, then it is a very little amount. I think that a normal let's say 250 ml beaker cannot absorb more than a few micrograms of chemicals. An besides that, if it is soaked in acid then most of it will dissolve and what does not dissolve also will remain stuck in the glass after this.

The only thing which would scare me is if the glass was used for experiments with plutonium or other strongly radioactive compounds. A few micrograms of such compounds may do great harm. Here, however, we are not talking anymore about chemical toxicity.

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Simbani
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Only really, really dangerous substances could harm you in these ppm-amounts. The most dangerous substances would indeed be strongly radioactive elements or molecules, or very few natural proteins like one of the botuliniumtoxin-neurotoxin (mouse: 3ng/kg inhaled, human 10ng/kg inhaled or 1-2ng/kg intravenous). radioactive substances are probably more dangerous, they don´t break down like proteins and cannot be destroyed by any means.

unionised
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Perhaps you should use lab glassware rather than tableware.
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If you wanted to depart from sanity completely, you could swill out the glassware with hydrofluoric acid, to etch away the surface. Followed, of course, by washing in calcium hydroxide solution to convert any residual acid to harmless calcium fluoride.

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Arthur Dent
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When I started doing basic chemistry, my main purposes were distillation of spirits and working with heavy metals, two things that shouldn't be mixed, and not taking any chances, any and all vessels used for my distillation/fermentation experiments were purchased new.

The only pieces of glassware that I use for distillation that are not new are my graham condenser and my vigreux column, both of which were thoroughly cleaned with a solution of HCl and water, then bleach, then H<sub>2</sub>SO<sub>4</sub> with peroxide.

Both were relatively clean and I am fairly confident that the cleaning process was adequate for my purpose. My friend who gave me the condenser told me it was only used for university experiments and seldom at that.

The advice above, of using only brand new, unused glassware for food stuff is a sound one.

Robert

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GammaFunction
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 Quote: Originally posted by Arthur Dent The advice above, of using only brand new, unused glassware for food stuff is a sound one. Robert

Apologies if this sounds argumentative, but why is this good advice? The example you gave explains what you did, but not why it is necessary. (I would understand simply not mixing the two classes of glass, metals and spirits, after an initial thorough cleaning)

For instance, is it possible for heavy metals to be retained on glass in milligram quantities after aggressive cleaning?

In any case, normal borosilicate glass contains about 0.01% uranium, thorium, and lead. And lead crystal ...
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