The intravenous toxicity of tetra-alkyl lead compounds in rhesus monkeys

Abstract

Intravenous doses of tetraethyl lead (TEL) at 6 mg/kg/day and 0.6–1.2 mg/kg/day, or tetramethyl lead (TML) at 6 mg/kg/day and 1.2–2.4 mg/kg/day, were given to rhesus monkeys. At the end of the dosing period a proportion of monkeys from each group was retained for a recovery period before being killed. TEL at 6 mg/kg killed 3 out of 4 monkeys after 5 days' dosing. These monkeys consistently showed gastrointestinal disturbance, abnormal reflex responses, muscle tremors and decreased brain cholinesterase levels. Monkeys that died during the dosing period showed degeneration of peripheral nerve axons and skeletal muscle fibres. No treatment-related histological changes were found in any monkey given alkyl lead at the lower dosage levels. Muscle and nervous tissue examined at the end of the recovery phase appeared to be histologically normal. The lead was rapidly excreted in the urine, and mean blood lead values at the end of the study were lower than during the dosing period. When dosing stopped, lead levels in most tissues rapidly returned to normal.