Fig. 3. Pimephales promelas 24 h LC50 values (grey bars) and LT50 values (black bars) for 100% cell-free filtrate of P. parvum cultures exposed to natural sunlight for 0.5, 1 or 2 h. Toxicity was not observed in 2 h treatment (LC50 .100%, LT50 . 24 h).