More than 55,000 pounds of GNP Company chicken have been recalled due to a possible sand and black soil contamination. GNP, the Minnesota-based parent company, claims that the contamination was caused by “extraneous materials” added by an employee who has now been fired and is currently under investigation by law enforcement. According to a GNP release, the contamination is an “isolated product tampering incident.”

One only retail item, 4-pound bags of Just BARE Whole Chicken, has been recalled. This product is sold in grocery stores and has the UPC code 024105594057. The items were produced between June 6 and June 9. The recalled Just BARE Chicken has a use or freeze by date of June 26, 2016, and customers who have purchased that item are encouraged to throw the product way or return it to where they purchased the chicken.

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Bulk and custom items also manufactured by GNP were recalled, according to the USDA Food Safety & Inspection Service. They are not, however, available to the public for purchase.

Even though the sand and black soil are considered natural and benign substances, GNP strongly advises consumers not eat the chicken if you bought it because they “cannot say with 100% certainty that the product is safe for consumption.”

This article originally appeared on CookingLight.com.