Acute cadmium toxicity studies upon nine species of aquatic insects.

Continuous-flow bioassays were employed to determine 96.hour median tolerance limits (TLm), for the stonefly. Pteronnrcrllu hadia (Hagen) (TLm was 18.0 mg Cd/l) and the mayfly, Ephemerella grundis grarzdis Eaton (TLm was 28.0 mg Cd/l). Ninety-six hours TLm values for other species of aquatic insects tested were not determined, since these species were relatively insensitive to cadmium. Insects exposed for four days in cadmium-containing water, then placed in tap water, show a linear rate of cadmium loss. This loss may lower or prevent mortality under ideal conditions.