The effect of polychlorobiphenyls (Aroclor 1242) on bicarbonate-C14 uptake by Euglena gracilis

Aroclor 1242 is inhibitory to long-term batch growth of Euglena gracilis at 10 ppm. Exposure to PCB's, subsequent to an initial drop of 50% in the first 30 minutes, does not appear to inhibit photosynthesis on a per cell basis over the time span of four hours. Consequently our experimental findings suggest that inhibition of population growth does not lie directly in the photosynthetic pathway despite the initial inhibition by Aroclor 1242 on Euglena gracilis in "light". "Dark" absorption of bicarbonate appears to decrease with increased PCB exposure. This decrease may be causally related to the population growth inhibition observed.