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The Food and Drug Administration says it will be testing all orange juice entering the U.S. after low levels of the fungicide carbendazim were found in juice.

"We have initiated testing of orange juice both at ports of entry and in the United States," Michael Taylor, the FDA's deputy commissioner for food, told ABC News via email today. "Very preliminary results show levels well below the level of any safety concern. … Our testing is just getting started."

Carbendazim is used on fruit to kill fungi or fungal spores. It is not okayed  for use on oranges in the U.S., but it is approved for use in Brazil.

The FDA was alerted to the presence of the fungicide by a company that found carbendazim in its own juice as well as the juice of competitors. The FDA has not identified the company but did say that the contaminated juice was from Brazil.

According to the U.S. Department of Agriculture, 26.4 percent of orange juice consumed in the U.S. in 2010 was imported, and 56.4 percent of those imports came from Brazil.

However, the FDA spokeswoman said via email that the U.S. does "not receive fresh oranges from Brazil."

Carbendazim has been found to cause birth defects in rodents. Studies also have shown that in human cells in laboratories, the chemical can cause chromosome problems. However, the chemical has not been shown to harm humans.

The FDA said today that if the chemical is detected in any juice, it will not be allowed in the country. The U.S. agency said that the highest level of carbendazim found so far was still 1,000 times lower than the level of concern.

Although the FDA has started testing orange juice on store shelves, no products have been recalled. In addition, the EPA believes the fungicide levels in juice do not pose a public health threat and has not found any juice with levels higher than its level of concern.

No recalls are planned if the detected levels in juice in stores are low.

ABC News' Richard Besser and Lisa Stark contributed to this report.