The National Organic Program (NOP), which regulates use of the USDA Organic seal, allows a short list of synthetic ingredients to be used for very specific purposes in the production of organic foods. 

All of the synthetic substances on the approved National List were reviewed by the National Organic Standards Board (NOSB) in an open, public, transparent participatory standards development process that is unique in government policy.

Each item on NOP synthetics list is allowed because it is a vital tool for organic food manufacturers, and the best option available at this time. Each one is allowed only if it has passed the following stringent criteria:

1. The substance needed cannot be produced from a natural source and there are no organic substitutes;
2. The substance's manufacture, use, and disposal do not have adverse effects on the environment and are done in a manner compatible with organic handling;
3. The nutritional quality of the food is maintained when the substance is used, and the substance, itself, or its breakdown products do not have an adverse effect on human health as defined by applicable Federal regulations;
4. The substance's primary use is not as a preservative or to recreate or improve flavors, colors, textures, or nutritive value lost during processing, except where the replacement of nutrients is required by law;
5. The substance is listed as generally recognized as safe (GRAS) by Food and Drug Administration (FDA) when used in accordance with FDA's good manufacturing practices (GMP) and contains no residues of heavy metals or other contaminants in excess of tolerances set by FDA; and
6. The substance is essential for the handling of organically produced agricultural products.

While the word "synthetics" may conjure imagery of nasty chemicals, the fact is that synthetics play many helpful roles in our lives. Baking powder is made by a synthetic process, as are nearly all vitamins and mineral supplements. (By the same token, many naturally occurring substances used in conventional food production, such as arsenic, nicotine and strychnine, are harmful and therefore prohibited in organics). Here are a few examples of synthetics that play beneficial roles in certain organic products:

Organic applesauce contains the synthetic ascorbic acid (Vitamin C). Vitamin C is an antioxidant that keeps the sauce from turning brown when you open the jar. If the organic label were not allowed to include synthetics, applesauce using organic apples could only use the "made with organic ingredients" label, which only guarantees that 70% of those apples be organic. Under this lesser label, manufacturers would have the option to include up to 30% non-organic apples in their sauce. This is bad for organic farmers (less demand for organic apples) and ultimately bad for consumers, who could no longer choose a USDA-certified product and know they are getting all organic fruit.

The synthetic calcium hydroxide (a hydrated version of naturally occurring limestone) is used in the processing of organic sugar, to remove impurities from the sugar after the cane is pressed. Calcium hydroxide itself does not remain in the final product, but because it is used in processing, all products containing organic sugar involve synthetics.

We believe that it is important to continue to allow in the organic program the small number of synthetics that have been approved by the NOSB. To ban foods using synthetics from carrying the organic label would make organic food less accessible for most people, limit the selection of organic goods available, and drive up prices for organic items. In addition, it would reduce the demand for organic farm goods, slowing the conversion of farmers to organic methods. Over the long term, that would mean more non-organic product on grocer's shelves and more non-organic substances on the land and in our environment -- a bad situation for organic farmers and consumers alike. It is important to take the larger perspective and realize that, in today's world filled with pollutants and potentially toxic substances, the imperfect but ever-evolving process of organic growth (under the strictest organic standards in the world) is the brightest hope for the future.

Notes:
1. A complete list of the 29 synthetics approved for organic processing is here. In comparsion, conventional food manufacturers may use thousands of additives.
2. See the complete regulatory text on the USDA site.