The Environmental Protection Agency (EPA) is investigating the safety of milk products, according to an official who spoke to The Washington Post on condition of anonymity because the agency has not yet publicly disclosed the findings.
The agency has ordered the testing of dairy products produced in the United States, Canada, Mexico and Puerto Rico for possible mercury contamination.
The agency says it will use a test to determine the amount of mercury found in milk products.
The agency said in a statement on Thursday that it has not tested milk products made in Mexico or Puerto Rico because the milk has been labeled as being from a plant in the U.S. That is the same product that is manufactured in Mexico.
The FDA did not immediately respond to a request for comment from The Associated Press.
At least 10,000 cases of the bacterial toxin salmonella, also known as Enterococcus, have been reported nationwide since last year, and more than 5,000 deaths have been linked to the bacteria, according the CDC.
Last week, a Texas man died after eating contaminated milk from a California farm, and the USDA reported that milk from three of the four U.N. food-safety conferences held in recent years had been tainted with salmonellae.