Silicon Dioxide

Is silicon dioxide allowed as an anti-caking agent in livestock feed?

By Gwen Ayers

Silicon dioxide (SiO₂), also know as silica, is a chemical compound which has many different crystalline forms and a wide range of applications. It is used in everything from the production of widow glass and optical fibers to defoamers and cement. The term “Silicon Valley” was coined because of the use of silicon in the computer industry. Among its many uses, it quite often appears as a flow agent or anti-caking agent in animal feeds and human foods.

When many people think about silicon dioxide, they likely think of the natural material we commonly refer to as sand. However, silicon dioxide doesn’t just come from a beach. In its nonsynthetic form it is commonly known as quartz, which is one of the most abundant minerals on the earth’s surface, and is a significant component of many different types of rocks. Silicon dioxide can also be produced synthetically through a variety of methods.

The NOP Rule §205.237(a) allows for the use of nonsynthetic, nonagricultural substances to be used as livestock feed additives and feed supplements, unless specifically prohibited. Synthetic materials used for the same purposes must be on the National List at §205.603. Therefore, before silicon dioxide can be used in a feed for organic livestock, it must be determined whether or not the silicon dioxide is synthetic. Only nonsynthetic, mined mineral versions of silicon dioxide are allowed to be used in feed for organic livestock.

To make things especially tricky, the NOP Rule allows synthetic silicon dioxide for some uses in human food at §205.605(b). Therefore, if a silicon dioxide supplier says that their product is allowed for use in “organics”, clarification is still needed. Synthetic silicon dioxide is not on §205.601 (for crops) or §205.603 (for livestock). Materials from 205.605(b) are not transferable to livestock or crop production. Therefore, synthetic silicon dioxide is not allowed in livestock feed products.

Revised and updated in July 2019 by OMRI Technical Director Doug Currier. This article was originally published in the Summer 2011 edition of the OMRI Materials Review newsletter.