Oh nuts! Just when you thought it was safe to eat peanut butter again (the stuff in jars is fine but be wary of baked goods that contain it), the feds are warning consumers to avoid pistachios. The alert comes in the wake of a voluntary recall of around a million pounds of the little green nuts due to possible salmonella contamination.

The U.S. Food and Drug Administration (FDA) and the California Department of Public health are investigating the possibility that pistachios shipped on or after September 1 by Setton Pistachio of Terra Bella, Calif., were to blame for several reported cases of salmonella.  The FDA said it's conducting genetic testing on samples from recalled batches to determine if salmonella strains in them match those in people sickened by the bacterial infection.

"FDA is working closely with the pistachio industry and recommends that consumers avoid eating pistachio products until further information is available about the scope of affected products," the agency said in a statement.

Healthy people infected with salmonella often experience symptoms including fever, diarrhea (which may be bloody), nausea, vomiting and abdominal pain, but it can be fatal to young children, the elderly and those with weakened immune systems. In rare cases, the organism can get into the bloodstream and cause severe illnesses such as endocarditis (heart infection) and arthritis.

As of deadline, Setton had recalled specific lots of bulk roasted in-shell and shelled pistachios in 2,000-pound, 1,800-pound, 1,700-pound and 1,000-pound bags sold to wholesale customers nationwide after discovering that some shelled pistachios it sold late last year tested positive for salmonella.

Also on the recall list: Setton Farms brand roasted salted pistachios in 9-ounce bags stamped with "Best Before" dates between Jan. 6, 2010 and Jan. 19, 2010, that were distributed in Florida, Georgia, Kentucky, North Carolina, South Carolina, Tennessee and Virginia. If you have any of these products, do not eat them and return them to the place of purchase for a full refund, the company says. 

Health officials caution the recall may expand, because the potentially tainted pistachios were also used as ingredients in many other goods.

Worried you may have consumed—or bought—tainted snacks? Setton has established a toll free number (888 228-3717) that consumers can call for further information.  You can also check out the FDA's Web site, which is keeping tabs on all products recalled.

The FDA said that it first learned about the problem on March 24 when Kraft Foods reported that its Back To Nature Trail Mix was contaminated with salmonella. Kraft traced the contamination to pistachios from Setton and launched a recall.

Supermarket chain Kroger Co. late last week recalled its Private Selection shelled pistachios due to potential salmonella contamination. That recall affects pistachios sold at Kroger, Ralphs, Fred Meyer and a host of other stores owned by Kroger in 31 states.

Setton, the country's second-largest pistachio producer, said this is its first recall in its 13-plus years in the biz.

"Setton Pistachio is committed to quality products and consumer safety," the company said in a statement, "and is taking aggressive action to prevent the need for any future recalls of its products."

The move comes on the heels of a nationwide outbreak of salmonella poisoning traced to peanut butter and paste produced at a Peanut Corporation of America plant in Georgia that sickened nearly 700 people and may have been linked to the deaths of nine others.

For more on salmonella poisoning, read ScientificAmerican.com's In-Depth Report.

Photo credit: iStockphoto.com