Condensations of the Carcinogenesis Bioassay Technical Reports.

Caprolactam (aminocaproic lactam, 2-oxohexa-methylenimine, CAS No. 105-60-2), the monomer used in the production of nylon-6, was selected and testing initiated by the Carcinogenesis Testing Program, National Cancer Institute (now part of the National Institute of Environmental Health Sciences/National Toxicology Program) because nearly one billion pounds per year are produced, because of the widespread use in food packaging materials and clothing, and because no carcinogenicity studies had been done (1). Nylon 6 resins/fibers are used extensively in carpets, knit fabrics, hosiery, thread, hairbrushes, replacement parts for automobiles and machinery, flotation devices, and food packaging. Highly soluble in water, caprolactam reportedly leaches from clothing made from polyamide fibers when soaked in simulated perspiration (2). Ferguson and Wheeler (3) reported irritation of the skin, eyes, nose, and throat in workers occupationally exposed to capro-lactam dust or vapor at concentrations ranging from 10 to 100 ppm. Methods Male and female inbred Fischer 344 rats and male and female hybrid B6C3F1 mice, obtained from the Frederick Cancer Research Center, were used in this study. Control and treated groups contained 50 animals of each sex and species. For 103 consecutive weeks all groups received Ralston Purina Laboratory Chow. Treated groups were fed this