Lead and lead compounds are used in a variety of products, including piping (lead water pipes were once a common source of poisoning), weights, professional paints, dyes, ceramics, ammunition, homeopathic remedies, and ethnic cosmetic preparations. Lead compounds are toxic by ingestion, by inhalation and, rarely, by skin exposure. Metallic lead, if ingested, is absorbed if it remains in the gut.
Acute poisoning is rare. Clinical features include metallic taste, abdominal pain, vomiting, diarrhoea, ANOREXIA, fatigue, muscle weakness and SHOCK. Neurological effects may include headache, drowsiness, CONVULSIONS and COMA. Inhalation results in severe respiratory-tract irritation and systemic symptoms as above.
Chronic poisonings cause gastrointestinal disturbances and constipation. Other effects are ANAEMIA, weakness, pallor, anorexia, INSOMNIA, renal HYPERTENSION and mental fatigue. There may rarely be a bluish ‘lead line’ on the gums. Neuromuscular dysfunction may result in motor weakness and paralysis of the extensor muscles of the wrist and ankles. ENCEPHALOPATHY and nephropathy are severe effects. Chronic low-level exposures in children are linked with reduced intelligence and behavioural and learning disorders.
Management of patients who have been poisoned includes removal from source, gastric decontamination if required, and X-RAYS to monitor the passage of ingested metallic lead through the gut. It is essential to ensure adequate hydration and renal function. Concentrations of lead in the blood should be monitored and, where these are found to be toxic, chelation therapy should be started.
Several CHELATING AGENTS are now available, such as DMSA (Meso–2,3-dimercaptosuccinic acid), sodium calcium edetate (see EDTA) and PENICILLAMINE. (See also POISONS.)