Lung tumor incidence after intrabronchial administration of the nonionic contrast agent metrizamide.
OBJECTIVE
Metrizamide has been used for examination of the gastrointestinal tract and tracheobronchial tree of infants. Contrast agents may enter the lungs during such examinations. The current study was undertaken to determine whether there would be any later pulmonary effects when metrizamide was administered to the lungs of weanling mice.


METHODS
One hundred fifty mice (18-21 days old), divided into groups, received either 75 microL of metrizamide, using the manufacturer's diluent (190 mg iodine [I]/mL), or saline solution administered to the lungs by injection into the trachea. The mice were observed for the duration of their lives. Moribund animals were killed. At death, all animals underwent necropsy. The lungs were fixed in formalin, and histologic sections were examined for pathologic changes.


RESULTS
The incidence of lung tumors was increased (P less than .05) in the lungs of mice receiving metrizamide compared with those receiving saline. Eighteen percent of the lung tumors in the metrizamide-treated mice were lymphomas, a histologic type not found in the saline-treated controls.


CONCLUSIONS
A hypothesis proposing that metrizamide may be an initiator of carcinogenic transformation rather than a carcinogen was developed.
Baker
D G
DG
Department of Radiology, University of Virginia Health Sciences Center, Charlottesville 22908.
Alford
B A
BA
Feldman
P S
PS
D000230:Adenocarcinoma / Q000139:chemically induced* / Q000453:epidemiology; D000818:Animals; D001980:Bronchi; D005260:Female; D008175:Lung Neoplasms / Q000139:chemically induced* / Q000453:epidemiology; D008223:Lymphoma / Q000139:chemically induced* / Q000453:epidemiology; D008793:Metrizamide / Q000008:administration & dosage / Q000633:toxicity*; D051379:Mice; D008813:Mice, Inbred ICR
D008793:Metrizamide