POTENTIAL CARCINOGENICITY OF FOUNDRY FUMES - A COMPARATIVE IN-VIVO IN-VITRO STUDY

Epidemiological studies of workers exposed to fumes in the iron and st eel foundry industry have consistently demonstrated an increased relat ive risk of lung cancer of approximately 1.4. Foundry fume is a comple x mixture of gases and fine particles generated during the casting pro cess when molten metal is poured into sand moulds bound together with organic binders. The chemical composition of fume varies according to foundry process and, specifically, binder composition. Previous in vit ro studies have demonstrated that some fumes have mutagenic activity a nd that this varies with fume type. The current study has examined the potential carcinogenicity of three fumes in a 2-yr in vivo rodent bio assay using an intrabronchial pellet implantation technique. The toxic ity and genotoxicity of the fumes were tested concurrently in a number of in vitro assays including those identifying mutagenicity, unschedu led DNA synthesis, free radical DNA damage and micronucleus induction. The rodent bioassay failed to demonstrate a carcinogenic response, al though an increase in preneoplastic lesions was seen in all fume-treat ed groups relative to controls. When tested in vitro, the fumes were p ositive in many assays and activity correlated with the polycyclic aro matic hydrocarbon content of the fumes. The employment of a combinatio n of in vitro assays for different genotoxic endpoints, such as those presented in the current study, provides information useful for the ov erall assessment of carcinogenicity of complex mixtures such as foundr y fume. Copyright (C) 1997 Elsevier Science Ltd.