**3.4.1 Biliary excretion**

Studies show that when radiolabelled aflatoxin B1 was feed to rats, the reported plasma halflife for radioactivity was 91.8 hours. Twenty-three days after dosing, 70% of the radioactivity had been excreted; 55% was present in the faeces compared to 15% in the urine (Coulombe and Sharma, 1985; Herwaarden et al., 2006).

#### **3.4.2 Urinary excretion**

Urinary excretion shows that approximately 15% of radiolabelled aflatoxin B1 was excreted in rats' urine 20-24 hours after ip administration. The major metabolites were the aflatoxin M1 (45% radioactivity) and P1 (<10%), and aflatoxin B1 -N7-guanine (16%). The later is the major degradation product of hepatic B1-DNA adducts (Groopman, 1994).Eighty percent of the excreted B1 -guanine occurred in the urine during the 48-hour period after dosing (Essigmann et al,1982); a dose-dependent correlation between B1 and B1 -guanine has been observed in male rats (Bennett et al., 1981; Baerschi et al., 1989).
