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I have a digital thermometer with a probe. The probe is stainless steel but the cable and probe housing are apparently made of PVC. In my last brew I just submerged the whole probe in the boiler before the grain steep and left it there until I had cooled the wort. It was a 75m boil.

It's occurred to me now that this was a really stupid idea. The thermometer still seems to be working ok but I'm worried that chemicals will have leached into the beer. Should I throw the beer out or drink it? I can't really find any useful info on whether PVC is toxic under those circumstances.

UPDATE ON THIS Thanks very much for your answers. In the end I opted to throw out this batch. I expect it would have been perfectly fine but I don't want to be sitting there with cancer in twenty years wondering about it.

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Was it designed to be used in contact with food? –  FrustratedWithFormsDesigner May 7 '12 at 18:20
Well, the thermometer is certainly for food use, although I bought it from eBay and it's clearly an object that's been imported from China so who really knows whether it meets any real safety criteria. But I suppose the proper way to use it is the stick the metal probe into something, which isn't exactly what I did on this occasion. –  Edmond Bramhall May 8 '12 at 8:35

2 Answers 2

up vote 3 down vote accepted

I would be cautious. I'm not a chemist, but here is what I could find on the subject:

The biggest risk appears to come from plasticizers used to make your PVC probe flexible. PVC is very brittle; the plasticizers are used combat that. A study published in the Journal of Applied Polymer Science shows high rates of leaching of plasticizers in PVC at high temperatures. PVC powder alone appears to be fairly inert, according to Ullmann's Encyclopedia of Industrial Chemistry, but Vinyl chloride monomer (VCM) is highly carcinogenic and is an upstream product in the manufacturing of PVC.

Does your thermometer carry an NSF logo? NSF logos indicate the device has passed certain safety tests for use in a food service environment.

I know it is really difficult to throw out a batch of beer; it may be fine to drink, too. The way I would approach this issue is by considering the incremental impact of routinely being concerned about what you're ingesting (i.e. a few dozen cigarettes never killed anyone, but a lifetime of smoking does kill). If it were mine, I'd probably keep the beer and be as cautious as possible down the road.

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as a side note, digital meat thermometers with a thin flat cord attaching a probe to a base station work REALLY WELL! I splurged and bought a high quality one ($30) and it's amazing. You insert the metal probe into the mash and the thin cord allows you to close the lid and monitor temp on the base station. You can even set it to alarm at certain temperatures. Not a necessity, but it does make things easier!

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