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Title: Toxicology of welding fume particles in experimental animals : a study of the physical and chemical nature of welding fume particles in relation to inhalation, and its toxicological consequences in the rat, guinea pig and man
Author: Lam, Hua Fuan
ISNI:       0000 0001 3604 1400
Awarding Body: University of Bradford
Current Institution: University of Bradford
Date of Award: 1976
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Investigations have been carried out on the elimination, fate and toxicity in the rat and guinea pig of fumes inhaled from manual and MIG arc welding. The factors governing the characteristics of the fume particulates were determined and the conditions necessary to produce consistent fume samples were standardised. Flux coated electrode fume (FE) and MIG welding fume(MW)particles differed markedly in their surface topography, surface area, particle size, particle aggregation, elemental content and dissolution rate. In inhalation experiments, animals exposed to the two types of welding fume gave different deposition factors and clearance values. Fume material in alveolar nodules may be removed in two fractions, initially by a transport mechanism to the lymph nodes and later by the dissolution of particles retained in nodular deposits. Chromium was eliminated most rapidly from FE deposits followed by cobalt, iron and zinc respectively. From MW deposits, the respective order was nickel, chromium, cobalt, iron and zinc. 'In vitro' dissolution studies showed that the relative solubilities of the elements from welding fume particulates were similar to their respective leaching from lung deposits. FE deposits induced a localised fibrotic reaction, due to deposition of collagen and thick bundles of reticulin fibres. Little collagen fibres were present around MW deposits. However, in some animals a diffuse fibrotic reaction was observed. The localised fibrosis was discussed in terms of silica present in FE material, whereas the diffuse fibrosis was postulated as the result of a hypersensitive reaction. Guinea pigs could be sensitized to MW material and chromium, present in high concentration, was implicated in the reaction. The offending antigen is believed to be the conjugate formed by the soluble sensitizing chemical from the fume material and a fraction of the protein present in the lung. Animals with diffuse fibrotic lung reaction showed intense lymphoid germinal activity, with the presence of plasma cells, lymphocytes and lymphoblasts consistent with hypersensitivity. The lung damage was attributable to T-cell and/or antibody mediation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available