I have purchased black olives produced and packed in Spain. Is there any risk related with health? The black olives have an ingredient containing ferrous gluconate as a color stabilizer.

That is a difficult question as it is probably impossible to know just how much of the substance is in your jar. Ferrous gluconate is a source of iron, often prescribed to treat iron deficiency anemia (not enough iron in the body to make oxygen-carrying hemoglobin). As such an adult can be prescribed up to 1 gram a day, and it's hard to believe they would be adding much more iron then that. As with all such things, try one! I'm sure many others have already. If you don't have a problem have a few more. Enjoy. There are many sights that will tell you of side effects and things to look for.