Carcinogenesis Bioassay of 11-Aminoundecanoic Acid (CAS No. 2432-99-7) in F344 Rats and B6C3F1 Mice.
11-Aminoundecanoic acid is the monomer used in the manufacture of the polyamide, nylon-11. Aminoundecanoic acid is synthesized through a series of reactions from ricinoleic acid isolated from castor bean oil. Nylon-11 is used in automobile parts, industrial fabrics (e.g. filter bags, work clothes, and netting), and brushes because of its resistance to vibration and shock and its stability when in contact with fuels. Nylon-11 resins are approved by the U.S. Food and Drug Administration for use on food contact films. A carcinogenesis bioassay of 11-aminoundecanoic acid was carried out by administering diets containing 7,500 or 15,000 ppm of 11-aminoundecanoic acid to F344 rats and B6C3F1 mice. Groups of 50 rats and 50 mice of either sex were administered the test chemical for 104 weeks (rats) or 103 weeks (mice). Controls consisted of 50 untreated rats and 50 untreated mice of each sex. Nonneoplastic effects included dose-related decreases in mean body weight gain and survival for male rats and for mice of each sex; a dose-related increased incidence of hyperplasia of the transitional epithelium of the kidney and urinary bladder in rats of each sex; and mineralization of the kidney in dosed mice of each sex. Neoplastic nodules of the liver in dosed male rats (control 1/50, 2%; low dose 9/50, 18%; high dose 8/50, 16%; P<0.01) and transitional-cell carcinomas of the urinary bladder in high-dose male rats (control 0/48, 0%; low dose 0/48, 0%; high dose 7/49, 14%: P<0.01) were observed at significantly increased incidences compared with controls. Malignant lymphomas occurred at a significantly (P<0.05) increased rate in low-dose male mice (control 2/50, 4%; low dose 9/50, 18%; high dose 4/50, 8%). Under the conditions of this bioassay, 11-aminoundecanoic acid was carcinogenic for male F344 rats, inducing neoplastic nodules in the liver and transitional-cell carcinomas in the urinary bladder. The test chemical was not carcinogenic for female F344 rats. No clear evidence was found for the carcinogenicity of 11-aminoundecanoic acid in B6C3F1 mice of either sex, although the increase in malignant lymphoma in male mice may have been associated with administration of 11-aminoundecanoic acid. Levels of Evidence of Carcinogenicity: Male Rats: Positive Female Rats: Negative Male Mice: Equivocal Female Mice: Negative