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Today I decided to reheat 3 x 40 gram silica gel canisters with the blue/pink silica gel for the first time, and after I decided to order some more. While shopping, I noticed people say how it is a carcinogen, and that my family and I could now be at risk for cancer. Is this true?

It was in the toaster oven of the kitchen for 5 minutes, 2x each since by the time the canisters cooled off they became pink again before I put them where I needed to.

So am I looking at a risk, or is what I have done too minimal to worry about?

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    $\begingroup$ The colouring used to indicate whether or not the beads are dry does indeed have some associated toxicity. With the amount you have, however, I don't think it should be a problem. Labs commonly keep large quantities of the stuff in the oven, and even then the only precaution we take is heatproof gloves to protect from the heat $\endgroup$ – NotEvans. Jul 20 '16 at 7:14
  • $\begingroup$ Can you please explain your procedure? Did you reheat it in sealed canisters? If yes, then your silica gel didn't get drier(water just stayed there), but you are safe. If canisters are open then were you using a separate oven (the one that is not used for food)? Is the oven electric or gas? $\endgroup$ – sixtytrees Jul 20 '16 at 13:40
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    $\begingroup$ Related: Blue silica gel more harmful than the orange ones? $\endgroup$ – Loong Jul 20 '16 at 13:54
  • $\begingroup$ The canisters were inside of the Hydrosorbent 40 Gram Canisters. I put them into the small toaster oven, where we sometimes warm food up, and it is electric. $\endgroup$ – tacoman50 Jul 20 '16 at 14:43
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I have to assume things to answer this question. It would be great if you could include a picture of the actual stuff you have so that I may assess whether my assumption was correct or not.

The only aggregate state of desiccant silica gel, whether it be blue gel, orange gel or a colourless one, that I have seen to date is best described as a very coarse granulate. From these, unless you vividly shake the canisters repeatedly, there should be no dust evolution. Stuff like that is routinely stored and handled in chemical laboratories without anybody ever giving a damn because of dust — much unlike the very fine silica gel used for chromatography which can very much, as sixtytrees points out, cause silicosis.

The carcinogenic stuff inside blue gel is a cobalt compound. The salts of cobalt are only carcinogenic if you indigest them, and they do not permeate well through skin. They are even less prone to produce dust or carcinogenic volatiles even when heated to a hundred or so degrees. What they can do is stay on the skin after you touched the gel and then be transferred onwards, for example in your mouth on the crunchy apple you decided to eat — so wash your hands thoroughly if you accidentally handled the actual gel and did not use gloves.

Orange gel is slightly different, it uses organic moisture indicators. These have a much more significant vapour pressure than inorganic salts do. On the upside, these are also less carcinogenic. So the overall effect is probably similar.

Aside from that, you are at a very low risk. Sitting by a campfire is very likely more carcinogenic than putting blue gel desiccant into the oven for a few minutes.

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Main danger of silica is that it can cause silicosis. https://en.wikipedia.org/wiki/Silicosis This is because silica is not soluble in water, cannot be broken down by enzymes and silica dust can get into air very easily. Silica isn't carcinogenic, but silicosis is a bad disease too.

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  • $\begingroup$ The silica was inside of the canisters in their silica form. Can dust be created from the toaster oven heating it up, and is the amount I listed something that should make me worried? Edit: also I heard that the blue color meant toxic/carcinogen, which Is why I worried. $\endgroup$ – tacoman50 Jul 20 '16 at 14:46
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From an above comment from the OP that clarifies the problem:

The canisters were inside of the Hydrosorbent 40 Gram Canisters. I put them into the small toaster oven, where we sometimes warm food up, and it is electric. – tacoman50

Good lab safety requires that you never mix chemicals and food in any manner. Thus you should never use an oven for both chemicals of any sort and food.

The whole point is to draw an absolute line rather than trying to determine that something is "not too dangerous." Who knows what the silica gel may have adsorbed besides water.

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  • $\begingroup$ The thing is whether these were sold for lab use or for non-lab use. $\endgroup$ – Jan Aug 19 '16 at 16:12

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