Metabolic fate of the precursors of N-nitroso compounds. II. Salivary secretion and urinary excretion of nitrosatable compounds in man.

Abstract

Levels of nitrosatable compounds in saliva and urine were determined. The mean value, which was calculated as equivalent to dimethylamine (DMA) in 25 human saliva samples cellected from 11 subjects was 0.3±0.2ppm. When a subject ingested the foods containing low levels of volatile nitrosatable compounds the concentration of nitrosatable compounds in saliva was less than 0.2ppm over the day, but increased to 1.0ppm 1hr after the ingestion of 100mg of DMA·HCl with 100ml of water. DMA remaining in the oral cavity after the ingestion of DMA·HCl disappeared within 20min. No changc in the concentration of nitrosatable compounds was observed when the saliva collected 1hr after the ingestien of DMA·HCl was incubated a t 37°C for 2hr. DMA was identified as the main nitrosatable compound in saliva, which was cellected after the ingestion of DMA·HCl, by thin-layer chromategraphy and gas liquid chromatography. The pattern of the time course of urinary excretion of nitrosatable compounds after the ingestion of DMA·HCl was almost similar to that of the salivaly secretion. About 95% of DMA ingested was presumcd to be excreted as nitresatable compounds into 24-hr urine.The mean value of the amounts of nitrosatable compounds excreted in the 24hr urine collected from 9 subjects was 21.1±9.3mg and that of volatile nitrosatable compounds contained in the foods and beverages ingested for the experimental period was 10.4±6.9mg.