Scleroderma has been associated with silicosis in a number of studies. [Rom, p. 379] 1,022 cases of silicosis were reported in the state of Michigan between 1985 to 2006, Medical records were available for 790 cases and showed a diagnosis of scleroderma in two (a prevalence ratio of 28.3). [
PMID 20957678] Silicosis affects the immune system; patients have increased susceptibility to tuberculosis and some fungal infections. [LaDou, p. 379] "Because some SSc autoantibodies cross-react with certain virus-associated epitopes, molecular mimicry has been considered a possible pathogenetic link between viral infection and SSC." [Cecil, 24th Ed, p. 1706] The female-to-male ratio of patients with SSc is about 4:1. [Merck Manual, p. 266] In a study of autoimmune disease mortality in 26 US states and occupational exposures, no increased risk of scleroderma was found for those in jobs likely to include exposure to silica or solvents. [
PMID 17907164] "Immunologic mechanisms and heredity (certain HLA subtypes) play a role in etiology. SSc-like syndromes can result from exposure to vinyl chloride, bleomycin, pentazocine, epoxy and aromatic hydrocarbons, contaminated rapeseed oil, or L-tryptophan." [Merck Manual] The results of this meta-analysis suggest that silica exposure is associated with increased risk for the development of SSc and specifically in males. However, the evidence to date is not sufficient to conclude that silica is a causative factor for SSc." [
PMID 20047060] A number of scleroderma-like disorders after occupational or environmental exposures have been reported. For the disease caused by vinyl chloride, see "Acroosteolysis." "Toxic oil syndrome" affected thousands in Spain in 1981 after ingestion of cooking oil contaminated with aromatic amines. In 1989 an epidemic of eosinophilia-myalgia syndrome occurred after consumers ingested an L-tryptophan remedy contaminated with aromatic amines. [Rosenstock, p. 537-8]