What you see: Specks of grime stuck to an egg
What it is: Chicken feces (eww), possibly also dirt or bits of the carton
Eat or toss: Eat! But use some caution and avoid letting the soiled areas contact surfaces in your kitchen
When I sent a photo of this egg to poultry specialist Ken Anderson, he quickly diagnosed the dirty specks as “residue fecal material.” Gross, yes, but, don’t cancel your scramble just yet.
“Does that mean that the egg contents are bad? No, it does not,” Anderson said. “The issue here is that if you were going to go ahead and break that egg into a skillet, if some of that shell were to get into the egg or the cookie dough then you’ve got a cross-contamination issue.”
If you then cook everything thoroughly, to the 165 degrees Fahrenheit needed to instantly kill salmonella (or make sure everything in the skillet or pan gets above 145 for several minutes while cooking), then you still don’t have anything special to worry about. But, should you clean off the egg?
The quickest approach would be to just make sure that when you crack the egg, you steer clear of the dirty area and wash your hands thoroughly after disposing of the shell. You could also wipe off the egg, but make sure to immediately put the cloth you use in the laundry and only use it on one egg. The USDA advises against washing eggs generally as the wash water (and any accompanying bacteria) could be sucked into the egg.
Also, to minimize cross-contamination, use this egg before the others in the carton.
American eggs are washed before reaching consumers
While it’s possible to find a dirty egg like this sold commercially in the U.S., it’s uncommon. American eggs are washed per specific methods prescribed by the USDA.
Washing eggs removes bacteria, but it also diminishes a natural, protective layer around the egg. Known as the cuticle, this transparent layer may have microbes on it, but it also helps prevent problematic bacteria from getting into the egg. If you’ve ever been to a country where eggs aren’t typically refrigerated, it’s likely because the eggs aren’t washed and still have the protective cuticle layer. There are pros and cons to washing or not washing and preserving the cuticle, which we talk about more in this post about what you should do if you leave your eggs out overnight.
What about eggs from backyard chickens?
If you're eating eggs that haven't been regulated by the USDA and are clearly soiled, Deana R. Jones of the U.S. National Poultry Research Center advises against giving them a water wash on your own. If you use the wrong temperature water you could actually make it easier for bacteria to slip into pores in the shell. Instead, she suggests using a paper towel or cloth to wipe off each egg, and making sure to use a different cloth or part of the cloth for each egg. Again, you'll want to promptly put the soiled cloths in the wash.
Deana R. Jones. Research Food Technologist. Egg Safety and Quality Research Unit. U.S. National Poultry Research Center. USDA Agricultural Research Service.
Kenneth E. Anderson, Ph.D. Professor, Poultry Extension Specialist. Director, North Carolina Layer Performance and Management Program. Prestage Dept. of Poultry Science. North Carolina State University
Keith Warriner. Microbiologist. Department of Food Science. University of Guelph
Shell Eggs From Farm to Table. United States Department of Agriculture. Food Safety and Inspection Service.
I forgot to put my eggs in the fridge. Can I still eat them? EatOrToss. Jan. 14, 2018.
Egg Grading Manual. USDA.