Federally imposed processing safeguards prevented an estimated 190,000 cases of Salmonella poisoning from broiler chickens in the late 1990s, according to a study by the U.S. Department of Agriculture.

The statistical study compared food-poisoning data in the years before and after imposition of the sometimes-controversial Hazard Analysis and Critical Control Point (HACCP) program in the mid-1990s.

Previous studies had concluded that HACCP (pronounced “hassip”)  programs in poultry processing plants had reduced the incidence of Salmonella in broilers by more than 50 percent.  But the new study asked the follow-up question: Did the new safety measures actually prevent outbreaks of food poisoning?

And the study — published in Foodborne Pathogens and Disease — concludes that it did, resulting in far few cases of Salmonella infection across the nation.

Chicken carcasses have long been understood to be a high risk for Salmonella poisoning. While thorough cooking to 165°F can kill the harmful pathogen, raw chicken and its juices can cross-contaminate other foods and food-prep surfaces, so ideally chicken shouldn’t be contaminated in the first place.

The HACCP program, introduced in stages between 1996 and 2000, identified points in the processing plant where the poultry is especially prone to contamination.  Armed with that information, processors were able to alter their operations to reduce the risk.

The new study, by Michael Williams and Eric D. Ebel at the USDA’s Food Safety Inspection Service, used data from the Centers for Disease Control and Prevention and from other health agencies to analyze the effects of the safety programs.

The authors estimated that about 190,000 fewer people were sickened with Salmonella between 1996 and 2000.

Subsequent improvements in infections rates have been far more modest, presumedly because HACCP programs had been in place for some time, the authors said.

The HACCP program dates to the 1960s, when the National Aeronautics and Space Administration (NASA) asked the Pillsbury Company to help develop a safe food system for astronauts, with food safety being a high priority. Pillsbury scientists studied food-processing and transport, identifying the points at which food was most likely to become contaminated with Salmonella or other microbes.

At the same time, the U.S. food-processing industry was growing much faster than government inspectors could keep up with. So the government applied what NASA had learned to the food industry in general.

While reports of Salmonella outbreaks have increased in recent years, health officials report that the actual incidence of food poisoning has declined.  And the new FSIS study suggests strongly that HACCP is one of the reasons for that decline.

Each year there are about 40,000 lab-confirmed cases of salmonellosis reported in the U.S., and about 400 of those people die. Because people with milder cases may not seek medical treatment, of if they do they may not be screened for Salmonella, the CDC estimates the actual number of infections may be 30 or more times greater. Children younger than five are the most vulnerable to the disease.

In 2010, Consumer Reports found Salmonella in 14 percent of the supermarket chicken it tested.  Last year, the Institute for Environmental Health (IEH) tested 100 retail chickens at the request of the food-safety law firm Marler Clark, sponsor of Food Safety News. Nineteen percent of the samples tested positive for Salmonella.

Of 13 organic chickens tested by the IEH lab, four were positive for Salmonella, indicating poultry processing is problematic whether or not the chicken is raised on industrial-scale farms.

Under stricter standards that went into effect in July, no more than 7.5 percent of raw chicken carcasses can test positive for Salmonella. The previous tolerance level was 20 percent.