Challenge testing for welding fume

I have seen a patient for a legal report – who thought he had copd from cadmium exposure from welding. Currently he has normal lung function as he stopped working 3 years ago – so he doesn’t have copd. However, the symptoms at the time could have been compatible with asthma / hypersensitivity- he got increasing cough and phlegm with chest tightness occasional wheezing and felt like he had flu occasionally when he went home. This was better on rest days. Now he has no such symptoms and his Spirogram is completely normal when he does a technically adequate one. Do you think there would be any merit in challenge studies in him at this point? Clearly this wouldn’t make a clinical difference but I was wondering if it would improve his case?

Occupational Asthma, Specialist, 12/31/2007, 12/31/2007,

Welding fume is one of the most commonly reported causes of occupational asthma on the SWORD database. Stainless steel welding is the best sorted with chrome as the sensitising agent, however most welders do not work with stainless steel. The precise sensitising agent for most welding asthma is unknown. The only unit set up for challenge testing with actual welding is in Helsinki. Stainless steel welders can be challenged with nebulised potassium dichromate more readily. The best way to validate occupational asthma in welders is from serial measurements of PEF at and away from work, where the exposures are always relevant (unlike artificial challenges such as potassium dichromate). Most believe that challenge tests are not indicated for purely legal reasons, when the diagnosis is made on the balance of probabilities. A negative challenge does not exclude occupational asthma, and a positive challenge can be regarded as non-specific unless the measured exposure in the challenge chamber is less or similar to that measured at work, and suitable asthmatic controls have negative challenges. If your patient wishes to continue as a welder (or with indirect exposure to welding fume), challenge tests may be attempted after confirming occupational asthma from serial PEF measurements to see if a particular agent can be identified which can be removed/avoided, allowing continuing employment as a welder. We have seen a number of workers exposed to personal or robotic welding fume from spot welding through zintec coated steel, where the zinc fume is the cause of occupational asthma (with positive challenges to zinc salts). The febrile reaction could suggest metal-fume fever, for which zinc fume is the commonest cause. Hannu T, Piipari R, Tuppurainen M, Nordman H, Tuomi T, Occupational asthma caused by stainless steel welding fumes: a clinical study , Eur Respir J, 2007;29:85-90, Moore V, Robertson A, Jaakkola M, Pantin C, Burge PS, 15 Years of SHIELD: a reporting scheme for occupational asthma, Eur Respir J Suppl, 2006;28:245s, Beach JR, Dennis JH, Avery AJ, Bromly CL, Ward RJ, Walters EH, Stenton SC, Hendrick DJ, An epidemiologic investigation of asthma in welders, Am J Respir Crit Care Med, 1996;154:1394-1400, Vandenplas O, Dargent F, Auverdin J, Boulanger J, Bossiroy J, Roosels D, Vande Weyer R, Occupational asthma due to gas metal arc welding on mild steel, Thorax, 1995;50:587-589, Malo JL, Malo J, Cartier A, Dolovich J, Acute lung reaction due to zinc inhalation, Eur Respir J, 1990;3:111-114, Marquart H, Smid T, Heederik D, Visschers M, Lung function of welders of zinc-coated mild steel: cross-sectional analysis and changes over five consecutive work shifts, Am J Industr Med, 1989;16:289-296, Malo JL, Cartier A, Occupational asthma due to fumes of galvanized metal, Chest, 1987;92:375-377, Keskinen H, Kalliomaki PL, Alanko K, Occupational asthma due to stainless steel welding fumes, Clin Allergy, 1980;10:151-159,

12/31/2007