BLUE-BABY SYNDROME
"The resistance of chemicals, or lack thereof to alteration by the acidic
pH of the stomach, or
by enzymes of the stomach or intestine, or by the existence of intestinal
flora, is of extreme
importance. A toxicant may be hydrolyzed by stomach acid or biotransformcd
by enzymes of
the microflora of the intestine to new compounds with greatly different toxicity
than the parent
compound."
Examples:
Snake venom is less toxic when administered orally than intravenously.
broken down by digestive enzymes of GI tract
Intestinal bacteria, Aerobacter aerogenes, degrade DDT to DDE.
Ingestion of well water with a high nitrate content has produced methemoglobinemia
much
more frequently in infants than in adults.
higher pH of infant GI tract
greater abundance of Escherchia coli (E. coli)
convert nitrate to nitrite
nitrite produces methemoglobinemia
chemical oxidation of heme irons of hemoglobin (2+ =>
3+)
=> methemoglobin (cannot combine reversibly with O2 and
CO)
decreases oxygen content of blood
anemic hypoxia
pigment is greenish-brown to black in color
blue-baby syndrome
Additionally, low pH of stomach facilitates rxn of nitrites with secondary
amines =>formation
of carcinogenic nitrosamines.
Intestinal flora also reduce aromatic nitro groups to aromatic amines that
may be goitrogenic or
carcinogenic.
Nitrates also associated with:
nervous system impairments
birth defects .pa
Casarett and Doull's TOXICOLOGY: the Basic Science of Poisons (Eds. M.O.
Amdur, J.
Doull and C.D. Klassen) Pergamon Press, NY pp. 1033.
