Penetration of non‐electrolytes through animal integuments

Abstract

Abstract The rates of penetration were studied of three non‐electrolytes (DDT, Famphur, dimethoate) through the integuments of six animals ( Tenebrio molitor , the meal worm adult; Gryllus domesticus , the house cricket; Periplaneta americana , the cockroach; Bufo woodhousei , the garden toad; Anolis carolinensis , the Carolina chameleon; and Phrynsoma cornutum , the Mexican horned toad). The non‐electrolytes were selected with the intention of varying the polarity widely. The olive oil‐water partition coefficients of the above compounds were 199, 19.2 and 0.593. The compounds were applied in 1 μl drops of acetone. In all cases, an initial very brief period of extremely rapid penetration was followed by a long period of much slower penetration. Penetration during the period of rapid penetration was too fast to be resolved by the method used. Penetration during the slower period always followed first order kinetics. During the second slower period, the greater the polarity of a compound, the more rapidly it penetrated into every animal studied but Gryllus domesticus .