This is what it says about the product (Kay-Kob) on the back of the bag:

"KAYTEE Kay-Kob is cleaner, brighter, and more aborbant than other cob bedding availiale today. From the start, the corn cobs used are stored indoors, which sets KAYTEE Kay-Kob apart from the others. Other cob beddings are usually left outside exposed to rain, snow, dust and other contaminants. Moisture and dust can produce bacteria, discoloration, and reduce the aborbancy in the cob bedding. Storing indoors insures Kay-Kob meets the industry's highest standards of quality and is the healthiest cob bedding for your pet."

This is one of the many reasons why I love Kaytee. I think they have the best products on the market, well, besides Super Pet.