Iron appears to play a major role in catalysing
free radical production, leading to lipid peroxidation and DNA damage. We, therefore, investigated the effect of colloidal
iron deposited in the peritoneum. Wistar male rats were given either
ferric saccharate,
ferric saccharate and
nitrilotriacetic acid (NTA), NTA or saline. NTA was shown previously to 'free'
iron to promote lipid peroxidation and an
iron chelate of NTA is known to be carcinogenic to the kidney.
Iron at a dose of 5 mg kg-1 day-1, and saline at a dose of 0.5 ml day-1 were injected i.p. for 3 months. NTA at a dose of 83.5 mg kg-1 day-1 was give i.p. for 5 months. All the rats were killed about a year later for histological examination. In nine of the 19 rats treated with
ferric saccharate, mesothelial
tumors were induced in the serosa of the tunica vaginalis or the length of the spermatic cord. Among rats treated with
ferric saccharate and NTA, seven had localised
mesotheliomas in the above locations and six had wide-spread peritoneal
mesotheliomas. No mesothelial
tumors developed in either NTA treated or saline treated rats. No pleural
mesotheliomas were found in any group. These findings add to the evidence that
iron is involved in some carcinogenic processes.