PHOTODYNAMIC BIOASSAY OF POLYCYCLIC AIR POLLUTANTS.

Fifteen fractions of organic atmospheric particulates from several American cities were bioassayed for photodynamic activity using paramecium caudatum and results obtained were expressed as apparent potencies relative to an arbitrary benoz(a)pyrene standard. All six crude benzene extracts assayed showed photodynamic activity, with a correlation evident between apparent relative potencies as determined by bioassay, and benzo(a)pyrene concentrations as determined by chemical analysis. Five aliphatic fractions were photodynamically inactive. The single aromatic fraction tested had high activity. Three oxygenated fractions showed photodynamic activity, despite the absence from them of benzo(a)pyrene and other polycyclic hydrocarbons of known structure commonly found in atmospheric particulates. Such oxygenated fractions are reportedly carcinogenic. This pilot study suggests that photodynamic bioassay may provide a rapid, simple, and economical biological index of potential carcinogenic hazard attributable to polycyclic hydrocarbons. The utility of the assay for this purpose should be further evaluated. 14 references, 2 figures, 4 tables.