Toxicity and retention of DDT in adult frogs, Rana temporaria L.

Abstract

The acute LD₅₀ value of DDT in adult summer frogs was only 7·6 mg/kg.The symptoms of poisoning caused by DDT point to nervous damage. The toxicity was further increased by starving. The retention of DDT was followed using (¹⁴C)-labelled DDT. It accumulated most in tissues containing fat. Thus the fat body and liver retained much of the DDT while only a very small amount was found in skeletal or heart muscle. In female frogs a large quantity of DDT is stored in the ovary, its large size and high fat content possibly accounting for this phenomenon. Moderate amounts of DDT were found in kidneys and nervous tissue. In addition, an autoradiographical study revealed considerable radioactivity in bones and spleen.

Starved animals retained higher amounts of DDT in their tissues, with the exception of the fat body, than did the fed animals. DDT was found to disappear extremely slowly. Its disappearance was, however, enhanced by previous DDT treatment since DDT-treated animals retained much less of the test dose than did the untreated controls. It is thus possible that DDT induces the activity of drug-metabolising enzymes which may lead to increased biliary excretion of the drug.