WASHINGTON– Walmart has recalled nearly 10,000 cases of apple juice across the United States after finding potentially harmful levels of inorganic arsenic.

The U.S. Food and Drug Administration upgraded the recall to a more urgent status on Friday, after announcing it on August 15. The new classification states that the affected product may cause temporary adverse health effects, but that serious or irreversible medical problems are unlikely.

The recall affects 9,535 cases of Great Value brand apple juice sold in 25 states, Puerto Rico and the District of Columbia. Florida-based manufacturer Refresco Beverages US Inc. voluntarily recalled the contaminated six-packs of 8-ounce (227-gram) juice bottles after discovering levels of the chemical contaminant that exceeded industry standards.

A Refresco spokesman did not immediately respond to emails seeking comment on Sunday.

“The health and safety of our customers is always our highest priority,” Walmart spokeswoman Molly Blakeman said in a statement. “We have removed this product from our affected stores and are working with the supplier to investigate the matter.”

According to the National Institutes of Health, very small amounts of both inorganic and organic arsenic are found in many foods. Testing is done routinely because slightly elevated levels of either form can cause symptoms such as vomiting, abdominal pain, diarrhea, numbness, and muscle cramps.

Inorganic arsenic is more toxic to humans than the naturally occurring form of the mineral arsenic, and the health effects of exposure are more severe, according to the FDA. The U.S. Environmental Protection Agency has classified inorganic arsenic as a carcinogen, a substance that causes cancer.

The levels found in the recalled apple juice bottles are so low that the FDA does not believe they have such serious health consequences.

The FDA has not released any reports of possible illnesses related to the apple juice recall.