Germ contamination and controversial dyes: How healthy are colored eggs from the supermarket?. How safe are boiled eggs actually? Consumer advocates repeatedly warn against the use of questionable dyes.
The eggs' shelf life can also be shortened due to damage. What you need to consider when buying eggs and what healthy alternatives are available. In some eggs the yolk is greenish-blue in color. This discoloration does not pose a health risk. It occurs when the iron in the egg reacts with sulfur compounds from the egg yolk.