Immunotoxicology of arc welding fume: worker and experimental animal studies

Abstract

Arc welding processes generate complex aerosols composed of potentially hazardous metal fumes and gases. Millions of workers worldwide are exposed to welding aerosols daily. A health effect of welding that is of concern to the occupational health community is the development of immune system dysfunction. Increased severity, frequency, and duration of upper and lower respiratory tract infections have been reported among welders. Specifically, multiple studies have observed an excess mortality from pneumonia in welders and workers exposed to metal fumes. Although several welder cohort and experimental animal studies investigating the adverse effects of welding fume exposure on immune function have been performed, the potential mechanisms responsible for these effects are limited. The objective of this report was to review both human and animal studies that have examined the effect of welding fume pulmonary exposure on local and systemic immune responses.

Figure 1

Scanning electron micrograph of SS welding fume collected onto a filter during welding using a flux-cored electrode. Note the chain-like agglomerates of much smaller, spherical primary particles. Welding fume samples were collected onto 47-mm Nuclepore polycarbonate filters (Whatman, Clinton, PA). The filters were cut into equal sections and mounted onto aluminum stubs with silver paste. The deposited welding particles were viewed using a JEOL 6400 scanning electron microscope (JEOL, Inc., Tokyo, Japan).

Figure 2

Comparison of the response to L. monocytogenes following gas metal arc (GMA)-mild steel (MS) or -stainless steel (SS) welding fume pre-exposure. Rats were exposed by inhalation to either GMA-MS or GMA-SS fume at 40 mg/m³ for 3 h/day for 3 days and then challenged with L. monocytogenes infection. At 3 days post-infection, colony-forming units (CFU) increased significantly and body weight decreased with exposure to either fume (adapted from Antonini et al., 2007, 2009). When represented as fold change from respective air-exposed L. monocytogenes challenged sham, there was a greater effect following GMA-SS welding fume exposure compared to GMA-MS; *p < 0.05 MS vs SS.