By Kim Smiley

Two Iowa farms have recently been at the center of the largest egg recall in US history.  Over half a billion eggs were recalled in August after more than 1,500 people were sickened by eggs tainted with salmonella.

How did this happen?  Where did the contamination come from?  How did tainted eggs make it onto supermarket shelves?

The investigation is still ongoing, but we can begin a root cause analysis of this problem by building a Cause Map.  A Cause Map provides a simple visual explanation of all the causes that were required to produce the incident.  A good place to start building a Cause Map is to identify the impacts to the organizational goals.  Causes are then added to the map by asking “why” questions.  (Click on the “Download PDF” button to view a Cause Map of this issue.)

In this example, we’ll consider the safety goal first.  The safety goal was impacted because nearly 1,500 people got sick because they consumed eggs that were contaminated with salmonella.  Why did they eat contaminated eggs?  Contaminated eggs were eaten because they were sold.  Why?  Because the eggs were contaminated at some point and there was inadequate regulation to prevent them from being sold.

Investigators are still determining the exact source of the contamination, but there is significant information available that can be added to the Cause Map.  The eggs were contaminated with salmonella because the hens laying the eggs were contaminated. (This strain of bacteria can be found inside a chicken’s ovaries and is passed on to eggs.)  The exact source that contaminated the hens is still being determined, but testing by the FDA has determined that the hens were likely contaminated after arriving at the farms.  FDA investigators have found a number of sanitation violations, including rodents which are a known carrier of salmonella.  Salmonella is not passed from hen to hen, but is typically passed from rodent droppings to chickens.

As more information comes available we can add to the Cause Map.  Hopefully, the investigation will result in solutions that can be applied and prevent this situation from occurring again.