The U.S. officials and the American beef industry are skeptical about the finding of an unusually high level of dioxin – 6.26 picograms – an amount that exceeds Korea’s 5-picogram limit.

USDA spokesman Keith Williams told meatingplace.com on Friday that the skepticism is based on the inconsistency with the level of dioxin the U.S. found in  its beef samples.

Williams was quoted as saying: "Let's put it this way: If we found 6.26 picograms of dioxin [in our samples], public health officials would be all over it."

According to meatingplace.com, USDA plans to request information on how the Koreans performed the testing and what type of dioxin inspectors discovered.

Dioxins are a group of environmentally persistent pollutants commonly found in the air, water and soil in the U.S., which have been known to be cancer-causing agents or carcinogens.

A study conducted years ago by the U.S. Environmental Protection Agency scientists found relatively high levels of dioxins in food derived from animals, particularly in milk, beef, and inland freshwater fish.

Early this month, the Korean government found risky bone chips in three shipments of beef from the U.S., which prompted the Koreans to reject all three affected shipments.  

The USDA officials said early that South Koreans just wanted to find some excuse to reject the U.S. beef.