People can experience adverse effects of silicon dioxide if they inhale the fine particles. Long-term exposure to silica dust may pose a serious risk to health.
However, studies about the side effects of using silicon dioxide in food have found it to be of little risk to human health.
What is silicon dioxide?
Silicon dioxide, or silica, is a combination of silicon and oxygen, two very abundant, naturally occurring materials.
There are many forms of silica. They all have the same makeup but may have a different name, depending on how the particles arrange themselves. In general, there are two groups of silica: crystalline silica and amorphous silica.
Where is it found in nature?
Dark leafy greens, such as kale, contain silicon dioxide.
Silicon dioxide occurs widely in nature. The Agency for Toxic Substances and Disease Registry (ATSDR) give an idea to just how common this compound is.
It is easiest to recognize by its common name, quartz, which makes up about 12% of the earth's crust. However, silicon dioxide also occurs naturally in everything from water and plants to animals.
Silica sand covers many beaches, and it makes up most of the rocks on earth. In fact, silica-containing minerals or silica itself make up more than 95% of the earth's crust.
Silicon dioxide also exists in numerous plants that humans regularly consume, such as:
- dark, leafy greens
- some grains and cereals, such as oats and brown rice
- vegetables, such as beets and bell peppers
Silicon dioxide also occurs naturally in the human body, though it is still unclear the exact role it plays.
Why is silicon dioxide used in food additives?
Manufacturers use silica to make everything from glass to cement, but it also has a use in the food industry as an additive and anticaking agent. This type of food additive prevents foods from caking or sticking together in clumps. This may help ensure a product's shelf life, protect against the effects of moisture, and keep powdered ingredients from sticking together and helping them flow smoothly.
Safety of silicon dioxide
Many food additives tend to raise concerns from people who want to be aware of what they are eating, and silicon dioxide is no different.
While the name may seem unfamiliar, silicon dioxide is a natural compound. Many studies suggest that there is no cause for concern when people are consuming silicon dioxide in normal doses, such as the small amounts that manufacturers put in food products to prevent caking.
A review by the European Food Safety Authority (EFSA) goes over the results of studies on silica as a food additive. In animal models, researchers noted no accumulation of silicon after the animals repeatedly ate silica.
People should also note that there are different grades of silica. The silica found as a food additive is not the same grade of silica that producers use to make cement, for instance.
The Food and Drug Administration (FDA) in the United States also regulate how companies use silica in food.
The FDA regulations allow manufacturers to include silicon dioxide as a food additive if they only use the smallest amount they need, and the amount does not exceed 2% of the weight of the food.
Side effects and risks of silicon dioxide
Some researchers have called for further investigation into the types of silica that find their way into food products. These include nanoparticles, which are silica particles that are much smaller than most of the particles that occur in nature.
The concern is that these tiny particles could reach different areas of the body and even get into the cells themselves.
Research appearing in the Journal of Applied Toxicology investigated the effect of silica nanoparticles as food additives. The study indicated that the silica nanoparticles had a low potential to cross the gastrointestinal tract when a person eats them.
The researchers concluded that there is a low risk of using silica nanoparticles as a food additive, but they still called for more long-term research.
While most people think standard silicon dioxide is generally safe, the EFSA have expressed concerns about using silica nanoparticles in food, as there are no long-term safety studies.
However, it is hard to differentiate between nano and non-nano silica, and many manufacturers are not clearly stating that there are nanoparticles in their products.
So, while silica particles that are above the nano size are safe and probably have no risk of being toxic for humans, there is not enough research to say the same about nanoparticles.
So, the researchers in the above study want stricter guidelines when manufacturers use silicon dioxide as a food additive.
Inhalation of silica dust can increase the risk of respiratory conditions.
Adverse effects are possible with silica. However, research surrounding the risks of silica tends to focus on silica dust that people inhale, as that is where the health risks are highest.
As the ATSDR state, it is inhaling silica dust over long periods that can be serious. This situation is most common in people who work in quarries or factories that process silica.
Long term inhalation of silica dust may lead to issues in the lungs, including:
- silicosis, a progressive, irreversible lung disease
- lung cancer
- chronic obstructive pulmonary disease, or COPD
- increased risk of tuberculosis
The long-term exposure to silica may also affect the kidney and increase the risk of autoimmune diseases.
Silica has a very low risk for toxicity when taken orally. The EFSA note that even after administering very high doses of up to 9,000 milligrams of silica per kilogram of body weight, no adverse effects appeared.
Silicon dioxide is a compound that occurs naturally. It exists abundantly in plants and within the earth's crust, and even makes its way into humans and other animals. There is still no evidence to suggest that silicon dioxide is dangerous as a food additive. However, regularly inhaling silicon dust is very dangerous.
Also, there may be changes coming to the guidelines surrounding silicon dioxide as a food additive, as the current guidelines do not consider issues such as particle size or the upper limit for consumption.
People who are becoming more conscious of what they eat may worry when they see silicon dioxide in their food, but it is unlikely to cause any adverse effects in normal amounts.