VPT 421: Veterinary Toxicology (2+0)

ABSORPTION AND FATE

• Lead almost always enters the body through mouth.
• Only a small portion of lead is absorbed and over 98% is excreted in faeces.
• After absorption, lead binds to haemoglobin in the RBCs and serum albumin. Only 1% of absorbed lead is in free form.
• It is in dynamic equilibrium with lead bound to erythrocytes and serum albumin.
• Absorbed lead is stored mainly in the bones after redistribution and its subsequent mobilization is similar to that of calcium.
• About 95% of the body burden of lead is found in the bone. This trapping of lead in bones is called as 'bone sink for lead'.
• Bone sink is an important detoxification mechanism in chronic exposure to lead in small amounts. Although in long bones highest content of lead is noticed, after recent exposure, it is also found in the flat bones.
• Deposition of lead in the bones and its subsequent mobilization form the bones is similar to calcium.Lead is excreted in faeces, urine and milk.
• Lead crosses both the blood brain barrier and the placental barrier.