Are Silica Gel Beads Poisonous?

Silica gel is a type of silicon dioxide used to control humidity
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Silica gel beads are found in those little packets accompanying shoes, clothing, and some snacks. The packets contain round or granular bits of silica, which is called a gel but is actually solid. The containers typically carry dire "Do Not Eat" or "Keep Away from Children" warnings, so naturally one would assume that they are poisonous—but what really what happens if you eat silica?

What Happens If You Eat Silica Gel Beads?

Usually, nothing happens if you eat silica gel. In fact, you probably consume it already. Silica is added to improve flow in powdered foods. It occurs naturally in water, where it may help confer resistance against developing senility. Silica is just another name for silicon dioxide, the main component of sand, glass, and quartz. The "gel" part of the name means that the silica is hydrated or contains water. If you eat silica, it won't be digested, so it will pass through the gastrointestinal tract to be excreted in feces.

If silica is harmless to eat, though, why do the packets carry a warning? The answer is that some silica contains toxic additives. For example, silica gel beads may contain poisonous and potentially carcinogenic cobalt(II) chloride, which is added as a moisture indicator. You can recognize silica containing cobalt chloride because it will be colored blue (dry) or pink (hydrated). Another common moisture indicator is methyl violet, which is either orange (dry) or green (hydrated). Methyl violet is a mutagen and mitotic poison. While you can expect most silica you encounter to be non-toxic, ingestion of a colored product warrants a call to Poison Control. It's not a great idea to eat beads even if they don't contain toxic chemicals because the product is not regulated as a food, meaning it may contain contaminants that you wouldn't want to eat.

How Silica Gel Works

In order to understand how silica gel works, let's take a closer look at what exactly it is. Silica is synthesized into a vitreous (glassy) form that contains nanopores. When it's being made, it is suspended in a liquid, so it's truly a gel, much like gelatin or agar. When it dries, it becomes a hard, granular material called silica xerogel. The substance is made into granules or beads, which can be packaged in paper or another breathable material to remove humidity.

The pores in the xerogel are about 2.4 nanometers in diameter. They have a high affinity for water molecules. Moisture gets trapped in the beads, helping to control spoiling and limit chemical reactions with water. Once the pores fill up with water, the beads are useless, except for decorative purposes. However, you can recycle them by heating them. This drives the water out so that the beads can absorb moisture once again. To do this, all you need to do is heat the gel in a warm oven (anything over the boiling point of water, which is 100 degrees Celsius or 212 degrees Fahrenheit, so a 250-degree Fahrenheit oven is fine). Once the water is removed, allow the beads to cool and then store them in a waterproof container.