Description

Lead is a highly toxic trace mineral. In recent years human exposure to lead poisoning has changed in origin and probably has increased in magnitude.

The human body can tolerate only 1 to 2 milligrams (about 0.00003 of an ounce) of lead without suffering toxic effects. Two pounds of food contaminated by only 1 part per milligram of lead, so there is not a very wide margin of safety

Absorption and Storage

Lead contained in food is poorly absorbed and is excreted mainly in the feces. Lead may enter the body via the skin and the gastrointestinal tract. The lead that is absorbed enters the blood and is stored in the bones and the soft tissues, including the liver. Up to certain levels of consumption, lead excretion keeps pace with ingestion so that retention is negligible.

Dosage and Toxicity

Critical levels of intake, above which significant lead retention occurs, cannot be quoted with any accuracy.78 Toxic intake can come from consumption of moonshine whiskey and foods stored in lead-glazed earthenware pottery that has been fired at too low a temperature, preventing sufficient fixation of the lead and allowing it to leach out.

Sources of poisoning include drinking water that is soft and acidic and erodes lead from lead piping, food from lead-lined containers, lead-based paint, cosmetics, cigarettes (because of the lead-containing insecticide applied to tobacco), the burning of coal, peeling lead-based paint or plaster and lead-based paint coating pencils often chewed on by children, and motor vehicle exhausts. The accumulation of lead in the body from motor vehicle exhausts is caused directly by inhalation and indirectly through deposition in the soil and plants along highways and in urban areas.

Acute lead toxicity is manifested in abdominal colic, encephalopathy (dysfunction of the brain), myelopathy (any pathological condition of the spinal cord), and anemia. Lead is able to cause abnormal brain function |% competing with and replacing other vital minerals, as zinc, iron, and copper, which regulate mental processes. Acute lead poisoning attacks the central nervous system and is a possible cause of hyperactivity children. Lead poisoning in children may cause

disorders, autism, and epilepsy. A definite relationship has been established between ingested from soft drinking water and mental relation in children. The lead from drinking water water ingested by pregnant women can cross the placenta settle into the brain of the fetus.

Lead intoxication can result from a condition in children called pica, the eating of lead-containing dirt, paper, and paint. Depression is a symptom of chronic lead poisoning, as are headaches, restlessness, irritability, inability to concentrate, impairment of memory, insomnia, hallucination, muscular aches, nausea, and indigestion. Consumption of alcohol allows higher levels of lead to settle in soft tissues, including the brain.

The usual treatment for lead poisoning during acute stages consists of a diet high in calcium plus injections of a calcium chloride solution and administration of vitamin D. Sufficient calcium prevents the accumulation of lead in the body by reducing its absorption from the intestinal tract. Too little calcium in the body results in higher levels of lead in the blood, bone, and soft tissues.

Vitamin C at doses up to 6 grams per day can help lead excretion. The amino acids cysteine and methio-nine and supplementation of all essential minerals also help.

An effective way that may prevent lead poisoning is to include a small amount of algin in the daily diet. Algin is a nonnutritive substance found in Pacific kelp, which is sometimes used as a thickening agent in the preparation of various foods. It attaches itself to any lead that is present and carries it harmlessly out of the system.