Lead poisoning is one of the types of metal poisoning caused by swallowing or breathing in lead. Lead poisoning can hurts the brain and other parts of nervous system. It can cause several mental and physical impairment. Lead enters in our body by inhalation, ingestion and absorption through skin. Exposure may occur over a short period of time (acute poisoning) or over a prolong period (chronic poisoning). Lead has no biological function in the body. It accumulates in the body and affects practically all organ systems. Lead exposure can cause chronic and debilitating health impacts in all age groups, but it is particularly harmful to young children. Lead in children can slow down growth and development of body, reduced cognitive abilities, dyslexia, damage hearing and speech, cause behavior problems. Absorption of large amounts of lead can cause coma, convulsions and even death.

Lead:

Lead is naturally occurring toxic metal found in the earth’s crust.  Lead can be found in all parts of our environment. Lead is a common environmental pollutant.  Much of it comes from human activities such as mining and manufacturing. Lead is used widely in a variety of industries because of its properties:

  • Lead have low boiling point
  • It mixes with other metals easily to form alloys
  • Lead can be easily oxidized
  • Lead is anticorrosive

Lead is used for manufacture of storage batteries, jewelry, toys, painting and potteries, ship building, glass manufacture and several others. The greatest source of environmental lead is gasoline.

Mode of absorption:

There are mainly three ways to enter in our body:-

  • Inhalation of fumes and dust of lead or its compounds.
  • Ingestion of lead by food or drinks.
  • Absorption through skin.

Sign and symptoms:

Lead poisoning can cause variety of signs and symptoms in adults, which depends on the individual and the duration of lead exposure. Symptoms are nonspecific and someone with elevated lead levels may have no symptoms. Symptoms usually develop over weeks to months of exposure. The main symptoms in adults are:

  • Headache
  • Memory loss
  • Reduced sensations
  • Difficulty sleeping
  • Abdominal pain
  • Constipation
  • Poor appetite
  • Anemia
  • Kidney failure
  • Male reproductive problems

Complications in children:

Children are at high risk of lead poisoning. Symptoms may be different in adults and children. The main symptoms in children are:

  • Vomiting
  • Constipation
  • Dyslexia
  • Weight loss
  • Anemia
  • Damage hearing and speech
  • Cause behavior problems
  • Reduce IQ
  • Reduced cognitive abilities
  • Slow down growth and development of body

Causes of lead poisoning:

The body can store 150 to 400mg of lead and blood levels average about 25 μg/100ml. Normal adults ingest about 0.2 to 0.3 mg of lead per day largely from food and beverages. The effects can be detected when blood lead level is > 50 μg/100ml. 90 percent of ingested lead is excreted in the faeces. Lead are absorbed from the gut enters the circulation, and 95 percent enters the red blood cells. It is then transported to liver and kidneys and finally transported to the bones where it is laid down with other minerals. Although bone lead is thought to be ‘metabolically inactive’. It may be released to the soft tissues again under conditions of bone resorption. Lead probably exerts its toxic action by combining with essential SH-groups of certain enzymes.

  • Lead interferes with metabolism of bones and teeth.
  • Lead alters the permeability of blood vessels and collagens synthesis.
  • Lead may be harmful to developing immune system, causing production of excessive inflammatory proteins.
  • Lead interferes with enzymes that maintain the integrity of the cell membrane.
  • Lead interferes with the release of neurotransmitters.
  • Lead also interferes with DNA transcription.

Diagnosis lead poisoning:

Diagnosis of lead poisoning is based on clinical sign and symptoms and medical history of the lead exposure in patient.

Diagnosis of lead poisoning can be done by:

  • Measurement of lead in blood and urine. They provide quantitative indicators of exposure. The effects can be detected when blood lead level is > 50 μg/100ml and lead in urine is over 0.8 mg/liter.
  • Measurement of coproporphyrin in urine (CPU) is useful screening test. It is less than 150 μg/liter.
  • Measurement of amino levulinic acid in urine (ALAU) indicates the absorption of lead. If it exceeds 5mg/liter, it indicates clearly lead absorption.
  • Lead in bones can be measured by X-ray.

Treatment of lead poisoning:

For the proper treatment the patient have to avoid further exposure of lead. Treatment for lead poisoning varies depending on how much lead is present in the blood.

  • Most clinicians will agree with chelation therapy at > 45 μg/100ml. Succimer, calcium disodium edentate, British anti- Lewisite are the chelating agent which chemically binds with lead, making it weaker so the body can get rid of it naturally.
  • Saline purge removes lead from the gut.
  • D- penicillamine promote lead excretion in urine.
  • Calcium, iron and vitamin C decrease the absorption of lead in body. They should be included in diet. 

Preventive measures:

  • Lead compounds should be substituted by less toxic materials
  • Keep your house free from dust
  • Proper ventilation in home
  • Workers should use respirators
  • Wear mask and other protective clothing
  • Use lead-free paint in your house
  • Personal hygiene (Hand washing)
  • Test your water for lead
  • Clean faucets and aerators regularly
  • Periodic medical examination of workers
  • Health education