PERCUTANEOUS-ABSORPTION OF DIAZINON IN HUMANS

Diazinon is an organophosphorus insecticide which, through general use , comes into contact with human skin. To investigate its percutaneous absorption, human volunteers were exposed for 24 hr to C-14-labelled d iazinon applied in acetone solution (2 mug/cm2) to the forearm or abdo men, or in lanolin wool grease (1.47 mug/cm2) to the abdomen. Complete void urine samples were collected daily for 7 days. Percutaneous abso rption ranged from 2.87 +/- 1.16% (mean +/- SD, n = 6) to 3.85 +/- 2.1 6% of the applied dose, and there were no statistically significant di fferences with regard to site or vehicle of application. In rhesus mon keys, over the 7 days after iv dosing (2.1 muCi [C-14]diazinon, 31.8 m ug) a total of 55.8 +/- 6.8% (n = 4) of the dose was excreted in the u rine, and 22.6 +/- 5.2% was eliminated in the faeces (78.4% total acco untability). In in vitro percutaneous absorption studies with human ab dominal skin, 14.1 +/- 9.2% of the applied dose accumulated in the rec eptor fluid over 24 hr of exposure to 0.25 mug/CM2 (acetone vehicle). The calculated mass absorbed was the same (0.035 mug/cm2) for both in vitro and in vivo absorption through human skin.