On a scale of 1 to 5, in which 5 is the most potent allergen, trivalent chromium was graded as 3 and hexavalent as 5, i.e. extreme sensitizer. The difference probably depends on the pattern of employment. The causes of allergy to chromium salts vary from country to country, depending on the industry and the chemical environment. Humans often have multiple sensitivity to metals. In most instances in which an allergic reaction is attributed to a metallic chrome object, nickel is the actual sensitizer.
Stainless steel is reviewed here from a dermato-allergological point of view.
Chromium may be present in the electrode rods used in electric arc welding. During welding chromium may be oxidised to the hexavalent form and be present in the fumes as a result of the combination of temperature, oxygen and of alkali metals commonly present in welding rod coatings. Galvanising and electroplating Iron sheets are best protected from rusting by galvanising them with zinc applied either by electroplating or by dipping them in molten zinc. To prevent the zinc corroding, oxidising or whitening with moisture, the metal is coated with chromate. Electroplating consists of coating one metal with a layer of another metal by means of an electric current.