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Current requirements for the registration of agrochemicals, particularly in the U.S.A., often require the provision of dermal absorption data. In this process the rat is often used and complex in vivo studies, using large numbers of animals, are performed. We have compared the data obtained from in vivo and in vitro dermal absorption studies using eight pesticides with a range of physicochemical properties. Measurements were made of the 14C-labeled pesticides which could be washed from the skin, were associated with (on/in) skin, or absorbed through the skin following dermal applications in vivo and in vitro at various time points over a 24-hr exposure period. Good agreement was found between the amounts washed from and associated with the skin in vivo and in vitro. Over the time period 4-24 hr after application the in vitro experiments predicted the in vivo absorption within a factor of 2-3. These results show that, with a range of pesticide molecules, the in vitro method accurately predicted in vivo absorption supporting the utilization of the in vitro method for risk assessment from exposure to pesticides and other chemicals.

The removal of salicylate by extracorporeal circulation of blood through a column of encapsulated activated charcoal (haemoperfusion) has been studied experimentally in intoxicated dogs (greyhounds). The average time taken to reduce the whole blood salicylate level to one-half of the initial equilibrium level in 30 kg dogs was 2 hrs. A half-life of 3 hrs is predicted for salicylate removal by haemoperfusion in a 70 kg man and this rate of removal is shown to be comparable to that reported for haemodialysis. No unacceptable adverse physiological, biochemical, or haematological effects were found to result from haemoperfusion. The possible use of this technique in the management of severe salicylate poisoning in man is discussed. Haemoperfusion is foreseen as providing a method of rapid removal of salicylate in circumstances where forced diuresis is contra-indicated or inadequate and haemodialysis is not readily available.