You might want to read this first.A study just published in the journal Clinical Infectious Diseases
(PDF link) takes us back to 2009, when an E. coli outbreak was traced back to the consumption of raw Nestle Toll House cookie dough.
Actually, that raw cookie dough was the culprit of this outbreak isn't news -- we just wanted to grab your attention with a timely lede, like Gut Check was taught to do in journalism school* -- but officials never determined how the cookie dough became contaminated in the first place.
The newly published study examines the possible causes of contamination and suggests a surprising possibility.
The study finds that what you might have considered the prime suspect, eggs, were unlikely to have been the cause as they were pasteurized, and the investigation found no issues with the pasteurization process. Several other ingredients (molasses, sugar, baking soda) were also found to be unlikely sources, as they went through "pathogen kill steps" before being added to the dough.
That left two contenders, chocolate chips and flour. The study rules out chocolate chips for two reasons: 1) there wasn't a strong link between chocolate-chip cookie dough (as opposed to any cookie dough) and E. coli cases; and 2) no illnesses were linked to chocolate chips made in the same facility and sold and consumed separately.
Which leaves good ol' flour as, in the study's words, the "prime suspect."
Low levels of Salmonella contamination can occur in wheat flour, and flour and flour-based mixes have been implicated in foodborne Salmonella outbreaks. Generic E. coli species have also been found in flour; 1 US study found E. coli in 12.8% of commercial wheat flour samples examined. ...Because flour is frequently purchased in large quantities by manufacturers for use in food products, if contaminated flour were responsible, a single purchase of contaminated flour might have been used to manufacture multiple lots and varieties of dough over a period of time.
So, in conclusion, don't eat raw cookie dough. Or raw pizza dough. Or raw any dough.
Or think of it this way: Dough sounds just like "D'oh!"
* - Gut Check didn't actually attend journalism school. Though we imagine they would have taught us to use "could kill you" in headlines as often as possible.(h/t: NPR)
'Tis the season for baking cookies, which means 'tis also the season for sneaking a bite or two of raw cookie dough.