US EPA

1485552 

Journal Article 

The Absorption, Fate and Excretion in Rats of the Water-Soluble Azo Dyes, FD and C Red No. 2, FD and C Red No. 4, and FD and C Yellow No. 6 

Radomski, JL; Mellinger, TJ 

1961 

Yes 

Journal of Pharmacology and Experimental Therapeutics
ISSN: 0022-3565
EISSN: 1521-0103 

NIOSH/00099748 

136 

259-266 

The metabolism of water soluble azo dyes FD-and-C-Red-No-4, FD-and-C-Red-No-4 and FD-and-C-Yellow-No-6 was studied in rats. Dye was administered to the rats orally by stomach tube, 100 milligrams of dye to each rat; by intravenous injection to rats whose bile ducts were cannulated by a polyethylene tube leading from the common bile duct; and by infusion of 350 micrograms of dye over a 4 hour period, into a tube inserted into the spleen. Urine and bile were collected over an 8 hour period. Dye recovery after oral administration was measured by spectrophotometry. 1-Amino-4-naphthalene sulfonic-acid in bile and urine was determined fluorimetrically after chromatography, and ring chromatography was used to identify urinary metabolites. The maximum amount of dye recovered in the feces after a single oral dose was 2.2 percent for FD-and-C-Red-No-4. Administration of neomycin and tetracycline antibiotics to reduce intestinal flora increased the secretion of FD-and-C-Red-No-2 to 8.5 percent. Approximately 100 percent of the dye was recovered in 1 to 2 hours after a single intravenous injection of dye to rats with cannulated bile ducts. When dye was administered by infusion into the spleen, 100 percent of FD-and-C-Red-No-2 was recovered from the urine; 82.3 percent of FD-and-C-Red-No-4 was excreted in the bile and 4.0 percent in the urine; and 73.1 percent of FD-and-C-Yellow-No-6 appeared in the bile and 20.3 percent in the urine. The authors conclude that the bulk of the dye is reduced to aromatic amines and amino-sulfonic-acids by bacteria in the intestinal tract when dye is administered orally and that the source of the reduction products found in the urine and bile is absorption from the intestines after the dye is reduced by intestinal flora. 

DCN-182532; Laboratory animals; Chemical exposure; In vivo study; Metabolites; Urine chemistry; Aromatic amines; Azo dyes; Chemical analysis; Enteric bacteria