Determination of the Distribution of Malathion in Rats Following Various Routes of Administration by Whole-Body Electronic Autoradiography

The distribution of [¹⁴C]-malathion, an organophosphorus pesticide, in rats after intravenous, oral and dermal administration was carried out using electronic autoradiography of whole body sections of treated animals. The study indicated that a major difference in the disposition of [¹⁴C]-malathion occurred following various routes of administration to rats. Following intravenous administration, the liver and kidney accumulated extremely high levels of the chemical. After oral administration, [¹⁴C]-malathion absorption from the stomach was slow and its excretion followed mostly the fecal route. Dermal application of [¹⁴C]-malathion may represent a high risk for exposure to the organophosphorus pesticide where the entire skin, not only the site of application, may act as reservoir for the compound.