For tips to ensure egg safety, see below.
In summer 2010, about half a billion eggs were recalled in the U.S. due to suspected salmonella contamination. Dr. William Schaffner, an infectious disease expert at Vanderbilt University, said that, right now, some of the safest eggs available to Americans are from small farms.
William Schaffner: The local farm is not an absolute guarantee of safety. But eggs from local farms are more apt to be safe from salmonella than from large farms, simply because in the large operations, if you get some contamination, it can spread widely.
He said that at industrial farms – the farms that supply most supermarkets around the U.S. – hundreds to thousands of hens might become infected at the same time.
William Schaffner: The infected hen can actually instill the salmonella into the interior of the egg as it’s being made in the hen, and the only way we can avoid that infection is by cooking the eggs thoroughly when we get them. And by ‘thoroughly,’ I mean no runny scrambled – which is unfortunate because that’s the way I like them.
He added that, in the United Kingdom, farmers must, by law, vaccinate their chickens against salmonella. He said the same rules are not mandated, at present, by the U.S. Food and Drug Administration.
William Schaffner: In the United Kingdom, where they had a big egg salmonella problem, they started to use a vaccine in the hens that pretty much eliminated their salmonella problem. If that vaccine has been so successful in England, why don’t we vaccinate our chickens here in the United States?
Shaffner explained why salmonella is so dangerous, in the first place. Salmonella is potent bacteria from fecal matter, he said. While salmonella usually just causes food poising, it can be life-threatening for the very young and old.
William Schaffner Occasionally the salmonella can get out of the intestinal tract and into the bloodstream.
He said that Salmonella-tainted eggs present a tricky problem, because it’s not just an issue of cleaning the eggs.
William Schaffner: The hens are contaminated, and as the egg is produced, their fecal matter can cover the surface of the eggs. Well, if that were all, we could wash the eggs before they go to market. And, in fact, we do – in a chlorine solution.
The salmonella is actually embedded inside the egg, by an egg-laying hen that’s somehow been infected. He said the UK had a similar salmonella problem with their eggs, which was very much improved by requiring farmers to vaccinate their eggs.
William Schaffner: If that success looks real, why don’t we vaccinate chickens here in the United States. What I’ve heard, just over the fence, that when the FDA looked at this, they were not completely convinced by the data that the vaccine was effective. But that was then, and this is now, and I believe we need to reexamine the data.
To ensure egg safety, it helps to:
* Avoid eggs that are on the egg recall list.
* Only buy eggs with a USDA grade shield on the label (US Grade AA, A, etc).
* Store eggs in their original carton and use them within 3 weeks.
* Throw away cracked eggs.
* Keep eggs and foods prepared with eggs refrigerated at less than or equal to 45 degrees F.
* Cook eggs thoroughly and don’t let your kids eat raw or undercooked eggs.
* Use pasteurized eggs in recipes that call for raw eggs.
* Wash your hands, utensils, and kitchen surfaces after handling eggs so that you don’t cross-contaminate other foods with Salmonella that may be on your eggs.
* Seek medical attention if your child develops any Salmonella symptoms.
* Consider using pasteurized shell eggs or a pasteurized egg product if your child has a weakened immune system or is otherwise at higher risk for a serious Salmonella infection until the egg recall is fully resolved.
Finally, Dr. Schaffner pointed out that Americans continue to have the best food supply in the world, and the safest. But, he added, that doesn’t mean that the U.S. food supply is safe as it could be, as the egg recall of 2010 shows.
Beth Lebwohl researches, writes and helps produce science content in audio and video formats for EarthSky. She is one of the authors on EarthSky.org, a script-writer for our podcasts, and helps host our English science podcasts in 90-second, 8-minute and 22-minute formats. Beth came to EarthSky in 2006 from the American Museum of Natural History's Department of Astrophysics, where she was surrounded by some of the greatest telescope-building, equation-wielding, code-writing physicists of our time. And they made her think . . . this science thing . . . it's pretty cool.