Lung Tumours in Mice. Incidence as affected by Inhalation of Certain Carcinogenic Agents and Some Dusts

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Abstract
Six dusts, or mixtures of dusts, suspected of causing human lung tumors were each tested on a group of 150 mice (75 dusted, 75 controls). The dusts were: (1) Precipitated silica containing methylcholanthrene; (2) Steel grindings; (3) A mixt. of equal parts of alumina, precipitated silica and brown oxid of Fe; (4) Radio-active dust from Czechoslovakia; (5) A mixture containing the same 3 substances as 3 plus CaCO3; (6) Tarred road dust. For (1) the dusting nearly doubled the incidence of primary lung tumors. Steel dust (2) caused tumors in 13.6% vs. 7.7 in the controls. Alumina is thought to have an inhibitory effect on the development of lung tumors in silicosis. The dusting with mixture (3) produced only a slight increase of lung tumors. There was a definite increase of tumors caused by Czechoslovak dust (cf. Campbell, 1940, Brit. Med. Jour. 2: 275). Of the dusted mice 20.3% had lung tumors vs. 2.1% among controls. Dust (5) caused tumors in 19.4% vs. none among controls. Tarred road dust (6) produced a nine-fold increase, 13.1% vs. 1.4% in controls. 20 references.