Absorption, Distribution & Excretion:
… A single oral dose of 0.025 mCi (0.38 mg) [14C]melamine /was administered/ to adult male Fischer 344 rats. Within the first 24 hr, 90% of the administered dose was excreted in the urine. Negligible radioactivity appeared in breath and feces. There was little difference in blood, liver or plasma concentrations of 14C, suggesting that melamine distributes in body water. The only organs showing radioactivity levels much higher than plasma were the kidney and bladder. The bladder level was by far the highest, a finding probably due either to back diffusion from urine or to contamination of bladder tissue with urine. Virtually no residual radioactivity was observed in tissues examined at 24 hr or later. The elimination-phase half-life calculated from plasma data, 2.7 hr, was in good agreement with the urinary-excretion half-life of 3.0 hr. The renal clearance of melamine was 2.5 mL/min.
[Mast RW et al; Food Chem Toxicol 21 (6): 807-10 (1983) ]**PEER REVIEWED** PubMed Abstract
… Following oral administration of 250 mg/kg melamine to rats, 50% of the mother compound was excreted with the urine within 6 hrs. … Crystals found in the urine were composed of dimelamine monophosphate, amounting to nearly 20% of the administered dose. After feeding melamine to dogs, 60 – 86.5% of the mother compound was recovered in the urine within 24 hrs. …
[European Chemicals Bureau; IUCLID Dataset, Melamine (CAS # 108-78-1) p.79 Available from the Database Query page at: http://ecb.jrc.it/esis/esis.php as of June 26, 2007. ]**PEER REVIEWED**
Doses of 2.4 g/kg cause diuresis & elimination of fine crystals of dimelamine monophosphate in urine.
[Lefaux, R. Practical Toxicology of Plastics. Cleveland: CRC Press Inc., 1968., p. 330]**PEER REVIEWED**
After administration of a single oral dose of 0.38 mg (14)C-melamine to adult male Fischer 344/N rats, 90% of the administered dose was excreted in the urine within the first 24 hours. Negligible radioactivity was detected in exhaled air and feces; and radioactivity was concentrated in the kidney and bladder. Virtually no residual radioactivity was observed in tissue after 24 hours or more. Chromatography of the radioactivity found in plasma or urine indicated that melamine is not metabolized in rats.
[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work)., p. V39 340 (1986)]**PEER REVIEWED**
sources: Hazardous Substances Data Bank