DNA-protein cross-links in welders: molecular implications

A new method for detecting DNA-protein cross-links involving selective precipitation of DNA containing cross-linked proteins by K(+)-sodium dodecyl sulfate was utilized in the peripheral WBC of 21 male metal arc welders and in 26 male controls of similar age and racial characteristics who were not exposed to welding fumes. DNA was quantitated by Hoechst fluorescence. Although the concentration of nickel and chromium in the peripheral blood did not differ between subjects in the two groups, one-fourth of the welders had levels of DNA-protein cross-links that were above the upper limit of the controls. Mean cross-link values were 1.85 +/- 1.14% (SD) among the welders and 1.17 +/- 0.46% among the controls, a 58% statistically significant difference (P = 0.01). Thus, many welders appeared to be burdened with an excess of DNA-protein cross-links, suggesting exposure to cross-linking agents and, possibly, a detectable biological effect of potential genotoxic consequences.