occupational asthma from chromium
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Is it possible to become sensitised (respiratory) to the grindings of a chrome-containing prosthesis; or does the chrome need to be in the form of a hexavalent salt?
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I do think that one can become sensitised to metallic agents (Cr, Ni, Co) present in alloys at zero valence, because the metals can oxidise in body fluids (sweat, interstitial fluid in the skin, lining fluid in the respiratory mucosa) and so bind to proteins thus causing immune sensitisation etc. I don’t think we have proofs of this happening in the airways or lungs, but this is commonly accepted as a mechanism for allergic contact sensitisation. Think of Ni in piercings, cheap jewelry, and even coins; cobalt asthma can certainly occur in people exposed to metallic cobalt; I don’t know for sure about Cr, but although only Cr6+ (as opposed to Cr3+) is considered toxic, allergenic and carcinogenic, this does not mean that metallic Cr cannot become Cr6+ in the right environment (I believe this is the case when welding stainless steel). In other words, if it can happen in the skin, there is no reason it cannot happen in respiratory mucosa … although it may not occur as frequently as in the skin.
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We see quite a lot of occupational asthma in welders of stainless steel, where I imagine the exposures are mainly to oxides of chrome. We challenge them with potassium dichromate, which is clearly a hexavalent salt. The others we see are mainly electroplaters where the chrome will be ionised. We see cobalt asthma (and GIP) in dry grinders of hard metal, where I think that it is unlikely that the cobalt is ionised. Again we challenge them with a salt, cobalt chloride
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