Renal tumors in rats given trisodium nitrilotriacetic acid in drinking water for 2 years

One hundred and ninety-six albino male rats [Crl/COBS CD (SD) BR] were given 1,000 ppm trisodium nitrilotriacetic acid (NTA) in drinking water for 2 years. One hundred and ninety-two control rats were given water without NTA. Animals that had a palpable mass or that appeared clinically ill were killed. All survivors were killed at 704 days. A significantly (P less than 0.05) higher proportion of the NTA-treated rats vs. 11.2% of the controls). The largest difference between the NTA-treated rats and the controls in tumor incidence was associated with renal adenoma. The NTA-treated group contained 25 rats with renal adenomas and 4 with renal adenocarcinomas. Only 5 control rats had renal adenomas; none had renal adenocarcinomas. No statistically significant differences were observed for any of the other tumor types among the NTA-treated rats and the controls. The overall incidence of renal tubular cell hyperplasia and nephritis was similar in the treated and control groups. However, a significantly greater number of NTA-treated rats had more severe grades of hyperplasia. Thus NTA when administered continuously in drinking water at a concentration of 1,000 ppm is tumorigenic to the rat kidney.