[Experimental substantiation of MPEL of dibenz(a,n)anthracene in atmospheric air].

Overt dependence of lung tumour development on the values of the dose administered was shown in experiments on inbred white rats under intratracheal administration of various doses of dibenz (a, h) anthracene (DBA); minimal-effect dose and maximal no-effect dose of DBA were established in the experiment. A theoretically calculated allowable dose was used to calculate MAC of the chemical under study for the ambient air 5 ng/m3 was recommended as an average 24-hour maximum allowable concentration of DBA in ambient air.