Lead poisoning

lead poisoningLead poisoning (also known as plumbism, saturnism) is a condition caused by lead accumulation in the body.  

Description
Lead is a heavy metal that is considered to be one of the most powerful poisons. Lead intoxication is an exposure to high levels of lead that causes severe health problems. Typically it affects the nervous system and may be even fatal. The Institute for Health Metrics and Evaluation (IHME) suggests that about 9% of the global cases of intellectual disability when a cause is not known may be the consequence of the plumbism.

Causes and sources of lead
Lead can get into the body by breathing in or swallowing lead-containing substances.

Lead may be found in paint especially the one that was used for painting houses in the USA before 1978. Lead is used during production of the food cans; lead pipes, brass plumbing fixtures and copper pipes soldered with lead may release lead into tap water. Lead may contaminate the soil, be found in the toys, cosmetics, pottery, folk remedies and lead bullets. People may be exposed to lead while working in auto repair, mining, battery manufacturing and others

Heavy metal cause the damage to cell structures, interfere with the DNA expression, and synthesis of vitamin D. The cell membranes become fragile especially the membranes of the red blood cells causing anemia. The metabolism of calcium, bones and teeth as well as the function of  the immune system are disturbed.


Risk factors
Children, especially those who are younger than 6 are supposed to be at a greater risk of lead poisoning as long as they tend to put objects into the mouth. Predisposition of children to lead poisoning is associated with the increased absorption of lead in the gastrointestinal tract in comparison with the adults.
The lead-containing paint was used widely during house-building before 1978 in the US. Now a lot of people still live in old houses and may get exposed to lead.

Some occupations are associated with the plumbism such as steel welding, lead mining and manufacture, auto and radiator repair, battery, plastic and glass manufacture, etc.

[See also: Carbon Monoxide Poisoning]


Symptoms
Usually lead poisoning develops over a long period of time – months or years (chronic poisoning), because lead has an accumulative effect. Although sometimes when the dose is very large the symptoms develop rapidly (acute poisoning). A variety of symptoms may occur.

Children experience developmental retardation, irritability, loss of appetite and weight, fatigue, abdominal pain, vomiting, constipation and seizures.

Adults develop insomnia, depression, irritability, headache, memory loss, delirium and even coma. They feel weak and discoordinated, the speech is slurred, they have high blood pressure, joint and muscle pain, headache, abdominal pain, cramps and mood disorders.  Affected persons report to have tremor and tingling of the extremities, sometimes they experience wrist and foot drop, unusual taste, hallucination and may lose their hearing and sight totally or partially. Other symptoms of the disease include anemia, seizures, nausea, diarrhea/constipation, reproductive system disorders (sperm dysfunction in men and pregnancy complication in women), kidney failure may occur.

The skin is pale and/or livid. On the gums bluish lines may be found as well as leukonychia striatum (white stripes on the nails).

It is estimated that commonly the first symptoms of the lead poisoning appear when the blood level of lead reaches the number 40-60 µg/dl, although the level of lead does not correlate with the severity of the symptoms.


Diagnosis
The blood lead level is measured to confirm the diagnosis. According to the CDC the upper limit for blood lead for adults is 10 µg/dl (10 µg/100 g) and for children – 5 µg/dl. X-ray examination of children reveals dense metaphyseal lines in the bones.

Treatment

Plumbism can be treated, although the damage to the nervous system cannot be reversed.

It is obligatory to eliminate the source of the lead and correct the diet of the affected person. Increased intake of food that contains iron and a variety of vitamins helps to reduce the level of lead in the body.

The high level of lead in the blood, severe poisoning and symptoms of encephalopathy are the indications for chelation therapy given by mouth or EDTA (calcium disodium ethylenediaminetetraacetic acid) chelation therapy given by injection. Chelating agents bind lead and reduce the poisoning.
Anticonvulsants may be used to lessen seizures, corticosteroids and mannitol are used to reduce the swelling of the brain.