Is burning silica gel dangerous?

January 11, 2007 11:57 AM

Last week at a friends house we were sitting around a nice fire, when my brother found one of those silica gel packets, and (stupidly) threw it in. The room almost immediately filled with noxious fumes, and our throats hurt for a couple days afterwards. What happened when that silica burned, and was any permanent damage done?
posted by splatta to science & nature (8 comments total)

Well silica on its own is not toxic, at a high enough temperature it turns it glass if you add sodium. But I would be willing to bet that there is more in those little packets then just silica, so it probably wasnt good for you.
posted by BobbyDigital at 12:01 PM on January 11, 2007

From wikipedia:

Alone, silica gel is non-toxic, non-flammable and chemically unreactive. However, some of the beads may be doped with a moisture indicator, such as cobalt (II) chloride, which is toxic and may be carcinogenic. Cobalt (II) chloride is deep blue when dry (anhydrous) and pink when moist (hydrated). This is the reason most silica gel packets are labeled as dangerous or poisonous when eaten.

Crystalline silica dust can cause silicosis but synthetic amorphous silica, which is what silica gel is, does not cause silicosis. A chemically similar substance with far greater porosity is aerogel.
posted by jimmy0x52 at 12:03 PM on January 11, 2007

Oh yeah and just in case that didn't scare you enough:

Silicosis

Silicosis (also known as Grinder's disease and Potter's rot) is a form of pneumoconiosis caused by inhalation of crystalline silica dust, and is marked by inflammation and scarring in forms of nodular lesions in the upper lobes of the lungs.

The full name for this disease is pneumonoultramicroscopicsilicovolcanoconiosis, and at 45 letters it is the longest word in the English language. (The name has been described as a "trophy word" -- its only job is to serve as the longest word [1] .)

Silicosis (especially the acute form) is characterized by shortness of breath, fever, and cyanosis (bluish skin). It may often be misdiagnosed as pulmonary edema (fluid in the lungs), pneumonia, or tuberculosis.

The symptoms of silicosis include:

* Tachypnea or shortness of breath after physical exertion
* Dry or severe cough, often persistent and accompanied by hoarseness of the throat
* Fatigue or tiredness
* Changes in breathing pattern (rapid breathing or shallow breathing)
* Loss of appetite
* Chest pain
* Fever

In advanced cases, the following may also occur:

* Cyanosis
* Cor pulmonale
* Respiratory insufficiency

Patients with silicosis are particularly susceptible to tuberculosis (TB) infection - known as silicotuberculosis. The reason for the increased risk - 10-30 fold increased incidence - is not well understood. It is thought that silica damages pulmonary macrophages, inhibiting their ability to kill mycobacteria.
posted by jimmy0x52 at 12:16 PM on January 11, 2007

I was under the impression that silicosis was from long-term inhalation of silica dust (e.g. occupational exposure from cement manufacture, construction etc) not from silica gel. And actually I believe jimmy0x52's initial post said as much.
posted by madokachan at 12:30 PM on January 11, 2007

The actual packet was probably made of a woven plastic of some sort. That stuff is nasty when it combusts. Silica itself is pretty harmless, and cobalt chloride wouldn't vaporize (although it would turn the flame a pretty color.)
posted by ikkyu2 at 12:45 PM on January 11, 2007

I'd say that if any of you still have any eye or throat irritation at this point it wouldn't hurt to see a family doctor - in many small household fires the injuries are caused by inhaling smoke laced with chemicals. (My uncle was in a house fire.) It can do a number on your lungs. When this happened did you throw open windows and/or leave the room? Because that stuff sounds nasty. Glad that it sounds like no one was hurt.
posted by batgrlHG at 1:01 PM on January 11, 2007

I believe in many cases olefin or Tyvek® is the packaging of choice, as it allows water vapor through but not liquid water, and it is strong enough to keep the silica inside without tearing.

The incineration or burning of Tyvek® is addressed on DuPont's FAQ for the product here.

I don't think you have a lot to worry about.
posted by exlotuseater at 5:33 PM on January 11, 2007

you are correct madokachan
posted by dubious at 7:36 PM on January 11, 2007