Study of the nephrotoxicity of iron oxide fumes released by welding in an experimental model

Wistar male rats were tested for effects on their kidneys after inhalation of freshly formed iron oxide welding fumes. An aggregation of iron pigment was found in the lungs of rats which were exposed to these fumes in a box for 30 min. Macrophages in the lungs took in some of the iron immediately. Twenty Wistar male rats were studied after exposure to fumes in a box for 3 h a day, 3 days a week, for 3 months. The rats were sacrificed and observed over a period of 1 year. Most of the iron was taken in by the macrophages, but remained in the lungs even after 1 year. Some of the iron was discharged from the lungs through lymphatics and some reached the mediastinal lymph nodes. Some of the iron reached the kidneys, forming an aggregate in renal tubular epithelial cells, and some regenerative changes with swelling of nuclei and cystic changes were seen in the kidneys of rats 4 months after exposure to the fumes. Although we could not induce renal cancer in the present experiment, we have concluded that inhalation of iron oxide fumes may cause some renal toxicities and ultimately renal cancer as observed in the welding population.