USDA Salmonella Bacteria on Chicken Testing Severely Flawed, New Study Finds

salmonella bacteria is frequently present in chicken

The USDA’s standard testing process for monitoring salmonella bacteria contamination on chicken may be producing a large percentage of false negatives, according to a new peer-reviewed study.

The study, which was carried out by USDA researchers, found that the latest data on salmonella contamination of chickens, which seems to show a steady decrease, with 3.9 percent in 2013 versus 7.2 percent in 2009, may be incorrect due to flawed testing protocols.

Current USDA methods for preventing salmonella involve spraying slaughtered, plucked, and eviscerated chicken carcasses with chemicals designed to kill pathogens including salmonella bacteria, before dunking them into a cold bath, which also contains these chemicals. A few randomly selected chickens are then bagged to be tested for salmonella. This method means that the chemicals are still present on the birds when they are tested, and that the chemicals can continue to kill salmonella bacteria while the results are being calculated, resulting in false negatives for contamination.

The authors concluded that “current procedures for the isolation and identification of Salmonella on poultry carcasses may need modification.”

Another 2012 report seems to confirm this. This experiment sampled chicken parts from the end of the production line, 26.2 percent of which were found to contain salmonella bacteria, six times the rate found on carcasses in the USDA tests in the same year.

Salmonella is one of the biggest food safety concerns in the U.S., with more than one million people contracting the infection every year, according to estimates from the Centers for Disease Control and Prevention, and an average of 20,000 hospitalizations and almost 400 deaths according to a 2011 report. Despite apparent declines in the presence of salmonella on chicken, salmonella poisoning rates have not declined in the past 15 years.

“Chicken is the item in the supermarket most likely to be contaminated with salmonella,” Mansour Samadpour, a food safety expert and chief executive of IEH Laboratories and Consulting Group, told Mother Jones.

Salmonella bacteria can also be transmitted via contaminated eggs or contaminated utensils, such as cutting boards and knives, particularly onto products to be consumed raw, such as salad and vegetables.

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Raw chicken image via Shutterstock

Emily Monaco
Emily Monaco

Emily Monaco is an American food and culture writer based in Paris. She loves uncovering the stories behind ingredients and exposing the face of our food system, so that consumers can make educated choices. Her work has been published in the Wall Street Journal, Vice Munchies, and Serious Eats.